export_renal function

Question 1

Tubuloglomerula feedback

Answer 1

• Macula densa detect inc GFR
• JGC in aff arteriole –> renin
• Mesangial cells help vaso con of aff to reduce GFR

Question 2

Secretion in PCT

Answer 2

• always ionised
• non-selective
• active
• basolat secreteion of drugs, must give penicillin with OAT-blocker to see effects longer

Question 3

Urea formation

Answer 3

Transamination of aa –> deamination –> free NH4+ –> NH3 in Urea

Question 4

High GFR needed for Urea excretion, why?

Answer 4

• Very small therefore l ittle bit lipid-sol
• w/o high GFR lots would diffuse into the blood
• synth in liver as job is to convert lipid sol –> water sol

Question 5

Bicarbonate balance, PCT

Answer 5

• lost as a buffer for CO2
• apical memb = imperm; basolat = perm
• intercalated cells w/ lost of c. annhydrase
• carbonic anhydrase –> HCO3- + H+ in epi cells
• HCO3- –> peritub cap.

Question 6

H+ balance

Answer 6

• secreted as bicarb ions reabs

* secreted as convert NH4+ –> NH3

Question 7

LoH creation of osmotic gradient

Answer 7

• water moves out of desc LoH
• no aquaporins in asc LoH
• Ions actively transported out
• more water out of desc LoH
• concentrating filtrate even more (if dehydrated = good)
• reabsorption only in CT by osmosis and ADH influence

Question 8

ADH control of urine concentration

Answer 8

• filtrate concentrated from LoH
• ADH released if dehyrated/low BP
• inserts aquaporins to DCT and Coll duct
• water moves from filtrate into peritubular cap

Question 9

Calcium reabsorption

Answer 9

• most in PCT
• facillitated diff by Vit D
• 50% is protein bound therefore NEVER filtered
• PTH stim active reab of Ca++
• Calcitonin inhibs this reabs

Question 10

Na+ Reabs

Answer 10

• 80% kidney energy
• most reabs in PCT (NaKPump, symp/antiporters)
• principle cells: NaKpump on basolat, leak on apical
• end of DCT and Col duct reabs finely tuned, sep from water reabs
• aldosterone stim activity and synth of more pumps

Question 11

K+ reabs

Answer 11

• ALL reabs,
• most in PCT, diffusion
• paracellular, after water
• secretion vital as more is excreted than filtered!
• aldosterone controlled

Question 12

What animal alters urine composition between the collecting duct and bladder?

Answer 12

Horse, glands in renal pelvis and upper ureter secrete mucus

Question 13

Control of urination

Answer 13

Internal sphincter = smooth m (invol)

• symp n, lumbar
• contracts, symp a1 receptors
  Ext sphincter = skel (vol)
• delay dilation by lumbar somatic motor nerves
• continuous stim by nACh to remain closed
  Detrusor relaxes - B2 N.A receptors

Question 14

Bladder emptying

Answer 14

When full, stretch receptors
Myogenic reflex = either pee or hold

• p-symp
• Ach on muscarinic R
• Detrusor contract; int sphincter relax
• inhibit somatic stim of ext sphincter

Question 15

When would protein in urine not indicate kidney impairment?

Answer 15

• Inflam of repro tract or urinary tract

* Sediment analysis would ID

Question 16

Expected SG of a hypovoloaemic patient

Answer 16

V high as aim to retain fluid for circulation

if not high enough –> renal problems

Question 17

Is Glycosuria always a sign of diabetes?

Answer 17

No.

• if blood sugar normal (~5 in dog) then suggestive of kidney impairment
• issue in PCT

Question 18

Define renal azotaemia

Answer 18

Inadequate urine concentration with azotaemia

Question 19

Isothenuria

Answer 19

= urine SG is same as protein free plasma (0.012)

Question 20

Hyposthenuria

Answer 20

USG =

Question 21

Hyposthenuria

Answer 21

more concentrated than plasma, 0.015+

normal urine

Question 22

Clearance

Answer 22

= rate at which a solute is either metabolised or excreted

ml/min

Question 23

To calc GFR from clearance of a solute it must be:

Answer 23

exogenous
100% filtered

continuous IV infusion

= INULIN

Question 24

Creatinine clearance

Answer 24

• constantly produced by skeletal muscle
• filtered and NOT reabs
• easy and cheap to measure
• if rising = 25% kidney fct left!

Question 25

Source of K+

Answer 25

food only

Question 26

In metabolic acidosis what do the Kidneys filter?

Answer 26

H+. * hyperkalaemia poss as no buffer * H+ buffered by bicarb- * K+ 100% reabs * if case need low K+ diet

Question 27

Phosphate balance

Answer 27

from diet, stored in bones. Some excretion, though variable.

Question 28

Pre-renal Azotaemia

Answer 28

reduced kidney function due to poor perfusion. eg hypovolaemic shock

Question 29

Renal Azotaemia

Answer 29

Kidney disease itself, ethylene glycol poison (antifreeze)

Question 30

Post-renal azotaemia

Answer 30

blockageof urine excretion eg. uritholiasis