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Endo
endocrine
| Term | Definition |
|---|---|
| Endocrine System | regulates long-term processes. Growth, development and reproduction. Uses chemical messengers to relay information and instructions between cells. |
| Hypothalamus | has both neural functions and releases hormones |
| Other tissues produce hormones | adipose cells, pockets of cells in the walls of the small intestine, stomach, kidney and heart |
| Direct communication | exchange of ions and molecules between adjacent cells across gap functions. occurs between two cells of same type. highly specified and relatively rare |
| Paracrine Communication | uses chemical signals to transfer information from cell to cell within a single tissue. Most common form of intercellular communication |
| Autocrine Communication | messages affect the same cells that secrete them. chemicals involved are autocrines. Example: prostaglandins secreted by smooth muscles cells cause the same cells to contract |
| Endocrine Communication | Endocrine cells released chemicals (hormones) into bloodstreams. Alters metabolic activities of many tissues and organs simultaneously |
| Synaptic Communication | ideal for crisis management. Occurs across synaptic clefts. Chemical message is "neurotransmitter". Limited to a very specific area. |
| Endocrine and nervous system | relay on release of chemicals that bind to a specific receptors on target cells. share chemical messenger (norepinephrine and epinephrine). regulated by negative feedback. function to preserve homeostasis by coordination and regulating activities |
| Hormones are | divided into three groups - Amino acid derivates, peptide hormones and lipid derivates. |
| Secretion and distribution of hormones | hormones circulate freely or travel bound to special carrier proteins |
| Amino Acid derivatives | Are small molecules structurally related to amino acids. Derivates of tyrosine (thyroid hormone), catecholamines (epinephrine, norepinephrine and dopamine). Derivatives of tryptophan melatonin (pineal gland) and serotonin) |
| Peptide hormone | are chains of amino acids. most are synthesized as pro hormones - inactive molecules covered to active hormones before or after they are secrete. |
| Glycoproteins | proteins are more than 200 amino acids and have carbohydrate side chains. TSH, LH & FSH |
| Short polypeptides/small proteins | short chain polypeptides - ADH, OXT (each 9 amino acids long). Small proteins - growth hormone (191 amino acids) prolactin (198 amino acid long). Includes all hormones secreted by: hypothalamus, heart, thymus, digestive tract, pancreas, and posterior lobe |
| Lipid derivatives | Eicosanoids - derived from arachidonic acid, a 20 carbon fatty acid processes (such as blood clotting) in extracellular fluids. Leukotrienes have a secondary role as hormones. |
| Prostaglandins | a second group of eicosanoids - involved primarily in coordinating local cellular activities. In some tissue is converted to thromboxane and prostacyclins which have a strong paracrine effects |
| Steroid hormone | derived from cholesterol. includes - androgens from testes in males, estrogen and progesterone from ovaries in female. corticosteroids from the adrenal cortex. calcitriol from kidneys. they circulate longer and secrete peptide hormones. |
| Hormones - transport and inactivation | hormones may circulate freely or travel bound to special carrier protiens |
| Free hormones | remain functional for less than 1 hour. diffuse out of bloodstream and bind to receptors target cells. are broken down and absorbed by cells of liver and kidneys. are brown down by enzymes in plasma or interstitial fluids. |
| thyroid and steroid hormones | remain in circulation much longer because most are "bound". Moran than 99 percent become attached to special transport proteins in blood. equilibrium state exists between free and bond forms. bloodstream contains a substantial reserve of bound hormones |
| Mechanisms of hormone action | binding of a hormone may - alter genetic activity, alter rate of protein synthesis, change membrane permeability |
| Hormone receptor | is a protein molecule to which a particular molecule binds strongly. different tissue have different combinations of receptors. presence or absence of specific receptor determines hormonal sensitivity |
| down regulation | Presence of hormone triggers a decrease in the number of hormone receptors. when levels of a particular hormone are high, cells become less sensitive to it |
| Up-regulation | absence of a hormone triggers an increase in the number of hormone receptors. when levels of a particular hormone are low, cells become more sensitive to it. |
| Hormone receptors | hormones that bind to receptors in a cell membrane (extraceullar receptor): first and second messenger, regulatory G proteins, water soluble hormones |
| Hormone receptors | Hormones that bind to intracellular receptors, - direct gene activation, steroid and thyroid hormones. the precise response depends on the type of target cel |
| Hormones that bind to receptors in the cel membrane - plasma membrane | Catecholamines and peptide hormones - are not lipid soluble, unable to penetrate plasma membrane, bind to receptor proteins at outer surface of plasma membrane (extracellular receptors) |
| Hormones that bind to receptors in the cel membrane - plasma membrane | Steroid and thyroid hormones - are lipid soluble, diffuse across plasma membrane and bind to receptors inside the cell (intracellular receptors) |
| Hormones and extracellular receptors | first and second messengers |
| Hormones and extracellular receptors | First messenger - hormones that bind to extracellular receptor, promotes release of second messenger in cells |
| Hormones and extracellular receptors | Second messenger - intermediary molecule that appears due to hormone - receptor interaction. may act as enzyme activator, inhibitor or cofactor. results in change in rates of metabolic reactions |
| Important second messengers | Cyclic-AMP (cAMP) - derivative of ATP, Cyclic-GMP (cGMP) - derivative of GTP calcium ions |
| Hormone secretion - humoral stimuli | changes in composition of extraceullar fluid, controls hormone secretion by heart, pancreas, parathyroid gland and digestive tract |
| hormone secretion - hormonal stimuli | arrival or removal of specific hormone |
| hormone secretion - neural stimuli | hypothalamus provides highest level of control, arrival of neurotransmitters at neuroglandular junctions |
| Permissiveness | one hormone cannot exert its effects without another hormone being present. Estrogen and thyroid hormone |
| Synergism | More than one hormone produces the same effects on a target cell. Glucagon and epinephrine |
| Antagonism | one or more hormones opposes the active of another hormone. Glucagon and insulin |
| Intergrative | hormones produce different and complementary results. Calcitriol and parathyroid hormone. |
| Nervous system modulation | the nervous system modifies the stimulation of endocrine glands and their negative feedback |
| Nervous system modulation | the nervous system can override normal endocrine controls. for example: control of blood glucose levels. |
| The hypothalamus | provides highest level of endocrine control |
| Pituitary gland | also called hypophysis (lies within sella turacica). hangs inferior to hypothalamus (connected infundibulum). releases 9 important peptide hormones. Hormones bind to extracellular receptors (use cAMP as a secondary messenger) |
| Pituitary gland | divided into anterior lobe and posterior lobe |
| Anterior lobe | also called adenhypophysis. hormones "turned on" endocrine glands to support other organs. Three regions: pars distalis, pars tuberalis, pars intermedia. no direct neural contact with hypothalamus |
| Pituitary - hypothalamic control of anterior lobe | two classes: releasing hormones - stimulate synthesis and secretion of one or more hormone. inhibiting hormones- prevent synthesis and secretion of hormones from anterior lobe. rate of secretion is controlled by negative feedbeck |
| Pars distalis | Tropic hormones - TSH, ACTH, Gonadrotropins - FSH & LH, True hormones - PRL & GH |
| Pars intermedia | MSH |
| TSH | thyrotropin. targets - thyroid gland action - triggers the release of thyroid hormone |
| ACTH | corticotropin target: cells that produce glucocorticoids (hormones that affect glucose metabolism) action: stimulates the release of steroid hormone by the adrenal cortex |
| Gonadotropins | regulates the activities of the GONADS tests in males and ovaries in femals reproduces reproductive cells as well as hormones |
| Hypogondism | abnormally low production of gonadotropins. FSH and LH |
| FSH | follitropin action: promotes follicle development in females, stimulates the secretion of estrogens (estradiol) in combination with LH. stimulates nurse cells in males. Nurse cells promote maturation of sperm target: ovaries & nurse cells |
| LH | Lutropin Action: in females: induces ovulation and promote ovarian secretion of estrogen and progesterone (which prepares the body for a possible pregnancy) in males: stimulates the production of sex hormones androgens target: cells of ovaries & teste |
| PRL | Prolactin action: in females: stimulates mammary gland development. in males: PRL helps regulate androgen by making interstitial cells to LH target: mammary glands |
| GH | somatotropin actions: stimulates cell growth and replication through protein synthesis. skeletal cells and chondrocytes are very sensitive to GH target: all cells |
| MSH | melanotropin (pars intermedia) action: stimulates melanocytes of the skin, increasing their production of melanin in fishes, amphibian and mammals. MSH is inhibited by the release of dopamine |
| Pituitary gland - posterior lobe | also called neurohypophysis contains unmyelinated axons of hypothalamic neurons supraoptic and paraventricular nuclei manufacture: ADH & OXT |
| ADH | vasopressin (VP) action: acts on kidneys to retain water and decrease urination target: kidneys |
| OXT | oxytocin action: in females - smooth muscle contraction (uterus) - labor & delivery males; stimulates smooth muscle contraction of sperm ducts and prostate gland target: uterus, mammary glands, ductus deferens and prostate gland |
| Thyroid gland | largest endocrine gland. consist of two lobes connected by narrow isthmus. thyroid follicles - hollow spheres lined by cuboidal epithelium. surrounded by capillaries, cells absorb iodide ions from blood. follicle cavity contains viscous colloid. |
| Colloid (thyroglobulin + iodine) | fills the lumens of the follicles and is the precursor of thyroid hormone |
| C (clear) cells | parafollicular cells - produce calcitonin |
| Thyroid hormone | major metabolic hormone. consists of T3 and T4 |
| TH | is concerned with glucose oxidation, increasing metabolic rate, heat production |
| TH | plays a role in: maintaining blood pressure, regulating tissue growth, developing skeletal and nervous system, maturation and reproductive capabilities |
| Thyroglbulin | globular protein synesizedn by follicle cells, secreted into colloid of thyroid follicles. contains the Amin acid tyrosine - the building block of thyroid hormones. |
| T4 | tetraiodothyroine - contains 4 iodine atoms |
| T3 | triiodothyronine contains 3 iodine atoms |
| Thyroid hormone effects | elevate oxygen and energy consumption; in children may cause rise in body temperature. increases heart rate and force of contraction. increase sensitivity sympathetic stimulation. |
| Calcitonin | a peptide hormone produced by the parafollicular or C cells. Lowers blood calcium levels in children. Antagonist to PTH. Calcitonin targets the skeleton. |
| Parathyroid glands | four parathyroid glands: embedded in the posterior surface of the thyroid gland. |
| PTH | produced by parathyroid chief cells in response to low concentrations of Ca2+. Antagonist of calcitonin |
| 3 effects of PTH | 1. stimulates osteoclasts and inhibits osteoblasts. 2. enhances reabsorption of Ca2+ at kidneys, reducing urinary loss. 3. stimulates formation and secretion of calcitroil by the kidneys |
| Follicular epithellium | T4 & T3 action: increase energy utilization target: most cells |
| C cells | Calcitonin action: decrease Ca2+ target: bone kidneys |
| Parathyroid (chief) cells | PTH action: increases Ca2+ target: bone, kidneys |
| Adrenal glands | paired, pyramid shaped organs atop the kidneys. |
| Adrenal medulla | neural tissue that acts as part of the ANS (norepinephrine and epinephrine) |
| Adrenal cortex | glandular tissue derived from embryonic mesoderm. Synthesizes and releases steroid hormones called corticosteroids. |
| Three layers of the adrenal cortex | zona glomerulsa - mineralcortioids (mainly aldosterone) zona fasciculata - glucocorticoids (mainly cortisol) zona reticularis - gonadocorticoids (mainly androgens) |
| Zona glomerulosa | mineralocorticoids - regulate electrolytes in extracelular fluids action: increase reabsorption target: kidneys |
| 4 mechanisms of Aldosterone secretion | renin-angiotensin mechanism - kidney release renin which is covered into angiotensin II that in turn stimulates aldosterone release. plasma concentration of sodium and potassium, ACTH, ANP |
| Zona fasciculata | Glucocorticoids (Cortisol) - keeping blood sugar levels relatively constant action: increase rates of glucose target: most cells |
| Zona reticularis | Gonadocorticoids (sex hormones) - produces mainly androgens that are converted to testosterone in the testies. Sex drive in females action: adrenal androgens stimulate pubic hair target: androgens |
| Adrenal medula | made of cells that secrete epinephrine and norepinephrine. blood glucose levels to rise. blood vessels to constrict. the heart beats faster action: cardiac activity target: most cells |
| Pancreas | lies betweenL inferior border of the stomach and proximal position of the small intestine. contains exocrine and endocrine cells |
| Exocrine pancreas | consists of clusters of gland cells called pancreatic acini and their attached duct. Takes up roughly 99% of pancreatic volume. gland and duct cells secrete alkaline, enzyme rich fluid. |
| Endocrine pancreas | consists of cells that form clusters known as pancreatic islets. Alpha cells produce glucagon, beta produce insole, delta produce peptide hormones, F cells secrete PP |
| Blood glucose level | when levels rise: beta cells secrete insulin within, stimulating transport of glucose across plasma membranes. When decrease, alpha cells release glucagon. |
| Glucagon | released by alpha cells, mobilizes energy levels |
| Insulin | is a peptide hormone released by beta cells |
| Alpha cells | Hormone: Glucagon action: mobilizes lipid reveres target: liver |
| Beta cells | Hormone: insulin action: facilities uptake of glucose by target cells target: most cells |
| Delta cells | hormone: GH-IH action: inhibits insulin and glucagon secretion target: other islet cells; digestive |
| F cells | hormone: PP action: inhibits gallbladder contraction target: digestive organs |
| diabetes mellitus | is characterized by glucose concentrations high enough to overwhelm the reabsorption capabilities of the kidneys |
| Hyperglycemia | abnormally high glucose levels in the blood in general |
| Glucose | appears in the urine and urine volumes generally become excessive (polyuria) |
| Type 1 | insulin dependent |
| Type 2 | non-insulin dependent |
| Pineal glands | small gland hanging from the roof of the third ventricle of the brain. day/night cycles |
| Other organs that have secondary endocrine functions | intestines (digestive system), kidneys (urinary system), heart (cardiovascular), thymus (lymphatic system and immunity), gonads (reproductive system) |
| Intestines | action: produce hormones important to coordinate of digestive activities target: other organs of digestive system |
| Kidneys | action: produce the hormone calcitri, produce the hormone EPO, produce the enzyme renin target: red bone marrow |
| Heart | action: produces natriuretic peptides (ANP and BNP) when blood volume becomes excessive target: kidneys, hypothalamus, adrenal gland |
| Thymus | action: produces thymosins (blend of thyme hormones) helps maintain normal immune defenses target: lymphocytes and other cells of the immune system |
| Adipose tissue secretion | action: leptin - appetite control target: hypothalamus |
| Gonads (male) | testes - produce androgens in interstitial sells -testosterone. secrete inhibit in nurse sells - supports differentiation and physical maturation of sperm |
| Gonads (female) | Ovaries - produce estrogens. principal estrogen is estradiol. after ovulation, follicle cells: reorganize into corpus luteum. release estrogen and progestins, especially progesterone |
| Reproductive system | the only system that is NOT essential to the life of the individual. |
| Gonads | are organs that produce gametes and hormones. ducts receive and transport gametes. accessory gland secrete fluids into ducts. |
| External genitalia | perineal structures |
| The reproductive tract | includes all chambers and passageways that connect ducts to the exterior of the body |
| male and female reproductive system | are functionally different, female produces one gamete per month - retains and nurtures zygote. male produce large quantities of gametes - produce 1/2 billion sperm per day |
| male reproductive system | testes or male gonads secrete male sex hormones (androgens) and produce male gametes (sperm) |
| female reproductive system | ovaries or female gonads. release one immature gamete (oocyte/egg) per month and produce hormones |
| Uterine tubes | carry eggs to uterus - if sperm reaches egg, fertilization is initiate and egg matures into ovum |
| Uterus | encloses and supports developing embryo |
| Vagina | connects uterus with exterior |
| meiosis I and meiosis II | produce haploid cell - 23 chromosomes each. Prophase I, Metaphase I, Anaphase I, Telophase |
| Spermatogenesis | occurs in the tests and horses from the hypothalamus, anterior lobe of the pituitary gland, and testes control male reproductive functions |
| Spermatozoa | testes, epididymis, ductus deferens, ejaculatory duct, urethra |
| Accessory organs | secrete fluids into ejaculatory ducts and urethra seminal glands (vesicles), prostate gland, bulbourethral glands |
| External genitalia (male) | scrotum - encloses testes. penis - erectile organ and contains distal portion of urethra |
| Gametes | contain 23 chromosomes. We have 46 chromosomes |
| Male reproductive system | testes produce immobile sperm that are not yet capable of federalizing an egg. |
| Other parts of reproductive system (male) | are responsible for functional maturation, nourishment, storage and transport of sperm |
| Immobile sperm | from testes moved by cilia lining into the epididymis - monitor and adjust composition of fluid produced by seminiferous tubules, recycle damaged sperm, store and protect sperm and facilitate their functional maturation |
| major function of accessory glands (male) | activate sperm, provide nutrients into sperm for motility, propel sperm and fluids along reproductive tract. produce buffers (to counteract acidity of urethral and vaginal environments) |
| SpermaTogenesis | is the process of spermatozoa production. begins at outermost cell layer in seminiferous tubules and proceeds towards lumen. |
| Contents of seminiferous tubules | spermatogonia, spermatocytes at various stages of meiosis, spermatids, spermatozoa, large nurse cells |
| Spermatogonia (stem cells) | divide by mitosis to produce two daughter cells. |
| Primary spermatocytes | begin meiosis and form secondary spermatocytes |
| secondary spermatocytes | differentiate into spermatids (immature gametes) |
| Spermatids | differentiate into spermatozoa |
| Spermatozoa | (sperm) lose contact with wall of seminiferous tubule. enter fluid in lumen |
| Spermatogenesis | begins at puberty; it is a continuous process; all stages of meiosis are seen in the seminiferous tubules and complete process takes 64 days. 1. mitosis, meiosis, spermiogenesis |
| SpermiOgenesis | is the last step of spermatogenesis. beings with spermatids. each spermatid matures into sperm attached to cytoplasm of nurse cells (process takes 24 hours) |
| Spermiation | at permeation a spermatozoon loses attachment to nurse cells and enters lumen of seminiferous tuble |
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