Body Fluids and Blood Flashcards
Definition of compartments
Physiological collections of organs and tissues containing water, divided by cell membranes
Definition of transcellular fluids
Come from ECS, have slow diffusion to and from plasma
Definition of osmole
Unit of the total no of freely diffusible entities in solution
(6.022x10^23 = 1mole)
Definition of osmolarity
1 osmole/litre
Definition of osmolality
1 osmole/kg
Definition of osmotic pressure
Determined by the total no of freely diffusible entities in solution
Definition of tonicity
Volume change of a cell placed in solution, only applies when solutions are separated by a semi permeable membrane
Definition of crystalloid osmotic pressure
Osmotic pressure of aqueous solutions of mineral salts or other water soluble molecules
Definition of oncotic/colloidal pressure
Osmotic pressure induced by proteins, otherwise known as colloidal pressure
Units of concentration
1M
1mole/litre
Units of concentration
mol, umol, nmol, pmol, fmol
10 10-3 10-6 10-9 10-12 10-15
Converting between kPa and mmHg
x7.5
Converting between mmHg and kPa
x0.133
3 main fluid compartments
Plasma
Interstitial space
Intracellular space (ICS)
Total water% of human body mass
60%
42l
What % of body mass is ICS + blood cells
40%
28l
What % of body mass is blood cells
3%
What % of body mass is interstitial space
15%
10.5l
What % of body mass is plasma
5%
3.5l
What % of body mass is ECS
20%
14l
What % of body mass is plasma + blood cells
8%
5.5l
What is the water content of lean tissue
0.7l/kg
But depends on fat content, more dense than water
Name the other fluid compartments
CSF (150ml) Aqueous, vitreous humor Synovial fluid Amniotic fluid GI tract secretions Lymph
All form part of the ECS, slow diffusion from the plasma
How to measure fluid compartments (dilution method)
Add known amount of substance (S) to unknown volume (V)
Measure conc after removing known volume
If calculating plasma volume with Evan Blue, use the haematocrit to work out blood volume
V=S/C
What substances should you use to measure fluid compartments in plasma
Distributes in space, non toxic, not metabolized quickly
Does not cross capillaries, must be large
Evans Blue, labelled Inulin, Albumin
What substances should you use to measure fluid compartments in ECS
Distributes in space, non toxic, not metabolized quickly
Does not enter cells easily
24Na, sucrose
What substances should you use to measure fluid compartments in the whole body
Distributes in space, non toxic, not metabolized quickly
3H2O
How to derive the spaces
IS
ECS-PV=IS
How to derive the spaces
ICS
TBW-ECS=ICS
What are the major constituents of body fluid
Ions
Proteins and cells in blood
Dissolved gases
Nutrients and metabolites
Importance of ionic composition in ECF, ICF
Ions determine osmolarity
Conc of Na+, K+, Ca2+, Cl- differ between ECF and ICF, important for cell function (membrane potential)
Osmolarity must be equal
What is the osmotic pressure and osmolarity
Determined by no of freely diffusible entities in solution
eg 140nmol/l of NaCl = 280mosm/l
Why must osmolarity be controlled
Osmolarity of plasma controls plasma volume
Osmolarity of ICF controls cell volume
1 osmole exerts a huge amount of pressure, cause cells to crenate or lyse
What is the osmolarity of plasma
290mosm/l
What is the tonicity of plasma
Isotonic solution = 0.9% w/v NaCl
Crystalloid osmotic pressure
For small diffusible tones
ICO, ECO are equal, ions not permeable across membranes
Crystalloid osmotic pressure only exists when the ions cannot diffuse across
Colloidal osmotic pressure
For proteins (70g/l) Exerts colloidal pressure in capillaries, cannot cross capillaries (25mmHg) Colloidal pressure balanced by outward hydrostatic pressure
Hydrostatic pressure vs colloidal pressure
Arteriole side
High hydrostatic pressure
Low colloidal pressure
Venule side
Low hydrostatic pressure
High colloidal pressure
Ionic composition of [Na+] in plasma
140mmol/l
Ionic composition of [K+] in plasma
4mmol/l
Ionic composition of [Ca2+] in plasma
2mmol/l
Ionic composition of [Cl-] in plasma
110mmol/l
Ionic composition of [HCO3-] in plasma
24mmol/l
Ionic composition of [Na+] in ICF
10mmol/l
Ionic composition of [K+] in ICF
120mmol/l
Ionic composition of [Ca2+] in ICF
100nmol/l
What does Na+ control in the plasma
Blood volume
What does K+ control in the ICF
Cell volume
Ions present in the plasma
Na+ K+ Ca2+ Cl- HCO3-
Ions present in the ICF
Na+ K+ Ca2+ Cl- Amino acids
Plasma proteins
Albumin
a, b, y globulin
Fibrinogen
Concentration and function of albumin
4.8g/l
Contributes to colloidal pressure
Transport and buffering of pH
Concentration and function of a, b, y globulin
0.7-0.13g/l each
Homeostasis
Transport
Immune system
Concentration and function of fibrinogen
3g/l
Haemostasis
Total mass of plasma proteins in 1l
70g
Components in blood
Plasma
Leukocytes
Packed cells (Erythrocytes)
Haematocrit of RBC in females
42%
Hematocrit of RCB in males
47%
RBCC, males, females
- 5x10^12/l
4. 8x10^12/l
Hb mass, males, females
160g/l
140g/l
Lifespan of RBC
120 days
Function of RBC
Carry O2
Buffer pH
Mean RBC volume
85fl
Causes of anaemia
Low Hb/cell count
Low RBCC
Defective haemoglobin
WBCC volume
Considerably fewer than RBCs
4-11x10^9/l
Function of WBC
Defense vs foreign materials
Inflammatory, allergic responses
% of lymphocytes and function
20-40%
Produce immunoglobulins
% of monocytes and function
2-8%
Migrate into tissues, form macrophages
% of neutrophils and function
50-70%
Chemotaxis
Phagocytosis
% of eosinophils and function
1-4%
Phagocytosis
Allergies
% of basophils and function
0.5%
Histamine and heparin release (like mast cells)
Oppose haemostasis
Total volume of platelets
150-400x10^9/l
Where do platelets come from
Megakaryote fragments
Function of platelets
Haemostasis
No nucleus, has dense granules
Changes shape, release granules, stick together when activated