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Anatomy 2 Ch1

Endocrine system or whatever

QuestionAnswer
Hormones help regulate: extracellular fluid, metabolism, biological clock. contraction of cardiac & smooth muscle, glandular secretion, some immune functions, Growth & development, Reproduction
Exocrine glands secrete products into ducts which empty into body cavities or body surface–[sweat, oil, mucous, & digestive glands]
Endocrine glands secrete products (hormones) into bloodstream– [pituitary, thyroid, parathyroid, adrenal, pineal]
other organs that secrete hormones as a 2nd function hypothalamus, thymus, pancreas,ovaries,testes, kidneys, stomach, liver, small intestine, skin, heart & placenta
Hormones only affect ___ with specific membrane proteins called ____ target cells;receptors
Receptors are constantly being ... synthesized and broken down.
Down-regulation excess hormone leads to a decrease in number of receptors; receptors undergo endocytosis and are degraded–decreases sensitivity of target cell to hormone
Up-regulation deficiency of hormone leads to an increase in the number of receptors–target tissue becomes more sensitive to the hormone
Circulating hormones Go everywhere in body; circulate
Local hormones paracrines, autocrines
paracrines Adjacent cells alerted
Autocrine cell that releases the hormone is also the target cell
Lipid-soluble hormones: steroids, thyroid hormones, and nitric oxide [Cortisol and thyroxine]
Water-soluble hormones: amines; peptides, proteins, glycoproteins, and eicosanoids. [Insulin and TSH]
Protein hormones circulate in free form in blood. -Why? They stay in circulatory system and aren’t exited from body by means like urination
Steroid (lipid) & thyroid hormones must... attach to transport proteins synthesized by liver
Why Lipid & thyroid hormones attach to transport proteins improve transport by making them water-soluble, slow loss of hormone by filtration within kidney, create reserve of hormone
free fraction only 0.1% to 10% of hormone is not bound to transport protein
When hormones bind to receptors, cells may then... synthesize new molecules, change permeability of membrane, alter rates of reactions
Hepatocytes: Majority of liver cells. Cells are involved in: Protein synthesis. Protein storage. [insulin stimulates glycogenesis]
Adipocytes: Cell specialized for the storage of fat, found in connective tissue. [insulin stimulates triglyceride synthesis]
Action of Lipid-Soluble Hormones Hormone diffuses through phospholipid bilayer & into cell •Binds to receptor turning on/off specific genes•New mRNA is formed & directs synthesis of new proteins•New protein alters cell’s activity
Water-soluble hormones alter cell functions by ... activating plasma membrane receptors, which set off a cascade of events inside the cell.
The water-soluble hormone that binds to the cell membrane receptor is... the first messenger
A second messenger (usually cAMP) ... is released inside the cell where hormone stimulated response takes place.
Order of events in water-soluble hormone Hormone binds to receptor, Receptor activates G-protein insides cell, G-protein activates cAMP
Amplification of Hormone Effects example Single molecule of hormone binds to receptor•Activates 100 G-proteins•Each activates an adenylate cyclase molecule which then produces 1000 cAMP•Each cAMP activates a protein kinase, which may act upon 1000’s of substrate molecules
Permissive effect Asecond hormone, strengthens the effects of the first [ex:thyroid strengthens epinephrine’s effect upon lipolysis]
Synergistic effect– two hormones acting together for greater effect [ex:estrogen & LH are both needed for oocyte production]
Antagonistic effects– two hormones with opposite effects [ex:insulin promotes glycogen formation & glucagon stimulates glycogen breakdown]
Hormone secretion is regulated by... signals from nervous system, chemical changes in the blood or by other hormones
Negative feedback control (most common)–decrease/increase in blood level is reversed
Positive feedback control the change produced by the hormone causes more hormone to be released [ex: oxytocin in childbirth]
Posterior pituitary stores adh and oxytocin. Does not produce hormones
Anterior pituitary (not attached to hypothalamus) Makes many hormones.
the major integrating link between the nervous and endocrine systems. Hypothalamus
Hypothalamus receives input from ... cortex, thalamus, limbic system & internal organs
Hypothalamus controls ... pituitary gland with 9 different releasing & inhibiting hormones
Regulate virtually all aspects of growth, development, metabolism, and homeostasis. hypothalamus and the pituitary gland (hypophysis)
pituitary gland is located in the sella turcica of the sphenoid bone and is differentiated into the anterior pituitary, the posterior pituitary, and pars intermedia (avascular zone in between).
Attached pituitary to the brain Infundibulum
Anterior lobe (75%) develops from roof of mouth
Posterior lobe (25%) ends of axons of 10,000 neurons found in hypothalamus–neuroglial cells called pituicytes
The blood supply to the anterior pituitary is from the superiorhypophyseal arteries.
Hormones of the anterior pituitary Human growth hormone (hGH);Thyroid-stimulating hormone (TSH); Follicle-stimulating hormone (FSH); Luteinizing hormone (LH); Prolactin (PRL); Adrenocorticotrophic hormone (ACTH); Melanocyte-stimulating hormone (MSH)
Negative Feedback Systems Decrease in blood levels•Receptors in hypothalamus & thyroid•Cells activated to secrete more TSH or more T3 & T4•Blood levels increase
Positive Feedback Oxytocin stimulates uterine contractions•Uterine contractions stimulate oxytocin release•More oxytocin = more contractions•More contractions = more oxytocin
the most plentiful anterior pituitary hormone. Human growth hormone (hGH)
hGH acts indirectly on tissues by promoting ... the synthesis and secretion of small protein hormones called insulin-like growth factors (IGFs).
insulin-like growth factors (IGFs) IGFs stimulate general body growth and regulate various aspects of metabolism. Various stimuli promote and inhibit hGH production
Regulation of hGH, low blood sugar Low blood sugar stimulates release of GHRH (Growth hormone-releasing hormone) from hypothalamus–anterior pituitary releases more hGH, more glycogen broken down into glucose by liver cells
Regulation of hGH, high blood sugar •High blood sugar stimulates release of GHIH (growth hormone-inhibiting hormone) from hypothalamus–less hGH from anterior pituitary, glycogen does not breakdown into glucose
Follice Stimulating hormone (FSH) functions initiates the formation of follicles within the ovary–stimulates follicle cells to secrete estrogen–stimulates sperm production in testes
Luteinizing hormone (LH) in females stimulates... secretion of estrogen–ovulation of 2nd oocyte from ovary–formation of corpus luteum–secretion of progesterone
In males, LH stimulates ... the interstitial cells of the testes to secrete testosterone.
Prolactin (PRL) together with other hormones, initiates and maintains milk secretion by the mammary glands.
Adrenocorticotrophic hormone (ACTH) controls the production and secretion of hormones called glucocorticoids by the cortex of the adrenal gland–Mainly cortisol which can elevate BP and blood glucose levels.
Melanocyte-stimulating hormone (MSH) increases skin pigmentation although its exact role in humans is unknown
Hormones made by the hypothalamus and stored in the posterior pituitary are oxytocin (OT) and antidiuretic hormone(ADH).
Oxytocin during delivery baby’s head stretches cervix stimulating oxytocin release which nhances uterine muscle contraction helping deliver baby & placenta
Oxytocin after delivery Oxytocin stimulates contraction of the uterus and ejection (let-down) of milk from the breasts.
Antidiuretic hormone (ADH) stimulates water reabsorption by the kidneys and arteriolar constriction.–The effect of ADH is to decrease urine volume and conserve body water.
The thyroid gland is located... just below the larynx and has right and left lateral lobes. On each side of trachea is lobe of thyroid•Weighs 1 oz & has rich blood supply
Follicular cells produce... thyroxine (T4), triiodothyronine (T3) [The number stands for the amount of iodine]
Parafollicular cells produce... calcitonin; Involved in calcium homeostasis. Brings calcium levels down when too high
Formation of Thyroid Hormone Iodide trapping by follicular cells•Synthesis of thyroglobulin (TGB)•Release TGB into colloid•Iodination of tyrosine in colloid•Formation of T3&T4 by combining T1 and T2 together•Uptake & digestion of TGB by follicle cells•Secretion of T3 & T4 into blood
Thyroxine(T3) &Triiodothyronine (T4 ) thyroid hormones responsible for our metabolic rate, synthesis of protein, breakdown of fats, use of glucose for ATP production
Calcitonin responsible for building of bone & stops reabsorption of bone (lowers blood levels of Calcium)
The parathyroid glands are embedded on... the posterior surfaces of the lateral lobes of the thyroid. 4 pea-sized glands found on back of thyroid gland
Principal cells of parathyroid gland produce parathyroid hormone
Parathyroid hormone (PTH) regulates ... the homeostasis of calcium and phosphate
Parathyroid Hormone (PTH) increase blood Ca lvl&decrease blood phosphate lvl–increases number&activity of osteoclasts–increase rate of Ca&Mg reabsorption from urine & inhibits production in urine–promotes formation of calcitriol which increases absorption of Ca, Mg& HPO4-2 from GI
High or low blood levels of Ca+2 stimulates the release of different hormones... PTH or CT
The adrenal glands are located ... superior to the kidneys. 3 x 3 x 1 cm in size and weigh 5 grams
Adrenal glads consist of... an outer cortex and an inner medulla
Cortex produces ... 3 different types of hormones from 3 zones of cortex
Medulla produces epinephrine & norepinephrine
Zona glomerulosa secretes mineralocorticoids, mainly alosterone
Zona fasciculata secretes glucocorticoids, mainly cortisol
Zona reticularis secretes androgens
Mineralocorticoids activity 95% of hormonal activity due to aldosterone
Functions of mineralocorticoids Increase reabsorption of Na+ with Cl-, with bicarbonate and water following it–promotes excretion of K+ and H+
Hypersecretion of mineralocorticoids= tumor producing aldosteronism. High blood pressure caused by retention of Na+ and water in blood
Regulation of Aldosterone Dehydration,Na deficient/hemmorage, increased angiotensin II to adrenal cortex, increases aldosterone, in kidneys increased reabsorb of Na and water&secretion of K &H into blood, Increase blood volume
Glucocorticoids activity 95% of hormonal activity is due to cortisol. Help regulate metabolism.
Functions of glucocorticoids increase rate of protein catabolism&lipolysis–conversion of amino acids to glucose–stimulate lipolysis–provide resistance to stress by making nutrients available for ATP production–raise BP by vasoconstriction–anti-inflammatory effects reduced
anti-inflammatory effects reduced by glucocorticoids Skin cream; reduce release of histamine from mast cells•decrease capillary permeability•depress phagocytosis
Androgens From Zona Reticularis ; insignificant in males–may contribute to sex drive in females–is converted to estrogen in postmenopausal females
Chromaffin cells (Located in Adrenal medulla) Receive direct innervation from sympathetic nervous system. develop from same tissue as postganglionic neurons
Adrenal Medulla Produce epinephrine & norepinephrine•Hormones are sympathomimetic(effects mimic those of sympathetic NS–cause fight-flight behavior)•Acetylcholine increase hormone secretion by adrenal medulla
_____ increase hormone secretion by adrenal medulla Acetylcholine
Fight of flight The alarm reaction is initiated by nerve impulses from the hypothalamus to the sympathetic division of the autonomic nervous system and adrenal medulla
Fight or flight response has this effect... increased circulation to large muscles–promote catabolism for energy production–promotes ATP synthesis–nonessential body functions are inhibited(digestive, urinary & reproductive)
Pancreatic islets On pancrease (which is endo&exocrine gland). Also called islets of Langerhans.
Cell Types in the Pancreatic Islets (that we're studying) Alpha and Beta cells
Alpha cells (20%) produce glucagon
Beta cells (70%) produce insulin
Ovaries: estrogen, progesterone, relaxin & inhibin–regulate reproductive cycle, maintain pregnancy & prepare mammary glands for lactation
Testes: produce testosterone–regulate sperm production & 2nd sexual characteristics
Pineal Gland Small gland attached to 3rd ventricle of brain–Consists of pinealocytes & neuroglia–Melatonin responsible for setting of biological clock–Jet lag & SAD treatment is bright light
Growth Factors Substances with mitogenic qualities–cause cell growth from cell division. Many act locally as autocrines or paracrines
Selected list of growth factors epidermal growth factor (EGF), platelet-derived growth factor (PDGF), fibroblast growth factor (FGF), nerve growth factor (NGF), tumor angiogenesis factors (TAFs), Insulin-like growth factor (IFG), cytokines
Stress response is set of bodily changes called general adaptation syndrome (GAS)
Eustress: Productive stress & helps us prepare for certain challenges
Distress: Harmful stress; lower our resistance to infection
Created by: Devtemrys