body fluids and blood Flashcards
% and litres that make up intracellular space within total body water TBW
40% - 28L
how much is TBWin L of lean tissue/kg and how does fat affect it
42L
0.71/Kg
more fat, less water
% and L of interstitial space
15% TBW
10.5L
% and L of plasma space
5%, 3.5L
L of extracellular space
14L
list other fluid compartments - transcellular fluids
CSF (150ml) Aqueous and vitreous humors of the eye synovial fluid amniotic fluid GI tract secretions lymph
how can we measure fluid compartments - dilution method?
V = S/C
add known amount of substance (S) to unknown volume (V), C=grams per litre
what substances can be used in measuring fluid compartments - plasma volume?
not metabolised quickly, non-toxic, distrivutes
- does not cross capillaries
- large size, Evans blue, labeled Inulin, albumin
what substances can be used in measuring fluid compartments - ECS
- does not enter cells easily
- 24Na, sucrose
what substances can be used in measuring fluid compartments - TBW
- distributes with all water
- 3H2O
how do we derive interstitial space and intracellular space?
interstitial = ECS-plasma vol intracellular = TBW - ECS
major constituents of body fluids
- ions in solution: cations (Na, K, Ca, Mg) and anions (Cl, HCO3, PO4)
- proteins
- dissolved gases, nutrients, metabolites
- cells in blood
ionic composition of ECF and ICF
- Na, Cl and K major ions - determine osmolarity
- concentrations of Na, K and Ca differ a lot (members potential, signalling) but osmolarity must be equal in ICF and ECF
how is one unit osmole described
6.022 x 10^23 entities = 1 mole
differne between osmolarity and osmolality
osmolaRity = 1 osmole (mosm) per litre osmolaLity = 1 osmole per Kg
relationship of osmoles to pressure
1 osmle in 22.4 litres exerts 70mmHg
1 osmole/litre exerts >17,000mmHg
osmolarity of plasma
290 mosmol/litre
difference between crystalloid and oncotic osmotic pressure
crystalloid due to small diffusable ions e.g.Na, Cland K.
oncotic(or colloidal): pressure exerted by proteins (do not cross capillary walls) - 25mmHg
[protein]=70g/L
plasma ionic compositions?**
Na=140mmol/l
K=4mmol/l
Ca=2mmol/l
Cl=110
bicarbonate=24
intracellular ionic compositions
Na=10mmol/l
K=120mmol/l
Ca=100nmol/l
amino acids, Cl, proteins etc
composition of plasma proteins and functions
total=70g/litre
- albumin: 48g/l: plasma oncotic pressure, transport, puffering pG
- a, B and gamma globulins (0.7-13g/l each): haemostasis, transport, immune system
- fibrinogen (3g/l): haemostasis
blood cell composition
erythrocytes (RBC)
leucocytes (WBC)
platelets
erythrocytes life span
lifespan - 120 days
RBC count in M and F
male=5.5 x 10^12 per litre
female - 4.8
