Renal: Sodium

Question 1

what is sodium necessary for

Answer 1

blood volume, pressure, organ perfusion

Question 2

what are kidneys designed to do to sodium? why

Answer 2

designed to retain it because evolutionarily salt was scarce

Question 3

normal sodium intake

Answer 3

rec 1600-2300, average 3500

Question 4

how is sodium lost

Answer 4

sweat, diarhea, vomiting, hyperglycemia, diuretics

Question 5

what do diuretics do

Answer 5

mess up kidney transport mechs, make you pee more, more sodium lost

Question 6

how is sodium gained

Answer 6

diet, processed and fast food

Question 7

how much filtrate is reabsorbed into the blood at each stage in the nephron

Answer 7

PT 70%, loop of henle 20-30%, distal 5-10%, cd 1-3%

Question 8

when you have. sodium deficit how much gets excreted

Answer 8

less sodium gets excreted and more gets reabsorbed

Question 9

what fluid volume is measured to monitor sodium balance

Answer 9

the plasma volume and ecf

Question 10

where are sensors to sense sodium (3)

Answer 10

atrial baroreceps in carotid body and aortic arch, afferent arteiole in kidney, and atrial stretch receptor in the heart

Question 11

what do aortic arch receps respond to

Answer 11

they register pressure in the aoorta, then signal vagus nerve x, then to brainstem

Question 12

what do carotid sinus receps respond to

Answer 12

tehy register blood going to the brain, then signal sinus nerve, nerve ix, then brainstem

Question 13

describe what happens when the baroreceps sense high vol blood

Answer 13

when they sense high blood volume, they have higher nerve signalling. through sensory nerve fibers they inhibit sympathetic outflow, and cause less heart activity

Question 14

describe what happens when the baroreceps sense low vol blood

Answer 14

when there is low volume, they have lower nerve traffic, activate the symp system more, and increase cardiac output

Question 15

when the sns is activated what does the renin angitenion system do

Answer 15

when the carotid is too empty, the sns gets activated. it secretes renin. renin converts angiotensinogen to ang , which uses ace to turn into ang 2. ang2 increases water and salt reabsorption (which will bring bp back up)

Question 16

when the sns is inactivated what does the renin angitenion system do

Answer 16

this means that there was high wall pressure in ther carotid. so sns is inactivated, renin is not secreted. ang 2 is never made, thus cant reabsorb salt and water.

Question 17

describe the renin angiotensin pathway

Answer 17

renin secreted, convers angiotensinogen to angiotension 1. angiotensin 1 gets converted to angitensin 2 by ace. ang 2 acts on the at1 receptor to increase salt and water reabsorption

Question 18

how does the afferent arteriole respond to low pressures

Answer 18

afferent arteriole is in the kidney. if pressures fall, we want to raise bp. so renin is secreted, and RAAS pathway ensures, and water and salt reabsorption occurs

Question 19

what does the macula densa have to do with low pressure in afferent arteriole

Answer 19

it senses arterial bp, and when there is low bp secretes renin

Question 20

how does ang 2 impact NHE3

Answer 20

NHE3 is in the proximal tubule. if ang 2 has been made it means that we want to facilitate more salt and water reabs. so, ang 2 will stimulate nah exchange to bring more sodium into pt

Question 21

how does ang 2 impact NCC

Answer 21

the ncc is in the distal convoluted tubule. its only responsible for reabsorbing 5-10% of the sodium. ang 2 will indirectly stimulate the ncc, and increase the na, cl reabs

Question 22

where is NHE3

Answer 22

the proximal tubule

Question 23

where is NCC

Answer 23

the distal convoluted tubule

Question 24

what are the hemodynamic effects of ang 2

Answer 24

hemodynamic effects are actual alterations to the blood vessels. when ang 2 is released, it constricts the efferent arteriole.

Question 25

what happens when ang 2 increases efferent resistance? why?

Answer 25

it lowers the hydrostatic pressure n the peritubular cap, but increases oncotic pressure, so it pulls water from the tubule

Question 26

how is aldosterone made

Answer 26

ang 2 stimulates aldosterone release in the adrenal cortex. so, aldosterone is only gonna be made when ang 2 is made. and ang 2 is only made when we want to reabsorb salt and water…

Question 27

what does aldosterone do in the collecting duct? what transporter does it impact?

Answer 27

we know the collecting duct is only responsible for reabsorbing 1-3% of the sodium. it increases the number of enac channels

Question 28

describe the pathway of aldosterone in blood to reabs of sodium into blood

Answer 28

aldosterone combines with a cytoplasmic receptor

toegther, ald and receptor initiate nucleus transcription

translation and synthesis leads to new atp ase and new enac channels

proteins induced by aldosterons modulate the existing channels and pumps

you get more na in (to blood), more k in the lumen

Question 29

what are the ways in which the sodium transfer of kidney is affected when you have no sodium, no water

Answer 29

no sodium no water, want to reabsorb both

the baroreceptors arent active, so sns is active. it stimulates the RAAS, producing ang 2

and 2 increases nhe, ncc activity, and contricts efferent arteriole, and generates aldosterone to impact enacs to increase na reabs

Question 30

why does hot tub have same effect as high sodium

Answer 30

transmits pressure to interstit space, increases water in vasc compartment, baroreceptors expand. less ang 2, less na reabs (if you have excess sodium, you wouldnt want to excrete it)

Question 31

what happens in the kidney when you have high sodium

Answer 31

when you have high sodium, you want to excrete more. therefore barorecep activation is increased, and RAAS shutdown. excess sodium also signals atrial stretch receps

Question 32

where are the atrial stretch receps? what do they do

Answer 32

in the heart – in reponse to atrail stretch, myocytes secrete a hormone to reduce sodium reabs

Question 33

how does more sodium activate atrial stretch receps?

Answer 33

higher vasc volume, higher stretch, higher ANP produced.

Question 34

what does increase atria naturetic peptide do

Answer 34

reduces appetite (brain)
vasodilates to lower pressure (heart)
increases gfr and lowers na reabs (kidney)

Question 35

whats the overall goal of activation of atrial stretch rceeps

Answer 35

when activated, reduce the reabs of sodium

Question 36

how does anp affect collecting duct cells? what does it block?

Answer 36

joins onto the anp receptor, and makes cgmp
blocks enac, blocks na k atpase, blocks sodium symporters

Question 37

does the body immediately respond to increased sodium?