Exam 3 Lecture: Body Fluid and Osmolarity

Question 1

What is the main ECF ion?

Answer 1

Na

Question 2

What is the main determinant of ECF osmolarity?

Answer 2

Na

Question 3

What will an increase in the amount of ECF Na do to the ECF volume?

Answer 3

it will increase it

Question 4

What will a decrease in the amount of ECF Na do to the ECF volume?

Answer 4

it will decrease it

Question 5

Where is the only site of ECF Na regulation?

Answer 5

the kidney

Question 6

What is osmolarity?

Answer 6

the concentration of osmotically active things

Question 7

How does the kidney regulate ECF osmolarity?

Answer 7

by changing ECF Na concentration

Question 8

How does the kidney regulate ECF volume?

Answer 8

by changing ECF Na amount

Question 9

What does high Na concentration in the ECF lead to?

Answer 9

an increase in ECF osmolarity and cause water movement out of cells; cells will shrink

Question 10

What does low Na concentration in the ECF lead to?

Answer 10

a decrease in ECF osmolarity and cause water to move into the cells; cells will swell

Question 11

What do the terms hypo- and hypernatremia define?

Answer 11

the ECF Na concentration

Question 12

What is hyponatremia?

Answer 12

low Na concentration in the ECF

Question 13

What is hypernatremia?

Answer 13

high Na concentration in the ECF

Question 14

What are some symptoms of hypernatremia?

Answer 14

rupture of cerebral vessels/hemorrhage, muscle weakness, behavioral changes/ataxia, coma leading to death

Question 15

What are some conditions that lead to hypernatremia?

Answer 15

• limited access to water supply
• diabetes insipidus
• loss of hypotonic fluids
• salt poisoning

Question 16

What are some symptoms of hyponatremia?

Answer 16

cerebral/pulmonary edema, muscle weakness, uncoordination and seizures

Question 17

What are some conditions that lead to hyponatremia?

Answer 17

• hyperglycemia
• GI fluid loss/third space fluid loss
• congestive heart failure
• liver failure
• psychogenic polydispia

Question 18

How is ECF Na concentration controlled?

Answer 18

by adjusting ECF water levels

Question 19

What does adding or subtracting Na into the ECF do?

Answer 19

it affects the ECF volume because water will ultimately follow it

Question 20

What is the mechanism used for adding water to the ECF?

Answer 20

a combination of increased ADH release and thirst

Question 21

What are ECF osmolarity changes detected by and what do the detectors due?

Answer 21

sensed by osmoreceptors that either shrink or swell the hypothalmus which triggers or prevents ADH realease from the posterior pituitary

Question 22

What do osmoreceptors stimuulate aside from the swelling and shrinking of the hypothalmus?

Answer 22

stimulate the thirst center

Question 23

What do the osmoreceptors do if the ECF osmolarity is high?

Answer 23

They shrink, increasing ADH release (to bring water into the extracellular space), and the animal becomes thirsty and drinks

Question 24

What do the osmoreceptors do if the ECF osmolarity is low?

Answer 24

They swell, reducing the amount ADH release and inhibiting the thirst response

Question 25

What is hypervolemia?

Answer 25

high ECF volume

Question 26

What is hypovolemia?

Answer 26

low ECF volume

Question 27

What are symptoms of hypervolemia?

Answer 27

ascites, pulmonary edema

Question 28

What are symptoms of hypovolemia?

Answer 28

directly related to the low circulating volume - hypovolemic shock, organ damage

Question 29

What does changing the amount of Na in the ECF do?

Answer 29

changes the ECF volume

Question 30

Why do kidneys change ECF Na amount?

Answer 30

to regulate imbalances in ECF volume

Question 31

What does salt poisoning lead to?

Answer 31

hypervolemia

Question 32

What do low aldosterone levels lead to?

Answer 32

impaired renal Na retention leading to low

Question 33

What senses ECF volume change?

Answer 33

baroreceptors in the left atria and pulmonary vessels

Question 34

What senses change in ECF pressure?

Answer 34

baroreceptors located in the aortic arch and sinus

Question 35

If baroreceptors stretch, what happens?

Answer 35

no ADH is released

Question 36

If baroreceptors do not stretch, what happens?

Answer 36

ADH is released

Question 37

What do JG cells do in response to stretch in afferent arterioles?

Answer 37

release renin

Question 38

When baroreceptors sense decreased volume, what do they do?

Answer 38

they relay a signal to the brain to increase sympathetic flow to the kidney

Question 39

What is the main neurotransmitter of the sympathetic nervous system?

Answer 39

norepinephrine

Question 40

What does norepinephrine do?

Answer 40

it is a vasoconstrictor that constricts efferent more than efferent and increases GFR

Question 41

True or False: Starling forces only effect the glomerulus

Answer 41

False: they effect the paritubular capillaries too

Question 42

What do Starling's forces contribute to?

Answer 42

regulating movement of ions and water from the tubular fluid to the capillary

Question 43

What happens to hydrostatic pressure in the peritubular capillary if GFR goes up?

Answer 43

It goes down, because a greater amount of the plasma has been filtered less is making its way to the peritubular capillaries

Question 44

What happens to oncotic pressure in the peritubular capillary if the GFR goes up?

Answer 44

it goes up because elevated filtration will increase protein concentration in the peritubular capillaries

Question 45

How does norepinephrin work in the proximal tubule?

Answer 45

it stimulates Na reabsorption

Question 46

When baroreceptors sense high volume, what happens?

Answer 46

they release natriuretic peptide release

Question 47

How does the renin-angiotensin system increase ECF volume?

Answer 47

1. constricts efferent arterioles to increase GFR and change Starling's forces to increase Na and water uptake 2. stimulates NaH antiporter to increase Na uptake 3. stimulates ADH release to increase water uptake 4. Stimulates aldosterone release to increase Na uptake

Question 48

How do natriuretic peptides fix high volume?

Answer 48

1. increase Na and water load entering tubules 2. inhibits renin release from juxtaglomerular apparatus to inhibit RAS 3. inhibits ADH release by inhibiting RAS 4. Inhibits aldosterone release by inhibiting RAS 5. inhibits NaCl reabsorption in the collecting duct by inhibiting Na channels

Question 49

What does increased natriuretic peptide lead to?

Answer 49

decreases Na reabsorption which reduces water reabsorption and decreases ECF volume

Question 50

What must happen in regards to Na in the case of hypovalemia?

Answer 50

Na absorption must increase

Question 51

What must happen in regards to Na in the case of hypervalemia?

Answer 51

Na excretion must increase

Question 52

What mechanisms work to increase Na absorption in the case of hypovalemia?

Answer 52

baroreceptors that increase sympathetic flow and the juxtaglomerular apparatus

Question 53

What does the juxtaglomerular apparatus stimulate?

Answer 53

the RAS system which leads to the production of angiotensin

Question 54

What mechanisms work to increase Na excretion in the case of hypervalemia?

Answer 54

baroreceptors that release natriuretic peptides