water compartments

Question 1

what does water do in the body

Answer 1

lubricant
transport of nutrients
body temp regulation
waste disposal

Question 2

how much of a newborn’s TBW is water

Answer 2

80%

Question 3

how much of an adult woman’s TBW is water

Answer 3

50%

Question 4

how much of an adult man’s TBW is water

Answer 4

60%

Question 5

intracellular fluid contains what cations and anions

Answer 5

mostly K+
mostly PO4—
protein anions

Question 6

ICF contains (very importantly) a large number of…

Answer 6

proteins

Question 7

ECF contains what ions

Answer 7

Na+, Cl- and HCO3-

Question 8

what should not be present in ECF

Answer 8

proteins

Question 9

what is in plasma incl. cations and anions

Answer 9

Plasma consists of a water solvent containing product of digestion, hormones, electrolytes, waste products and plasma proteins.

Major cations: Na+
Major anions: Cl- & HCO3

Question 10

describe how the fluid content of the body is divided up

Answer 10

60%ICF, 5% plasma (ECF), 30% interstitial fluid (ECF), 5% other fluid (GI secretions etc)

Question 11

what is the average osmolality of the body

Answer 11

300mOsm/kg

Question 12

when will a solute move through a membrane to correct eqm

Answer 12

when the membrane is permeable to that solute

Question 13

what is osmotic pressure

Answer 13

the pull to bring water through a permeable membrane into a more concentrated solute in order to achieve eqm

Question 14

what is hyperosmotic?

Answer 14

the solution has greater osmotic pressure than the other side of the membrane (eg the fluid in the cell)

Question 15

what have the greatest osmotic power and why

Answer 15

electrolytes because they draw water across the membrane but can’t diffuse across themselves

Question 16

give some examples of non-permeant solutes

Answer 16

NaCl, KCl, sucrose

Question 17

give an example of a permeant solute

Answer 17

eg glucose, urea, glycerol

Question 18

what is tonicity

Answer 18

volume of the cell at eqm

Question 19

what is a hypotonic solution?

Answer 19

less concentrated solute than in the cell - water will diffuse into the cell

Question 20

what is the physiological osmolality set point

Answer 20

280-300 mOsm/l

Question 21

what is a hyperosmolar solution

Answer 21

one with higher osmotic pressure than on the other side of the membrane.

Question 22

describe the thirst to drinking pathway

Answer 22

osmoreceptors in the hypothalamus respond to high plasma osmolality (increase os 1-2%), ADH vasopressin is released by the pituitary gland which causes water to be reabsorbed in the kidneys. Other signals are sent to encourage water-seeking behaviour

Question 23

describe the blood loss ->normal hydration pathway

Answer 23

• decrease in plasma volume
• stimulation of specialised volume receptors
• increase of angiotensin II - vasoconstrictor
• in the ADRENAL CORTEX, aldosterone is released
• Reabsorption of Na+ in the kidney - wherever salt goes, water follows

Question 24

what is the negative feedback loop when blood vol is too high

Answer 24

• Atria are stretched due to high BP
• ANP is released
• 3 targets: kidneys, hypothalamus &posterior pituitary, adrenal cortex
• Angiotensin goes down (vasodilation), ADH and aldosterone go up

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Question 25

What is the Vd

Answer 25

The amount of water it would take to dilute the drug given to the concentration it currently is in the plasma