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OAT Biology
Endocrine and reproductive system
| Term | Definition |
|---|---|
| endocrine glands | synthesizes and secrete hormones directly into the circulatory system |
| exocrine glands | secrete substances transported by ducts |
| hypothalamus | - regulatory center of the endocrine system - part of the forebrain and located directly above the pituitary gland - responds through secretions of hormones from neurosecretry cells -hormones regulate pituitary gland secretions via negative feedback |
| gonadotropin releasing hormone (GnRH) | - stimulates the anterior pituitary to secrete follicle stimulating hormone (FSH) and luteinizing hormone (LH) |
| releasing hormones of the hypothalamus | - stimulate or inhibit the secretions of the anterior pituitary - are secreted into the hypophyseal portal system |
| negative feeback | product of the pathway inhibits its own production |
| corticotropin-releasing factor/hormone (CRF/CRH) | - when the plasma levels of adrenal cortical hormones drop - signals the pituitary cells to release ACTH |
| thyrotropin-releasing hormone (TRH) | stimulates the anterior pituitary to release thyroid hormones T3 and T4 |
| growth hormone-releasing hormone (GHRH) | stimulates the anterior pituitary to release growth hormone |
| pituitary gland (hypophysis) | a small trilobed gland at the base of the brain below the hypothalamus and is connected to the infundibulum |
| infundibulum | contains both the hypophyseal portal system and neurosecretory axons connecting the hypothalamus to the posterior pituitary gland |
| anterior pituitary | sythesizes both direct hormones which act on their target organs |
| tropic hormones | stimulate other endocrine glands to release hormones |
| follicle-stimulating hormone (FSH) (tropic) | - in women causes maturation of ovarian follicles which secrete estrogen - in men stimulates maturation of seminiferous tubules and sperm production |
| luteinizing hormone (LH) (tropic) | - in women, LH stimulates ovulation and maintenance of the corpus luteum - LH is responsible for regulating progesterone secretion in women - in men, LH stimulates the interstitial cells of the testes to synthesize testosterone |
| adrenocorticotropic hormone (ACTH) (tropic) | stimulates the adrenal cortex to synthesize and secrete glucorticoids and regulated by corticotropin-releasing factor |
| thyroid-stimulating hormone (TSH) (tropic) | stimulates the thyroid gland to synthesize and release thyroid hormones, thyroxine (T4) and triiodothyronine (T3) |
| prolactin (direct hormone) | stimulates milk production in female mammary glands |
| endorphins (direct hormone) | neurotransmitters that have pain-relieving proporties |
| growth hormone (GH) (direct) | - promotes bone and muscle growth - promotes protein synthesis and lipid mobilization and catabolism |
| melanocyte-stimulating hormone (MSH) (direct) | - secreted by the intermediate lobe of the pituitary - in mammals, plays a role in tanning - in amphibians, causes darkening of the skin to better camouflage |
| posterior pituitary | does not synthesize hormones - stores and releases the peptide hormones oxytocin and ADH |
| oxytocin | - secreted during childbirth increases the strength and frequency of the uterine muscle contractions - stimulates milk secretion in the mammary glands |
| postive feedback loop | product of a system increases its own synthesis |
| antidiuretic hormone (ADH) | - increases water permeability in the collecting duct of the nephron - secreted when plasma osmolarity increases - regulated in a negative feedback manner |
| corticosteroids | - bound to transport transcortins - exert their action by determining which gene is transcribed in the nuclei |
| gluocorticoids | - cortisol and cortisone - involved in glucose regulation protein metabolism - raise blood glucose levels by promoting protein breakdown, gluconeogenesis, and decreasing protein synthesis - antagonistic to the effects of insulin |
| mineralcorticoids | - regulate plasma levels of sodium and potassium -stimulated by angiotensin II and inhibited by ANP |
| angiotensin II | regulated by the lung and kidney are sensitive to blood pressure changes |
| atrial natriuretic peptide (ANP) | produced by the heart and serves as another regulator of blood pressure |
| androgens | - male sex hormones - secreted from the adrenal cortex in small quantities in both men and women - in men, most are produced by the testes - in women, overproduction has masculinizing effects such as excessive facial hair |
| epinephrine (adrenaline) | - increases the conversion of glycogen to glucose in liver and muscle tissue - increase in blood glucose levels and increase in the basal metabolic rate - increase rate and strength of the heartbeat and dilute and constrict blood vessels |
| norepinephrine (noradrenaline) | - increase rate and strength of the heartbeat and dilute and constrict blood vessels - promote the release of lipids by adipose tissue |
| thyroid | - controlled by TSH which stimulates TRH - releases triiodothyronine (T3) and thyroxine (T4) |
| thyroxine (T4) and triiodothyronine (T3) | - formed from the glycoprotein thyroglobulin - T3 is 5x more potent than T4 - are transported via plasma proteins - all of the T4 in the body is formed and secreted by the thyroid gland (only 20% of T3 is produced by the thyroid) |
| hypothyroidism | thyroid hormones are under-secreted or not secreted at all - slowed heart rate and respiratory rate - fatigue - cold intolerance - weight gain - low levels of metabolism |
| hyperthyroidism | thyroid hormones overstimulated - increased metabolic rate - excessive warmth - profuse sweating - palpitations - weight loss - protruding eyes |
| calcitonin | - decreases plasma Ca2+ concentration by inhibiting the release of Ca2+ from bone and promoting the storage of Ca2+ in bones |
| gonads | - GnRH from the hypothalamus acts on the anterior pituitary to release gonadotropins |
| gonadotropins | - LH and FSH - in men, act on the testes to produce testosterone and foster the maturation of sperm cells - in females, causes the secretion of estrogen and progesterone |
| parathyroid glands | - four small pea-shaped structures embedded in the posterior surface of the thyroid - synthesize and secrete parathyroid hormone (PTH) |
| parathyroid hormone (PTH) | - regulates plasma Ca2+ concentration - raises the Ca2+ concentration in blood by simulating Ca2+ release from the bone and decreasing Ca2+ excretion in the kidneys |
| islets of langerhans | - small glandular structures - composed of alpha and beta cells - alpha produces and secrete glucagon - beta produce and secrete insulin |
| glucagon | - peptide hormone in the pancreas - released when blood glucose levels are low - stimulates protein and fat degradation - conversion of glycogen to glucose and gluconeogenesis |
| insulin | - protein hormone in the pancreas - secreted in response to a high blood glucose concentration - acts on glucose transporters on the cell membrane of liver, muscle, and adipose cells - stimulates of fats from glucose and the uptake of amino acids |
| renin | an enzyme that converts the plasma protein angiotensinogen to angiotensin I |
| erythropoietin (EPO) | glycoprotein that stimulates red blood cell production |
| sexual reproduction | - occurs via the fusion of two gametes - the production of functional sex cells by adult organisms - the union of these cells form a zygote - the development of the zygote into another adult completes the cycle |
| gametogenesis | the production of gametes |
| testes | - produce sperm in tightly coiled seminiferous tubules - located in the scrotum - external pouch maintains temperature at 2°C to 4°C lower than the body temperature |
| ovaries | produce oocytes (eggs) |
| spermatogenesis | sperm production occurs in seminiferous tubules |
| oogenesis | egg production occurs in the ovaries |
| fertilization | union of the egg and sperm nuclei to form a zygote with a dipoid number of chromosomes |
| internal fertilization | - practiced by terrestrial vertebrates and provides a direct route for sperm to reach the egg cell - increases the chance for fertilization success and females produce fewer eggs |
| epididymis | - where sperm cells mature - a structure resting atop of testes |
| pathway of sprem through the male reproductive system | seminiferous tubules --> epididymis --> vas deferens --> ejaculatory duct --> urethra --> penis |
| sertoli cells | - located in the seminiferous to support the development of maturing sperm cells - FSH acts on these cells |
| leydig cells | - stimulate testosterone production in the testes - LH acts on these cells |
| testosterone | - a steroid hormone - produced in the testes and induces secondary male sex characteristics including facial and pubic hairs also voice changes - induces male sexual differetiation for embryogenesis |
| primary spermatocytes | - undergos meiotic division - diploid cells |
| secondary spermatocytes | - two haploid cells - secondary meiotic division |
| spermatids | - four haploid - undergo a final series changes that increase their mobility resulting in mature sperm |
| acrosome | - caplike structure derived from the Golgi apparatus - contains enzymes needed to penetrate the tough outer covering of the ovum |
| spermatoza | mature sperm |
| follicles | multilayered sac of cells that contains, nourishes, and protects an immature ovum |
| ovulation | once a month, an immature ovum is released from the ovary into the abdominal cavity drawn by cilia into the fallopian tube |
| primary oocytes | - immature ova - diploid cells that form by mitosis in the ovary - one primary oocyte per month completes meiosis I yielding two daughter cells of unequal size |
| secondary oocyte | - a polar body of unequal size expelled from the follicle during ovulation |
| estrogens | - a steroid hormone necessary for normal female maturation - stimulate the development of female reproductive tract, contribute to the development of secondary characteristics and influence libidio - responsible for the thickening of the endometrium |
| progesterone | - a steroid hormone secreted by the corpus luteum along with estrogen during the luteal phase of the menstrual cycle - stimulates the development and maintenance of the endometrium in preparation for implantation |
| follicular phase | - focuses on the follicle, specifically the growth of the follicle - begins with the cessation of menses results in a decrease in progestrone |
| ovulation | - caused by a surge in LH - a peak in estrogen levels - women ovulates approx 1 every 4 weeks until menopause |
| luteal phase | - LH levels are relatively high but begin to drop due to hormone interaction with corpus luteum - the more progesterone the less LH is present causing degradation of the corpus luteum triggering menstruation |
| menstruation | - not fertilized ovum the corpus luteum atrophies due to a decrease in LH - drop in progestrone and estrogen levels causes the utrine line with superficial blood vessels to shed giving rise to the menstrual flow |
| human chorionic gonadotropin (hCG) | - a LH analog - maintains the corpus luteum ensuring a continuous supply of estrogen and progesterone needed to maintain the uterus |
| fertilization | - an egg can be fertilized during the 12-24 hours after ovulation - often occurs in the lateral widest portion of the fallopian tube - sperm must travel through the vagianl canal, cervix, uterus, into the tubes to reach the ovum |
| acrosomal process | - occurs when sperm is in contact with the ovum - sperm forms a tubelike structure |
| cortical reaction | - acrosomal reaction triggers it - causing calcium ions to be released into the cytoplasm |
Created by:
Jalisa.bland
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