Shared Flashcard Set

Details

Physiology Weight Loss
Terms I Do Not Know Yet
207
Physiology
Graduate
10/25/2016

Additional Physiology Flashcards

 


 

Cards

Term
Endocrine glands
Definition
Pituitary, thyroid, adrenal, parathyroid, pancreatic islets
Term
Example of autocrine action
Definition
Local, binding receptor on surface of same cell; used by prostaglandins (eicosanoids) in uterine smooth muscle contraction and pregnancy
Term
Role of Nitric Oxide
Definition
Regulates tone of smooth muscle cells and many other jobs (different flash card)
Term
Hydrophobic hormones
Definition
Non-polar, uncharged; carrier proteins in plasma; secreted immediately (usually)
Term
Hydrophilic hormones
Definition
Dissolve well in water; polar, charged; stored in secretory vesicles
Term
Amide hormones
Definition
Derived from tyrosine- catecholamines, thyroid hormones, dopamine, norepinephrine, epinephrine
Term
Peptide hormones
Definition
Produced by pituitary gland as RF, act on peripheral endocrine glands; also insulin made by endocrine pancreas
Term
C-peptide
Definition
Induces conformation for cross-binding of pro-insulin, cleaved in Golgi, packaged in secretory vesicle with insulin - best measurement of endogenous insulin production
Term
Hydrophilic hormone signaling
Definition
Receptors on cell surface, signal through 2nd messengers (GPCR or TRK receptor)
Term
Hydrophobic hormone precursors
Definition
Cholesterol --> steroids
Tyrosine --> thyroid hormones
Arachadonic aicd --> eicosanoids
Term
Hydrophobic hormones with Type I Receptors and action
Definition
Steroid hormones; hormone-receptor complex enter nucleus, bind HRE, promote gene expression
Term
Hydrophobic hormones with Type II Receptors and action
Definition
Vitamin A, Vitamin D, retinoids, thyroid hormones; receptors already bound to DNA, receptors repress gene expression when inactive
Term
Releasing hydrophilic hormones
Definition
Accumulate when secretion not required; PLC makes IP3, Ca released in cytosol, facilitate fusion of vesicles with hormones to plasma membrane; cAMP and cGMP modulate process of secretion too
Term
Half-life of hormone
Definition
Time for 1/2 to disappear from plasma, depends on % bound to carrier protein at any given time
Term
Metabolic Clearance Rate
Definition
mg/min removed / [mg/ml] in plasma = ml plasma/min
Term
Methods of hormone removal
Definition
Uptake and degradation by target cell, metabolic degradation in the liver, urinary or biliary excretion
Term
Radioimmunoassay
Definition
mAb bind radioactive hormone; higher concentration of hormone leads to less radioactive antibody complex
Term
ELISA
Definition
Ab bound to substrate, catalyze reaction to make fluorescent product - intensity related to hormone concentration
Term
Receptor downregulation
Definition
Compensate for increased hormone plasma levels, leads to reduced affinity of hormone for receptor even if normal hormone levels return
Term
Reduced responsiveness of hormone receptor
Definition
Increased hormone concentration doesn't produce relevant increase in biological response
Term
Reduced sensitivity of hormone receptor
Definition
Shift to right in dose-response curve - need high concentration of hormone to induce 50% maximal response
Term
Hypophysiotropic hormones
Definition
Releasing hormones - released from 1st capillary bed in hypothalamus and go to 2nd capillary bed in AHP, where released to trophic cells
Term
Magnocellular neurons
Definition
Present in supraoptic and paraventricular nuclei of hypothalamus; project into posterior pituitary, release ADH and oxytocin
Term
Cells releasing oxytocin and vasopressin
Definition
Magnocellular neurons of supraoptic and paraventricular nuclei in the median eminence of hypothalamus
Term
CRH overview
Definition
Secreted by paraventricular nuclei of hypothalamus
41 amino acids
Stimulates POMC gene expression and ACTH secretion by corticotrophs
Term
ACTH overview
Definition
39 amino acids
Secreted by corticotrophs, go to adrenal cortex to stimulate glucocorticoid and weak androgen production
Tropic and trophic
Term
TRH overview
Definition
3 amino acid peptide
Stimulates XP of alpha and beta subunits of TSH and TSH secretion of TSH by thyrotrophs
Stimulates PRL synthesis by lactotrophs
Term
TSH overview
Definition
Glycoprotein secreted by thyrotrophs
Stimulates T4, T3 production by follicular cells in thyroid
Tropic and trophic effect on thyroid
Term
GHRH overview
Definition
40/44 amino acids
Produced in arcuate and ventromedial nuclei of hypothalamus
Stimulates GH gene expression and secretion by somatotrophs
Term
GH overview
Definition
191 aa chain secreted by somatotrophs
Promotes body growth, TAG lipolysis, counterregulatory
Inhibits insulin action, IFG-1 must be involved also
Term
LHRH overview
Definition
10 aa chain stimulating FSH and LH secretion by gonadotrophs
Term
FSH overview
Definition
Glycoprotein promoting development of ovarian follicles and regulation of spermatogenesis
Term
LH overview
Definition
Glycoprotein promoting ovulation, formation of corpus luteum
Stimulates estrogen and progesterone formation
Testosterone production by testes
Term
SRIF overview
Definition
14 amino acid chain, aka somatostatin
Released by anterior periventricular region of hypothalamus
Inhibit GH secretion (somatotroph), TSH secretion (thyrotroph)
Term
Dopamine as hormone
Definition
Catecholamine, inhibits PRL synthesis and secretion by lactotrophs
Term
PRL
Definition
199 amino acid chain, essential for milk production by lactating mammary gland (not tropic or trophic)
Term
Negative feedback
Definition
Endocrine cell hormones give negative feedback to both hypothalamus and anterior pituitary; sometimes positive feedback to somatostatin; TH and EH seen in blood, too little RH
Term
Tropic vs. trophic effect
Definition
Tropic - exert action on other endocrine gland
Trophic - promote healthy state of target cells affection - growth
Term
Glands modulated by H-P axis
Definition
Adrenal gland, thyroid gland, testes, ovaries
Term
CRH feedback
Definition
Glucocorticoids inhibit ACTH and CRH release; expect low ACTH when high glucocorticoids; stress increases ACTH to make more glucocorticoids
Term
CRH action in pituitary cell
Definition
Receptor, Gs, adenylyl cyclase, cAMP, PKA, phoshporylation, increase POMC mRNA, POMC --> ACTH and beta-LPH
Term
CRH secretion levels
Definition
Pulsatile, circadian rhythm, highest in morning, lowest while asleep
Term
TRH secretion levels
Definition
Tonic pattern of secretion, constant levels reach pituitary
Term
TRH action on thyrotroph
Definition
Gq, PLC, PIP2, DAG and IP3, PKC and Ca, increase transcription of 2 TSH subunits, promote secretion
Term
TRH feedback
Definition
T3 and T4 decrease TRH, TSH, positive feedback on somatostatin; highest in early morning
Term
Counterregulatory hormones
Definition
Glucagon, epinephrine, cortisol, growth hormone
Term
GH responsibilities
Definition
Neonatal growth, metabolism of carbs, lipids and proteins; counteract insulin, increase plasma glucose
Term
GH feedback loops
Definition
GH and IGF-I have negative feedback on GHRH (and GH) and positive feedback on somatostatin
Term
GH action on somatotrophs
Definition
increase cAMP, PKA while SRIF reduces these pathways, lead to GH release
Term
GH direction action
Definition
Stimulate lipolysis in adipose by stimulating HSL to increase adipocyte responsiveness to lipolytic stimuli; stimulate AA transport in muscle
Term
GH indirect action
Definition
Synthesize trophic hormone IGF-I
Term
IGF-I
Definition
70 amino acid peptide hormone, made in liver, mitogenic and trophic effect on many tissues
Autocrine signal to promote chondrocyte proliferation to enlarge metaphysis and end up with osteoblasts making bone matrix
Term
Dual effector mechanism
Definition
GH bind receptor on prechondrocyte to differentiate into chondrocyte and secrete IGF-I, which signals to promote chondrocyte proliferation and enlarge metaphysis and end up with osteoblasts producing bone matrix
Term
GH release pattern
Definition
Pulsatile, highest values around midnight in stage 3-4 slow wave sleep; higher at all times of day in adolescents than adults; increased with exercise or emotional/physical stress
Term
GH receptor
Definition
TKR, act by JAK/STAT pathway, then phoshporylation
Term
IGF receptor
Definition
traditional TKR, using protein phosphorylation
Term
GH diabetogenic action
Definition
Make muscles and adipocytes resistant to insulin activity leading to hyperglycemia resembling DM Type II
Term
Prolactin roles and stimulation
Definition
Stimulate milk production in mammary gland and breast growth (usually inhibited by PIF), suckling of baby blocks dopamine; inhibits LH and FSH production; positive feedback
Term
Milk-releasing hormones
Definition
Prolactin, estrogens and oxytocin
Term
Panhypopituitarism
Definition
Affects entire pituitary gland (trauma or vascular injury)
Term
Partial damage to pituitary
Definition
Often affects single cell type, single hormone
Term
Pituitary adenoma
Definition
Affect 1 type of secreting cell, 1 hormone; can lead to bitemporal hemianopsia
Term
Bitemporal hemianopsia
Definition
Altered eyesight due to pituitary adenoma if growth leaves sella turcica and pinches of optic pile
Term
Acromegaly
Definition
Excess GH in adulthood; thicker bones, indicative facial features
Term
Gigantism
Definition
Excess GH in childhood before epiphyseal fusion - taller
Term
Pituitary dwarfism
Definition
Childhood GH deficiency - short with proportional limbs and torso
Term
ADH
Definition
AVP, vasopressin - made by supraoptic + paraventricular nuclei
Respond to increased plasma osmolarity or hypovolemia
Act on V2 and V1 receptors
Term
V2 receptor
Definition
AVP - Gs, cAMP, increase AQP2 in nephron collecting duct, increase water permeability, leading to concentrated urine and more water retention
Term
V1 receptor
Definition
AVP - PLC, IP3, Ca, contract smooth muscle and arterioles, increase peripheral resistance, vasoconstriction, increase BP
Term
Diabetes insipidus
Definition
Excessive diuresis due to lack of AVP
Polyuria, polydipsia, no hyperglycemia, no hyperglycosuria
Term
Oxytocin stimulation and role
Definition
Stimulation: sight/sound/smell of infant, dilation of cervix in labor and orgasm, neural input during childbirth
Role: induce contraction of myoepithelial cells in lactation and uterus during labor
Term
Leptin
Definition
Expressed by adipose tissue, plasma levels rise with more fat deposit, exogenous ineffective at reducing appetite
Leptin receptors in hypothalamus, affecting TSH and GH
Term
How does thyroid hormone make changes?
Definition
Activity is exerted at the gene expression level - though technically not necessary for life
Term
Thyroid hormone storage
Definition
Synthesized and stored in follicles, colloid in follicle lumen is 10-25% thyroglobulin which has T3, T4 stored on it; unusual for hydrophobic hormones - EXCEPTION
Term
Effectiveness of replacement therapy
Definition
Works for thyroid hormone because tonic secretion at all times, not as good for adrenal hormones which act at certain times
Term
Dietary iodide
Definition
150 µg/day RDA - deficiency can lead to hypothyroidism
Term
Sodium/Iodine Symporter (NIS)
Definition
Uptake from blood using Na gradient set up by Na/K ATPase, low blood iodine stimulates NIS activity
Term
Thyroid peroxidase
Definition
Oxidizes iodide to iodine, oxidizes attaches I to make MIT and DIT, couples precursors to make T3 and T4
Term
Pendrin
Definition
Channel by which Iodine enters lumen, insensitive to tSH, only based on iodide concentration
Term
T3 vs. T4 secretion
Definition
T4 secreted 5x more than T3; linked to Thyroglobulin until TSh hormone stimulation
Term
Propylthiouracil (PTU)
Definition
Inhibits thyroid peroxidase (TPO), treatment for hyperthyroidism
Term
Megalin receptor
Definition
Present on pseudopodia upon TSH stimulation, leading to uptake of colloid into follicular cells in endosomes
Term
TSH stimulation action on thyroid cells
Definition
Follicular cells extend pseudopodia with Megalin receptor, re-uptake colloid in endosomes, fuses with lysosomes to hydrolyze thyroglobulin, release T3 and T4 into capillaries and recycle everything else; TSH stimulates Megalin expresion, NIS synthesis, TPO activation
Term
Thyroxin-binding globulin
Definition
Glycoprotein secreted by liver, binds 70% T4, 80% T3
Increased in pregnancy
Term
T3 and T4 binding and free in blood
Definition
Most to TBG, some to transthyretin and albumin, <1% free, leading to long half-life (1 day T3, 7 days T4)
Term
Action of T3
Definition
T3 --> Type II THR --> complex with Retnoid X Receptor, bind TRE on DNA --> several hours for effect due to changes needed in gene expression on respiration, morphology, ion homeostasis
Term
Deiodinase Type 1
Definition
T4 --> T3 peripherally in liver, kidneys, thyroid; contains selenocysteine
Term
Deiodinase Type 2
Definition
T4 --> T3 in cytosol of skeletal muscle, CNS, pituitary, placenta; contains selenocysteine
Term
Deiodinase Type 3
Definition
Liver, kidneys, deactivate T3 and T4 by iodine removal; Reverse T3 - 40% T4 deiodination product, mostly inactive on THR; contains selenocysteine; inactivation occurs by inner ring deiodination
Term
5' deiodinase reaction
Definition
Less active in fetus, fasting, trauma, illness
Term
T4 production in fasting and illness
Definition
Not increased, Deiodinase 2 in CNS and pituitary make enough T3
Term
Goiter
Definition
Result of increased trophic effect of TSH for long time leading to enlarged thyroid gland
Term
T3 impact on mitochondria
Definition
May regulate its use of O2, increased ml/min O2 in hyperactive gland
Term
Major effects of thyroid hormones
Definition
Brain maturation in fetus, regulating GH release, regulating BMR, thermogenesis
Term
Secondary Hypothyroidism
Definition
Impaired TRH or TSH production by hypothalamic or pituitary failure
Term
Hashimoto disease
Definition
Autoimmune Ab directed against TPO enzyme or TSH receptor leading to destruction of gland - type of primary hypothyroidism; tissue atrophy/destruction of thyroid
Term
Myxedema
Definition
Most common hypothyroidism with insufficient iodide in diet
Weight gain, reduced BMR, fatigue, cold sensitive, peripheral edema, goiter; osmotic water retention leads to swollen skin in face, hand or feet in severe case
Term
Neonatal hypothyroidism
Definition
Irreversible mental retardation if untreated - macroglossia, less active, constipation, small with poor feeding
Term
Graves Disease
Definition
Primary hyperthyroidism with autoAb to TSH receptor, overstimulation of thyroid gland
Weight loss, fatigue, increased BMR, muscle wasting, enlarged gland due to DIFFUSE TOXIC GOITER - can see protruding eye bulb - diagnose with uptake of radioactive iodine - more in women
Term
Living without adrenal function
Definition
Cannot survive without continuous intake of water, salt, energy metabolites - no easy replacement therapy
Term
Primary hormone products of adrenal cortex regions
Definition
Zona glomerulosa - mineralicorticoids - aldosterone
Zona fasciculata and reticularis - glucocorticoids and weak androgens - cortisol, corticosterone, DHEA, androstenedione
Term
Aldosterone receptor
Definition
Not very specific, glucocorticoids can act on it a bit - 11beta-dehydrogenase can inactivate cortisol to cortisone to allow only aldosterone to act on receptor in peripheral tissue
Term
11beta-dehydrogenase
Definition
Converts active cortisol to inactive cortisone in peripheral tissues to allow mineralocorticoid receptors to only be activated by aldosterone
Term
Role of androgenic steroids
Definition
Main androgenic hormones in blood of female; most androgens made by testes in male - support prepubescent development (mostly masculinizing hormone)
Term
Storage of adrenal cortex hormones
Definition
Produced on demand, NOT stored
Term
Cholesterol side-chain cleavage enzyme
Definition
Converts cholesterol to pregnenolone in mitochondria, first step in synthesis of all adrenal cortex hormones
Term
Aldosterone synthesis
Definition
Cholesterol to pregnenolone by cholesterol side-chain cleavage enzyme; convert to 11-deoxycorticosterone by 21-hydroxylase; convert to corticosterone by 3beta-hydroxysteroid dehydrogenase; convert to aldosterone by aldosterone synthase (only in zona glomerulosa)
Term
Cortisol synthesis
Definition
Cholesterol to pregnenolone by cholsterol side-chain cleavage enzyme; convert to 17OH pregnenolone by 17a-hydrolyase; 3beta-hydroxysteroid dehydrogenase and 21-hydroxylase to deoxycortisol; 11beta-hydrolyase to cortisol
Term
DHEA synthesis
Definition
Cholesterol to pregnenolone by cholesterol side-chain cleavage enzyme; conert to 17aOH pregnenolone by 17a-hydroxylase; lyase activity of 17a-hydroxylase forms DHEA - can form androstenedione from here
Term
17-alpha-hydroxylase
Definition
Necessary for production of cortisol, DHEA, androstenedione - only present in zona fasciculata and zona reticularis
Term
Location of adrenal cortex hormone synthesis
Definition
Pregnenolone formed in mitochondria, rest of formation occurs in SER
Term
Adrenarche
Definition
Beginning of 17aOH-pregnenolone lyase activity, starting around age 7-8 before puberty, leading to dvelopment of pubic and axillary hair
Term
DHEA and androstenedione conversion
Definition
Can be converted to testosterone or more potent DHT or estradiol in peripheral tissues; most synthesis in adrenal cortex, especially in females
Term
21-hydroxylase deficiency
Definition
Reduced mineralicorticoids and glucocorticoids with increased precursors - virilization and hirsutism in females; salt wasting, hypovolemia, hypotension in severe cases
Term
ACTH effect on adrenal cortex hormones
Definition
ACTH regulates glucocorticoids and androgens, minimally affect aldosterone; acts through melanocortin-2 receptor and stimulation of cholesteryl ester hydrolase for cholesterol to enter mitochondria; long-term regulation at gene expression level
Term
11beta-ketoreductase
Definition
Converts corticosterone to cortisol to make it more active peripherally
Term
ACTH, cortisol secretion timing
Definition
Pulsatile, 10 bursts/day, mostly diurnal, highest right before waking; abolished by coma/blindness/constant light and dark
Term
Increased cortisol
Definition
Stress, pain, trauma, infection, exercise - can lead to adrenal hypertrophy in chronic stress; macrophages release ILs in trauma and infection; beta-endorphin analgesic when pain
Term
Adrenal steroid binding in blood
Definition
90% bound to CBG (liver glycoprotein); 6-7% bound to albumin, 3-4% free, long half-life
Term
17-ketosteroids
Definition
Cortisol and androgens bound to glucuronic acid and sulfuric acid respectively to increase water solubility for disposal in urine - can be measured to assess adrenal activity
Term
Adrenal steroid receptor type
Definition
Type I receptor; glucocorticoid binds GRE, promote gene expression, synthesis - takes hours for effects
Term
Glucocorticoids in prolonged fast
Definition
Lead to protein breakdwon in skeletal muscle to make more glucose; increase enzymes in gluconeogenesis, mobilize use of stored fat by activating HSL
Term
Glucocorticoid as anti-inflammatory
Definition
Reduce NO, decrease capillary permeability; synthesize lipocortin to reduce prostaglandins and leukotrienes; decrease # of T-cells, B-cells and mast cells (therapy to reduce immune response)
Term
Additional roles of glucocorticoids
Definition
Bone growth regulation, excrete excess H2O (inhibit ADH), regulate thyroid hormones, regulate progesterone/estrogen activity
Term
Aldosterone regulation
Definition
Regulate by Angiotensin II in renin-angiotensin system and by K levels (increase), child in extracellular fluid volume
Term
Aldosterone effect on kidney
Definition
Na retention, K excretion, H2O retention, increase BP - act at distal tubule and collecting duct, increase Na channels; increase Na/K ATPase on basolateral side of cells
Term
ACTH-independent glucocorticoid increase
Definition
Adrenal adenoma/adenocarcinoma or increased consumption of glucocorticoids - adrenal gland atrophy, low plasma ACTH
Term
ACTH-dependent increase glucocorticoids
Definition
Pituitary adenoma overproducing ACTH (Cushing disease) or paraneoplastic syndrome
Term
Cushing Syndrome symptoms
Definition
Increased protein metabolism, glucose mobilization, lipolysis, fat redeposition, immune suppression, striae rubrae, muscle weakness, tissue wasting, hyperglycemia not reversed by insulin
Term
Cushing Disease
Definition
Benign pituitary adenoma secreting ACTH - ACTH will be increased, excess glucocorticoids mainly
Term
Paraneoplastic syndrome
Definition
Hypersecreting adenoma, cancer patient with a 2nd benign tumor in lungs leading to ACTH increased secretion
Term
Adrenal cortex adenoma affecting glucocorticoids
Definition
Negative feedback will still be intact so ACTH decreased but increased glucocorticoids
Term
Chronic glucocorticoid consumption
Definition
Negative feedback still intact so ACTH will be low but Cushing disease present due to increased glucocorticoids
Term
Addison Disease - Primary insufficiency
Definition
Autoimmune deficiency, ACTH high due to reduced negative feedback; ACTH and alpha-MSH high so darker skin color; decreased hair growth in females (low androgens); glucocorticoid or aldosterone deficiency
Term
Symptoms of glucocorticoid deficiency
Definition
Hypotension, hypoglycemia, fatigue
Term
Symptoms of aldosterone deficiency
Definition
Hyperkalemia, salt craving, altered cardiac function
Term
Addison disease - Secondary insufficiency
Definition
Pituitary ACTH deficiency, ACTH low, aldosterone not affected because under control of renin-angiotensin system - slow onset during stress leading to Addisonian crisis - need cortisol replacement and administration of fluids/glucose
Term
Addisonian crisis
Definition
Slow onset of adrenal cortex hormone insufficiency during time of stress; no glucocorticoids leads to hypotension, acute circulatory failure, need cortisol replacement and administration of fluids and glucose
Term
Primary aldosteronism
Definition
Conn's tumor secreting aldosterone leads to increased ECF volume, mild hypertension, hypokalemia, metabolic acidosis (H ions secreted)
Term
Secondary aldosteronism
Definition
Over-produced renin or stenosis of renal artery
Term
Adrenal medulla hormone storage
Definition
Norepinephrine and epinephrine are stored in chromaffin cells; 90% secrete Epinephrine, 10% secrete epinephrine; product released by ACh stimulation
Term
Chromaffin cell innervation
Definition
Multiple ganglionic cholinergic sympathetic nerve fibers into chromaffin cells; some release dopamine but not stored
Term
Synthesis of catecholamines progression
Definition
Tyrosine --> Dopa (by tyrosine hydroxylase-rate-limiting)
Dopa --> Dopamine --> Norepinephrine --> Epinephrine
Term
Timing for Epi/Norepi effects
Definition
10-30 seconds; weaker for few minutes; short half-life; no negative feedback regulation by hypothalamus of pituitary
Term
Hemodynamic effects of adrenal medulla hormones
Definition
Increase HR, cardiac output, BV tone, ECF volume, increase BP, dilate coronary vessels, contract skin vessels
Term
Metabolic effects of adrenal medulla hormones
Definition
Similar to glucocorticoids, stimulate glycogenolysis and gluconeogenesis; epinephrine is 10x more active at these processes
Term
Catecholamine degradation
Definition
MAO and COMT act on Epi and Norepi, eventually excreted as vanillylmandelic acid (VMA)
Term
Pheochromocytoma
Definition
Benign tumor of chromaffin cells in adrenal medulla
Symptoms: sweat, pallor, palpitations, increase BP
Diagnosis: increased VMA in urine, treat with adrenergic a-receptor blockers until surgical resection
Term
Catecholamine underproduction
Definition
Rest of nervous system compensates but can reveal underlying autonomic dysfunction - postural hypotension, e.g.
Term
Hormones secreted by beta cells of pancreas
Definition
C-peptide, amylin, insulin
Term
Blood supply of endocrine pancreas
Definition
Center of islet --> periphery --> capillary --> portal vein with secreted hormones (somatostatin thus will not inhibit insulin from beta cells)
Term
Endocrine pancreas innervation
Definition
Sympathetic and parasympathetic fibers with cholinergic stimulation to increase insulin secretion
Term
Pancreatic polypeptide
Definition
Secretion stimulated by gastric distension, vagal stimulation, nutrients; inhibited by hyperglycemia and somatostatin; activate Y4 receptor, reducing gastric emptying time, affects motility of upper intesine
Term
Amylin
Definition
Co-secreted with insulin; post-prandial inhibition of glucagon, reduces gastric motility to help clear glucose from blood
Term
Why is measuring insulin unreliable?
Definition
50-60% endogenous insulin immediately extracted by liver, some exogenous insulin as well; C-peptide is much more reliable
Term
A1C test
Definition
Test for glycosylated hemoglobin, significantly increased in DM; glycosylation is irreversible and RBC live for 4 months so it is reliable indicator of average plasma glucose levels, try to keep <7%
Term
Insulin stimulation to oral glucose
Definition
Greater magnitude due to incretin effect (increased beta-cell sensitivity) - rapid and massive insulin increase
Term
Insulin stimulation to IV glucose
Definition
Biphasic - first rapid peak and slower more prolonged peak, no incretin; release all stored and then synthesize more; possible 3rd phase after 1.5-3 hours, can last up to 48 hours - diabetic has slow increase in insulin for many hours
Term
Glucose entering beta cell of pancreas
Definition
GLUT2 receptor --> G6P by glucokinase --> oxidize to ATP --> close K channels --> depolarize --> open Ca channels --> exocytose granules with insulin
Term
Sulfonylureas
Definition
Block K channels, control extent and timing of insulin release for individuals with Type 2 Diabetes Mellitus
Term
Insulin release stimulators
Definition
Hyperglycemia, amino acids, acute LCFA, incretin, gastrin, secretin, GIP, CCK, acetylcholine, sulfonylureas
Term
Insulin release inhibitors
Definition
Somatostatin, norepinephrine, epinephrine, long-term LCFA
Term
alpha-adrenoreceptor stimulation
Definition
Decrease cAMP, inhibit insulin release - stress for mobilizing glucose to produce energy
Term
beta-adrenoreceptor stimulation
Definition
Induce cAMP release to stimulate insulin release
Term
Glucagon release stimulators
Definition
Hypoglycemia, amino acids (protein meal), acetylcholine, norepinephrine, epinephrine
Term
Glucagon release inhibitors
Definition
Fatty acids, somatostatin, insulin
Term
CHO vs. protein meal effect on I,G
Definition
CHO meal - high insulin, low glucagon
Protein meal - high insulin, high glucagon
Term
Protein Tyrosine Phosphatase 1B
Definition
deP'ylate and inactivate IR - insulin downregulates its own receptor by inducing this degradation - downregulation of IR leads to some reduced sensitivity to insulin seen in obesity and DM type II
Term
Lipoprotein lipase
Definition
Help FA go from blood to adipose, target for insulin, leads to storage of FA, no lipolysis
Term
Glucagon target cells
Definition
Primarily liver, also adipose, NOT MUSCLE; enter liver by portal vein; only acts on adipose at low insulin level
Term
Stimulation of glucagon receptor on beta cell
Definition
cAMP increases leading to insulin secretion from beta cell
Term
Stimulation of insulin receptor on alpha cell
Definition
cAMP decreases leading to inhibition/decrease in glucagon secretion
Term
Diabetes Type I symptoms
Definition
Hyperglycemia, polyuria, dehydration, polydipsia, eat more food, weightloss
Untreated: renal failure, erectile dysfunction, blindness, peripheral nerve lesions; increased rate of atherosclerosis
Term
DM Type I
Definition
Reduced/absent Insulin secretion; glucago predominates; immune-mediated destruction of beta cells (1A), lack of glucose can lead to ketoacidosis
Term
DM Type II progression
Definition
Normal insulin secretion in response to glucose --> reduced sensitivity of insulin receptor --> develop hyperglycemia --> pancreas increase insulin release --> reduced responsiveness to insulin (irreversible)
Term
Insulin resistance
Definition
Decreased glucose transport and metabolism in skeletal muscle and adipocytes, impaired suppression of hepatic glucose
Term
Ketoacidosis in DM
Definition
Common in DM Type I, rare in DM Type II; Type I generally progresses faster
Term
Ca levels and binding amounts
Definition
9.0-10.5 mg/dL (2.3-2.6 mM) - 50% free ionized 40% protein-bound, 10% complex with anions - equilbrium
Term
Effect of phosphate, citrate, acidosis, alkalosis on free Ca
Definition
More phosphate - less free Ca (crash injury)
More citrate - less free Ca (transfusion)
Acidosis - more free Ca
Alkalosis - less free Ca (hyperventilation)
Term
Ca roles
Definition
Nerve and muscle excitation, muscle contraction, enzyme function, bone mineral balance
Term
Phosphate roles
Definition
Bone structure, pH buffer
Term
PTH vs. Vitamin D effect on Ca levels
Definition
PTH involved in short-term regulation
Vitamin D involved in long-term regulation
Term
Ca and phosphate levels, what happens if increased
Definition
Both near saturation point, increases can lead to precipitate or calcifications
Term
PTH
Definition
84 aa hormone synthesized and secreted by chief cells in parathyroid gland (where oxyphils present too)
Term
PTH half-life
Definition
2-4 minutes; rapidly metabolized
Term
PTH activation
Definition
Secreted in non-mature form, further metabolism by liver to separate, N-terminus active - can go affect bone and kidney
Term
PTH roles
Definition
Increase bone resorption, increase renal Ca absorption at distal tubule, decrease phosphate resorption from proximal and distal tubule, increase synthesis of Vitamin D
Term
Calcium Sensing Receptor (CASR)
Definition
Detects reduction of circulating free Ca ions in plasma, leading to increased PTH secretion; mutations lead to diseases including familial hypocalciuric hypercalcemia
Term
Metals with effects on PTH secretion
Definition
Lithium stimulates PTH, Mg and Ca can stimulate or inhibit; Aluminum inhibits PTH
Term
PTH receptors
Definition
GPCRs increasing cAMP, increase IP3, Ca - also bind PTHrP which can be secreted by some tumor cells to increase bone turnover to make from for metastasis
Term
PTH action on bone
Definition
Activate GPCR on osteoblast to produce RANK-L and IL-6 - stimulate resorption of osteoclasts; chronic elevation inhibits bone formation in osteoblasts; intermittent PTH stimulates osteoblasts to produce bone matrix
Term
PTH on kidney
Definition
Ca resorption on distal convoluted tubule, much faster increase of blood Ca than bone resorption but 90% Ca recovered in proximal convoluted tubule with no PTH
Term
PTH on Vitamin D
Definition
Stimulate 1,25 hydroxylase to convert Vitamin D to most active metabolite
Term
Vitamin D3 transformation
Definition
Circulate bound to proteins, 1,25 hydroxylase in liver, and stored in adipose and muscle; further hydroxylated in kidney by 1,25 hydroxylase stimulated by PTH; active form is calcitriol
Term
1,25 hydroxylase stimulators
Definition
PTH during hypocalcemia, estrogens, prolactin, GH
Term
Vitamin D action
Definition
steroid hormone with Type 2 receptor, 1000x greater affinity in active form, complex with Retinoic acid X receptor --> heterodimeric TF binding, VDRE includes calbindin
Term
Vitamin D roles
Definition
Increase intestinal absorption of Ca and phosphate, stimulate maturation of osteoclast progenitor, inhibit PTH synthesis (negative feedback), weak positive reabsorption of Ca and phosphate in kidney
Term
Vitamin D in gut
Definition
Increase duodenum Ca absorption from 10% to 70% - direct opening of Ca channels on surface of intestinal cells
Term
Vitamin D in bone
Definition
Stimulate osteoblast cytokine production, osteoclast progenitors mature and enhance bone osteoclast degradation; increase osteoblast bone matrix formation (through osteopontin and osteocalcin)
Term
25-OH D-24-hydroxylase
Definition
Stimulated by increased calcitriol, induces biodegradation of Vitamin D (negative feedback), synthesized by enhanced PTH
Term
Calcitonin
Definition
32 aa peptide made by parafollicular C-cells of thyroid to reduce Ca and phosphate levels in blood - uses same CASR to detect calcium levels
Term
Calcitonin roles
Definition
Direct inhibition of osteoclast bone resorption, excrete Ca and phosphate from kidney, therapeutic use to fight osteoporosis; deficiency has no effect on Ca levels
Term
Osteoporosis
Definition
Reduced total bone mass which can be due to Ca diet deficiency, Vitamin C deficiency, reduced mechanical stress and advanced age
Term
Hypercalcemia
Definition
Often seen in primary hyperparathyroidism
Symptoms: Inotropic effect, HTN, mental confusion, salt and pepper skull
Term
Hypocalcemia
Definition
Hypoparathyroidism of crash injury (mass phosphate release)
Symptoms: hyperreflexia, muscle cramps, tingling, twitching (tetany)
Trousseau Sign and Chvostek Sign
Term
Trousseau sign
Definition
Keep BP cuff above arterial pressure for 3 minutes, generate contraction, opposition of thumb, contraction of joints if hypoparathyroidism
Term
Chvostek sign
Definition
Tap emergence of facial nerve at angle of jaw - look for contraction of same side in upper lips - test for hypoparathyroidism
Supporting users have an ad free experience!