Chapter 26 - Fluid Balance

ICF

where most of the body’s water is found

K, proteins, HPO4

more of these are found in the ICF

Na, Cl, bicarb

more of these are found in the ECF

plasma, IF

two components of ECF

lymph, CSF, humors, serous fluid, synovial fluid

components of IF

electrolytes

anything that dissociates into ions in water, often have a charge and are the most abundant solutes

non-electrolytes

more body fluids are these

young skinny male

this person would have the highest water content

diet

where does most of our water come from?

hypothalamic thirst center

this controls the thirst mechanism

osmoreceptors

this detect changing ECF osmolality

obligatory water loss

the idea the body will always lose water, even if we never drink water

osmoreceptors, baroreceptors

release of ADH is dependent on these two types of receptors

central diabetes insipidus

this condition is marked by a decrease in ADH production by the hypothalamus or lack of PPG release

polyuria, dilute urine, dehydration

s/s of central diabetes insipidus

nephrogenic diabetes insipidus

condition where ADH is produced and released in normal amounts but the kidneys don’t respond to it

280

how many mOsm of the ECF solute come from Na?

out, in

plasma membranes are impermeable to Na, it is almost always kept

___ of cells and ____ the ECF

PCT, nephron loop

where most Na is reabsorbed

aldosterone

this hormone causes increased reabsorption of Na into the DCT and collecting ducts, increasing ECF volume

diuretic, natriuretic, decreased Na reabsorption

effects of ANP

estrogen

this sex hormone has a similar effect to aldosterone

diuretic

progesterone is slightly ________ (relating to urine)

glucocorticoids

in high plasma levels these exert very strong aldosterone-like effects and can cause edema

H+

K moves in the opposite direction of this, acting as a pH buffer

DCT, collecting ducts

principal cells secrete K in these regions

type A

this type of intercalated cells can reabsorb K when levels are very low, but not very well

secretion, excretion

high ECF K concentrations drive this

reabsorption

low ECF K concentrations drive this

stimulates secretion

aldosterone effect on K

7.35-7.45

ideal blood pH

alkalosis

blood pH of 7.45 or higher

physiological acidosis

blood pH of 7.35 or lower

carbonic acid, bicarb salt

two pieces of the bicarbonate buffer system

converting a strong acid to a weak acid using bicarb salt

converting a strong base to a weak base using carbonic acid

dihydrogen phosphate

weak acid in phosphate buffer system

monohydrogen phosphate

weak base in phosphate buffer system

bicarbonate

main ECF buffer system

phosphate, protein

main ICF buffer systems

urine

phosphate buffer system is used for this pH (aside from ICF)

blood plasma

protein buffer system is used for this pH (aside from ICF)

amphoteric

proteins are this, able to act as an acid or a base

increase

increasing CO2 levels will cause RR/respiratory depth to _________

decrease

decreasing CO2 levels will cause RR/respiratory depth to _________

long-term

renal regulation is important for __________ acid base balance

bicarb content in blood

renal mechanism of regulating pH

PCT, type A intercalated cells

these can generate new bicarb to be released

H+

this must be secreted into filtrate at the same time as bicarb

type B intercalated cells

in collecting ducts these can reabsorb H+ while secreting bicarb ions from filtrate

45 mmHg

a PCO2 over this value indicates respiratory acidosis

35 mmHg

a PCO2 value under this value indicates respiratory alkalosis

metabolic acidosis/alkalosis

any acid-base imbalance that does not involve CO2

metabolic acidosis

this results from low bicarb levels, causes are excessive alc intake or long term diarrhea

metabolic alkalosis

this results from high bicarb levels, causes are excessive vomiting and excessive base intake

CNS depression, death

effect of a blood pH under 6.8

muscle tetany, convulsions, death

effect of a blood pH over 7.8

respiratory compensation

changes in RR/depth when the lungs compensate for metabolic imbalances

renal compensation

when the kidneys compensate for the acid-base imbalances of respiratory organs