body fluids

Question 1

from what methods can our bodies gain water?

Answer 1

food - 30%
drink - 60%
metabolism - 10%

Question 2

what is the total body fluid of a 70kg man?

Answer 2

42L - 60% of body weight

Question 3

what percentage of body fluid is the ECF and ICF?

Answer 3

ECF - 20%

ICF - 40%

Question 4

what ions are mainly found in the ECF and ICF?

Answer 4

ECF - Na+, Cl- and HCO3-

ICF - K+ and PO4^3-

Question 5

what are the major solutes contributing to osmolality?

Answer 5

Na+, Cl-, Glucose & urea

Question 6

what are solutes?

Answer 6

inorganic salts

Question 7

how can solutes be classified?

Answer 7

o Electrolytes – inorganic salts (ie: Na+, K+, Cl-)

o Non electrolytes

Question 8

which has more osmotic power; electrolytes or non-electrolytes?

Answer 8

electrolytes

Question 9

what is osmotic pressure?

Answer 9

the process that controls movement of solvents (water) across a membrane

Question 10

define osmolarity

Answer 10

measure of solute concentration expressed as the number of osmoles (Osm) of solute per litre of solution

Question 11

what factors affect osmolarity and why?

Answer 11

pressure and temperature bc these can affect volume

Question 12

define osmolality

Answer 12

the measure of osmoles of solute per kilogram of solvent – Osm/kg

Question 13

what is the normal range for plasma osmolality?

Answer 13

280-300mOsm/Kg

Question 14

which is used in clinical labs; osmolality or osmolarity?

Answer 14

osmolality

Question 15

what are the two forces that control the equilibrium int he ECF and how are these generated?

Answer 15

hydrostatic pressure - force produced by the heart pumping

oncotic pressure - proteins in the plasma

Question 16

what are the main forms of transport in a cell?

Answer 16

simple diffusion
facilitated diffusion
active transport

Question 17

what is the major determinant of plasma and ECF osmolality?

Answer 17

sodium

Question 18

what parts of the brain control the CNS and the thirst mechanism?

Answer 18

Subfornical Organ (SFO) and the Organum Vasculosum of the lamina terminalis (OVLT

Question 19

where is ADH released from?

Answer 19

posterior pituitary gland

Question 20

when is ADH released?

Answer 20

increased plasma osmolality

decreased plasma volume

Question 21

what receptor detects plasma osmolality?

Answer 21

osmoreceptors of the hypothalamus

Question 22

what receptors detect plasma volume?

Answer 22

baroreceptors of the great veins and right atrium

Question 23

what effect does ADH have on collecting ducts?

Answer 23

makes collecting duct cells more permeable to water –> increases water reabsorption

Question 24

what effect does ADH have on urine output?

Answer 24

Low ADH levels  dilute urine and reduced volume of body fluids

High ADH levels  concentrated urine

Question 25

what factors can trigger ADH release?

Answer 25

prolonged fever, excessive sweating, vomiting, or diarrhea, severe blood loss and traumatic burns

Question 26

what cells do ADH target?

Answer 26

aquaporins

Question 27

where is aldosterone released from?

Answer 27

adrenal cortex

Question 28

what triggers aldosterone release?

Answer 28

reduced sodium | increased potassium

Question 29

what cells are the target of aldosterone?

Answer 29

• Na+/K+ ATPase and epithelial Na+ channel (ENaC)

Question 30

what hormone is released in response to low plasma volume?

Answer 30

ADH

Question 31

what hormone is released in response to plasma osmolality changes?

Answer 31

aldosterone

Question 32

what hormone is released when there is high plasma volume?

Answer 32

atrial natriuretic peptide (ANP)

Question 33

where is ANP released from?

Answer 33

cardiac atria

Question 34

what triggers the release of ANP?

Answer 34

increased blood volume which stretches the atria

Question 35

what hormones control plasma osmolality and volume?

Answer 35

ADH angiotensin II aldosterone ANP

Question 36

how much water is reabsorbed in the PCT?

Answer 36

80%

Question 37

in a healthy individual, what should the 24 hour urine osmolality be?

Answer 37

500 and 800 mOsm/kg

Question 38

after 12-14 hours of fluid intake restriction, what should the urine osmolality be?

Answer 38

over 800mOsm/kg

Question 39

what conditions arise as a result of failures of body fluid balance?

Answer 39

dehydration water intoxication oedema

Question 40

in what people is dehydration common?

Answer 40

very young and elderly people

Question 41

what causes water intoxication?

Answer 41

too much water too quickly urine blockage

Question 42

what is an oedema?

Answer 42

Swelling of the tissue due to accumulation of fluid in ECF

Question 43

what are the four main causes of oedema?

Answer 43

1. Increased capillary hydrostatic pressure - capillary hydrostatic pressure > Osmotic pressure = fluid leave the capillary. 2. Loss of plasma proteins 3. Obstruction of lymphatic circulation 4. Increased capillary permeability (inflammation)