Blood Flashcards
How much blood does the average 70kg man hold?
5 litres.
How is blood dispersed throughout the body?
1L lungs
3L systemic venous circulation
1L heart and arterial circulation
What are the functions of blood?
Carriage of physiologically active compounds Clotting Defence Carriage of gas Thermoregulation Maintenance of ECF pH
What is blood composed of?
Plasma
Red blood cells
White blood cells
Platelets
What is the function of plasma?
Circulates biologically active molecules and proteins.
What does plasma consist of?
Water, plasma proteins.
Can plasma proteins cross the capillary wall?
Not usually.
What are the most common plasma proteins?
Albumin
Globulin
Fibrinogen
What does the inability of plasma proteins to permeate the capillary wall generate?
Colloid oncotic pressure.
What forces is the net movement of fluid between a capillary and the interstitial space exposed to?
Capillary hydrostatic pressure
Plasma protein concentration
What does capillary hydrostatic pressure favour?
Favours movement of fluid out of the capillary.
What does plasma protein concentration favour?
Favours movement of fluid into capillary.
What is hypoproteinaemia?
Condition in which the plasma protein concentration is too low.
What condition occurs when the plasma protein concentration is too low?
Hypoproteinaemia.
What is hypoproteinaemia characterised by?
Oedema due to loss of oncotic pressure and accumulation of fluid.
What is the formation of blood cells called?
Haemopoiesis.
What is haemopoiesis?
The formation of blood cells.
What are blood cells derived from?
Haemopoietic stem cells.
What are the types of blood cell?
Erythrocytes (RBC)
Leukocytes (WBC)
Platelets
How are erythrocytes formed?
Erythropoiesis.
What is erythropoiesis?
Formation of red blood cells.
How are red blood cells characterised?
Small, biconcave shape, no nucleus- increases surface area for nutrient diffusion, red due to haemoglobin.
What makes erythrocytes red?
Haemoglobin presence.
What are the most abundant blood cell?
Erythrocytes.
What is erythropoiesis controlled by?
Erythropoietin.
What does erythropoietin do?
Catalyses the development of pluripotent stem cells into erythrocytes.
When can erythropoietin concentration be increased?
When RBC are needed more- e.g. during haemorrhage, anaemia etc.
What are leukocytes?
White blood cells.
What are leukocytes involved in?
Immune response.
How are leukocytes formed?
Leukopoiesis
How are leukocytes characterised?
Larger cells, nucleated, pathogenic defence.
Why is leukopoiesis more complex than erythropoiesis?
Involves a cocktail of cytokines.
What do the cocktail of cytokines in leukopoiesis include?
Colony stimulating factor
Interleukins
What do colony stimulating factors and interleukins feature in?
Cocktail of cytokines within leukopoiesis.
Where are cytokines released from?
Endothelial cells
Fibroblasts
Mature WBC
What does bacterial infection stimulate?
Increased production of neutrophils.
What does viral infection stimulate?
Increased production of lymphocytes.
Why is the cytokine cocktail in leukopoiesis described as dynamic?
It can be altered to produce certain types of cells during specific times of need (e.g. specific infections).
What are platelets?
Membrane bound fragments derived from megakaryocytic.
Are platelets nucleated?
Rarely.
What is the formation of platelets governed by?
Thrombopoietin.
What do platelets do in clotting?
Adhere to damaged cell endothelium and exposed connective tissue.
Do platelets adhere to healthy cell endothelium?
No.
What is the haematocrit?
The ratio of the RBC volume in comparison to the total volume of blood.
What is the usual RBC percentage in the haematocrit?
40-50% - lower in women.
When would the haematocrit differ?
Pathological conditions, anaemia, pregnancy etc.
What is viscosity of blood?
Blood viscosity describes the thickness of blood in comparison to water.
What does blood viscosity depend on?
Haematocrit
Temperature
Flow rate
