Introduction to Blood Flashcards
Describe some functions of blood
- Carriage of physiologically active compounds
- Thermoregulation
- Maintenance of ECF pH
Approx. how much blood is there in a healthy 70kg man?
5 litres
Describe the approximate distribution of blood in the body
1L in lungs
3L in systemic venous circulation
3L in heart and arterial circulation
What percentage of body weight is blood in the average woman?
7-8%
How much blood is in an average neonate?
350mo (about a coke can)
Describe the composition of blood
Plasma, red and white blood cells, platelets
Describe the composition of plasma
95% water - circulates biological active compounds; contains plasma proteins
What categories of plasma proteins are there?
Albumin, globulins and fibrinogen (and other clotting factors)
What three types of globulins are there?
alpha, beta and gamma
What is colloid oncotic pressure?
A type of osmotic pressure exerted by plasma proteins tending to draw fluid into the circulatory system
Movement of fluid between capillary and interstitial space is subject to what two forces?
Hydrostatic pressure and colloid oncotic pressure
As colloid pressure is relatively constant, movement of fluid therefore depends on a balance between what?
Capillary hydrostatic pressure (CHP) and interstitial hydrostatic pressure (IHP)
What is hypoproteinaemia?
Abnormally low levels of circulating plasma protein
What are the causes of hypoproteinaemia?
Prolonged starvation, liver disease, intestinal diseases, nephrosis (kidney disease)
What is a common characteristic of hypoproteinaemia?
Oedema due to loss of oncotic pressure
What is the lifespan of an erythrocyte?
120 days
Describe the action of erythropoiesis
Pluripotent stem cells differentiate into erythroblasts in presence of erythropoietin - erythroblasts mature into erythrocytes
How do neutrophils entrap microorganisms?
NETS (Neutrophil extracellular traps)
Describe the process of leukopoiesis
Cytokines released from endothelial cells, fibroblasts and white blood cells stimulate mitosis and maturation of leukocytes
How does the proportion of neutrophils to lymphocytes change depending on the infection type?
Bacterial - more neutrophils
Viral - more lymphocytes
What are platelets?
Membrane bound cell fragments of megakaryocytes
What hormone governs the production of platelets?
Thrombopoietin
What is a haematocrit?
Centrifuged sample of whole blood tissue which displays separate constituent parts of tissue
