5. Fluid compartments

Question 1

What percentage of the fluid in the body is intracellular?

Answer 1

55%

Question 2

What percentage of the fluid in the body is interstitial fluid?

Answer 2

36%

Question 3

What percentage of the fluid in the body is blood plasma?

Answer 3

7%

Question 4

What percentage of the fluid in the body is transcellular fluid?

Answer 4

2%

Question 5

Barriers in extracellular environments

Answer 5

Compartmentalise for different composition and function

e.g. Plasma membrane separates EC and IC fluids

Question 6

How do layers of cells forming junctions with each other separate extracellular fluids?

Answer 6

Epithelial cell layers separate various interstitial spaces.
Endothelial cells line blood vessels, and are the main barrier separating the fluid of the blood (the plasma) and IC fluids.

Question 7

What is the main cations of intracellular and extracellular fluids?

Answer 7

Extracellular: Na+
Intracellular: K+

Question 8

What is the main anions of intracellular and extracellular fluids?

Answer 8

Extracellular: Cl-
Intracellular: Free organic phosphates

Question 9

Name an important signalling cation found in intracellular and extracellular fluid

Answer 9

Ca 2+

Question 10

What are the concentrations, in mmol/l, of Na+, K+ Ca2+, Cl-, Organic Phosphates and proteins in extracellular fluid?

Answer 10

Na+: 150 mmol/l
K+: 5 mmol/l
Ca2+: 2 mmol/l
Cl-: 110 mmol/l
Organic phosphates: 5 mmol/l
Proteins: 1 mmol/l

Question 11

What are the concentrations, in mmol/l, of Na+, K+ Ca2+, Cl-, Organic Phosphates and proteins in intracellular fluid?

Answer 11

Na+: 10 mmol/l
K+: 150 mmol/l
Ca2+: 10^-4 mmol/l
Cl-: 5 mmol/l
Organic phosphates: 130 mmol/l
Proteins: 2 mmol/l

Question 12

What is the pH inside and outside cells?

Answer 12

outside: 7.4
inside: 7.1

Question 13

Define osmolarity

Answer 13

a measure of the concentration of all solute particles in a solution
expressed as the total number of solute particles per litre.

Question 14

Osmolarity in intracellular and extracellular fluid

Answer 14

Equal

except in some parts of the kidney

Question 15

Define osmosis

Answer 15

movement of water down its own concentration gradient, to an area of higher osmolarity
Can change cell volume

Question 16

Define permeability

Answer 16

state of being permeable

Question 17

What happens if membrane is permeable to water and solutes?

Answer 17

Both diffuse down concentration gradient

After equilibrium, there is no net volume change

Question 18

What happens if membrane is impermeable to 1 or more solutes?

Answer 18

Net change in volume will occur as only water can move

If significant, cell may rupture

Question 19

What feature does osmolarity not take into account and what is a more useful measure?

Answer 19

Cell permeability

Tonicity is more useful

Question 20

Define tonicity

Answer 20

The strength of a solution as it affects final cell volume

Question 21

What 2 elements does tonicity depend on?

Answer 21

Cell membrane permeability

Solution composition

Question 22

Hypertonic solution

Answer 22

Osmolarity of impermeant solutes out > in

Cell shrinks

Question 23

Hypotonic solution

Answer 23

Osmolarity of impermeant solutes out < in

Cell swells

Question 24

Isotonic solution

Answer 24

Osmolarity of impermeant solutes out = in

Cell volume is unchanged

Question 25

What feature do real cells have which prevents them from bursting due to having a higher osmolarity inside the cell than outside?

Answer 25

They have sodium-potassium pumps
Maintains a lower concentration of sodium inside than outside
Pump makes membrane effectively impermeable to Na+, as any Na+ that diffuses in is pumped out again (no net movement)

Question 26

What does intracellular osmolarity of impermeant solutes (mainly high conc. proteins and low conc. Na +) balance?

Answer 26

Extracellular osmolarlity of impermeant solutes (mainly high conc. Na+).

Question 27

What is the function of university of Wisconsin solution (UW)?

Answer 27

to reduce hypothermic cell swelling and enhance preservation for transplantation

Question 28

What does UW solution provide?

Answer 28

No Na+ or Cl- (no influx possible)
Extracellular impermeant solutes (lactobionate ions, raffinose (a sugar))
Macromolecular colloid (starch)
Together, these factors reduce cell swelling in cooled tissues.

Question 29

Why are rapid cooling and tissue preservation solutions required for transplant organs?

Answer 29

Sodium pumps stop working <15 degrees
Na+ and Cl- enter cells with water and K+
Cells swell and bleb which can cause cell death

Question 30

What determines solute and fluid movement across a normal capillary?

Answer 30

Balance between opposing pressures: hydrostatic and osmotic

Question 31

Colloid osmotic pressure (COP)

Answer 31

Osmotic pressure due to plasma proteins

more protein inside than outside vessel

Question 32

What happens if hydrostatic pressure > COP ?

Answer 32

Plasma leaks out of vessel

Question 33

What happens if hydrostatic pressure < COP ?

Answer 33

Plasma flows into vessel

Question 34

What is oedema?

Answer 34

swelling of a tissue because of excess interstitial fluid

Question 35

Describe oedema

Answer 35

Abnormal collection of fluid in the interstitium due to the leakage of fluid from capillaries
Leakage exceeds capacity of the lymphatics to collect and return it to the circulation

Question 36

What do lymphatic capillaries collect?

Answer 36

interstitial fluid that is destined for return to the blood circulation via nodes or lymphatic ducts in subclavian region

Question 37

What type of sign is oedema?

Answer 37

A cardinal sign of inflammation

Question 38

How do insect bites causes inflammatory oedema?

Answer 38

Local blood vessels leak so swelling occurs as rate of leakage is greater than that of drainage

Question 39

Describe hydrostatic oedema

Answer 39

If overweight with high BP there is increased hydrostatic pressure in vessels
This pushes more fluid out of vessels and can lead to accumulation of interstitial fluid

Question 40

Why may a breast cancer survivor have compromised lymphatic function and resulting oedema?

Answer 40

If axillary lymph nodes are removed, pathway of drainage from upper limb is remove= accumulation of fluid

Question 41

What causes oedema in elephantiasis?

Answer 41

Parasitic worms block lymph vessels, thereby preventing lymphatic drainage.
Lymphatics in the right groin region can be blocked, preventing drainage of interstitial fluid from the right lower limb