L7 Ion Water Balance

Question 1

Na reabsorption in the nephron

Answer 1

Proximal
Ascending limbs (No descending limb)
Distal tubule
Collecting duct

Question 2

Reabsorption in proximal tubule

Answer 2

Glucose or amino acid / Na symport
Active Na transport on basal
Water paracellular transport
Na/bicarbonate reabsorption using Na/H antiport

Question 3

How is bicarbonate reabsorbed

Answer 3

Na in, H out
H combines with HCO3 to form CO2
CO2 goes back into cell
Gets converted into HCO3 and reabsorbed into blood stream

Question 4

Specificity of transporters

Answer 4

Low specificity

Question 5

By the end of the proximal tubule…

Answer 5

2/3 Na/Cl, small proteins
All aminos
All glucose
Bicarbonate
Secretion of organic ions

Question 6

Reabsorption percentage in loop

Answer 6

25 percent NaCl

15 percent water

Question 7

Descending vs ascending loop

Answer 7

Descending: impermeable to salt but permeable to water
Ascending: impermeable to water but permeable to salt
Both are passive reabsorption

Question 8

Thick ascending limb transporters

Answer 8

Apical: Na/K/2Cl symporter
Basolateral: Na/K ATPase

Question 9

Reason for paracellular transport of ions in ascending thick limb

Answer 9

Cl reabosorption makes tubular fluid Positive, so Cations flow away

Question 10

Fluid leaving the loop is

Answer 10

hyposmotic

Question 11

Distal tubule reabsoprtion

Answer 11

8 percent of NaCl

NaCl symport on apical, Na/K ATPase on basolateral

Question 12

Collecting duct cells

Answer 12

Principal cells: Absorb Na, Secrete K

Intercalated cell: acid base balance

Question 13

Collecting duct reabsorption

Answer 13

Na absorption

K secretion

Question 14

Low pressure baroreceptors
High pressure baroreceptors
Loation

Answer 14

Low pressure: Left atrium, left pulmonary vessels: change in blood volume
High pressure: aortic arch, carotid sinus : change in blood pressure

Question 15

Actions of ADH

Answer 15

increase water permeability of late distal tubule and collecting duct by increasing aquaporons

Question 16

Regular osmolarity
Diuresis osmolarity
Antidiuresis osmolarity

Answer 16

250 mOsm/kg
50 mOsm/kg
1200 mOsm/Kg

Question 17

Renin released in response to

Answer 17

drop in perfusion pressure
decreased NaCl to macula densa
Sympathetic input to juxtagolmerular cells

Question 18

angiotensin II effects

Answer 18

Vasoconstriction
Stimulate ADH release
Sympathetic activity
Aldosterone secretion

Question 19

How does aldosterone work

Answer 19

increase NaCl reabsorption in distal tubule and collecting duct by increase transport proteins

Question 20

Natriuretic peptides

Types

Answer 20

Secreted when heart dilates, increase NaCl and water secretion
Atrial: secreted from heart
Brain: secreted from ventricles

Question 21

Effects of natriuretic peptides

Answer 21

Vasodilation of afferent arterioles
Vasoconstriction of efferent arterioles
Inhibition of renin
inhibition of ADH

Question 22

Euvolemia

Answer 22

normal volume

Question 23

Effects of Volume expansion on 
Proximal
thick ascending
Distal
Collecting

Answer 23

Proximal decrease reabsorption
Thick ascending increase
Distal: increase
Collecting: decrease

Question 24

Ingested K is mediated by

Answer 24

insulin
epinephrin
aldosterone

Question 25

K reabsorption

Answer 25

67 percent absorbed in proximal tubule thru paracellular transport
Thick ascending thru Na/K/2Cl symport and paracellular transport
Distal tubule: Principal cells secrete, intercalated cells absorb

Question 26

Factors affecting K

Answer 26

Increased plasma K
-stimulate aldosterone release
-stimulates principal cells to secrete K to take up Na
Increased flow: increase K secretion

Question 27

Where are the main changes when K is high/low

Answer 27

Distal tubule and cortical collecting duct