Mounish Savier Practice

Excretory system
Osmoregulation: the absorption and secretion of water and solutes to maintain proper water balance between the organism and its surroundings. A) Marine Fish: Hypoosmotic-rarely urinate and constantly drink water: outside environment is saltier than internal environment so water is constantly lost by osmosis B) Fresh water Fish: Hyperosmotic- rarely drink water and constantly urinate; they are more salty than outside water; water constantly diffuses into fish. Excretory Mechanisms of Various organisms: 1. Contractile Vacuoles: found in protists, accumulate water and merfe with plasma membrane and relase water to environment. 2. Flame Cells: found in planaria; distributed along branched tube system permeating flatworm, body fluids filtered across flame cells, internal cilia move fluids through system. Wastes secreted through pores 3. Nephridia: in pairs (mostly in earthworms); fluid enters through nephrostome; concentrated as it goes through collecting duct; at the end concentrated waste materials are excreted through excretory pore. 4. Malpighian tubules: in many arthropds and insects; tubes attached to midsection of digestive tracts. 5. Vertabrate kidney: million induvidual filtering tubes called nephrons. Two kidneys produce waste (urine)- pass through uretes to the bladder then excreted through urehtra. Nephron is carefully positioned in kidney, so that tube winds from outer portion (cortex) down through medulla, thene back to cortex, then down through medulla, and draining to center of kidney: renal pelvis. HUMAN EXCRETION!!!!! 1. Bowman's Capusle: nephron begins with bulb-shaped body at one end. Branch of capilarries from the renal artery known as the afferent artiole enters the capusle and forms a ball of capillaries known as the glomerulus, then exits out of the capsule (efferent artiole) 2. Convoluted tubule: winding tube that begins with the proximal convoluted tubule and ends with the distal tubule joins collecting duct. Middle of tubule is the loop of Henle shaped like a hairpin has ascending and descending tubule; surrounding tubule is dense network of capillaries originating from efferent and afferent artioles of glomerulus- merge into renal vein as they exit nephron. 3. Collecting duct: the distal convoluted tube empties into collecting duct descends in same direction as descending limb toward center of kidney. Single collecting duct shared by numerous nephrons and empties into renal pelvis drains into ureter. PROCESSES: 1. Filtration: When blood enters glomerulus, pressure forces water and solutes through the

capillary walls into Bowman's capsule. Solutes include glucose, salts, vitamins, nitrogen wastes, and any other substance small enough to pass through capillary walls. Large substances stay in capillary walls. Material that enters capsule, known as filtrate, flows into convoluted tubule. 2. Secretion: Filtrate passes through proximal tubule and later through distal tubule, aditional material from the intersitital fluis join the filtrate. Added matterial (coming from capillary network surrounding nephron) is selctively secreted into convoluted tubule by both passive and active transport. 3. Reabsorption: As the filtrate moves down loop of Henle, becomes more concentrated due to passive flow of H2O. As filtrate moves up loop of Henle, it becomes more dilute due to passive and active transport of salts out of the tubule. At end of loop, filtrate is not more concentrated interstitial fluids surrounding the nephron are more concentrated with salts. Next, filtrate descends through collecting duct toward renal pelvis. As it passes through salts concentrated in interstitial fluids, water passively moves out of collecting duct and into interstitial fluids. When filtrate drains into renal pelvis it is concentarted urine. Hormones!! (2) 1. Antidiuretic Hormone (ADH)- increases reabsorption of water by body and increases concetration of salts in urine. Increasing permeability of collecting duct to water. As a result, urine becomes more concentarted as water diffuses out of collecting duct as the filtrate descends into the renal pelvis. 2. Aldosterone: increases reabsorption of water and Na+ increase permeability of distal tubule and collecting duct to Na+. As a result, more Na+ diffuses out of this tubule and duct. Since Na+ increases salt concentration outside tubule, water passively flows. NITROGEN! 1. Aquatic animals excrete NH3 directly into surrounding water. 2. Mamals convert NH3 to urea in livers---less toxic than NH3 requires less water to excrete in urine. 3. Birds, insects, reptiles convert urea to uric acid uric acid is mostly insoluble in water, precipitates and forms solid. HORMONES! SOURCE Posterior pituitary HORMONE ADH oxytocin Anterior Pituitary TSH ACTH FSH LH TARGET Kidneys mammary glands Thyroid Adrenal Cortex ovaries, testies ovaries, testies ACTION Increases reabsorption of water stimulates release of milk Scretion of T4 an T3 secretion of glucocorticoids regulates oogenesis and spermatogenesis regulates oogeneis and

spermatogenesis Anterior (non-tropic) PRL GH Pancreas (alpha cells) Pancreas (beta cells) glucagon insulin Mammary glands bone, muscle liver Liver, muscles, fat Production of milk stimulates growth Increases blood glucose Lowers blood glucose

Adrenal gland (medulla) Epinephrine and nonepinephrine Adrenal gland (cortex) glucocorticods

Blood vessesl, liver and Increases blood glucose, heart constricts blood vessels General kidney Increases blood glucose and reabsorption of Na+ and excretion of K+ Increases cellular metabolism lowers blood Ca+ Inreases blood Ca2+ Spermatogenesis, secondary sex characteristics Menstrual cycle, secondary sex characteristics menstrual cylce, pregnancy Circadian rythms

Thyroid

T4 (thyroxin) and T3( triiodothyronine) Calcitonin

General bone bone Testes, general

Parathyroid Testis

PTH testosterone

Ovary

Estrogen progesteron

Utuerus, general

Pineal Gland

meatonin

body

RAAS! 1) -feedback mechanism that responds to decreased blood pressure, which can result from excessive sweating or inadequate fluid intake -stimulates kidneys to reabsorb more water and cause arterioles to constrict -stimulates adrenal glands to release aldosterone reabsorb more water -increases blood pressure. -when dehydrated ADH is released by posterior pituitary to kidney where increases water reabsorption, (distal and collecting tubules) -alcohol blocks inhibition of ADH!!!! 2) -JGA-located at afferent arteriole supplies blood to glomerulus -blood pressure drops renin initiates chemical reactions that convert plasma protein called angiotensinogen to angiotenisn II rauses blood pressure by constricting atreioles, decreasing blood flow to many capillaries. AGT II also stimulates proximial tubules to reabsorb NaCl and water.

Reudcing amount of salt and water in urine and raises blood volume and pressure. AGTII stimulates adrenal glands to release aldosterone increasing absorption of Na+ and water. -feed back circuit that functions in homeostasis -drop in BP truggers renin relases form JGA rise in BP due to actions of AGT II and aldosterone reduce renin relase. -release of ADH is response to increase in osmolarity of blood. *situation that causes excessive loss of both salt and body fluids will reduce blood volume without increasing osmolarity. (doesnt change ADH release) RAAS will respond by increasing water and sodium reabsorption. ADH and RAAS parterns in homeostasis. -ANF opposes RAAS-- walls of atria of heart release ANF in response to incresse BP and volume ANF inhibits relase of renin in JGA, reabsorption of Na+ in ductsa nd reduces aldosterone release.