Lec46_Na_Handling

Question 1

Are salt and water regulated together or independently?

Answer 1

independently

Question 2

What general thing regulates water balance?

Answer 2

ADH [which responds to plasma osmolarity and volume status]

Question 3

What general thing regulates salt balance?

Answer 3

volume [by things that responds to changes in blood volume]

Question 4

What 4 things regulated Na?

Answer 4

• aldosterone
• ANP
• sympathetics
• angiotensin II

Question 5

What regulates K?

Answer 5

adrenal cortex –> aldosterone release which causes K secretion from principal cells

Question 6

what regulates pCo2/pO2?

Answer 6

chemoreceptors –> changes in ventilation

Question 7

What regulates Ca?

Answer 7

Ca-sensing receptor on parathyroid hormone [PTH]

Question 8

What regulates cortisol?

Answer 8

pituitary feedback

Question 9

What are 3 things that increase Na in body? What are they released in response to?

Answer 9

Aldosterone
Sympathetic nerves
Angiotensin II

• they are responding to changes in MAP or body volume not Na level

Question 10

What percent of serum osmolality does Na and counter ion account for?

Answer 10

97% [280 of 300ish]

Question 11

What will increasing plasma Na do to H2O in vasculature?

Answer 11

• increasing plasma Na moves H2O into vasculature

- leads to decreases H2O excretion

Question 12

What is normal serum K?

Answer 12

4 mEq/L

Question 13

What is normal serum Hgb?

Answer 13

15 g/dL

Question 14

What is normal serum Na?

Answer 14

140 mEq/L

Question 15

Does serum Na measure concentration or total Na level?

Answer 15

concentration

Question 16

Does the body see serum Na?

Answer 16

No – it just sees serum osmolarity

Question 17

What is normal Na handling after you ingest a lot of Na?

Answer 17

• ingest Na
• increase serum Na
• increase plasma osmolarity
• get compensatory mech to restore normal osmolarity

Question 18

What are the 2 initial compensation mech for increased Na [increased osmolarity] in plasma?

Answer 18

• increased ADH –> increase water retention

- thirst –> increase water intake

Question 19

What are 6 specific compensatory mech for increased blood volume?

Answer 19

1. higher BP: increased RBF and same GFR –> causes lower FF
2. Higher NaCl sensed at macula densa: causes decreased renin realse and thus decreased angiotensin II and aldosterone
3. less Na reabsorbed in collecting duct
4. decreased oncotic pressure in PTC so less favorable gradient for H2O reabsorption
5. less Na reabsorbed in principal cells
6. increased ANP

Question 20

What is net result of compensatory mech responsible for increased blood volume?

Answer 20

• increase water and Na excretion to return to normal BV

Question 21

What happens to plasma osmolarity, ADH, water balance, volume status, urinary salt excretion when excessive Na ingestion?

Answer 21

plasma osm: initial increase
ADH: initial increase
water balance: initial increased intake [thirst]
volume status: hypervolemia
urinary salt excretion: increased [to return normal V]

Question 22

How much Na secretion when you are hypovolemic?

Answer 22

• excrete little Na because you are trying to retain volume of H2O that comes with it
• increased RAA, decreased ANP, increased sympathetics

Question 23

What are ADH and RAA levels in hypovolemia?

Answer 23

• ADH and RAA both eleveated

Question 24

What is treatment for hypovolemic hypernatremia?

Answer 24

• replace slat and water to fix hypovolemia and electrolyte imbalance
• ex. give normal saline

Question 25

What does hypovolemic hypernatremia mean?

Answer 25

- salt deficit but even bigger H2O deficit

Question 26

Do people with access to water become hypernatremic

Answer 26

very rarely

Question 27

What is normal handling of water ingestion?

Answer 27

- ingest water - get decrease in serum Na conc - decrease plasma osmolality - ADH release suppressed dilute urine excreted

Question 28

What is minimum urine osmolatiry?

Answer 28

50 mosm/L with no ADH

Question 29

What is max amount of maximally dilute urine you can excrete per day?

Answer 29

16 L water/day

Question 30

If you ingest more than 16 L/day of water without ingesting osmoles how much urine will you excrete?

Answer 30

- you will excrte 16 L of urine | - you will retain water beyond that

Question 31

If you are hypervolemic will you retain or secrete Na?

Answer 31

secrete Na regardless of hyper vs hypo natremia - because you sense high volume which causes you to want to get rid of salt/water

Question 32

If you consume a bunch of water why aren't you necessarily hypertensive or swollen?

Answer 32

- the increased water you consume doesn't necessarily stay into the vasculature

Question 33

How do you get mOsm from Na conc of blood?

Answer 33

mOsm is [Na]*2 | ex. Na = 115 mEq/L, mosm = 2*115 = 230 mOsm/L

Question 34

How much of water is in intercellular space?

Answer 34

60%

Question 35

How much of water is in interstitial space?

Answer 35

32%

Question 36

How much of water is in blood volume?

Answer 36

8%

Question 37

What is source of side effect confusion in excess water intake?

Answer 37

- get extra water - some of that water goes into cells to equalize osmolarity - brain is in skull so brain starts to swell like everywhere else but there is no space for it to happen - get cerebral edema

Question 38

What is primary polydipsia?

Answer 38

- too much water intake in excess of consumed salt | - get hypervolemic, hyponatremic, secrete lots of Na in urine

Question 39

What is treatment for primary polydipsia?

Answer 39

water restriction [maybe also hypertonic saline]

Question 40

What is euvolemia?

Answer 40

too much water, normal salt | - primary polydipsia

Question 41

What is hypovoluemia?

Answer 41

too little water but even lower salt | - GI/kidney loss

Question 42

what is hypervolemia?

Answer 42

too much water and salt but more water than salt | - CHF, cirrhosis