c Body Fluid Balance

intracellular fluid is

inside the cells

intracellular fluid :

all water and electrolytes inside cell membranes

intracellular fluid is how much of body water

63%

extracellular fluid is

outside cells

extracellular fluid is how much of body water

37%

extracellular fluid consists of

interstitial fluid, blood plasma, and lymph

interstitial fluid is in

tissue spaces

blood plasma is in

blood vessels

lymph is in

lymphatic vessels

ex of transcellular fluids

cerebrospinal fluid, aqueous and vitreous humors in eye, synovial fluid in joints, serous fluid

body fluid composition

water and electrolytes

intracellular fluid is high in

K+, Mg 2+, PO4-3, and SO4-2 ions

extracellular fluid is high in

Na+, Cl-, Ca+2, and HCO3- ions

hydrostatic pressures

remains equal and stable in cells and interstitial fluids

osmotic pressure is

exerted by impermeant solutes

most fluid movement results from

changes in osmotic pressure

water intake is controlled by

the thirst centers in the brain

water output is controlled by

kidneys + sweat

the body loses as little as 1% of its water as osmotic pressure of extraceulluar fluid

increases

person feels thirsty when

osmoreceptors are stimulated in the hypothalamus

when water is absorbed by stomach and small intestine → osmotic pressure of extracellular fluid

returns to normal

ADH is most important hormone for

water balance

during dehydration extracellular fluid is

concentrated

increases osmotic pressures does what (dehydration)

stimulates osoreceptors in the hypothalamus

osmoreceptors in hypothalamus stimulates (dehydration)

ADH secretion

ADH increases permeability of (dehydration)

renal distal tubules and collecting ducts to water allows for water reabsorption

after drinking excess water extracellular fluid is

less concentrated

decreased osmotic pressures, osmoreceptors is stimulated (excess water)

inhibits ADH secretion

distal tubules and collecting ducts are (excess water)

impermeable to water

distal tubules and collecting ducts being impermeable leads to

water reabsorption decrease, and urine volume increases

increase ADH →

increase osmotic pressure

electrolyte intake :

Na+, K+, Ca+2, Mg+2, Cl-, SO4-2, PO4-3, HCO3-, H+

aldosterone reabsorbes (in kidney)

Na

aldosterone excretes (in kidney)

K+

Na+ and K+ are regulated by

aldosterone

if aldosterone increases

Na+ increases, K+ decreases

if aldosterone decreases

Na+ decreases, K+ increases

calcitonin is released by

thyroid gland

calcitonin is release to

decrease serum calcium and phosphate

calcitonin inhibits

osteoclast (decrease bone absorption)

calcitonin activates

osteoblast

calcitonin increases

the excretion of Ca and P in kidney

Parathyroid hormone is released to increase

serum calcium

Parathyroid hormone is released to decrease

phosphate

Parathyroid hormone inhibit

osteoblast

Parathyroid hormone activate

osteoclast

Parathyroid hormone in kidney

reabsorb Ca

Parathyroid hormone excrete

P

Parathyroid hormone in intestines

increase absorption of Ca and P with the help of vitamin D

acidosis

pH < 7.35

alkalosis

pH > 7.45

homeostatic mechanisms help

maintain pH (.35-7.45)

buffers are

chemicals which act to resist pH changes

Chemical buffer (1st line)

bicarbonate, phosphate and protein buffer system

bicarbonate buffer stystem

H+. + HCO3- ←> H2CO3

physiological buffer (2nd line)

repertory and renal systems

reparatory CO2

excretion

renal excretion

H-ion

COPD is difficulty breathing

out (CO2 accumulate)

accumulates CO2 increases (COPD)

CO2 → respiratory acidosis (pH < 7.35)

kidney response to acidosis : increase (COPD)

the secretion of H-ion

kidney response to acidosis : bring the pH (COPD)

back to normal (7.35)

hyperventilation increase release of

CO2 → decrease CO2 in blood

hyperventilation leads to

respiratory alkalosis (pH>7.45)

kidney response to alkalosis : decrease

the secretion of H-ion

kidney response to alkalosis : reabsorb

the H ion

kidney response to alkalosis : bring the pH

back to normal

diabetes (uncontrolled) : increase

keto-acid in blood

keto-acid in blood → (diabetes)

metabolic acidosis pH<7.35

diabetes lung response: increase

ventilation → remove more CO2 → decrease CO2