Regulation of Na/H2O Balance

Question 1

intracellular osmolarity?

Answer 1

K+

Question 2

interstitial osmolarity?

Answer 2

Na+

Question 3

plasma osmolarity

Answer 3

protein (usually albumin

Question 4

ICF vs. ECF?

Answer 4

ECF: Na, Cl, HCO3-, Ca
ICF: K, protein (slightly lower pH)

Question 5

osmotic equilibration

Answer 5

osmotic pressure determines distribution of body water

Question 6

total body sodium content?

Answer 6

major in ECF

• water and sodium are regulated independently
• prevent large changes in plasma osmolality

Question 7

increase sodium content?

Answer 7

water from ICF to ECF
also renal retention of water

increased ECF volume

increased sodium expands ECF and effective circulating volume

Question 8

total body Na content

Answer 8

dietary intake - urinary excretion

Question 9

plasma Na

Answer 9

regulated by changes in water balance

Question 10

decreased ECF volume

Answer 10

increased Na conservation

Question 11

increased ECF volume

Answer 11

increased Na excretion

Question 12

reabsorption of Na

Answer 12

proximal tubule 65% and loop of henle 25%

fine tuning in distal nephron

Question 13

thick ascending limb

Answer 13

co-transporter
-Na/K/Cl

important in establishing medullary hyperosmolarity

inhibited by loop diuretics

messes up medullary gradient
-can’t concentrate urine

Question 14

promotion of Na reabsorption

Answer 14

renal sympathetics
RAAS
aldosterone

Question 15

promote Na excretion

Answer 15

ANP, BNP
urodilatin
intrarenal prostaglandins

Question 16

hypovolemia

Answer 16

increases sympathetics

• stimulate Na and H2O reabsorption (aldosterone)
• increased granular cell stimulation
• leads to increased renin secretion

decreases GFR (therefore decreased fluid delivery to macula densa (increases renin)

Question 17

promotion of renin secretion

Answer 17

renal sympathetics
-beta-1 in JG apparatus

decreased NaCl to macula densa (tubuloglomerular feedback)

intrarenal baroreceptor
-afferent arteriolar vasoconstriction leads to decreased pressure at granular cells

Question 18

loop diuretics and renin?

Answer 18

renin secretion increases (senses hypoperfusion)

Question 19

ANG II

Answer 19

systemic arterial contsriction (increased BP)

renal constriction (efferent > afferent)

Na reabsorption in PCT (Na-H exchanger), TAL, CCD

thirst**

ADH and aldosterone secretion

contracts mesangial cell (decrease GFR)

decreased medullary blood flow (bc of efferent )

Question 20

ADH

Answer 20

secreted from pituitary

Question 21

aldosterone

Answer 21

secreted from adrenal cortex

Question 22

thirst

Answer 22

stimulated by ANG II

Question 23

ANG II arteriolar constriction affect?

Answer 23

decreased RBF
GFR maintained

because efferent > afferent

Question 24

ANG Ii and medullary blood flow?

Answer 24

decreased

Question 25

aldosterone

Answer 25

late distal convoluted tubule and collecting duct - stimulates sodium reabsorption - leaves lumen-negative potential - passive Cl- reabsorb and K/H secretion stimulates K secretion (hypokalemia) stimulates H secretion (H-ATPase)

Question 26

hyperkalemic patients?

Answer 26

can give diuretics

Question 27

hyperaldosteronism**

Answer 27

excessive K and H excretion metabolic alkalosis hypokalemia

Question 28

stimulation of aldosterone release?

Answer 28

hyperkalemia high ACTH levels ANG II

Question 29

feedback of aldosterone

Answer 29

increased pressure feeds back to inhibit aldosterone

Question 30

ANP

Answer 30

increases Na and H2O excretion increases GFR inhibits Na reabsorption suppress renin and aldosterone and ADH systemic vasodilator

Question 31

affect of ANP

Answer 31

afferent arteriolar dilation | efferent arteriolar constriction

Question 32

ANP release

Answer 32

stimulated by increased atrial pressure

Question 33

urodilatin

Answer 33

secreted by DCT and collecting duct in response to increased pressure and volume suppresses Na and H2O reabsorption by medullary collecting duct * * no effect on systemic circulation - unlike ANP BNP

Question 34

intrarenal prostaglandins

Answer 34

PGE2 -increased GFR by dilating renal arterioles suppress Na reabsorption in thick ascending limb and cortical collecting duct increased urinary Na excretion to protect kidney from damage** -ibuprofen be careful

Question 35

effect of prostaglandins on concentration in renal medullary tissue

Answer 35

solute concentration goes down | can't concentrate urine (no good)

Question 36

ADH

Answer 36

released by hypothalamus (posterior pituitary) stimulated by ANG II also stimulated by osmoreceptors

Question 37

major stimuli for ADH release?

Answer 37

hyperosmolarity (major)*** volume depletion hypothalamic more important than hepatic osmoreceptors

Question 38

volume depletion

Answer 38

potentiates ADH response to hyperosmolarity | -prevents inhibition of ADH release

Question 39

too much water

Answer 39

hyponatremia

Question 40

too little water

Answer 40

hypernatremia

Question 41

too much Na

Answer 41

edema | -fluid from vascular to interstitium

Question 42

too little Na

Answer 42

volume depletion

Question 43

hemorrhage response?

Answer 43

hypoperfusion - increased renin (RAAS increase) - increased sympathetic activity constriction renal arterioles (sympathtic) -constriction of efferent (ANG II) increased Na and water reabsorption