Chapter 18 Continued
Chapter 18 Continued BIOL 224
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This 7 page Class Notes was uploaded by Gail Chernomorets on Saturday September 10, 2016. The Class Notes belongs to BIOL 224 at University of Nevada - Las Vegas taught by Sean Neiswenter in Fall 2016. Since its upload, it has received 139 views. For similar materials see Human Anatomy and Physiology II in Biology at University of Nevada - Las Vegas.
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Date Created: 09/10/16
09/08 Chapter 18 cont’d Hypothalamic Control of the Anterior Lobe • Releasing hormone and inhibiting hormone - only from the hypothalamus • Endocrine and nervous system work together - neither one controls the other • Maintain very minimal fluctuation The Pituitary Gland • Thyroid-stimulating hormone (TSH) - aka thyrotropin - regulation • thyrotropin-releasing hormone (TRH) - function • to stimulate the release of thyroid hormones from the thyroid gland • Adrenocorticotropic hormone (ACTH) - aka corticotropin - regulation • the release in response to corticotropin-releasing hormone (CRH) from the hypothalamus - function • stimulates release of glucocorticoids by the adrenal cortex → secretes numbers of steroids → sugar metabolism ex. cortisol • Follicle-stimulating hormone (FSH) - aka follitropin - releasing hormone is gonadotropins - regulation • release in response to gonadotropin-releasing hormone (GnRH) from the hypothalamus - function • promote follicle development and estrogen secretion in females, sperm maturation in males • Luteinizing hormone (LH) - aka lutropin - releasing hormone is gonadotropins - regulation • release in response of gonadotropin-releasing hormone (GnRH) from the hypothalamus - function • promote ovulation and progesterone secretion in females, testosterone secretion in males • Prolactin (PRL) - aka mammotropin - not a tropin hormone - “pro” – before - “lactin” – lactate - chemical messenger - regulations 1. prolactin – releasing factors from the hypothalamus stimulate production 2. prolactin – inhibiting hormone (PIH; dopamine) inhibits production - function • stimulate mammary gland development and milk production ** Levels of prolactin in blood are a part of negative feedback - stimulate release of dopamine • Growth hormone (GH) - aka somatotropin - regulations 1. stimulated by GH-RH from hypothalamus 2. release inhibited by growth hormone-inhibiting hormone - function • stimulate cell growth and replication, stimulates production of somatomedins by liver which promote AA uptake and protein synthesis - targets the liver - secretes number of other messengers that lead to growth and development of other tissues ** Figure 18-9 • Look over as good reference for pituitary hormones • MSH - stimulate hormone - no significant levels in adults - important in kids - seen in pregnant women and people with some diseases - high levels in some patients cause over stimulation The Posterior Lobe • aka neurohypophysis • Separately develop from anterior love • More nervous tissue • Contains unmyelinated axons of hypothalamic neurons • Supraoptic and paraventricular nuclei secrete - antidiuretic hormone (ADH) - oxytocin (OXT) • Does not synthesize, stores and secretes Hormones of Posterior Lobe • Antidiuretic hormone (ADH) - aka vasopressin • “vaso” – vessel • “pressin” – pressure → increase blood pressure - reduces urination - reduces water loss - mechanism for preventing dehydration - regulates blood solute concentration rises (less water) or blood pressure drops (less volume) - function • decrease water loss at the kidneys • Oxytocin (OXT) - regulation • responds to sensory nerve stimulation - function • tactile stimulation • stimulate smooth muscle contraction in uterus, ductus deferens, and prostate gland → Let down reflex - ejection of milk in females (forces milk from the gland) - plays a role in bonding **Positive Feedback ex. Childbirth & breast-feeding • The more oxytocin released during childbirth the more stretch of the uterus and uterus cervix. When continuously done, more oxytocin gets released until the baby is out • Tactile stimulation causes oxytocin to be released (from baby suckling nipple). Allows milk to be released. Will continue being released until baby lets go • Anything that affects hypothalamus can affect response - anxiety, stress • can prevent milk flow - baby crying • can trigger let down reflex • can trigger lactation • Plays through nervous system stimulation, anything that interferes gets fed through emotions and mood - can affect release of milk The Thyroid Gland • Inferior to thyroid cartilage • 2 lobes connected by isthmus • Thyroid follicles - spheres lined by simple cuboidal epithelium • Follicular cells surround follicle cavity • Colloid contains thyroid hormones - center of large follicle • Hormones (2) - Thyroxine (T4) - Triiodothyronine (T3) ** Produced by follicular cells Functions of Thyroid Hormones • Target = most cells in body • Derived from amino acids • Binds to receptors inside cell - cytoplasm (increases in available ATP) - surfaces of mitochondria - nucleus • Alters metabolism • Increases - energy utilization - oxygen consumption - growth and development - temp in kids ** Metabolic Processes • How they get across membrane - cells have transport molecules so the hormone latches on and moves across it Plasma Proteins • Bind most thyroid hormone in blood - about 0.3% of T3 and 0.03% of T4 are unbound • Not getting cleared out or removed • A lot of hormone put out, a tony amount of everything available - holds steady amount that is available for use → steady level, no fluctuation Calorigenic Effect • Cells consume more energy = increased heat • Increase in rate of cellular metabolism - in children à heat - in adults à burn calories ** Essential for normal growth/development in children - iodine in environment • lack of → developmental issues (children) → overgrown thyroid gland (adults) - TSH isn’t negatively reduced through thyroid hormone (not enough iodine) C (clear) cells • aka parafollicular cells • Produce calcitonin (CT) in response to high Ca levels in bloodstream - inhibits osteoclasts (targets bone) 2+ • slows the 2+te of Ca release from bone - takes Ca out of blood - stimulates Ca excretion by the kidneys • into urine • Work together to lower Ca levels Parathyroid Gland • 4 glands - embedded in the posterior surface of the thyroid gland • Parathyroid hormone (PTH) - aka parathormone - produced by parathyroid (chief) cells in response to low concentrations of Ca 2+ • Antagonist for calcitonin - blood calcium levels to increase Effects of PTH • 3 effects 1. stimulates osteoclasts (breakdown bone) and inhibits osteoblasts (growth of bone) 2+ • releases Ca from bone • reduces rate of calcium deposition in bone 2. enhances reabsorption of Ca in kidneys • reduces urine volume 3. stimulates formation and secretion of calcitriol by the kidneys • targets kidneys as well • Ca , PO 4bsorption by digestive tract • enhances PTH effects • increased absorption and release of other hormones Thyroid and Parathyroid • Antagonistic relationship with same goal to maintain blood calcium levels ** Figure 18-3 Possible essay question • Negative feedback Adrenal Glands • Superior to kidneys • 2 portions • Adrenal cortex - mostly cholesterol - stores lipids - manufactures corticosteroids • Adrenal medulla - secretory activities controlled by sympathetic division of ANS - produces epinephrine and norepinephrine • “fight or flight” • Neurological • Hypothalamus controls directly through sympathetic stimulation Cortex • 3 zones -zona glomerulosa -zona fasciculate -zona reticularis (all have different roles) • zona glomerulosa ** think salt - alter mineral concentration - produces mineralocorticoids • steroid hormones that affect electrolyte composition of body fluids - outer level • mineral composition ex. aldosterone + + → stimulates conservation of Na and elimination of K - reabsorption of sodium from urine • Presence of aldosterone - sodium in, potassium out • zona fasciculate - produces glucocorticoids • sugar • steroid hormone that affect (alter) glucose metabolism ex. cortisol - makes you fat - ACTH (anterior pituitary) stimulates secretion increase glucose synthesis and glycogen formation in the liver • causes glucose to be synthesized by liver - stimulate glucose – sparing in peripheral tissues • cells stop using glucose as primary source of energy • start burning fatty acids → lead to elevated glucose level for nervous system - show anti-inflammatory effects • when stressed • inhibits white blood cells and other immune functions → causes cold sore • stress hormone and takes over role of epinephrine once it is done • zona reticularis - minor role in adults - produces androgens under stimulation by ACTH • promotes bone and muscle growth as well as blood cell formation in women and children ex. mustache, chin hair • excessive production of hair on females - not important in adult men • negligible • men have testes for this purpose - role in sex development • especially in children and adolescents → signs of puberty Adrenal Medulla • Contains 2 types of secretory cells • One produces epinephrine (adrenaline) - 75% to 80% of medullary secretions • Other produces norepinephrine (noradrenaline) - 20% to 25% of medullary secretions Epinephrine and Norepinephrine (common in asthma inhalers) & (“fight or flight” response) • In skeletal muscles - mobilization of glycogen reserves, making sugar available for source of energy - acceleration of glucose metabolism • In adipose tissue - lipids are broken down and released into the bloodstream • free fatty acids - larger amounts of energy available • In the liver - main storage of glucose - glycogen molecules are broken down and glucose is released into the bloodstream - major storage of sugar in other tissues except skeletal (has own) • In the heart - increase in the rate and force of cardiac muscle contraction • response - increase blood pressure and movement of blood • In the lungs - allows more air flow The Pineal Gland • Pine cone shape • Lies in posterior portion of roof of third ventricle • Contains pinealocytes • Synthesize hormone melatonin - made by pinealocytes - role in sex, seasonality, sleep • Functions - inhibits reproductive functions • through negative feedback • via FSH/LH - protect against damage by free radicals • antioxidant - influence circadian rhythms • photosensitive entrainment (tired at night) • Decartes’ - seasonal affective disorder • no melatonin shut off in places that are always light ex. Alaska - high in children **stimulation of receptors of light causes pineal gland to be turned off
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