Renal Physiology

Question 1

What is in the ultrafiltrate?

Answer 1

Same components as blood plasma, minus the proteins

Question 2

What is the role of the cortical nephrons?

Answer 2

Absorption and secretion

Question 3

What is the role of the juxtamedullary nephrons?

Answer 3

Creating conditions to forma concentrated urine

Question 4

What occurs in the proximal tubule?

Answer 4

Most of the fluid is reabsorbed as isotonic NaCl, along with vital nutrients (glucose, amino acids)

Question 5

What is the role of the loop of Henle?

Answer 5

Controlling the concentration of the urine

Question 6

What is the role of the distal tubule?

Answer 6

Fine tuning of electrolyte conditions

Question 7

Which structure collects the water/solutes reabsorbed by the nephron?

Answer 7

Vasa recta

Question 8

What is the role of the juxtaglomerular apparatus?

Answer 8

Specialised hormone-secreting region

Question 9

What size do molecules have to be to pass the secondary processes of the glomerular capillary?

Answer 9

Anything <3.5nm can easily pass

Question 10

What are the filtration forces that enable fluid to cross the glomerular capillary wall?

Answer 10

Hydrostatic pressure in the capillary; osmotic forces across the capillary (due to plasma proteins)

Question 11

Which waste product can be used as a blood-borne biomarker for renal function/GFR?

Answer 11

Creatinine

Question 12

Is there any concentration of tubular contents in the proximal tubule?

Answer 12

No. Fluid remains isotonic

Question 13

What is the GFR in a normal young adult?

Answer 13

120ml/min

Question 14

How is sodium transported across the apical membrane of the PCT?

Answer 14

Co-transport with glucose/amino acids, antiporter with protons

Question 15

How is sodium transported across the baso-lateral membrane of the PCT?

Answer 15

Na/K/ATPase on baso-lateral membrane

Question 16

What happens if you put a cell into a hypotonic solution?

Answer 16

Water moves into the cell and it swells/bursts

Question 17

What happens if you put a cell into a hypertonic solution?

Answer 17

Water moves out of the cell and it crenates

Question 18

What is normal plasma osmolality?

Answer 18

290molsmol.kg^-1 H2O

Question 19

Where is ADH secreted from?

Answer 19

Posterior pituitary gland

Question 20

What is the overall function of ADH?

Answer 20

Increase the number of aquaporins in the collecting duct

Question 21

What occurs in the descending limb of the LoH?

Answer 21

Water leaves through aquaporins to the hyperosmotic medullary interstitium

Question 22

What occurs in the ascending limb of the LoH?

Answer 22

Na/K/2Cl- leaves cell via co-transporter to maintain hyperosmotic medullary interstitium

Question 23

What occurs in the ascending limb of the LoH?

Answer 23

Na+ (and K+/2Cl-) leaves cell via apical co-transporter and basolateral Na+ pump, to maintain hyperosmotic medullary interstitium

Question 24

What are the high pressure sensors of blood volume?

Answer 24

Arterial baroreceptors in the carotid sinus and aortic arch; juxtaglomerular apparatus of kidney

Question 25

What are the low pressure sensors of blood volume?

Answer 25

cardiac atria; pulmonary vasculature

Question 26

Where/why is renin secreted?

Answer 26

Renin secreted from the juxtaglomerular apparatus in response to low renal blood flow/pressure (aids water reabsorption at the distal tubule)

Question 27

What is the effect of increased circulating aldosterone?

Answer 27

Stimulates transcription of apical Na and K channels

Question 28

What is the overall effect of atrial natriuretic peptide?

Answer 28

Increased excretion of Na+ (and therefore water) in response to heightened blood pressure

Question 29

What are the main regulators of K+ secretion?

Answer 29

K+ itself and plasma aldosterone released from adrenal cortex (an increase in either will enhance secretion)

Question 30

What is the normal value of calcium in plasma?

Answer 30

2.2-2.6mmol/l

Question 31

What is the biologically active form of vitamin D3 called?

Answer 31

1,25-(OH)2-vitamin D3

Question 32

Which nerves are active when the bladder relaxes?

Answer 32

Hypogastric (sympathetic) and pudendal (somatic)

Question 33

Which nerve is active when the bladder contracts?

Answer 33

Pelvic nerve (parasympathetic)

Question 34

Where in the brain is the decision not to void the bladder made?

Answer 34

Medial pre-frontal cortex - inhibits the pontine micturition centre