Term
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Definition
| Released by glands or specialized cells into circulating blood and influence the function of cells at another location in the body. They migrate a great distance to the target organ. |
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Term
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Definition
| Secreted by cells into extracellular fluid and affect neighboring cells of a different type |
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Term
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Definition
| Secreted by cells into the extracellular fluid and affect the function of the same cells that produced them by binding to cell surface receptors |
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Term
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Definition
Secreted by neurons into circulating blood and influence cell function at another location in the body.
Located in hypothalamus
Have axons that terminate in posterior pituitary gland and median eminence and secrete several neurohormones: ADH, oxytocin, hypophysiotropic hormones |
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Term
Example of hormones with generalized
action |
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Definition
Growth hormone (from anterior pituitary)
Thyroxine (from thyroid) - increases rate of many chemical reactions in almost all of the body's cells |
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Term
| Example of hormones with specific actions |
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Definition
ACTH (from anterior pituitary) - stimulates adrenal cortex
Ovarian hormones
ADH - active at specific part of kidney |
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Term
| Example of hormones with specific actions |
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Definition
ACTH (from anterior pituitary) - stimulates adrenal cortex
Ovarian hormones
ADH - active at specific part of kidney |
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Term
| Examples of protein or polypeptide hormones |
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Definition
| TRH, CRH, GHRH, GHIH, GnRH, Growth hormone, TSH, ACTH, FSH, LH, Prolactin, ADH, Oxytocin, Calcitonin, Glucagon, Insulin, Parathyroid hormone, HCG, Human somatomammotropin, Erythropoietin, ANP, Gastrin, Secretin, Cholecystokinin (CCK), Pancreazymin (PZ), Leptin |
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Term
| Examples of steroid hormones |
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Definition
| Cortisol, Aldosterone, Testosterone, Estrogens, Progestins, 1,25-Dihydroxycholecalciferol |
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Term
| Examples of amino acid tyrosine derivatives |
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Definition
| Dopamine, Prolactin inhibiting facto (PIF), Thyroxine (T4), Triiodothyronine (T3), Epinephrine, Norepinephrine, Erythropoietin |
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Term
| Characteristics of steroid hormone synthesis |
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Definition
Usually synthesized from cholesterol
Synthesized in cytoplasmic vacuoles |
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Term
| Characteristics of steroid hormone storage |
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Definition
Very little storage in steroid-producing endocrine cells
Although, large stores of cholesterol esters in cytoplasm vacuoles can be rapidly mobilized for steroid synthesis after stimulus |
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Term
| Characteristics of steroid hormone regulation of release |
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Definition
Following synthesis, vesicular release is NOT NEEDED because they are lipid soluble
Steroids can diffuse across teh cell membrane and enter the interstitial fluid, then the blood
Regulation of the steroid hormone is regulation of synthesis |
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Term
| Characteristics of hormones in the blood when bound to plasma proteins |
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Definition
| Binding of hormones to plasma proteins greatly SLOWS their clearance from the plasma |
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Term
| Hormones that are transported bound to proteins |
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Definition
Steroid and thyroid hormones (<10% free in solution)
Inactive until they dissociate from plasma proteins
Serve as reservoirs, replenishing the concentration of free hormones when they are bound to target receptors or lost from the circulation |
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Term
| Mechanism by which hormones are cleared from the plasma |
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Definition
Metabolic destruction by the tissues
Binding with the tissues
Metabolized and excreted by the liver into the bile
Excreted by the kidneys into the urine |
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Term
| Location of receptors for different hormones |
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Definition
Protein, peptide and catecholamine hormones are located on the cell membrane
Steroid hormones (these easily penetrate the cell membrane) are located on cytoplasm receptors
T3 and T4 located on teh cell's nucleus |
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Term
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Definition
Associated with a number of hormone receptors
The alpha subunit is most associated with activating second messengers
There are both inhibitory and stimulatory G proteins |
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Term
| Activation and actions of adenylate cyclase-cAMP second messenger system |
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Definition
Adenylate cyclase catalyzes the formation of cAMP, which has a multitude of effects inside the cell to control cell activity.
cAMP - called a second messenger because it is not the hormone itself that directly institutes the changes |
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Term
| Other hormones that use adenylate cyclase as a 2nd messenger |
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Definition
| ACTH, FSH, glucagon, HCG, LH, PTH, secretin, somatostatin, TSH, vasopressin |
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Term
| Anterior pituitary hormones |
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Definition
Play major roles in control of metabolic functions
Growth hormone, Adrenocorticotropic hormone, Thyroid stimulating hormone, prolactin, FSH, LH |
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Term
| Control of the release of anterior pituitary hormones |
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Definition
by hypothalamic releasing and hypothalamic inhibitory hormones.
Secreted within the hypothalamus itself, and are conducted to anterior pituitary through minute blood vessels called hypothalamic-hypophysial portal vessels. |
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Term
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Definition
In anterior pituitary.
Secrete growth hormone
*30-40% |
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Term
|
Definition
In anterior pituitary
Secrete adrenocorticotropic hormone
*20% |
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Term
|
Definition
In anterior pituitary gland
Secrete TSH
*3-5% |
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Term
|
Definition
In anterior pituitary gland
Secrete prolactin
*3-5% |
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Term
|
Definition
In anterior pituitary gland
Secrete FSH and LH
*3-5% |
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Term
| Metabolic functions of growth hormone w/ fat |
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Definition
Uses up fat stores
Increases mobilization of fatty acids from adipose tissue
Increases free fatty acids in teh blood
Increases use of fatty acids for energy |
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Term
| Metabolic functions of growth hormone w/ protein |
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Definition
Increases rate of protein synthesis in most cells of the body
Increases uptake of amino acids through cell membranes
Increases DNA transcription (more mRNA)
Increases RNA translation
Decreases catabolism of protein and amino acids
Basically greatly increase the amount of proteins available for activities within the cell |
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Term
| Action of growth hormone on cartilage and bone growth |
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Definition
Increases deposition of protein by chondrocytic and osteogenic cells that cause bone growth
Increased rate of production of these cells
Converts chondrocytes into osteogenic cells, thus causing deposition of new bone |
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Term
| Growth hormone stimulating long bones |
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Definition
Stimulates growth in length at epiphyseal cartilages
Deposition of new cartilage, followed by conversion to new bone, which elongates diaphysis
Does NOT stimulate bone elongation after epiphyseal closure
Amount of growth is dependent on epiphyseal plates |
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Term
| Growth hormone stimulating osteoblasts |
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Definition
Osteoblasts in bone periosteum and some bone cavities deposit new bone on surfaces of older bone
Bones (especially membranous) become thicker throughout life under influence of GH
(forward protrusion of forehead and chin) |
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Term
| Characteristics of somatomedins |
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Definition
Somatomedins are insulin like growth factors
Formed in the liver
Many effects on growth similar to effects of insulin (also called insulin like growth factors)
4 somatomedins have been isolated. Most important one is Somatomedin C (also called IGF-I) |
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Term
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Definition
People of short stature can't synthesize
Strongly attached to a carrier protein and released slowly and has a half time of about 20 hours (GH has half time in blood of less than 20 minutes)
Prolongs the growth-promoting effects of the bursts of growth hormone secretion |
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Term
Control of the release and actions of ADH
with increased blood volume |
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Definition
Increased low pressure baroreceptors -> decrease ADH release
decrease osmoreceptors -> decrease ADH release |
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Term
| Physiological functions of ADH |
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Definition
Increases permeability of collecting ducts and tubules to water
Increased water reabsorbed conserving water in the body and producing very concentrated urine
Combines with membrane receptors that activate adenylate cyclase and cause the formation of cAMP inside tubular cell cytoplasm
This causes phosphorylation of elements in aquaporins highly water-permeable pores |
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Term
Control of the release and actions of ADH
with decreased blood volume |
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Definition
Decreased low pressure baroreceptors -> increase ADH release
Increased osmoreceptors -> increase ADH release |
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Term
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Definition
| Released from posterior pituitary then carried by the blood to the breasts |
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Term
| Physiological effects of oxytocin |
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Definition
Stimulates contraction of pregnant uterus (especially towards end of gestation, when release can trigger delivery)
Causes milk to be expressed from alveoli into ducts of breast |
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Term
| Uterine contractions and oxytocin |
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Definition
| Mediated by G protein. This activate ITP synthesis by phospholipase C. Also causes the release of Ca2+ and activation of calmodulin |
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Term
| Milk expression and oxytocin |
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Definition
oxytocin causes contraction of myoepithelial cells in latticework surrounding alveoli of mammary glands
Suckling stimulus causes sensory signals to be transmitted to hypothalamus
Sensory nerves go tot the oxytocin neurons in the paraventricular and supraoptic nuclei in the hypothalamus
Stress and pain can reduce oxytocin release |
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Term
| Where are androgens formed in the male |
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Definition
| Interstitial cells of Leydig in intertices between seminiferous tubules (constitute about 20% of the mass of the adult testes) |
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Term
| Action of testosterone in males - puberty |
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Definition
Development of adult primary and secondary sex characteristics
-enlargement of penis, scrotum, testes; growth of hair
-hypertrophy of laryngeal mucosa and larynx
-increase thickness of skin over body and increase ruggedness of subcutaneous tissue
-increases rate of secretion of body's sebaceous glands
-increase muscle mass
-increase bone matrix which causes additional calcium retention
-narrows pelvic outlet
-increases basic matabolic rate
-increase the # of rbcs
-increase reabsorption of Na in distal tubules of kidneys, but small in comparison to aldosterone |
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Term
| How testosterone acts at the cellular level |
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Definition
Increases rate of protein formation in target cells.
Often converted by 5 alpha-reductase to dihydrotestosterone, which binds with the receptor protein
The complex then migrates to the cell nucleus where it binds with nuclear protein and induces DNA-RNA transcription, which leads to progressive increase in cellular protein |
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Term
| Which hormones are involved in secretion of testosterone |
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Definition
Release begins with secretion of gonadotropin-releasing hormone by hypothalamus
This stimulates anterior pituitary gland to secrete 2 hormones: LH (stimulus for secretion of testosterone by testes)
FSH - stimulates spermatogenesis
Exert their effects on their target tissues in testes mainly by activating cAMP 2nd messenger |
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Term
| Secondary sex characteristics of testosterone |
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Definition
Growth of body hair, including underarm, abdominal, chest, and pubic hair. Loss of scalp hair androgenic alopecia can also occur Greater mass of thigh muscles in front of the femur, rather than behind it as is typical in mature females
Growth of facial hair
Enlargement of larynx and deepening of voice
Increased stature; adult males are taller than adult females, on average
Heavier skull and bone structure Increased muscle mass and strength
Broadening of shoulders and chest; shoulders wider than hips
Increased secretions of oil and sweat glands, often causing acne and body odor
Coarsening or rigidity of skin texture, due to less subcutaneous fat
A prominent Adam's apple
Higher waist to hip ratio than prepubescent or adult females or prepubescent males, on average |
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Term
Actions of Gonadotropin-releasing hormone
(GnRH) |
|
Definition
also known as LH-releasing hormone
stimulates the release of LH and FSH
Secreted intermittently a few minutes at a time once every 1-3 hours.
Total amount released is determined by frequency of these cycles of secretion and quantity of GnRH released with each cycle |
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Term
| Changes in levels of FSH and LH during first few days of each monthly female sexual cycle |
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Definition
Slight increase in FSH and LH secretion during the first few days of each cycle
increase in FSH is greater than LH and precedes it by a few days
Just before ovulation (around day 14 of cycle both LH and FSH jump, but LH much more than FSH...then a progressive decline until the start of the cycle again |
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Term
| Reason that a single follicle develops to maturation |
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Definition
FSH causes accelerated growth of 6-12 primary follicles each month
Follicles in turn can secrete er and pr
Er is secreted by the most mature follicle and causes increased numbers of FSH receptors on this follicle
Which makes the most mature follicular cell more sensitive to FSH
Increased estrogen prevents further release of FSH so less developed follicles involute
Only the largest follicle continues to grow and eventually ovulate because increased density of FSH receptors allows continued stimulation even with low amounts of FSH |
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Term
| Ovulation is produces by a surge or which hormone |
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Definition
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Term
| Follicular rupture and ovulation is most associated with what change in what hormone levels? |
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Definition
increased progesterone
(causes swelling of follicle and weakening of follicular cell wall) |
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Term
| Importance of corpus luteum |
|
Definition
it forms after ovulation
Causes sudden cessation of secretion of er, pr and inhibin -
which removes teh feedback inhibition of the anterior pituitary so the anterior pituitary begins secreting increasing amounts of FSH and LH again - FSH and LH initiate growth of new follicles and a new cycle begins
Decreased secretion of er and pr leads to menstruation |
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Term
| Where and what synthesizes er and pr |
|
Definition
mainly from cholesterol in the ovaries
(cholesterol derived from blood, but also to a slight extent from acetyl CoA) |
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Term
|
Definition
responsible for development of secondary sex characteristics
proliferation and growth of tissues and sex organs and reproductive tissues
increases size of internal and external genitalia
increases activity of cells that line the fallopian tubes
induce breast development
inhibit osteoclastic activity in bones and stimulate bone growth
slight increases in total body protein
increase in total whole-body metabolic rate
deposition of increased quantities of fat in subQ, butt and thighs
causes soft and smooth skin
can cause some Na and H2O retention by kidney tubules |
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Term
| Endometrial changes produced by er and pr |
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Definition
3 phases - proliferation of uterine endometrium (er phase)
development of secretory changes in endometrium (pr phase)
desquamation of endometrium (menstruation)(decrease in er and pr)
*see notes perhaps |
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Term
| Menstruation produced by what change in what hormone? |
|
Definition
If ovum is not fertilized, corpus luteum involutes and er and pr decrease to low levels of secretion
Menstruation caused by reduction of er and pr, especially pr
(also - progesterone decreases uterine contractions) |
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Term
| Mechanisms of control of synthesis and secretion of the thyroid hormones |
|
Definition
First must be cleaved from the thyroglobulin molecule and free hormones are released
Mechanism - colloid filled pinocytic vesicles enter apex of the thyroid cell
Colloid contains thyroglobulin with attached T3 and T4
Proteases from lysosomes digest the thyroglobulin molecules and release T4 and T3 in free form
These then diffuse through the base of the thyroid cell into the surrounding capillaries
3/4 of the iodinated tyrosine in the thyroglobulin remains monoiodotyrosine and diodotyrosine
Iodinated tyrosines are metabolized by deiodinase enzyme and are recylced |
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|
Term
Cellular action of thyroid hormones
(probably not really what he was meaning...learn the other cellular action slide) |
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Definition
Most T4 is converted to T3
T3 then translocates into the nucleus
Intracellular thyroid hormone receptors have a very high affinity for T3 with >90% of receptor bound thyroid hormone molecule is T3
Activates nuclear transcription of large numbers of genes
receptors are either attached to DNA genetic strands or located in proximity to them
Receptors usually form a heterodimer with retinoid X receptor at specific thyroid hormone response elements on the DNA
Activated receptors initiate transcription process
Proteins increased. Actions of thyroid hormone result from subsequent enzymatic and other functions of these new proteins |
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Term
| Physiologic action of thyroid hormones |
|
Definition
Increase cellular metabolic activity
Up to 60-100% increased BMR above normal
Increased rate of protein synthesis
Effects a wide range of physiological systems |
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Term
| Increased cellular metabolic activity from thyroid hormones |
|
Definition
Increased mitochondrial size, number, density, and metabolic activity
Increased rate of formation of ATP
Increased Na/K/ATPase activity and increased membrane transport
Increased metabolic heat production
Stimulation of carbohydrate metabolism (increased uptake of glucose, glycolysis, gluconeogenesis, insulin secretion)
Stimulation of fat metabolism |
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Term
| More physiologic action of thyroid hormones |
|
Definition
Increased vasodilation in most body tissues - increases blood flow
Cardiac output increased up to 60% above normal when excessive thyroid hormone is present and decreased to 50% of normal in severe hypothyroidism
Increased the rapidity of cerebration, nerve conduction velocity and synaptic activity and reflex speed
Nervousness and psychoneurotic conditions such as anxiety and paranoia with hyperthyroidism
Muscle tremor
Decreased periods of sleep in hyper
Constant tiredness with hypo |
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Term
| Actions of thyroid hormone on endocrine glands |
|
Definition
Increases - insulin secretion by pancreas, need for parathyroid hormone,
ACTH release from pituitary, adrenal glucocorticoids secretion by adrenal glands |
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Term
| How does thyroid stimulating hormone from the anterior pituitary gland increase thyroid secretion? |
|
Definition
Increased proteolysis of the thyroglobulin that has already been stored in the follicles
Release of thyroid hormones into the circulating blood and decreased amount of follicular substance
Increased activity of iodide pump and I-trapping in glandular cells
Increases the ratio of intracellular to extracellular concentration in the glandular substance to as much as 8x normal
Increases iodination of tyrosine to form thyroid hormones
Increases size and secretory activity of thyroid cells
Increases # of thyroid cells plus a change from cuboidal to columnar cells and much infolding of the thyroid epithelium into the follicles |
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Term
| TSH effects on thyroid hormone release |
|
Definition
Cyclic adenosine monophosphate mediates the stimulatory effect
TSH binds with specific TSH receptors on the basal membrane
Binding of receptors activates adenylate cyclase in the membrane, which increases the formation of cAMP
cAMP acts as a second messenger to activate protein kinase, which causes multiple phosphorylations throughout the cell
Secretion of TSH is regulated by thyrotropin releasing hormone
(cold is one of the best known stimuli for increasing rate of TRH release and TSH secretion)
(various emotional reactions can decrease TSH and therefore decrease secretion of thyroid hormones) |
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Term
| Which tissues form a large reservoir for Ca++ |
|
Definition
.1% of total body Ca++ is in extracellular fluid
1% is in the cells
98.9% is stored in bones |
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Term
|
Definition
Depresses nervous system and muscle activity (reflex activities of CNS are sluggish)
Decreases the QT interval of the heart
Lack of appetite and constipation, secondary to decreased contractility of gi smooth muscle
Effects appear when blood level of Ca++ increases above 12mg/dL and are marked when Ca++ levels rise about 15mg/dL |
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Term
| Actions of parathyroid hormone |
|
Definition
Controls extracellular Ca++ and Pi concentrations by regulating intestinal reabsorption, renal excretion, exchange between the extracellular fluid and bone of these ions
Excess activity of parathyroid gland causes rapid absorption of Ca++ salts from bones, with resultant hypercalcemia in extracellular fluid
Hypofunction of paraythyorid glands causes hypocalcemia, with resultant tetany |
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Term
| PTH on calcium and Pi concentration |
|
Definition
[Ca+ ] increases reaching plateau in about 4 hours following PTH infusion
[Pi] maximal decreases within 1 or 2 hours |
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Term
| PTH effects on bone, kidneys and intestines |
|
Definition
Increases Ca++ and Pi absorption from bone
Increases excretion Pi that is greater than increase absorption of Pi from bone
Increases Ca++ and Pi absorption from teh intestines
Decreases excretion of Ca++ by the kidneys |
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Term
| Mechanisms of cellular effect of parathyroid hormone |
|
Definition
| Not 100% sure what he wants us to know for this. May need to review a few of the parathyroid slides (like 35-45 ish or something?) |
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Term
| Mechanism of action calcitonin |
|
Definition
Calcitonin has effects opposite to those of PTH; tends to decrease plasma [Ca++] (major stimulus is increased [Ca+])
Decreasing absorptive activities of osteoclasts shifts balance in favore of deposition of Ca++ into bone
Decreases formation of new osteoclasts
Initial reduction of [Ca++] leads within hours to a powerful stimulation of PTH secretion, which almost overrides calcitonin effect
(maybe read the summary slides of parathyroid lecture - 51-55) |
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Term
| Synthesis and secretion of calcitonin |
|
Definition
Polypeptide (32 amino acids) hormone secreted by the thyroid gland
Occurs in parafollicular cells (C cells) lying in between the follicles of the thyroid gland
Constitute only about .1% of the human thyroid gland |
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Term
| Classes of adrenal hormones |
|
Definition
Medulla secretes epinephrine and norepinephrine
Cortex secretes corticosteroids (all synthesized from the steroid cholesterol)
2 Major types of adrenocortical hormones: Mineralcorticoids and Glucocorticoids
Small amounts of androgenic hormones which exhibit same effects in the body as male sex hormone testosterone |
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Term
|
Definition
Affect the electrolytes of the extracellular fluids - Na+ and K+ in particular
Aldosterone is principle mineralcorticoid |
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Term
|
Definition
Exhibit important effects that increase blood glucose concentration
Additional effects on both protein and fat metabolism that are equally as important to body function as their effects on carbohydrate metabolism
(cortisol is principle glucocorticoid) |
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Term
|
Definition
15% of adrenal cortex
Cells just underneath capsule
Only ones in adrenal gland capable of secreting significant amounts of aldosterone because they contain the enzyme aldosterone snythase
Secretion of these cells is controlled mainly by the extracellular fluid concentrations of angiotension II and K+ |
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Term
|
Definition
Middle and widest layer - 75% of adrenal cortex
Secretes primarily the glucocorticoids cortisol and corticosterone
Secretes small amounts of adrenal androgens and estrogens
Secretion controlled in large part by the hypothalamic-pituitary-adrenal axis via ACTH |
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Term
|
Definition
Deepest layer of cortex
Secretes adrenal androgens dehdydroepiandrosterone (DHEA) and androstenedione, as well as small amounts of estrogens and some glucocorticoids
ACTH also regulates secretion of these cells |
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Term
| Adrenocortical hormones are steroids derived from... |
|
Definition
cholesterol
80% of cholesterol used for steroid synthesis is provided by LDL in circulating plasma
LDLs diffuse from plasma into interstitial fluid and attach to specific receptors contained in structures called coated pits on adrenocortical cell membranes |
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Term
| Steroid synthesis from LDL |
|
Definition
Coated pits are then internalized by endocytosis, forming vesicles that eventually fuse with cell lysososmes and release cholesterol that can be used to synthesize adrenal steroid hormones
Transport of cholesterol into the adrenal cells is regulated by feedback mechanisms that can markedly alter the amount available for steroid synthesis |
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Term
| ACTH stimulates adrenal steroid synthesis by... |
|
Definition
Increases number of adrenocortical cell receptors for LDL
Increases activity of enzymes that liberate cholesterol from LDL |
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|
Term
| Control of adrenal steroid synthesis |
|
Definition
ACTH - increases conversion of cholesterol to pregnenolone and stimulates cortisol secretion
Angiotensin II increases converstion of cholesterol to pregnenolone and stimulates aldosterone secretion |
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Term
|
Definition
Very potent and accounts for 90% of all mineralcorticoid activity
Half life of 15 minutes |
|
|
Term
|
Definition
very potent and accounts for about 95% of all glucocorticoid activity
Half life of 60-90 minutes |
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|
Term
| Adrenal hormone transport |
|
Definition
|
|
Term
| Adrenal hormone metabolism |
|
Definition
Metabolized in the liver
Conjugated especially to the inactive glucuronic acid and to a lesser extent, sulfates
25% of conjugates are excreted in the bile and feces
75% of conjugates enter the circulation and filtered readily by the kidneys and excreted in the urine
Liver and kidney diseases decreases elimination |
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Term
|
Definition
Increases reabsorption of Na+ and increases secretion of K+ by renal tubules
Extrawcellular fluid volume increases due to increased h2O readsorption
Increases readsorption of NaCl and secretion of K+ by the excretory ducts in sweat glands and salivary glands (helps conserve salt in hot environments)
Increases Na+ absorption by intestines, which prevents loss of Na+ in the stools |
|
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Term
| Cellular mechanism of aldosterone action |
|
Definition
Aldosterone diffuses readily to interior of tubular epithelial cells
Combines w/ a highly specific cytoplasmic receptor protein - specific to aldosterone alone
Aldosterone-receptor complex diffuses into the nucleus, and induces DNA transcription to form mRNA
mRNA is read by ribosomes to form Na+-K+ ATPase active transport system, and H+ transport linked to Na+-K+ ATPase activity |
|
|
Term
| Cellular sequence of events that increase Na+ reabsorption |
|
Definition
Effect not immediate on Na+ transport but must await completion of protein synthetic pathway
About 30 min is required before new RNA appears in teh cells
About 45 min is required before the rate of Na+ transport begins to increase
Effect reaches maximum only after several hours |
|
|
Term
| Regulation of aldosterone secretion... |
|
Definition
...by zona glomerulosa cells is almost entirely independent of other corticosteroids
4 factors that regulate release
1 - increased [K+] extracellular fluid increases aldosterone secretion
2 - increased levels of angiotensin II increases aldosterone secretion
3 - increased [Na+] extracellular fluid decreases aldosterone secretion via renin-angiotensin system
4 - ACTH is necessary for aldosterone synthesis (although has little effect in controlling rate of secretion) |
|
|
Term
| Effects of cortisol on carbohydrate metabolism |
|
Definition
Increases gluconeogenesis (more amino acids available - release by protein metabolism in variety of tissues) and increases enzymes of gluconeogenesis pathways
Increases glycogen storage in liver
Decreases rate of glucose utilization by most cells (less oxidized form of NAD so less glycolysis)
Increases blood glucose concentration (if increase greater than 50% above normal - adrenal diabetes)
Increases insulin secretion |
|
|
Term
| Effects of cortisol on protein metabolism |
|
Definition
Decreases the protein stores in most extrahepatic cells
Decreases protein synthesis
Increases catabolism of protein already in the cells
Decreases amino acid transport
Decreases formation of RNA and subsequent protein synthesis, especially in muscle and lymphoid tissue
Increases blood amino acids
Increases liver and plasma proteins
Increases liver utilization of amino acids (increases: rate of liver deamination of aa, protein snythesis in liver, formation of plasma proteins by the liver, and rate of gluconeogenesis) |
|
|
Term
| Effect of cortisol on lipid metabolism |
|
Definition
Increases mobilization of free fatty acids (FFA) from adipose tissue
Increases [FFA] in plasma
Increases FFA utilization for energy compared to glucose
(exces cortisol secretion leads to odd patterns of adipose distribution - moon face, buffalo-like torso) |
|
|
Term
| Value of glucocorticoids in stress |
|
Definition
Released w/ varite of stressors
Rapid mobilization of amino acids and fats from their cellular stores (increases availability for protein synthesis and gluconeogenesis)
Increases utilization of energy rich fatty acids
Prob more related to suppression of immune response and inflammation rather than metabolic changes |
|
|
Term
| Anti-inflammatory effects of glucocorticoids |
|
Definition
Prevent early stages of the inflammateion process before inflammation even begins
Causes rapid resolution of the inflammation and increases rapidity of healing
Stabilizes mast cell and lysosomal membranes preventing the release of vasodilators, chemotaxic agents and proteolytic enzymes
Decreases permeability of the capillaries
Decreases both migration of white blood cells into the inflamed area and phagocytosis of the damaged cells
Suppress immune system
(could read more on this) |
|
|
Term
| Rate of healing enhanced by action of glucocorticocoids |
|
Definition
Mobilization of amino acids and use of these to repair the damaged tissues
Increased glucogenesis that makes extra glucose available in critical metabolic systems
Increased amounts of fatty acids available for cellular energy
Inactivating or removing inflammatory products |
|
|
Term
| Hormones secreted by beta and alpha cells of pancreas islets of Langerhans |
|
Definition
Beta cells secrete insulin (inhibits glucagon secretion)and amylin (inhibits insulin secretion)
Alpha cells secrete glucagon
(delta cells secrete somatostatin, which inhibits secretion of both insulin and glucagon) |
|
|
Term
| Metabolic effects of insulin |
|
Definition
Secreted in great quantity in response to rich carbohydrate diets
Promotes storage of excess carbohydrates as glycogen mainly in liver and muscles
Excess carbs that can't be stored as glycogon are converted under the stimulus of insulin into fats and stored in the adipose tissue |
|
|
Term
| Insulin and it's direct effect on protein metabolism |
|
Definition
Promotes amino acid uptake by cells
Promotes conversion of these amino acids into protein
Inhibits breakdown of the proteins that are already in the cells |
|
|
Term
| To initiate insulin's effect on target cells... |
|
Definition
first binds with and activates a membrane receptor protein
sensitivity of the receptor to insulin is critical in the effect of insulin and decreased sensitivity of the receptor is a mechanism of type 2 diabetes |
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Term
| Insulin activating target cell receptors |
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Definition
Insulin binds with the alpha subunits on the outside of the cell
Because of the linkages with the beta subunits, the portions of the subunits protruding into the cell become autophosphorylated which activates a local tyrosine kinase
T.K causes phosphorylation of multiple other intracellular enzymes including a group called insulin receptor substrates (IRS) |
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Term
| Insulin effects on carbohydrate metabolism |
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Definition
Glucose uptake by muscle. At rest utilizing fatty acids >> glucose
Increase membrane permeability to glucose during mod or heavy exercise (insulin dependent)
2 conditions increase use of large amounts of glucose
Immediately after a high glucose content meal w/ pancreas secreting large quantities of insulin |
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Term
| Insulin causes storage of glyocgen in muscel |
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Definition
| When not used metabolically, glucose is stored in the form of muscle glycogen instead of being used for energy, up to a limit of 2-3% concentration |
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Term
| Insluin causes promotion of liver uptake, storage, and release of glucose |
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Definition
Store excess glucose taken in at meals in the liver in the form of glycogen
Liver glycogen is released back into the blood when blood [glucose] falls and decreases release of insulin
Principle regulation of blood glucose concentration by this mechanism |
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Term
| Insulin's mechanism of hepatic glucose uptake and storage |
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Definition
Inactivation of liver phosphorylase, the principle enzyme that causes liver glycogen to split into glucose, preventing glycogen breakdown
Increases liver uptake of glucose from the blood
Increase glucokinase activity which phosphorylates glucose after it diffuses into the liver cells |
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Term
| When blood glucose decreases between meals |
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Definition
Causes pancreas to decrease insulin secretion
Decreased insulin then reverses all its effects
Decreased insulin and increase of glucagon activates enzyme phosphorylase, which splits glycogen into glucose 1-phosphate.
Glucose phosphatase activated by decreased insulin and forms free glucose to diffuse back into the blood |
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Term
| Insulin promotes conversion of all this excess glucose into fatty acids |
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Definition
Which are subsequently packaged as triglycerides
Transported as very-low-density lipoproteins in blood to adipose tissue and deposited as fat |
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Term
| Insulin effects on fat metabolism |
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Definition
2 major effects lead to fat storage in adipose tissue
-increases the utilization of glucose by most of the body's tissues which automatically decrease the utilization of fat, thus functioning as a fat sparer
-promotion of fatty acid synthesis
Synthesis occurs in liver cells with blood transport as lipoproteins to adipose cells
(read more on this in notes) |
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Term
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Definition
caused by excess usage of fats during insulin lack
Excess fatty acids in the liver cells increases mitochondrial carnitine transport mechanism for fatty acids
In mitochondria, beta-oxidation of the fatty acids then proceeds very rapidly, releasing extreme amounts of acetyl-CoA
Excess acetyl-CoA then condensed to
form acetoacetic acid, which is then released into the circulating blood
Can be used by liver and other cells to form beta-hydroxybutyric acid and acetone
Together these 3 substances are ketone bodies and ketoacidosis if severe can lead to coma and death |
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Term
| Insulin's effect on protein metabolism |
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Definition
Increases protein synthesis and storage because...
Stimulates transport of many amino acids into the cells
Increases translation of messenger RNA, thus forming new proteins
Increases rate of transcription of selected DNA genetic sequences in the cell nuclei, thus forming increased quantities of RNA and still more protein synthesis |
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Term
| Mechanisms of insulin secretion |
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Definition
Pancreatic B-cells have a large number of Type 2 glucose transporter (GLUT-2) that permit a rate of glucose influx that is proportional to the blood concentration in the physiologic range
Once inside the cells, glucose is phosphorylated to glucose-6-phospate by glucokinase (rate limiting for glucose metabolism, major mechanism for glucose sensing and adjustment of amount of secreted insulin
Glucose-6-phosphate is oxidzed to form ATP, which inhibits ATP sensitive K+ channels - depolarlizes cell membrane, opens Ca++ channels.
Influx of Ca++ stimulates fusion of docked insulin containing vesicles with the cell membrane and secretion into extracellular fluid by exocytosis |
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Term
| Factors and conditions that increase insulin secretion |
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Definition
Increased blood glucose
Increase blood free fatty acids
Increase blood amino acids
Gastrointestinal hormones (gastrin, cholecystokinin, secretin, gastric inhibitory peptide)
Glucagon, GH, cortisol
Parasympathetic stimulation; acetylcholine
Beta-Adrenergic stimulation
Insulin resistance; obesity
Sulfonylerua drugs (glyburide, tolbutamide) |
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Term
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Definition
Hormone secreted by the alpha cells of the islets of Langerhans when blood glucose concentration falls
Functions oppose that of insulin
Increases blood glucose concentration
Has profound hyperglycemic effect |
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Term
| Effects of glucagon on glucose metabolism |
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Definition
Glycogenolysis breakdown of liver glycogen
Increases gluconeogenesis in the liver
Increases the availability of glucose to the other organs of the body |
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Term
| Other effects at high [glucagon] |
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Definition
Slight increase in the strength of the heart
Increase blood flow in some tissues, esp the kidneys
Increased bile secretion
Inhibits gastric acid secretion |
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Term
| Characteristics of Type 1 Diabetes |
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Definition
Onset usually <20 y.o
<10% of all cases
Abrupt (acute or subacute onset)
Possible viral/autoimmune with destruction of islet cells etiology
Presence in 1st degree relative - risk factor
Is HLA association
Have insulin antibodies
Body weight is normal or thin
Very little or no endogenous insulin production
Ketoacidosis may occur
Insulin, diet and exercise is treatment |
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Term
| Characteristics of Type 2 Diabetes |
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Definition
Onset gradual, and usually over 40 yo
>90% of all cases
Etiology - obesity associated, decreased affinity of insulin receptors
Risk factors - pos fam hx; black, native american or asian; obesity and hyperlipidemia; increased age; previous IFG/IGT or gestational diabetes; HTN
No HLA association or insulin antibodies
Majority are obese
Variable endogenous insulin production
Ketoacidosis rare
Treat with diet, weight control, exercise, oral hypoglycemic agents and possibly insulin |
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Term
| Signs and symptoms of diabetes |
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Definition
Polyuria (1&2)
Polydipsia (1&2)
Polyphagia (1)
Weight loss (1)
Recurrent blurred vision (1&2)
Ketouria (1)
Weakness, fatigue, dizziness (1&2)
Often asymptomatic (2) |
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Term
| Test results that are evidence of diabetes |
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Definition
>126 mg/dl fasting glucose test (less than 110 is normal)
HbA1c test reveals avg blood glucose over a period of 2-3 months.
Measures the number of glucose molecules attached to hemoglobin (4-6% is considered normal) |
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Term
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Definition
Pallor
Perspiration
Piloecrection
Tachycardia
Nervousness, irritability
Shakiness, trembling
CNS symptoms of confusion, emotional lability, thickened speech, coma and convulsion |
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Term
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Definition
Excretion of metabolic waste products, drugs and other foreign chemicals and hormone metabolites
o Regulation of water and electrolyte levels by excretion and sequestration of electrolytes
o Regulation of blood pressure through renin-angiotensin system as well as electrolyte regulation
o Regulation of acid-base balance through the excretion and sequestration of bicarbonate, phosphates and hydrogen ion
o Regulation of red blood cell production through the release of erythropoietin
o Regulation of Ca++ metabolism through the production of the calcitrol, the active form of vitamin regulation of glucose levels through gluconeogensis |
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Term
| Innervation of external urinary sphincter |
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Definition
| By somatic nerves from pudendal nerve |
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Term
| Characteristics of the bladder |
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Definition
Bladder body & neck
Inner lining of the body in highly folded- rugae- allowing for expansion when filled with urine
Above the neck is the trigone area
Posterior urethra at the lowest end & the 2 ureters entering bladder obliquely at the upper end of the trigone
Detrussor muscle (smooth muscle of the bladder) shortens in all directions when activated
Low resistance electrotonic junctions between smooth muscle cells
Uniform contraction of detrussor muscle
This produces uniform increased pressure within the bladder |
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Term
| Characteristics of stress incontinence |
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Definition
Weakened pelvic floor muscles
Produced by abdominal contraction: sneeze, cough, laughing
Treated with pelvic floor exercises (Kegel) & surgery |
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Term
| Factors which determine excretion rate |
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Definition
Glomerular filtration
Reabsorption of substances from the renal tubules into the flood
Secretion of substances from the blood into the renal tubules
(rate @ which the substance is excreted in the urine depends on the relative rates of these 3 basic renal processes) |
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Term
| What happens to freely filtered substances which are not excreted? |
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Definition
| Freely filtered by the glomerular capillaries but neither reabsorbed nor secreted so excretion rate is equal to the rate at which it was filtered (creatinine) |
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Term
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Definition
Allows the kidneys to rapidly remove waste products from the body that depend primarily on glomerular filtration for their excretion
Allows all the body fluids to be filtered and processed by the kidney about 60 times each day |
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Term
| Reasons that large amount of urine is not formed even with the high GFR |
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Definition
If GFR increases only 10% (from 180-198L/day) it would raise urine volume 13-fold if tubular reabsorption remained constant
But a simultaneous increass of reabsorption keeps changes in urine formation within reasonable limits |
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Term
| 3 layers make up the filtration barrier |
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Definition
Capillary Endothelium- perforated by thousands of small holes called fenestrae which: are relatively large, have fixed negative charges that hinder the passage of plasma proteins
Basement membrane- meshwork of collagen & proteoglycan fibrillae that have large spaces through which large amounts of water & small solutes can filter; strong negative electrical charges assoc with the proteoglycans prevents filtration of plasma proteins
Glomerular layer of epithelial cells (podocytes) surrounding the outer surface of the capillary basement membrane- line the outer surface, discontinuous long footlike processes that encircle the outer surface of the capillaries
-slit pores between podocytes are gaps through which the glomerular filtrate moves
-Have negative charges, provide additional restriction to filtration of plasma proteins |
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Term
| Glomerular filtration barrier is... |
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Definition
Selective in determining which molecules will filter, based on their size & electrical charge
Electrolytes such as Na & small organic compounds such as glucose are free filtered
Increased M.W. of the molecule filterability rapidly decreases
Negatively charged large molecules are filtered less easily than positively charged or neutrally charged molecules
In nephropathies, the negative charges on the basement membrane are lost & some of the lower m.w. proteins filtered & appear in the urine > proteinuria/albuminuria |
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Term
| Factors that increase GFR |
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Definition
Increased Kf (capillary filtration coefficient)
Decreased Pb (Hydrostatic pressure in Bowman's capsule)
Decreased piG (colloid osmotic pressure in glomerular capillaries)
Increased PG (glomerular capillary hydrostatic pressure) |
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Term
| Effect of moderate increases in EFFERENT arteriolar constriction |
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Definition
Has double effect
At moderate constriction - slight increase GFR secondary to increase PG
With more severe constriction - decrease GFR secondary to decrease blood flow so considerable increase piG so increase piG is greater than the increase in PG |
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Term
| Effect of increased AFFERENT arteriolar constriction |
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Definition
| Decreased renal blood flow leads to decreased PG and therefore decreased GFR |
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Term
| Effects of increased systemic arterial pressure through the normal range |
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Definition
Increased arterial pressure (PA)
-increased renal arterial pressure ->increased PG
-increased PG -> increased GFR |
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Term
| Mechanism by which cerebral (voluntary) control of urination is expressed |
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Definition
Pontine excitatory and inhibitory centers
Cerebral control
-voluntary urination from teh abdominal muscle contraction
-voluntary constriction and relaxation of external sphincter |
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Term
| Effect of proteinemia on GFR |
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Definition
| Increased piG and decreases GFR |
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Term
| Primary physiological mechanism for normal regulation of GFR |
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Definition
Changes glomerular capillary hydrostatic pressure (PG) primary means for physiologic regulation of GFR
-increased PG increases GFR
-decreased PG decreases GFR |
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Term
| Principle mechanism by which the kidney excretes a dilute or a concentrated urine |
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Definition
Clearance
-Whole-body clearance means the total rate of removal of a substance by all organs
-renal clearance means the rate of removal of a substance by all organs
-definition of renal clearance is the volume of plasma completely cleared of a substance by the kidneys per unit time |
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Term
| Effect of urinary tract obstruction (e.g. kidney stones) on the forces which affect GFR |
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Definition
| Increase Pb and decrease GFR |
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Term
| The principle advantage of blood flow in the vasa recta of the renal medulla being bery low compared with flow in the renal cortex |
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Definition
Blood flow in the vasa recta of the renal medulla is very low compared with flow in the renal cortex
Blood flow in the renal medulla supplied by the vasa recta accounts for only 1 to 2 per cent of the total renal blood flow
Important role in allowing the kidneys to both maintain high GFR & form a concentrated urine |
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Term
| Factors responsible for the physiologic control of GFR and renal blood flow |
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Definition
Norepinephrine - decreases blood flow
Epinephrine - decreases blood flow
Endothelin - decreases blood flow
Angiotensin II - prevents decrease
Endothelial-derived nitric oxide - increases blood flow
Prostaglandins - increases blood flow
Sympathetic - decreases renal blood flow and GFR during severe, acute disturbances |
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Term
| Transport mechanisms of the loop of henle that contributes to counter-current exchange |
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Definition
Fluid enters loop of henle at 300 mOsm/L, same as leaving the proximal tubule
Active Na+ pump of thick ascending limb turned on, reducing the concentration inside the tubule and raising the interstitial concentration
Tubular fluid in descending limb and the interstitial fluid quickly reach osmotic equilibrium because of osmosis of H20 out of the descending limb
Hyperosmotic tubular fluid formed in the descending limb to flow into the ascending limb
Again, a 200 mOsm/L osmotic gradient is established, increasing interstitial fluid osmolarity to 500
Descending limb fluid reaches equilibrium with the even more hyperosmotic medullary interstitial fluid
Then steps repeated |
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Term
| Requirements for forming a concentrated urine |
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Definition
High level of ADH- increase permeability of the distal tubules & collecting ducts to water
High osmolarity of the renal medullary interstitial fluid- provides the osmotic gradient necessary for water reabsorption to occur in the presence of high levels of ADH |
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Term
| Major factors that contribute to the high solute concentration of renal medulla |
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Definition
Greater percentage of water is reabsorbed, the substance becomes more concentrated
Greater percentage of the solute is reabsorbed, the substance becomes more diluted
Change in the ratio of tubular fluid/plasma conc rate reflects changes in tubular fluid conc
-conc ration increases to greater than 1 if more water is reabsorbed than solute, or if there has been a net secretion of the solute into the tubular fluid
-conc ration becomes less than 1 when relatively more solute has been reabsorbed than water |
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Term
| Causes of nephrogenic diabetes insipidus |
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Definition
Inability of the kidneys to respond to ADH
Due to the failure of:
-Countercurrent mechanism to form a hyperosmotic renal medullary interstitium
-Distal & collecting tubules & collecting ducts to respond to ADH
-Diuretics that inhibit electrolyte reabsorption by this segment, can compromise urine concentrating ability
-Certain other drugs, such as lithium (used to treat manic-depressive disorders) and tetracyclines (used as antibiotics), can impair the ability of the distal nephron segments to respond to ADH
-Diseases can impair the concentrating mechanism, especially those that damage the renal medulla
-Lack of response to desmopressin
-Treatment for nephrogenic diabetes insipidus is to correct, if possible, the underlying renal disorder |
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Term
| Osmolarity control of ADH control system |
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Definition
In late distal tubule and cortical collecting tubules:
Osmolarity of fluid depends on ADH levels
Increased ADH increases water reabsorbed and increases solute and urea concentration
Decreased ADH decreases water reabsorbed and decreases osmolarity and more decreased osmolarity with continued active solute reabsorption
In medullary collecting ducts:
Tubular fluid osmolarity depends upon ADH and medullary interstitium osmolarity established by the countercurrent mechanism
Increased ADH and H20 reabsorbed and increase solute and urea concentration to 1200-1400 mOsm/L
Urea contributes as well |
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Term
| Cardiovascular reflex stimulation of ADH release |
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Definition
Increased blood volume stimulates low pressure baroreceptors (really volume receptors that stretch with increased blood volume) located in the right atrium and vena cava
Both neural and hormonal response to stimulation
Neural activation ascends via the vagus nerve (CN X)
Neural activation inhibits preoptic hypothalamic neurons that make ADH
Vagal afferents activate inhibitory interneurons that inhibit preoptic hypothalamic neurons.
Hormonal response is the release of atrial naturitic peptide (ANP)
ANP inhibits neurons in the AV3V (antero-ventral region of the third ventricle) region, an area related to ADH release
Both decrease ADH synthesis and release
Decreased ADH will decrease renal tubule permeability to H2O
Increased H2O reabsorbed and thus decreased blood volume |
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Term
| Factors that shift K+ into cells and decrease extracellular K+ concentration |
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Definition
Insulin
Aldosterone
Beta-adrenergic stimulation
Alkalosis |
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Term
| Factors that drive Na+ uptake in tubular cells |
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Definition
Extensive brush border on the tubular luminal side with 20fold increase area covered with Na+ carriers
When combined with exensive Na+K+ ATPase carriers very significant amounts of Na+ transport occurs
Na+ transport is also effected by:
-Na+ in the tubular fluid
-Back leek into the tubular lumen through the epithelial tight junctions, the rate of which is determined by the permeability of the tight junctions
-Interstitial physical forces, which determine the rate of bulk flow reabsorption from the interstitial fluid into the peritubular capillaries
-Response to hormones such as aldosterone |
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Term
| Primary factors that increase K+ secretion by tubular principal cells |
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Definition
Increases extracellular fluid K+ concentration
Increased aldosterone
Increased tubular flow rate
Increased hydrogen ion concentration |
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Term
| Mechanism by which kidneys can retain fluids when there is substantial loss of blood volume by hemorrhage |
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Definition
Renin angiotensin system
Osmoreceptor ADH feedback system
Low pressure baroreceptor reflexes |
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Term
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Definition
| Decrease blood volume > decrease Na+ delivery > Increase rennin release (circulates to catalyze conversion of angiotensinogen to angiotensin I > angiotensin II (by ACE) causes > increase aldosterone release from adrenal cortex & increase in Na/K ATPase activity in renal tubules > INCREASE in Na+ & H20 reabsorption |
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Term
| Osmoreceptor-ADH feedback system |
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Definition
Decrease blood volume > increase extraceullar fluid osmolarity > osmolarity shrinks osmoreceptor cells > increase of synthesis & release of ADH > increase H20 permeability in distal nephron tubules causes increase h2o reabsoprtion & excretion of a small volume of concentrated urine
-Increased blood volume, decreased osmolarity and decreased osmoreceptors activation of ADH synthesis and release |
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