Blood Flashcards
What is the average circulating volume?
5 litres (lungs=1, systematic venus circulation=3, heart and atrial circulation=1)
What are the functions of blood?
Carriers physiologically active compounds, clotting, defence, carriage of gas, thermoregulation and maintains pH
What physiologically active compounds does blood carry?
Enzymes, hormones and nutrients
What 2 substances are involved in clotting?
Prothrombin and fibrinogen
What provides defence?
Leukocytes
What gases does blood carry?
Oxygen and CO2
What is thermoregulation?
Maintaining body temperature through vasodilation (cold) and vasoconstriction (hot)
Where is pH maintained?
In the ECF
What is plasma?
Circulates biologically active molecules and compounds
What is plasma made out of?
95% water, 5% protein
What are the 3 sub categories of plasma proteins?
Albumin, globulin and fibrinogen
What happens when there is a small change in plasma protein composition?
Big problemo
Do plasma readily cross the cell wall?
No
What is the function of albumin?
Transports lipid soluble and steroid hormones and helps to create colloid oncotic pressure
What is the function of globulins?
alpha/beta- transport lipids and fat soluble vitamins
gamma- antibodies
What is the function of fibrinogen?
Clotting factors
What is oncotic pressure?
An osmotic potential created by plasma proteins displacing water as they can’t cross the capillary wall
What is the function of osmotic pressure?
It can pull water from the IF into the lumen and can move chemicals and nutrients as water moves
What is constant in oncotic pressure?
Concentration, volume can change
What is the most abundant out of WBCs, RBCs and platelets?
RBC-> WBC-> platelets
What has the highest lifespan out of WBCs, RBCs and platelets?
RBC: 120 days
WBC: 13-20 days
Platelets: 8-9 days
What is the function of RBCs?
Carries oxygen around the body using haemoglobin
What are the properties of RBCs?
Highly flexible, bi concave and are non-nucleated
What is another name for RBCs?
Erythrocytes
What is Erythropoiesis?
The formation of RBCs, form pluripotent stem cells -> erythroblast (mature RBCs). It takes 2-3 days
What stimulates erythropoiesis?
Erythropoietin
What secrets erythropoietin?
The peritubluar capillary cells found in kidneys. Increased secretion when oxygen supply to the kidneys is low
What causes oxygen supply to decrease in kidneys?
Hypoxia, haemorrhage, anaemia and lung disease
What are WBCs?
Leukocytes which are larger than RBCs and are nucleated
What is the function of WBCs?
They defend against pathogens and several different subcategories
What are the 5 types of WBCs?
Neutrophils, eosinophils, basophils, monocytes and lymphocytes
What are neutrophils?
They are the most common type of WBC that have a half life of 6 days. They are phagocytic and mainly deal with bacterial infection by trapping bacteria in NETS
What are eosinophils?
They attack pathogens that are too large for other WBCs and their numbers increase during an allergic reaction
What are basophils?
They release histamine and heparin which promotes inflammation
What are monocytes?
They are the largest WBC that have a life span of 72 hours. They migrate to other tissues and become macrophages
What are lymphocytes?
They are key components of the immune system and contain T and B cells
What is leukopoiesis?
The formation of WBCs by a controlled dynamic cocktail of cytokines which are released by endothelial cells, fibroblasts and mature WBCs.
What are the cytokines involved in leukopoiesis?
Growth stimulus factors and interleukins. They stimulate mitosis and the maturation of leukocytes
What is a monocyte?
Differentiated WBC that migrate to connective tissue where they become macrophages and live for 3 months
What is a macrophage?
A large WBC that engulfs bacteria via phagocytosis
What are platelets?
They are unique membrane bound fragments of megakaryocytes. They are formed by thrombopoietin
What is the function of platelets?
They attach to damaged capillary walls and exposed connective tissue to mediate blood clotting. They don’t attach to healthy epithelium
What is haematocrit?
The % of blood made up by RBCs, which is higher in males than it is in females. It can be changed due to certain factors e.g. altitude (increases)
What is blood viscosity?
The thickness of blood in comparison to water. It changes with haematocrit, temperature and flow rate
Is whole blood thicker than plasma?
Yes
