regulation of the composition of body fluids

Question 1

what is intracellular fluid?

Answer 1

• fluid inside the cell

Question 2

what is extracellular fluid?

Answer 2

• fluid outside the cell

Question 3

what does extracellular fluid include?

Answer 3

• intravascular fluid = blood plasma in blood vessels
• interstitial fluid = fluid between cells
• transcellular fluid = fluid in specific body regions

Question 4

what is the total volume made up of?

Answer 4

= 42L

• intracellular fluid = 28L
• extracellular fluid = 14L

Question 5

what is osmotic pressure?

Answer 5

= tendency of a solution to take in water

- the greater difference in osmotic conc = greater osmotic pressure

Question 6

what is the role of the kidneys in excretion?

Answer 6

= maintaining a constant of materials in the body fluids

Question 7

what is the thirst reflex feedback loop?

Answer 7

stimulus = high osmotic pressure in the blood
receptor = osmoreceptors in the hypothalamus detect high osmotic pressure
modulator = the thirst center in hypothalamus processes info from osmoreceptors and sends a nerve impulse to the cerebral cortex
effector = cerebral cortex triggers the conscious feeling of thirst and causes the person to drink water
response = water is absorbed via alimentary canal to increase water conc. in blood
feedback = feedback is negative as the response is opposite to the original stimulus. Decrease in osmotic pressure

Question 8

what is water intoxication?

Answer 8

• too much water
• body fluids become diluted and cells take in extra water by osmosis’
• lose water and salts through sweating and replace the loss with plain water

Question 9

what is the antidiuretic hormone?

Answer 9

• produced by the hypothalamus
• released from posterior lobe in the pituitary gland
• reabsorption of water

Question 10

what is the feedback loop for the reabsorption with the use of ADH?

Answer 10

stimulus = decreased blood volume (increased osmotic pressure)
receptor = osmoreceptors in hypothalamus activate thirst reflex
modulator = nerve signal to posterior pituitary gland which sends ADH into the bloodstream
effector = DCT + collecting duct
response = increases permeability of DCT + collecting duct = water is reabsorbed 
feedback = negative - decrease osmostic pressure

Question 11

what is aldosterone?

Answer 11

• secreted by the adrenal cortex

- released when decrease in conc of NA ions in the blood, decrease in blood pressure + volume

Question 12

the aldosterone feedback loop in response to decreasing blood volume?

Answer 12

stimulus = decreased blood volume 
receptor = baroreceptors in renal artery
modulator = several chemical messages ending with the release of aldosterone from the adrenal cortex 
effector = sodium pumps in DCT, the loop of Henle
response = sodium reabsorbed, increases ion conc in interstitial fluid