17.1-17.3 Kidneys

Question 1

liver

Answer 1

excrete waste as BILE, especially hydrophobic waste

in liver, HEME broken down to bilirubin and excrete in bile

liver synthesizes UREA, which carries excess nitrogen from protein breakdown (free ammonia is toxic), urea goes into the bloodstream and is excreted in urine

Question 2

kidney

Answer 2

removes small hydrophilic waste

Question 3

colon

Answer 3

absorbs fluids, excretes (or absorbs?) ions using Active transport

Question 4

kidneys

Answer 4

keeps things STABLE (homeostasis)

excretes HYDROPHILIC waste

maintains CONSTANT fluid VOLUME

Question 5

renal tubule (reservoir for waste)

Answer 5

cells protein goes remain in blood

WATER and small molecules (e.g. WASTE, GLUCOSE) are squeezed out into the RENAL TUBULE which contains the FILTRATE

the filter is called GLOMERULAR BASEMENT MEMBRANE

blood cells and plasma proteins are TOO BIG to fit through filter

Filtrate contains WATER, SUGARS, AMINO ACIDS, UREA (hydrophilic)

Question 6

selective reabsorption

Answer 6

retrieve important goods in the filtrate

Question 7

PCT

Answer 7

Proximal convoluted tubule - near the Bowman’s capsule, where WATER REABSORPTION takes place

70% of volume of filtrate is reabsorbed here

reabsorption of GLUCOSE and AMINO ACIDS by SECONDARY ACTIVE TRANSPORT

Question 8

secretion (?)

Answer 8

ACTIVE TRANSPORT into the filtrate

a back up method compared to glomerulus

Question 9

ADH/vasopressin - WATER RETENTION - INCREASES BP

Answer 9

POSTERIOR pituitary

prevents diuresis (water LOSS in urine), by INCREASE WATER REABSORPTION in the DISTAL NEPHRON.

without ADH, this region is impermeable to water

water RETURNS to the blood

INCREASE blood pressure

Question 10

aldosterone (renal cortex) - SALT KEEPER - INCREASES BP

Answer 10

Increases reabsorption of Na+ by DISTAL NEPHRON

INCREASES plasma osmolarity, INCREASES thirst and water RETENTION, increases BLOOD PRESSURE

Increased Na+ INCREASES blood pressure

When blood pressure is high, aldosterone is NOT released, resulting in sodium LOSS in urine, plasma osmolarity FALLS

Question 11

descending loop of henle

Answer 11

WATER EXITS, flowing into high osmolarity medullary interstitium

Filtrate becomes MORE concentrated

Question 12

concurrent multiplier

Answer 12

the descending and ascending limbs of Henle do DIFFERENT THINGS

Filtrate increases in concentration going down

Ascending is NOT permeable to water, but LOSES ions from high osmolarity filtrate into renal medullary interstitium (what loses ions? see thick ascending limb)

MAKES MEDULLA SALTY, INCREASE WATER REABSORPTION, makes urine with HIGHER osmolarity than plasma

Question 13

Thick ascending limb

Answer 13

ACTIVE TRANSPORT of ions (Na+, K+, Cl-) OUT of filtrate and passive return of K+ TO filtrate

DILUTES tubular fluid

Question 14

Vasa recta

Answer 14

collects water reabsorbed from the filtrate

Question 15

Renin

Answer 15

an enzyme that catalyzes conversion of angiotensinogen (plasma protein made in liver) into angiotensin I, which is converted to angiotensin II by ACE (in the lungs)

VASOCONSTRICTION = increase BP

JG cells secrete RENIN

Question 16

JGA

Answer 16

macula densa is part of DISTAL TUBULE

juxtaglomerular cells (JG) found in afferent arteriole

JG cells are BARORECEPTORS that monitor blood pressure

Question 17

Macula Densa

Answer 17

CHEMORECEPTORS that monitor the osmolarity of FILTRATE in the DISTAL TUBULE

Question 18

decreased filtrate osmolarity => REDUCED FILTRATION RATE -> macula densa stimulates JG cells to releases RENIN -> raising blood pressure

Answer 18

also DILATION of afferent arteriole, increasing blood flow to the glomerulus

Question 19

carbonic anhydrase

Answer 19

found in epithelial cells throughout the nephron, except for flat (squamous) cells of thin loop of Henle

Convert CO2 into carbonic acid, which dissociates into bicarb and proton