Urinary System Chp. 25 (Test 4) Flashcards Preview

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What are the functions of the urinary system?

regulation of extracellular fluid environment in body. eliminating waste --> urine.
returning useful substances back to blood.
regulating blood volume and blood pressure.
make an secrete renin - controls blood pressure.


What are the two types of nephrons?

cortical nephron and juxtamedullary nephron.


What are the processes used by the kidneys in making urine?

glomerular filtration, tubular reabsorption, tubular secretion, and water conservation.


What occurs in the process of glomerular filtration?

takes place in the renal corpuscle and produces a cell and protein free filtrate. a passive process.


What occurs in the process of tubular reabsorption?

process of selectively moving substances from the filtrate back into the blood. almost everything filtered is reclaimed. glucose, amino acids, and 99% of water and salt.


What occurs in the process of tubular secretion?

process of selectively moving substances from the blood into the filtrate.


What occurs in water conservation?

water is returned to the blood.


How does fluid pass the barriers that constitute the filtration membrane?

1. glomerular capillaries- are fenestrated. so they have pores and are "leaky"
2. basement membrane- physical barrier. blocks proteins.
3. filtration slits on foot processes of podocytes- slits are physical barriers that keep out proteins.


What is glomerular filtration rate?

the volume of filtrate produced by both kidneys in a minute. the average GFR is 125 mL/min


What are the interacting control mechanisms of the GFR?

renal autoregulation, sympathetic control, hormonal control.


What is renal autoregulation of GFR?

ability of a nephron to regulate blood pressure to keep GFR steady.
-myogenic mechanism: smooth muscle in afferent arteriole constrict or dilate to maintain normal blood flow in the glomerulus.
-tubularglomerular feedback mechanism: juxtaglomerular complex controls, monitors, and influences GFR.


What is sympathetic control of GFR?

also known as neural control. causes vasoconstriction. all arteries in kidney. reduction in GFR. decrease in filtrate production, decrease in urine production. increases blood volume, increases blood pressure. wins over renal autoregulation.


What is hormonal control of GFR?

if drop in blood pressure, juxtaglomerular complex cells release renin. which makes angiotensin II, which causes whole body vasoconstriction. afferent and efferent arterioles vasoconstrict, which decreases GFR. increases blood pressure.
aldosterone causes sodium reabsorption. h2o follows sodium. increases of blood volume, increase in blood pressure.


What process occurs in the proximal convoluted tubule?

65% of filtrate is reabsorbed. reabsorption of Na, H2O Cl, HCO3, and amino acids. reabsorption is not subject to hormonal control. there is a limit to the amount of solutes reabsorbed in the PCT.


What is transport maximum?

maximum amount of transport proteins to reabsorb solutes.


What process occurs in the nephron loop (loop of henle)?

generates a salt gradient. enables collecting duct to concentrate urine and conserve water. H2O is reabsorbed from the descending limb via osmosis. the ascending limb is impermeable to H2O. Na, Cl, and K are reabsorbed via secondary active transport.


What process occurs in the distal convoluted tubule?

~25% of filtrate is still there. it is subject to hormonal control. Na and Cl are reabsorbed via primary active Na transport. Ca is reabsorbed by passive uptake via Parathyroid Hormone


What are the hormones that effect the distal convoluted tubule?

aldosterone, antidiuretic hormone, atrial natriuretic peptide hormone, and parathyroid hormone.


What is the action of aldosterone?

causes more reabsorption of Na, Cl, and H2O.
secretes K, lowers urine volume, lowers sodium levels in urine.


What is the action of antidiuretic hormone?

DCT and collecting duct. makes them more permeable to H2O. increases H2O reabsorption. urine volume drops.


What is the action of atrial natriuretic peptide hormone?

excretes Na and H2O in urine. blood volume decreases, blood pressure decreases. inhibits Na reabsorption.


What is the action of parathyroid hormone?

promotes Ca reabsorption.


What is countercurrent multiplier?

interaction between the flow of filtrate through the ascending and descending limb of nephron loop


What is countercurrent exchange system?

flow of blood through ascending and descending limb of vasa recta.
vasa recta traps salt within interstitial fluid but transports H2O out of renal medulla.


What is renal function?

is a clinical evaluation of kidney function. it's an indication of state of the kidney and it's role in GFR.


Where is the internal urethral sphincter found?

smooth muscle. at the base of urinary bladder.


Where is the external urethral sphincter found?

skeletal muscle. near the urogenital diaphragm.


What is micturition?



What is the events of micturition?

1. bladder filling- reflex to spinal cord
2. motor response- detrusor muscle starts to contract.
3. relaxation of internal urethral sphincter
4. sensory signal- pons. pontine micturition center. cerebrum-is it appropriate?
a. if appropriate- both sphincters relax. empty bladder.
b. if not appropriate- pons inhibits relaxation of sphincters. holding your bladder


What is the micturition reflex?

a series of contractions of the urinary bladder in response to increased pressure in the bladder


What are the three ways that the body regulates acid/base balance?

buffer systems, respiratory control, and renal control.


What is an acid?

any chemical that releases H+ ions


What is a base?

any chemical that accepts H+ ions


What is a buffer?

anything that resist change in pH


What are the main buffer systems?

1. bicarbonate buffer system
CO2+ H20 --> H2CO3 --> H+ + HCO3
CO2 + H20 HPO4- + H+


What is the respiratory control of pH?

breathing. changing CO2 levels. 1-5 minutes.


What is the renal control of pH?

ridding the body of hydrogen ions in urine. hours to days.


What is acidosis?

too much H+. ECF pH falls below 7.35


What is alkalosis?

too little H+. ECF pH rises above 7.45


What is the cause of kidney stones?

hypercalcemia, dehydration, pH imbalances, kidney infections, or enlarged prostates.


What is the treatment for kidney stones?

pain meds, lots of water, stone dissolving meds. in worse cases lithotripsy - breaking up of stones, or surgery. drinking cranberry juice is a preventative.


What is renal insufficiency?

inability to filter blood properly, amount of filtrate produced is lowered greatly. leads to kidney failure. caused by chronic kidney infections, trauma, or heavy metal poisoning. symptoms are abnormal urine, blood in urine, and fatigue.


What is hemodialysis?

artificial means of removing waste products from blood, due to the kidneys inability to do so.