Physiology 26: Urine Formation By The Kidneys I: Gfr, Renal Blood Flow, And Their Control

Front 1

Where is erythropoietin made?

Back 1

mostly kidney

Front 2

Where is calcitriol made?

Back 2

kidney

Front 3

What is calcitriol?

Back 3

most active form of vitamin D, needed for calcium absorption

Front 4

What is the kidney's role in gluconeogenesis?

Back 4

during fasting, it can make glucose to help the liver

Front 5

Describe the flow of blood (which arteries it goes through) form the renal artery into a glomerulus?

Back 5

renal artery > interlobar artery > arcuate artery > interlobular arteriole > afferent arteriole > glomerular capillary

Front 6

How does urine flow from the collecting duct to the ureter?

Back 6

collecting duct > pyramids> papilla > minor calyx > major calyx > renal pelvis > ureter

Front 7

What is the duct of Bellini?

Back 7

collecting duct

Front 8

What is a cortical nephron?

Back 8

has a short loop of Henle so it the nephron only has a small part in the renal medulla

Front 9

What is a juxtamedullary nephron?

Back 9

a nephron that has a long loop of Henle that extends deep into the renal medulla

Front 10

What is the detrussor muscle?

Back 10

smooth muscle that regulates bladder emptying

Front 11

Bladder nerve supply

Back 11

pelvic nerves via sacral plexus

Front 12

Bladder external sphincter nerves

Back 12

pudendal (S2, S3)

Front 13

What level does sympathetic stimulation of the bladder come from?

Back 13

L2 (hypogastric nerve) (L2 is the lowest level of sympathetics)

Front 14

Peristalsis of the ureter is done by which nerves (parasympathetics or sympathetics)

Back 14

parasympathetics

Front 15

What is the vesicoureteral reflex?

Back 15

urine is sent backwards into the ureter during contraction (incomplete closure of the ureter in the bladder wall)

Front 16

What is the uretorenal reflex?

Back 16

renal arteriole constriction due to kidney stone pain in the ureter

Front 17

Micturation reflex is moderated by what sensation?

Back 17

stretch in the bladder walls

Front 18

What is a tabetic bladder?

Back 18

loss of bladder control due to injury/fibrosis to the sacral nerves

Front 19

Urinary excretion rate =

Back 19

(Filtration rate) - (Reabsorption rate) + (Secretion rate)

Front 20

What types of things are reabsorbed in the proximal tubule?

Back 20

bicarbonate, electrolytes, Amino Acids, glucose,

Front 21

Why is GFR putting so much sodium into the urine if it just reabsorbs it anyways?

Back 21

to quickly get everything out of the blood

Front 22

FIltration fraction=

Back 22

GFR/Renal plasma flow = 20% normally. this is the % of blood that is filtered as it passes through the kidney

Front 23

5 layers of the glomerular membrane

Back 23

endothelium - lamina rara - lamina densa - lamina rara - podocytes

Front 24

What type of capillaries are found in the glomerulus?

Back 24

fenestrated

Front 25

How is solute size related to filtration rate?

Back 25

inversely proportional; large things have a harder time leaving

Front 26

Which molecules are filtered more easily? Negatively or Positively charged compounds

Back 26

positive charges are excreted more easily. negatively charged heparin sulfate repels the negative compounds (proteins) and keeps them out of the urine

Front 27

What is minimal change nephropathy?

Back 27

loss of negative repulsion in glomerular membrane = more proteins can enter urine. there is little change in histology, most pathology is due to loss of negative charges

Front 28

What is more likely to be filtered through a normal glomerular membrane? Neutral particle or a positively charged particle?

Back 28

positively charged particle will pass through more easily

Front 29

Increased glomerular capillary pressure has what effect on GFR?

Back 29

increases; more force pushing water out

Front 30

Increased Bowman's capsule colloid pressure has what effect on GFR?

Back 30

increases; more water moves into the capsule to dilute the high colloid capsule

Front 31

Increased Bowman's capsule hydrostatic pressure has what effect on GFR?

Back 31

lowers GFR; resists some fluid movement into the Bowman's capsule

Front 32

Increasing filtration fraction has what effect on plasma colloid pressure in the efferent arteriole?

Back 32

increases the colloid pressure since we removes more water in the glomerular capillaries

Front 33

Why does constriction of the efferent arteriole lead to increased GFR in acute conditions?

Back 33

less blood flow is being removed from the glomerular capillaries = back-up of blood in the capillaries = more time for the blood to filter

Front 34

Why does constriction of the efferent arteriole lead to decreased GFR in chronic conditions?

Back 34

efferent arteriole constriction leads to a higher concentration of proteins in the blood over time since more water is getting out = Donnan effect = negative proteins are holding positive charges (Na+) in the blood and they are not getting filtered out and water stays with them in the blood

Front 35

What is the relationship of sodium reabsorption to oxygen consumption?

Back 35

directly proportional; the kidney cells need oxygen to transport solutes out of the tubular fluid (Na+ is active transport)

Front 36

Why do major changes in the BP not effect the GFR much?

Back 36

auto-regulation in the kidney

Front 37

What effects do sympathetics have on GFR?

Back 37

decrease GFR; constrict arterioles = low blood flow = less GFR

Front 38

What effect does endothelin have on GFR?

Back 38

decrease GFR; constrict arterioles = low blood flow = less GFR

Front 39

What effect does angiotensin II have on GFR?

Back 39

increases GFR/prevents decrease in GFR; angiotensin 2 is released when there is renal artery stenosis or low flow to the afferent arteriole. angiotensin 2 will constrict the efferent and keep GFR normal in this common situation

Front 40

What effect does nitric oxide have on GFR?

Back 40

increases GFR by vasodilationg = more blood blow = more filtration

Front 41

What does glomerulotubular balance refer to?

Back 41

the kidney will adjust reabsorption and secretion in coordination with GFR to keep the final urine concentration what it needs to be (i.e. if GFR was low, there will be more secretion in the proximal tubule)

Front 42

What does the macula densa sense?

Back 42

it detects low NaCl in the distal tubule. then causes release of renin (eventually gets aldosterone to put Na into the blood)

Front 43

If there is a low NaCl level detected in the distal tubule urine by the macula densa, what happens to afferent arterioles?

Back 43

vasodilate to increase GFR; JG cells also release renin into the afferent arterioles

Front 44

What is the myogenic autoregulation of renal blood flow?

Back 44

maintains constant GFR even when there is high BP; if there is high BP, stretching of the vessel walls opens calcium channels and causes vasoconstriction to decrease GFR. prevents excessive GFR increase under high pressure

Front 45

Why does a high protein intake lead to increased GFR?

Back 45

high AA in the blood = more AA in urine = more AA reabsorption = more Na reabsorption with Amino Acids = less sodium to the macula densa = release of renin from JG cells = angiotensin 2 efferent arteriole constriction = backing up of blood in the glomerular capillaries = more GFR

Front 46

Why does a high glucose intake lead to increased GFR?

Back 46

high glucose in the blood = more glucose in urine = more glucose reabsorption = more Na reabsorption with glucose = less sodium to the macula densa = release of renin from JG cells = angiotensin 2 efferent arteriole constriction = backing up of blood in the glomerular capillaries = more GFR