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VET 113- Anatomy + F
Ch. 11- Endocrine System
Term | Definition |
---|---|
Endocrine Gland | ductless glands that secrete hormones directly into the bloodstreem |
Endocrinology | study of the endocrine system |
Hormones | chemical messengers secreted directly into blood vessels, produce effects at specific receptors in or on cells. |
Negative Feedback System | when specific hormone levels drop below needed levels, the appropriate endocrine gland is stimulated to produce more hormone, when levels reach normal production stops. |
Nervous System and Hormone Secretion | some endocrine glands use stimulation by the nervous system, uses the sympathetic nervous system (fight or flight). |
Major Endocrine Glands | -hypothalamus, pituitary gland (anterior and posterior pituitary), thyroid, parathyroid, adrenal gland (cortex and medulla), kidney, pancreas, gonads (testes and ovaries). |
Hypothalamus | part of the diencephalon (area of brain before brain stem), involved in appetite control, body temp reg, wake-sleep cycles. Controls the pituitary gland and has a portal system of blood vessels in anterior portion. Links conscious mind to body. |
Hypothalamus and the Anterior Pituitary | modified neurons secrete releasing and inhibiting factors. |
Hypothalamus and the Posterior Pituitary | modified neurons secrete ADH & Oxytocin. Hormones are stored in the posterior pituitary and are released into the bloodstream by nerve impulses from hypothalamus. |
Pituitary Gland | 2 separate glands w different structures, functions, and embryological origins |
Anterior Pituitary | Stimulated by hypothalamus and direct feedback from target organs and tissues to produce its hormones |
Posterior Pituitary | stores and releases hormones produced in hypothalamus |
Growth Hormone (GH) | known as somatotropin and somatotropic hormone. Part of the anterior pituitary, promotes growth in young animals and helps regulate metabolism. |
Prolactin | anterior pituitary hormone that triggers and maintains lactation. Production/release continues while teat is stimulated by nursing/milking. Mammary glands shrink once stimulation and milk production stops. |
Thyroid-Stimulating Hormone (TSH) | anterior pituitary hormone that deals w the growth and development of the thyroid gland. Secretion is regulated by feedback from the thyroid gland. |
Adrenocorticotropic Hormone (ACTH) | anterior pituitary hormone that deals w the growth and development of the adrenal cortex. Regulated by negative feedback from adrenal hormones. Can have a temporary override by nervous system during sudden stress. |
Follicle-Stimulating Hormone (FSH) | anterior pituitary hormone that is in males and females. Females- growth/development ovarian follicles, produces/secretes estrogen. Male- stimulates spermatogenesis |
Luteinizing Hormone (LH) | anterior pituitary hormone in males and females. Females- follicle maturation, ovulation, lutenization (corpus luteum developed). Male- testosterone productions by interstitial cells. |
Female FSH and LH | |
Male FSH and LH | |
Melanocyte-Stimulating Hormone (MSH) | anterior pituitary hormone that deals w color chnages in the pigment cells (melanocytes) of reptiles, fish, and amphibians. |
Posterior Pituitary | responsible for the anti-diuretic hormone and oxytocin. Stored in nerve endings (from Hypothalamus) and periodically released into the bloodstream in response to nerve impulses from hypothalamus. |
Antidiuretic Hormone (ADH) | pituitary hormone, receptors in hypothalamus detect changes in osmotic pressure of blood that results from dehydration/hemoconcentration. Causes kidneys to absorb more water > goes to bloodstream. |
Oxytocin | pituitary hormone that causes uterus to contract myometrium at breeding/parturition and stimulates uterine contractions. Also causes milk letdown in mammary glands |
Thyroid Gland | gland that is 2 lobes on either side of the larynx, hormones are produced in follicular cells. |
Thyroid Hormone Effects | -development of CNS, muscles, bones -regulates metabolic rate -metabolism of proteins, carbohydrates, and lipids similar to GH |
Calcitonin | maintains blood calcium levels, prevents hypercalcemia. |
Calcium Effects | -muscle contraction -blood clotting -milk secretion -formation/maintenance of the skeleton |
Parathyroid Hormone (PTH) | posterior pituitary gland that is known as parathormone, maintains blood calcium levels to prevent hypocalcemia. Are small pale nodules on/in/near the thyroid glands |
Adrenal Glands | located on the cranial pole of the kidneys. Has 2 glands, adrenal cortex and adrenal medulla |
Adrenal Cortex | produces steroid hormones (glucocorticoids, mineralocorticoids, and sex hormones). |
Glucocorticoids | hormone that has a hyperglycemic effect, maintains blood pressure, and resists the effects of stress. Ex. cortison, cortisol, corticosterone |
Mineralocorticoids | hormone that regulates electrolytes (mineral salts) ex. aldosterone |
Adrenal Medulla | hormone that develops from nervous tissue, controlled by the sympathetic nervous system. "fight or flight," increases heart rate and blood pressure, dilates air passageways in the lungs, decreases GI function. |
Pancreas | near the duodenum, controls exocrine and endocrine functions. Uses pancreatic islets (alpha cells, beta cells, delta cells). |
Insulin | a pancreatic hormone that lowers blood glucose, and aids in absorption of glucose, AA, and FA |
Glucagon | a pancreatic hormone that raises blood glucose levels, stimulates livers cells to convert glycogen to glucose, and stimulates gluconeogenesis (glucose production). |
Somatostatin | a pancreatic hormone that inhibits secretion of insulin, glucagon, and GH; diminishes GI activity |
Testes | this uses spermatogenesis. Testosterone is the primary androgen. |
Ovaries | controlled by follicle stimulating hormone (FSH) and lutenizing hormone (LH). Produces ova in cycles. Produces estrogen and progestins |
Estrogens | |
Progestins | produced by corpus luteum. High LH stimulates cells of ovulated follicle to multiply and develop corpus luteum. Progesterone is the principal progestin |
Kidneys | responsible for erythropoietin (red blood cell production). Production is stimulated by hypoxia, stimulates red bone marrow to increase production of red blood cells. |
Stomach | gastrin is produced on the wall of this. It is stimulated by presence of food, stimulates gastric glands to secrete hydrochloric acid and digestive enzymes, encourages muscular contractions of stomach wall. |
Secretin | hormone in the small intestine. Secretion occurs in response to presence of chyme (food) in duodenum. Stimulates pancreas to release sodium bicarbonate fluid to neutralize acidic chyme. |
Cholecystokinin | hormone in the small intestine. Secretion occurs in response to presence of chyme (food) in duodenum, stimulates pancreas to release digestive enzymes. |
Placenta | surrounds the fetus during pregnancy. Acts as interface with maternal circulation. Produces hormones to help support/maintain pregnancy (estrogen, progesterone, and chorionic gonadotropin in some species). |
Thymus | extends cranially from the level of heart into neck region, both sides of trachea in young animals, atrophies later in life. Develops the immune system. |
Pineal Body | influences cyclic activities, produces melatonin. Located in caudal end of the cleft that separates the 2 cerebral hemispheres. |
Prostaglandins | produced in a variety of body tissues, hormone-like substances derived from unsaturated fatty acids. Influence blood pressure and clotting, inflammation, GI, respiratory, reproductive, and kidney function |