blood 1

Question 1

how much blood is there in an average sized man? how is it distributed ?

Answer 1

5 litres-
1litre in lungs
3 litres in venous system
1 litre in the heart and arterial system

Question 2

what is the blood made up of? describe components briefly

Answer 2

red blood cells-erythrocytes: 
-main component of the blood
-contains a lot of haemoglobin
-non-nucleate
-long life span
white blood cells-leukocytes
-larger than RBCs
-nucleated

plasma

• contains plasma proteins (albumin, globulin alpha-beta-gamma, fibrinogen )
• contained within strict limits

platelets

• membrane bound
• very short lifespan

Question 3

what are the functions of the blood?

Answer 3

• adhere to damaged connective tissue: platlets
• involved in gas exchange: RBCs
• involved in immunity: WBCs
• carries active compounds round the body : plasma
• thermoregulation
• maintains ECF- plasma

Question 4

what controls the flow of fluid in and out of the plasma

Answer 4

plasma proteins rarely leave the plasma.
H20, glucose, ions do.
there is no change in the overall concentration of the plasma but there is a change in volume.
controlled by balance between colloid oncotic pressure (in) and capillary hydrostatic pressure( out)

Question 5

what happens when there is a low level of plasma proteins in the blood and how does this occur?

Answer 5

hypoproteinemia

due to starvation, liver, intestine or kidney disease

Question 6

how is blood for?

specifics for RBCs, WBCs and platelets

Answer 6

RBCs -Erythropoiesis
controlled by erythropoietin- increased secretion when  02 to kidneys decreases-hypoxia. 
Hypoxia occurs:
-anemia 
-haemorrage 
-lung/kidney disease
pluripotent stem cells--- erythroblast. 
Erythropoietin is secreted by
-peritubular capillary cells 
-hepatocytes 

WBCs- Leukopoiesis.
controlled by a mixture of cytokines- colony stimulating factors and interleukins.
fibroblast, mature WBCs and endothelial cells stimulate the production of cytokines.
lead to mitosis/maturation to produce leukocytes which can then differentiate further depending on the immune system requirements

Platelets-controlled by thrombopoietin.

Question 7

what is viscosity?

what does it depend on?

Answer 7

compares the thickness/stickiness of blood with water.
depends on temperature, flow rate, haematocrit.
plasma has a viscosity 1.8 water
RBCS have a viscosity 3.4 water

Question 8

haemotocrit

Answer 8

proportion of blood made up of RBcs