Term
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Definition
| pores in cell membrane allow signaling molecules, nutrients, and electrolytes to move from cell to cell |
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Term
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Definition
| released from neurons to travel across synaptic cleft to second cell |
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Term
| paracrine (local) hormones |
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Definition
| secreted into tissue fluids to affect nearby cells |
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Term
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Definition
| chemical messengers that travel in the bloodstream to other tissues and organs; chemical messengers that are transported by the bloodstream and stimulate physiological responses in cells of another tissue or organ, often a considerable distance away |
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Term
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Definition
| glands, tissues, and cells that secrete hormones |
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Term
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Definition
| the study of this system and the diagnosis and treatment of its disorders |
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Term
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Definition
–have ducts carry secretion to an epithelial surface or the mucosa of the digestive tract –‘external secretions’
–extracellular effects (food digestion) |
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Term
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Definition
–no ducts
–contain dense, fenestrated capillary networks which allows easy uptake of hormones into bloodstream
–‘internal secretions’
–intracellular effects such as altering target cell metabolism
-organs that are traditional sources of hormones |
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Term
| Comparison of Nervous and Endocrine Systems (Differences) |
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Definition
•both serve for internal communication
•speed and persistence of response
•adaptation to long-term stimuli
•area of effect |
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Term
| both serve for internal communication |
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Definition
–nervous-both electrical and chemical
–endocrine-only chemical |
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Term
| speed and persistence of response |
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Definition
–nervous-reacts quickly (1 -10 msec), stops quickly
–endocrine-reacts slowly (hormone release in seconds or days), effect may continue for weeks |
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Term
| adaptation to long-term stimuli |
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Definition
–nervous-response declines (adapts quickly)
–endocrine-response persists (adapts slowly) |
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Term
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Definition
–nervous-targeted and specific (one organ)
–endocrine-general, widespread effects (many organs) |
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Term
| Nervous and Endocrine Systems (Similarities) |
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Definition
•several chemicals function as both hormones and neurotransmitters
•some hormones secreted by neuroendocrine cells (neurons) that release their secretion into the bloodstream
•both systems with overlapping effects on same target cells
•systems regulate each other
–neurons trigger hormone secretion
–hormones stimulate or inhibit neurons
•target organs or cells |
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Term
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Definition
| those organs or cells that have receptors for a hormone and can respond to it |
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Term
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Definition
| •regulates primitive functions of the body from water balance and thermoregulation to sex drive and childbirth |
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Term
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Definition
| suspended from hypothalamus by a stalk |
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Term
| Pituitary Gland (Hypophysis) |
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Definition
•composed of two structures with independent origins and separate functions
–adenohypophysis (anterior pituitary)
–neurohypophysis (posterior pituitary) |
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Term
| adenohypophysis (anterior pituitary) |
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Definition
| arises from hypophyseal pouch (outgrowth of pharynx) |
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Term
| neurohypophysis (posterior pituitary) |
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Definition
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Term
| FSH (follicle stimulating hormone) |
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Definition
| •stimulates secretion of ovarian sex hormones, development of ovarian follicles, and sperm production |
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Term
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Definition
| •stimulates ovulation, stimulates corpus luteum to secrete progesterone, stimulates testes to secrete testosterone |
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Term
| TSH (thyroid stimulating hormone) |
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Definition
| –stimulates secretion of thyroid hormone |
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Term
| ACTH (adrenocorticotropic hormone) |
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Definition
| –stimulates adrenal cortex to secrete glucocorticoids |
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Term
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Definition
| –after birth stimulates mammary glands to synthesize milk, enhances secretion of testosterone by testes |
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Term
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Definition
–stimulates mitosis and cellular differentiation
•induces liver to produce growth stimulants
–insulin-like growth factors (IGF-I) or somatomedins (IGF-II)
•stimulate target cells in diverse tissues |
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Term
|
Definition
•present in fetus; absent in adult
•produces melanocyte stimulating hormone in animals influencing pigmentation of skin, hair, or feathers |
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Term
| Posterior Pituitary Hormones |
|
Definition
•produced in hypothalamus
–transported by hypothalamo-hypophyseal tract to posterior lobe
–releases hormones when hypothalamic neurons are stimulated
•ADH (antidiuretic hormone)
•OT (oxytocin) |
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Term
| ADH (antidiuretic hormone) |
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Definition
–increases water retention thus reducing urine volume and prevents dehydration
–also called vasopressin because it can cause vasoconstriction |
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Term
|
Definition
–stimulates labor contractions during childbirth
–stimulates flow of milk during lactation
–promotes emotional bonding between lactating mother and infant |
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Term
| Control of Pituitary Secretion |
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Definition
•rates of secretion are not constant
–regulated by hypothalamus, other brain centers, and feedback from target organs |
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Term
| Hypothalamic and Cerebral Control |
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Definition
–anterior lobe control
–posterior lobe control
•neuroendocrine reflex |
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Term
|
Definition
| releasing hormones and inhibiting hormones from hypothalamus |
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Term
|
Definition
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Term
|
Definition
| hormone release in response to nervous system signals |
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Term
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Definition
| increased target organ hormone levels inhibits release of hormones |
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Term
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Definition
| stretching of uterus increases OT release, causes contractions, causing more stretching of uterus, etc. until delivery |
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Term
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Definition
| by mobilizing fatty acids for energy, GH produces glucose-sparing makes glucose available for glycogen synthesis and storage |
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Term
|
Definition
| promotes Na+, K+, & Cl- retention by kidneys, enhances Ca+2 absorption in intestine |
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Term
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Definition
-attached to roof of third ventricle beneath the posterior end of corpus callosum
–tiny mass of shrunken tissue in adults
•may synchronize physiological function with 24-hour circadian rhythms of daylight and darkness
•may regulate timing of puberty in humans |
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Term
|
Definition
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Term
|
Definition
•plays a role in three systems: endocrine, lymphatic, and immune
•bilobed gland in the mediastinum superior to the heart
–goes through involution after puberty
•site of maturation of T cells important in immune defense
•secretes hormones (thymopoietin, thymosin, and thymulin) that stimulate development of other lymphatic organs and activity of T-lymphocytes |
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Term
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Definition
| •largest endocrine gland •thyroid follicles secretes thyroxine (T4 because of 4 iodine atoms) and triiodothyronine (T3) –T4 which is converted to T3 –increases metabolic rate, O2 consumption, heat production (calorigenic effect), appetite, growth hormone secretion, alertness and quicker reflexes |
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Term
|
Definition
| •secrete parathyroid hormone (PTH) –increases blood Ca2+ levels |
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Term
|
Definition
•small gland that sits on top of each kidney
•they are retroperitoneal like the kidney |
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Term
|
Definition
–inner core, 10% to 20% of gland
•has dual nature acting as an endocrine gland and sympathetic ganglion of sympathetic nervous system
–when stimulated release catecholamines (epinephrine and norepinephrine) and a trace of dopamine directly into the bloodstream
•effect is longer lasting than neurotransmitters
–increases alertness and prepares body for physical activity
–increases blood pressure, heart rate, blood flow to muscles, pulmonary air flow and metabolic rate
–decreases digestion and urine production |
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Term
|
Definition
•surrounds adrenal medulla and produces more than 25 steroid hormones called corticosteroids or corticoids
•secretes 5 major steroid hormones from three layers of glandular tissue
–zona glomerulosa
–zona fasciculata
–zona reticularis |
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Term
|
Definition
•thin, outer layer
•cells are arranged in rounded clusters
•secretes mineralocorticoid |
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Term
|
Definition
•thick, middle layer
•cells arranged in fascicles separated by capillaries
•secretes glucocorticoids |
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Term
|
Definition
•narrow, inner layer
•cells in branching network
•secretes sex steroids |
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Term
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Definition
| regulate the body’s electrolyte balance |
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Term
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Definition
–regulate metabolism of glucose and other fuels
–helps body adapt to stress and repair tissues
–anti-inflammatory effect becomes immune suppression with long-term use |
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Term
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Definition
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Term
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Definition
| sets libido throughout life; large role in prenatal male development (includes DHEA which other tissues convert to testosterone) |
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Term
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Definition
| small quantity, but important after menopause for sustaining adult bone mass; fat converts androgens into estrogen |
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Term
| Adrenal Gland Interactions |
|
Definition
•medulla and cortex of adrenal gland are not functionally independent
–they stimulate the cortex to secrete corticosteroids when stress activates the sympathetic nervous system |
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Term
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Definition
•1-2 million pancreatic islets (Islets of Langerhans) produce hormones
–other 98% of pancreas cells produces digestive enzymes
•insulin secreted by B or beta cells
–secreted during and after meal when glucose and amino acid blood levels are rising
–stimulates cells to absorb these nutrients and store or metabolize them lowering blood glucose levels
–insufficiency or inaction is cause of diabetes mellitus (Type 1 diabetes) |
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Term
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Definition
-secreted by A or alpha cells
–also released to rising amino acid levels in blood, promotes amino acid absorption, and provides cells with raw material for gluconeogenesis |
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Term
|
Definition
-secreted by D or delta cells
–partially suppresses secretion of glucagon and insulin
–inhibits nutrient digestion and absorption which prolongs absorption of nutrients |
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Term
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Definition
-raise blood glucose concentration
–glucagon |
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Term
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Definition
-lowers blood glucose
–insulin |
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Term
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Definition
| both endocrine and exocrine |
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Term
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Definition
–whole cells
-eggs and sperm (cytogenic glands) |
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Term
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Definition
-gonadal hormones
–mostly steroids |
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Term
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Definition
| –estradiol, progesterone, and inhibin |
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Term
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Definition
–testosterone, weaker androgens, estrogen and inhibin
–testosterone and other steroids from interstitial cells (cells of Leydig) nestled between the tubules
•stimulates development of male reproductive system in fetus and adolescent, and sex drive
•sustains sperm production
–inhibin from sustentacular (Sertoli) cells
•limits FSH secretion in order to regulate sperm production |
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Term
|
Definition
•after ovulation, the remains of the follicle becomes the corpus luteum
–secretes progesteronefor 12 days following ovulation
–follicle and corpus luteum secrete inhibin |
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Term
| functions of estradiol and progesterone |
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Definition
–development of female reproductive system and physique including adolescent bone growth
–regulate menstrual cycle, sustain pregnancy
–prepare mammary glands for lactation |
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Term
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Definition
| where microscopic seminiferous tubules produce sperm |
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Term
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Definition
| keratinocytes convert a cholesterol-like steroid into cholecalciferol using UV from sun |
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Term
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Definition
–involved in the production of at least five hormones
–converts cholecalciferol into calcidiol
–secretes angiotensinogen (a prohormone)
•precursor of angiotensin II (a regulator of blood pressure)
–secretes 15% of erythropoietin (stimulates bone marrow)
–hepcidin –promotes intestinal absorption of iron
–source of IGF-I that controls action of growth hormone |
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Term
|
Definition
| –plays role in production of three hormones –converts calcidiol to calcitriol, the active form of vitamin D •increases Ca2+ absorption by intestine and inhibits loss in the urine –secrete renin that converts angiotensinogen to angiotensin I •angiotensin II created by converting enzyme in lungs –constricts blood vessels and raises blood pressure –produces 85% of erythropoietin •stimulates bone marrow to produce RBCs |
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Term
|
Definition
| •stimulates bone marrow to produce RBCs |
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Term
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Definition
| –cardiac muscle secretes atrial (ANP and BNP) and brain natriuretic peptides in response to an increase in blood pressure –decreases blood volume and blood pressure by increasing Na+ and H2O output by kidneys –opposes action of angiotensin II –lowers blood pressure |
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Term
| stomach and small intestine |
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Definition
| secrete at least ten enteric hormones secreted by enteroendocrine cells |
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Term
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Definition
-secretes leptin
–slows appetite |
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Term
|
Definition
–osteocalcin secreted by osteoblasts
–increases number of pancreatic beta cells, pancreatic output of insulin, and insulin sensitivity of other body tissues |
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Term
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Definition
–secretes estrogen, progesterone and others
•regulate pregnancy, stimulate development of fetus and mammary glands |
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Term
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Definition
| •all hormones are made from either cholesterol or amino acids with carbohydrate added to make glycoproteins |
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Term
| Hormone Synthesis: Steroid Hormones |
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Definition
| •synthesized from cholesterol – differs in functional groups attached to 4-ringed steroid backbone |
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Term
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Definition
-Protein based
•synthesized in same way as any protein
•Golgi does final transformation to hormone packaged for secretion |
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Term
|
Definition
•melatonin is synthesized from amino acid tryptophan
–thyroid hormone is composed of 2 tyrosines |
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Term
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Definition
| –absorb iodide (I-) ions from blood and store in lumen as a reactive form of iodine –synthesize thyroglobulin and store in lumen •forms colloid •contains lots of tyrosine –tyrosine and iodine combine to form thyroxine (T4) bound to thyroglobulin –stored in follicle
•TSH
–95% (T4) and 5% (T3) |
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Term
|
Definition
•most monoamines and peptides are hydrophilic
•steroids and thyroid hormone are hydrophobic
–transport proteins protect circulating hormones from being broken down by enzymes in the plasma and liver, and from being filtered out of the blood by the kidneys
–more than 99% of circulating TH is protein bound |
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Term
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Definition
•hormones stimulate only those cells that have receptors for them
•receptors are protein or glycoprotein molecules:
–on plasma membrane, in the cytoplasm, or in the nucleus
•receptors act like switches turning on metabolic pathways when hormone binds to them
•usually each target cell has a few thousand receptors for a given hormone
•receptor-hormone interactions exhibit specificity and saturation |
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Term
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Definition
–penetrate plasma membrane and enter nucleus
–take several hours to days to show effect due to lag for protein synthesis |
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Term
|
Definition
| –cannot penetrate into target cell |
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Term
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Definition
| •thyroid hormone enters target cell by diffusion –mostly as (T4) with little metabolic effect
•within target cell, (T4) is converted to more potent (T3)
•(T3) enters target cells and binds to receptors in chromatin
•activates genes |
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Term
| Peptides and Catecholamines: Hydrophilic |
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Definition
•hormone binds to cell-surface receptor
•activates or inhibits enzymes
•metabolic reactions:
–synthesis
–secretion
–change membrane potentials |
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Term
|
Definition
•hormones are extraordinarily potent chemicals
•one hormone molecule can trigger the synthesis of many enzyme molecules
•very small stimulus can produce very large effect |
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Term
| Modulation of Target Cell Sensitivity |
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Definition
•target cell sensitivity adjusted by changing the number of receptors
•up-regulation
•down-regulation |
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Term
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Definition
-means number of receptors is increased
–sensitivity is increased |
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Term
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Definition
-reduces number of receptors
–cell less sensitive to hormone
–happens with long-term exposure to high hormone concentrations |
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Term
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Definition
•most cells sensitive to more than one hormone and exhibit interactive effects
•synergistic effects
•permissive effects
•antagonistic effects |
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Term
|
Definition
–multiple hormones act together for greater effect
•synergism between FSH and testosterone on sperm production |
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Term
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Definition
–one hormone enhances the target organ’s response to a second later hormone
•estrogen prepares uterus for action of progesterone |
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Term
|
Definition
–one hormone opposes the action of another
•insulin lowers blood glucose and glycogen raises it |
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Term
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Definition
•most hormones are taken up and degraded by liver and kidney
•metabolic clearance rate (MCR)
–rate of hormone removal from the blood
–half-life
–faster the MCF, the shorter is the half-life |
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Term
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Definition
| time required to clear 50% of hormone from the blood |
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Term
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Definition
-caused by any situation that upsets homeostasis and threatens one’s physical or emotional well-being
•injury, surgery, infection, intense exercise, pain, grief, depression, anger, etc |
|
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Term
| general adaptation syndrome (GAS) |
|
Definition
–the consistent way body reacts to stress –typically involves elevated levels of epinephrine and glucocorticoids (especially cortisol)
–occurs in three stages:
1. alarm reaction
2. stage of resistance
3. stage of exhaustion |
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Term
|
Definition
•initial response
•mediated by norepinephrine from the sympathetic nervous system and epinephrine from the adrenal medulla
–prepare body to fight or flight
–stored glycogen is consumed
–increase in aldosterone and angiotensin levels
•angiotensin helps raise blood pressure
•aldosterone promotes sodium and water conservation |
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Term
|
Definition
•provide alternate fuels for metabolism
•stage dominated by cortisol
•pituitary secretes an increase in ACTH
–stimulates the adrenal cortex to secrete cortisol and other glucocorticoids
–promotes the breakdown of fat and protein into glycerol, fatty acids, and amino acids –for gluconeogenesis |
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Term
|
Definition
•when stress continues several months, and fat reserves are gone, homeostasis is overwhelmed
–marked by rapid decline and death
•protein breakdown and muscle wasting
•loss of glucose homeostasis because adrenal cortex stops producing glucocorticoids
•aldosterone promotes water retention and hypertension
–conserves sodium and hastens elimination of K+ and H+
–hypokalemia and alkalosis leads to death
•death results from heart and kidney infection or overwhelming infection |
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Term
|
Definition
-chemical messengers that diffuse short distances and stimulate nearby cells
–unlike neurotransmitters not produced in neurons
–unlike hormones not transported in blood
•a single chemical can act as a hormone, paracrine, or even neurotransmitter in different locations
–histamine
–nitric oxide
–somatostatin
–catecholamines |
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Term
|
Definition
•from mast cells in connective tissue
•causes relaxation of blood vessel smooth muscle |
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Term
|
Definition
| •from endothelium of blood vessels, causes vasodilation |
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Term
|
Definition
| •from gamma cells, inhibits secretion of alpha and beta cells |
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Term
|
Definition
| •diffuse from adrenal medulla to cortex |
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Term
|
Definition
–important family of paracrines
–derived from fatty acid called arachidonic acid |
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Term
|
Definition
| •mediates allergic and inflammatory reactions |
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Term
|
Definition
| •inhibits blood clotting and vasoconstriction |
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Term
|
Definition
| •stimulates vasoconstriction and clotting |
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Term
|
Definition
|
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Term
|
Definition
| relaxes smooth muscle in bladder, intestines, bronchioles, uterus and stimulates contraction of blood vessels |
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Term
|
Definition
|
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Term
|
Definition
•cortisol and corticosterone
•disadvantage –produce symptoms of Cushing syndrome
•aspirin, ibuprofen, & celecoxib (Celebrex)
•useful in treatment of fever and thrombosis |
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Term
|
Definition
–inadequate hormone release
–tumor or lesion destroys gland or interferes with its ability to receive signals from another gland
•autoantibodies fail to distinguish gland from foreign matter |
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Term
|
Definition
–excessive hormone release
–tumors or autoimmune disorder |
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Term
|
Definition
| tumor of adrenal medulla secretes excessive epinephrine and norepinephrine |
|
|
Term
| toxic goiter (graves disease) |
|
Definition
| autoantibodies mimic effect of TSH on the thyroid causing thyroid hypersecretion |
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Term
|
Definition
| any pathological enlargement of the thyroid gland |
|
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Term
|
Definition
| •dietary iodine deficiency, no TH, no -feedback, increased TSH stimulates hypertrophy |
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Term
|
Definition
-excess cortisol secretion
–rapid muscle and bone loss due to protein catabolism |
|
|
Term
| adrenogenital syndrome (AGS) |
|
Definition
| –enlargement of external sexual organs in children and early onset of puberty |
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Term
|
Definition
•most prevalent metabolic disease in world
–disruption of metabolism due to hyposecretion or inaction of insulin
–symptoms:
•polyuria, polydipsia, and polyphagia
•revealed by elevated blood glucose, glucose in urine and ketones in the urine |
|
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Term
|
Definition
–limit to how fast the glucose transporters can work to reabsorb
–excess glucose enters urine and water follows it
•causes polyuria, dehydration, and thirst |
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Term
|
Definition
|
|
Term
|
Definition
|
|
Term
|
Definition
|
|
Term
| Types of Diabetes Mellitus |
|
Definition
-Type 1 (IDDM) –5 to 10% of cases in US
-Type 2 (NIDDM) –90 to 95% of diabetics
–problem is insulin resistance |
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Term
|
Definition
| failure of target cells to respond to insulin |
|
|
Term
|
Definition
| cells cannot absorb glucose, must rely on fat and proteins for energy needs -weight loss and weakness |
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|
Term
| chronic pathology (chronic hyperglycemia) |
|
Definition
| –leads to neuropathy and cardiovascular damage from atherosclerosis and microvascular disease |
|
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Term
|
Definition
| nerve damage from impoverished blood flow can lead to erectile dysfunction, incontinence, poor wound healing, and loss of sensation from area |
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