kidneys & fluid/electrolyte balance (ch 19, 20)

Question 1

urinary system anatomy

Answer 1

kidneys (capsule, cortex, medulla, renal arteries & veins, renal pelvis) + accessory structures (ureter, urinary bladder, urethra)

Question 2

nephron anatomy

Answer 2

capsule of Bowman, proximal tubule, loop of Henle (descending and ascending limbs), distal tubule, collecting ducts

Question 3

the renal cortex is formed from…1
the renal medulla is formed from…2

Answer 3

1 Bowman’s capsules, proximal and distal tubules
2 loops of Henle and collecting ducts

Question 4

blood circulation though the kidneys

Answer 4

abdominal aorta - renal arteries (l/r) - smaller arteries - arterioles (afferent) - capillary bed in glomerulus - efferent arterioles - peritubular capillaries - (vasa recta in juxtamedullary nephrons) - venule - small veins - renal veins - inf vena cava

Question 5

juxtaglomerular apparatus

Answer 5

final part of ascending limb of Henle (with modified macula densa cells) + afferent arteriole (with modified granular cells) + efferent arteriole

Question 6

filtration barriers

Answer 6

glomerular capillary endothelium (fenestrated)
basement membrane formed from ECM (glycoproteins and collagen)
Bowman’s capsule epithelium (podocytes with extended foot processes)
–» filtration slits

Question 7

GFR (glomerular filtration rate) influenced by

Answer 7

filtration pressure (capillary blood pressure favours filtration, colloid osmotic pressure and capsule fluid pressure against filtration)

Question 8

GFR regulation

Answer 8

myogenic response
tuboglomerular feedback at the juxtaglomerular apparatus
hormones + autonomic innervation

Question 9

myogenic response

Answer 9

BP up, arteriole wall stretches, ion channels open, depolarization, contraction, blood flow decreases which lowers filtration pressure and GFR

Question 10

clearance of X

Answer 10

excretion rate of X / [X] in plasma

Question 11

filtration rate of X

Answer 11

[X] in plasma x GFR

Question 12

reabsorbtion

Answer 12

Na ions flow out of the filtrate into interstitial fluid of the medulla (along a concentration gradient into proximal tubule epithelial cells and with the help of K/Na ATPase out of the cell), water flows out of filtrate via osmosis, other ions and molecules follow the concentration gradient (changed by the passing of water)
the fluid gets back into the peritubular capillaries (they have low hydrostatic pressure and high colloid pressure)

Question 13

micturition control

Answer 13

motor control of external sphincter
parasympathic control of internal sphincter (activated by sensory neurons connected to stretch receptors in bladder -> interneuron inhibitory effect on somatic control and activation of parasymp. neuron that controls the smooth muscle of the bladder which contract and pull the internal sphincter open)

Question 14

vasopressin

Answer 14

secreted by post. pituitary (hypothalamic neuron)
directs aquaporin addition to collecting duct

Question 15

vasopressin secretion stimulated by

Answer 15

osmolarity receptors in hypothalamus (high osmolarity)
baroreceptors (low BP)

Question 16

countercurrent exchange system

Answer 16

solutes are actively transported into the interstitial fluid of the medulla (loop of Henle)
peritubular capillaries pick up the water that follows the solutes, preventing it from diluting the medulla

Question 17

aldosterone

Answer 17

acts on distal tubule + collecting duct (prolongs Na/K leak channel opening and increases channel number) - causes sodium reabsorption and potassium excretion)
secreted by adrenal cortex

Question 18

aldosterone secretion stimulated by

Answer 18

hyperkalemia
low BP

Question 19

natriuretic peptide

Answer 19

secreted by myocardial cells as a result of muscle stretch
increases water and Na excretion, decreases BP

Question 20

acid-base imbalances associated with …1 due to …2

Answer 20

1 potassium imbalances
2 H/K ATPases