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Physiology Ch.
Endocrine System
| Term | Definition |
|---|---|
| Endocrine glands are: | Ductless, and secrete hormones to be transported throughout body for internal secretion |
| Endocrine glands are very well _______. | Vascularized |
| Normal blood glucose level | 70/110 mg/dL |
| Target cells | Cells with specific receptors for hormone |
| Only cells with ______ are affected by hormone. | Specific receptor |
| Cell-cell communication is through | Gap junctions |
| Paracrine communication | Release chemical to nearby cells (local factors) |
| Endocrine communication | Throughout body |
| Neurological communication | In brain and at neuromuscular junction |
| Synergistic | Combination of hormones have a greater effect on target cell Ex: ADH and aldosterone (both cause body to store water) |
| Antagonistic | When two hormones provide opposite effects |
| Permissive | One hormone is required for another to work Ex: TH for GH |
| Ligands | Chemical messengers that bind to receptors |
| Hormonal stimulation | When hormone binds to get another released |
| Humeral stimulation | When target cell responds to a change in blood or nutrient chemical concentration |
| Nervous stimulation | Gland releases hormone when neuron stimulates it (no receptor is needed) |
| ____ and ____ hormones increase metabolism | TSH and TH |
| Receptors on target cells are _____, so they are affected by ____, ____, and _____. | Proteins, heat, tonicity, pH |
| Steroids | Lipid soluble molecules synthesized from cholesterol. Can pass directly through membrane and has receptors INSIDE cell/nucleus. Ex: gonadal steroids (estrogen and testosterone) |
| Because circulating steroid hormones are ________ in ______, they remain in circulation ____ than peptide hormones. | Bound to specific transport proteins, blood plasma, longer |
| Biogenic amines | Modifies amino acids including catecholamines, melatonin, and thyroid hormone (TH). Are water soluble EXCEPT for TH. |
| Protein hormones | Most hormones. Water soluble with receptors ON/IN cell MEMBRANE. |
| Local hormones | Don't circulate in blood; autocrine or paracrine signaling |
| Eicosanoids | Local hormone formed from fatty acids in phospholipid bilayer of membrane Ex: prostaglandins |
| Eicosanoid creation process | Phospholipase A2 generates arachidonic acid from phospholipids, then the acid is converted to specific eicosanoids by enzymes (postaglandins, thromboxanes, leukotrienes) |
| _______ hormones use carrier proteins because they ____ dissolve readily into blood. | Lipid-soluble, don't |
| Bound hormone | 90% of hormones, attached to carrier protein |
| Unbound (free) hormone | Able to exit blood and bind to target molecule (not attached to carrier protein) |
| Hormone release and its concentration in blood are _____ coorelated | Positively |
| Ways to eliminate hormones | Removed from blood by kidneys or degraded by enzymes in liver. |
| Half-life | Amount of time required to reduce hormone concentration by half |
| Water soluble hormones have a ____ half-life, steroids have a ______ half-life. | Short, long |
| Hormone-receptor complex | Formed when lipid-soluble hormone enters cell and binds to receptor |
| Hormone-response element (HRE) | Part of DNA the hormone-receptor complex binds to in order to generate a PROTEIN--which may have structural or metabolic effects |
| Water-soluble hormones use _______ receptors, lipid soluble do not. | Membrane |
| Signal transduction pathway (water soluble) | 1. Hormone binds to membrane receptor 2. Binding activates G-protein 3. G-protein activates membrane enzyme to catalyze formation of second messenger |
| G-protein | Internal membrane protein that binds to guanine nucleotide. Used in water-soluble signal transduction pathway |
| Second messenger | Chemical that modifies cellular activity |
| Adenylate cyclase | Enzyme activated by G-protein that generates cAMP as a second messenger |
| cAMP | Second messenger activated by adenylate cyclase that activates a protein kinase to phosphorylate other molecules |
| Protein kinase | Activated by cAMP to phosphorylate other molecules |
| Intracellular enzyme cascade | Where signal is AMPLIFIED with each enzymatic step, and has many places to be regulated |
| A cells response to hormone depends on _______, and its _______. | Number of receptors for hormone, simultaneous response to different hormones |
| Presence of functional receptor is an ______ requirement for hormone function. | Absolute |
| Number of receptors on a cell _____ change. | Can |
| Upregulation | Stimulating hormone induces increased formation of receptor molecules. Target tissue becomes more receptive to hormone. |
| Downregulation | Increased hormone concentration and increased binding with receptors makes there be less active receptors. |
| High levels of hormone cause: | Downregulation of receptors |
| Low levels of hormone cause: | Upregulation of receptors |
| Hypothalamus | Controls pituitary gland and produces oxytocin and ADH |
| Pituitary gland | Controls thyroid, adrenal, liver, testes, and ovaries |
| Posterior pituitary gland | Smaller, neural part of pituitary; where hypothalamic neurons project through infundibulum and release hormones. Storage and release site for oxytocin and ADH. |
| Somas of hypothalamic neurons going to posterior pituitary are in: | Paraventricular and supraoptic nuclei |
| Axons of hypothalamic neurons going to posterior pituitary are in: | Hypothalamo-hypophyseal tract of infundibulum |
| Anterior pituitary gland | Where hypothalamo-hypophseal portal system of blood vessels connect with hypothalamus. Has primary and secondary plexi. Release FLAGToP hormones. |
| Primary plexus | Porous capillary network of hypothalamus drained by hypophyseal portal veins |
| Secondary plexus | Capillary network of anterior pituitary fed by hypophyseal portal veins |
| Hypophyseal portal veins | Drain primary plexus and transports to secondary plexus |
| FLAGTOP anterior pituitary hormones | Follicle-stimulating hormone Luteinizing hormone Adrenocorticotropic hormone Growth hormone Thyroid-stimulating hormone MelanOcyte stimulating hormone Prolactin |
| Hypothalamus produces: | Releasing hormones |
| Neurosecretory cells | Cells in hypothalamus that make ADH and oxytocin and secretes it in response to neuron impulses |
| Antidiuretic hormone (ADH) | Made in supraoptic nucleus of hypothalamus. Decreases urine production, increases thirst, and constricts blood vessels |
| Oxytocin | Made in paraventricular nucleus of hypothalamus. For uterine contraction, milk ejection, and emotional bonding |
| Hypothalamus ______ stimulates anterior pituitary gland to release it hormones using _______. Anterior pituitary hormones go to ______. | Hormonally, regulatory hormones, general circulation |
| Releasing hormones | From hypothalamus. 5: TRH, PRH, GnRH, CRH, and GHRH. Increase secretion of anterior pituitary hormones (RH=releasing hormone) |
| Inhibiting hormones | From hypothalamus. 2: PIH and GIH (IH=inhibiting hormone), Decreases secretion of anterior pituitary hormones |
| Thyroid-stimulating hormone (TSH) | Anterior pituitary hormone triggered by TRH and causes release of TH from thyroid gland |
| Prolactin (PRL) | Anterior pituitary hormone triggered by PRH and inhibited by PIH. Causes milk production and mammary gland growth in females |
| Andrenocorticotropic hormone (ACTH) | Anterior pituitary hormone triggered by CRH. Causes release of corticosteroids by adrenal cortex |
| Gonadotrophins | Anterior pituitary hormones FSH and LH, release triggered by GnRH. Females: regulates ovarian development and secretes estrogen and progesterone Males: Sperm development and secretion of testosterone |
| Growth hormone (GH) | Anterior pituitary hormone triggered by GHRH and inhibited by GHIH. Causes liver to secrete insulin-like growth factors 1 and 2 (IGF's). |
| Amount of growth hormone is impacted by: | Age, nutrients, exercise, time of day, stress |
| _____ cells have receptors for GH, IGF's, or both. | All |
| Glycogenolysis | Breakdown of glycogen, stimulated by GH/IGF's |
| Gluconeogenesis | Breakdown of nutrients to glucose, stimulated by GH/IGF's |
| Lipolysis | Breakdown of triglycerides, stimulated by GH/IGF's |
| Glycogenesis | Synthesis of glycogen, inhibited by GH/IGF's |
| Lipogenesis | Formation of triglycerides, inhibited by GH/IGF's |
| Thyroid gland | Has L&R lobes with narrow isthmus at midline. Wraps around trachea |
| Follicular cells | Cuboidal epithelium of thyroid gland that surrounds central lumen and synthesizes thyroglobulin (producing TH) |
| Thyroglobulin | Synthesized by follicular cells of thyroid gland to produce thyroid hormone (TH) once attached to iodine |
| Colloid | Viscous, protein-rich fluid in follicular cells |
| Parafollicular cells | Cells between follicles of thyroid that makes calcitonin |
| _____ is attached to thyroglobulin in _____ of thyroid follicles, which eventually causes ___ and ___ to be released. | Iodine, colloid, T3, T4 |
| Hypothalamic-pituitary-thyroid axis | Due to things like cold, pregnancy, or low TH, hypothalamus releases TRH which causes anterior pituitary gland to release TSH, which binds to follicular cells to release TH |
| Follicular cells release ____ forms of TH into blood: ____ and ____. | Two, T3, T4 |
| Thyroid gland produces more ____ than _____, but ____ is the more active form. | T4, T3, T3 |
| TH increases _______ and _______. Is also ______: i.e. generates heat to raise temperature | Metabolic rate, protein synthesis, calorigenic |
| TH functions: | ATP production (greater glycogenolysis and gluconeogenesis), More lipolysis and less lipogenesis for glucose-sparing effect, increases respiratory rate and HR. |
| Glucose-sparing effect | Done by TH to save glucose for brain's neurons. |
| Calcitonin | Synthesized and released form parafollicular cells of thyroid in response to increased blood calcium or exercise. Makes kidneys filter more calcium into urine and inhibits osteoclast activity. |
| Most people have ____ parathyroid glands. | 4 |
| Parathyroid glands | Small structures on back of thyroid gland that contains chief and oxyphil cells to make PTH |
| Parathyroid hormone (PTH) | Released in response to lower blood calcium and accelerates conversion to calcitriol in kidney, release of calcium from bone by osteoclasts, kidneys excrete less calcium in urine, and calcitriol only increases absorption of calcium in SI. |
| Calcitriol | Accelerated production by kidney due to PTH, increases absorption of calcium in SI. |
| Adrenal glands | On superior surface of each kidney. Retroperitoneal with two regions |
| Adrenal medullary glands | Inner core of adrenal gland that releases epinephrine and norepinephrine with sympathetic stimulation |
| Adrenal cortex | Outer part of adrenal gland where many hormones and corticosteroids are produced. Regions are zona glomerulosa, zona fasciculation, and zona reticularis |
| Mineralocorticoids | Adrenal cortex hormone made in zona glomerulosa to regulate electrolyte levels Ex: Aldosterone stimulates Na+ retention and K+ secretion |
| Zona glomerulosa | Outer zone of adrenal cortex just inside outer capsule that is responsible for controlling salts (via mineralocorticoids) |
| Glucocorticoids | Adrenal cortex hormone made in zona fasciculata that regulates blood sugar Ex: Cortisol increases blood sugar |
| Zona fasciculata | Between zona glomerulosa and zona reticularis in adrenal cortex responsible for sugar regulation (glucocorticoids) |
| Cortisol | Increases blood sugar, produced in adrenal cortex |
| Gonadocorticoids | Adrenal cortex hormone made in zona reticularis that generates sex hormones (androgens) |
| Zona reticularis | Lowest part of adrenal cortex before it hits adrenal medulla, releases sex hormones |
| Androgens | Male sex hormones that convert to estrogen by females |
| _____ and ______ increase nutrient levels in blood. | Cortisol, corticosterone |
| Cortisol release is regulated by: | Hypothalamic-pituitary-adrenal axis |
| Cortisol uses ______ in blood and is regulated by _____ feedback. | Carrier proteins, negative |
| Pancreas | |
| Pancreatic islets | Contain clusters of endocrine cells (alpha and beta) |
| Alpha cells | In pancreatic islets, secrete glucagon to raise blood glucose |
| Beta cells | In pancreatic islets, secrete insulin to lower blood glucose |
| Insulin | Produces by pancreatic beta cells, makes glycogenesis occur |
| Some cells ____ require insulin to take up glucose: ____, _____, ______, and _____. | Don't, neurons, kidneys, hepatocytes, red blood cells |
| Two primary hormones to regulate blood calcium | Calcitriol and PTH |
| Vitamin D to calcitriol process | 1. UV light converts specific type of cholesterol in SKIN to Vitamin D (cholecalciferol), which is released into blood. 2. Vitamin D circulates throughout body -> calcidiol 3. Calcidiol circulates in blood -> calcitriol |
| Calcitriol | Stimulates absorption of calcium from SI into blood |
| ____ increases rate of conversion of Vitamin D to calcitriol | PTH |
| Vitamin D is converted to calcidiol by: | Liver enzymes |
| Calcidiol is converted by calcitriol by: | Kidney enzymes |
| Vitamin F | Cholecalciferol, made from type of cholesterol by UV light |
| Thymus epithelium | Secretes thymic hormones and is maturation site for T-lymphocytes |
| ANP (antinaturitic hormone) | Secreted by endocrine tissue in HEART atria |
| Erythropoietin | Secretes by kidneys |
| IGFs and angiotensinogen are secreted by: | Liver |
| Secretin and CCK are secreted by: | SI |
| Calcitrol is the ______ hormone that raises blood _____. | Active, calcium |
| Leptin is secreted by | Adipose ct |
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RunningMads
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