Fluid Compartments of the Body

Question 1

What does 1 litre of water weigh?

Answer 1

1 KG

Question 2

What is the physiology of a male?

Answer 2

Weighs 70kg
60% of body weight is water
TBW (total) = 42 L

Question 3

What is phsiology of a female?

Answer 3

50% body weight is water

TBW = 35 L

Question 4

Describe Adipose tissue?

Answer 4

Low water content 10-15%
More adipose in females
Content is high even in slim individuals
Responsible for TBW variation
TBW in same individual is remarkably constant

Question 5

What are compartments in fluid physiology?

Answer 5

Virtual

Question 6

What does body fluid divide into?

Answer 6

Extracellular fluid (interstital, plasma, transcellular)
Intracellular fluid

Question 7

Describe Intracellular fluid?

Answer 7

Virtual
Contained by cell membranes
potassium is major cation
Proteins and phosphate are major anions

Question 8

Describe Extracellular fluid?

Answer 8

Any non-intracellular compartment
Sodium is major cation
Chloride and bicarbonate are important anions
Several sub-compartments

Question 9

What is ECF Plasma fluid?

Answer 9

Fluid contained in blood

70ml per litre of plasma is of protein and lipid

Question 10

What does 1 litre of plasma have?

Answer 10

930mls of actual fluid

Question 11

What is ECF Interstitial fluid?

Answer 11

Occupies interstitial space
seperated from plasma fluid by capillary endothelium
Bathes the cells and is link between ICF and blood plasma
Virtual
Low in proteins
Excess ISF into plasma via lymph

Question 12

Describe ECF Transcellular fluid?

Answer 12

Everything else
Seperate from plasma by additional epithelium
Specialised function:
urine, csf, lymph, gi tract, synovial fluid, eye and ear parts

Question 13

Where is sodium high in?

Answer 13

Plasma, ISF and Urine

Question 14

Where is K high?

Answer 14

ICF and a bit urine

Question 15

Where is Mg high?

Answer 15

ICF

Question 16

Where is calcium high?

Answer 16

Plasma

Question 17

Where is chloride high?

Answer 17

Plasma
ISF
Urine

Question 18

Where is bicarb high?

Answer 18

Plasma ISF, Icf a bit

Question 19

What is the dilution principle about?

Answer 19

Quantity of dye tracer to target compartment , after equib measure dye conc

Question 20

What is the dilution principle?

Answer 20

Compartment volume (V) in ml = quantity of dye mg (Q) / conc of dye mg/ml (C)

Question 21

What is the volume of distrubution?

Answer 21

Q/C

Question 22

What is colourimetry?

Answer 22

Make up number of dye solutions to a known conc
shine light through and measure intensity of penetration
plot against calab curve

Question 23

What is osmolality?

Answer 23

analogous to the mole
non-disassociating substances identical to the mole;

n (no of ions) X molar conc

Question 24

What is a non-disassociating substance?

Answer 24

Glucose

Question 25

What is a disassociating substance?

Answer 25

NaCl into na and cl

Question 26

Describe body fluid osmolality?

Answer 26

Kept constant at 280-300 mosmol Kidney major regulatory role ICF and ECF osmolalities are identical as H2O readily cross cell memranes

Question 27

What are routes for water through cell membrane?

Answer 27

Abundant membrane water channels called aquaporins | - Diffusion , water is very concentrated soltion, SA of cell membrane very high to volume

Question 28

Describe Hydrostatic pressure?

Answer 28

Pressure exerted bt a fluid on the walls of a compartment

Question 29

Describe Osmotic pressure?

Answer 29

Equal to that and represents the pressure required to prevent net movement of water across a semi-permeable membrane

Question 30

What is Isotonic?

Answer 30

Solution which does not cause changes in cell volume - RBC doesnt do haemolysis in isotonic solutions

Question 31

What is Isosmotic?

Answer 31

Solutions having same osmolality - isotonic solutions always isosmotic, but isosmotic are not isotonic

Question 32

Why do RBCS burst?

Answer 32

Because urea readily diffuses and equilibrates across cell membrane and cancels own osmotic pressure

Question 33

What are effective osmoles?

Answer 33

Cause net water movement by being impermeant through reference membrane and exerting osmotic pressure e.g Extracellular NA

Question 34

What are Ineffective Osmoles?

Answer 34

Diffuse readily across membranes cancelling own osmotic pressure e.g urea

Question 35

What is plasma protein oncotic colloid pressure?

Answer 35

Osmotic pressure exerted by plasma proteins Large impermeant anions transcapillary fluid dynamics Pie symbol

Question 36

What is the gibbs-donnan effect?

Answer 36

Diffusible cations X Diffusible anions = diffusible cations x diffusible anions Total number of ions greater on side 1 than side 2, side 1 more osmotic pressure

Question 37

What is bulk flow?

Answer 37

Passive solute movement - solvent drag occurs in vessels in form of filtration across capillary membranes

Question 38

What are starling forces?

Answer 38

forces that determine capillary filtration and reabsorption - movement of water and solutes between plasma and ISF 90% - ordinary diffusion 10% starling forces

Question 39

What do starling forces consist of?

Answer 39

Capillary hydrostatic pressure | Plasma protein oncotic pressure

Question 40

What does hydrostatic pressure depend on?

Answer 40

Arterial BP Extent of transmission Venous pressure (resistance to flow)

Question 41

Describe plasma protein oncotic pressure?

Answer 41

25mmhg Constant as plasma proteins are effectively permeable Plasma proteins are effective osmoles as impermeant