Q & A Physiology

Question 1

How does water get made to move?

Answer 1

Under pressure

Question 2

What are the 2 different types of pressure?

Answer 2

Hydrostatic pressure and osmotic pressure

Question 3

Why do vasa recta get a lower hydrostatic pressure?

Answer 3

Because a lot of hydrostatic pressure is lost at the glomerulus

Question 4

What drives GFR?

Answer 4

Hydrostatic pressure which is controlled by afferent and efferent arteriole diameter.

Osmotic pressure controlled by transport of solutes to set up an osmotic gradient and selective water-proofing (aquaporins and ADH)

Question 5

What does glomerular filtration result in?

Answer 5

blood that does not contain any cells, protein complexes, and >50 kDa proteins

Question 6

What does GFR depend on?

Answer 6

Permeability of membrane

Surface area of membrane

Filtration pressure

Question 7

What determines filtration pressure?

Answer 7

Glomerular blood hydrostatic pressure drives filtration out of the glomerulus and osmotic pressure back into the glomerulus

Question 8

How is glucose transport done into the cells from the lumen during reabsorption?

Answer 8

Glucose concentration within cell is kept high by co-transporting glucose with sodium into the cell and then opening glucose transporters on the other side to go down the concentration gradient that was created. Most of this happens in the PCT

Question 9

How do we sense BP?

Answer 9

Stretch receptors (barorececeptors that sense stretch decrease and stimulate noradrenaline release)
Atrial mechanoreceptors which sense increase in stretch and release ANP
Afferent arteriole stretch (sense myogenic autoregulation)

Osmolarity
(Osmoreceptors sense increase in osmolarity of blood and release ADH)

Kidney function (tubuloglomerular feedback)

Question 10

What do mesangial (macula densa) cells produce?

Answer 10

Nitric Oxide

Question 11

How is GFR maintained?

Answer 11

Myogenic autoregulation (works well both ways)

AtII (complex; it constricts both arterioles to maintain GFR)

Question 12

What does ANP do?

Answer 12

Dilates Aff and constricts Eff to produce more GFR

Tubuloglomerular feedback (movement through kidney is too slow means low BP which interpreted as low salt at DCT and so Afferent arteriole is dilated increasing GFR.

Question 13

How does the sympathetic NS affect GFR?

Answer 13

It constricts AA and decreases GFR dramatically

Question 14

How does reabsorption get increased?

Answer 14

RAAS (AtII and aldosterone increase Na reabsorption and water follows increasing BP)

ADH opens up CD/CT aquaporins causing water to be reabsorbed

Question 15

How does reabsorption get decreased?

Answer 15

ANP Blocks Na+ reabsorption and water follows

Question 16

What happens when there is high amounts of aldosterone?

Answer 16

Potassium is leached

Question 17

Where is most AtII activity taking place?

Answer 17

At the afferent arteriole and the Proximal Convoluted Tubule.

AtII does affect DCT but not as much as PCT. Aldosterone does most of the work.

Question 18

What is NorAdrenaline’s effect on the Afferent arteriole?

Answer 18

Dramatic constriction

Question 19

Why can AtII act as a dipsogen?

Answer 19

It can pass the blood brain barrier through leaky tight junctions and interact with the receptors

Question 20

Why does AtII constrict afferent arteriole?

Answer 20

MAP is increased all around the body so it is a compensatory mechanism