Lecture 5 - The Cardiovascular System I Flashcards
Which two types of circulation are there in the body?
1- Systemic circulation: Blood from the heart is distributed around the body before returning to the heart
2- Pulmonary circulation: Blood from the heart flows to the lungs and back
Name three components (not water) of blood plasma.
Proteins
Nutrients
Enzymes
Hormones
Mineral salts
Organic waste materials
Gases
Name three types of blood vessels and their functions.
Arteries: Carries oxygenated blood away from the heart (with the exception of pulmonary and umbilical arteries) under high pressure. Smaller arteries are called arterioles.
Veins: Carries deoxygenated blood towards the heart (exceptions - pulmonary and umbilical veins) under low pressure. Small veins are called venules. They contain valves to aid in blood flow.
Capillaries: Smallest blood vessels that connect arterioles and venules. They specialise in the exchange of substances between the blood and cells/tissues.
Where are most blood plasma proteins synthesised in the body?
In the liver hepatocytes
List two functions of albumin
- Carrier of substances (lipids, steroid hormones)
- Maintains osmotic pressure
List two functions of globulins
- Immunity (immunoglobulins secreted by B-cells)
- Transports iron, lipids and vitamins
What is another name for ‘clotting factor 1’?
Fibrinogen
Name two cations (+)
Calcium, Magnesium, Sodium, Potassium
Name two anions (-)
Chlorine, Bicarbonate, Phosphate, Sulphate
Which four nutritional products of digestion pass into the blood for distribution?
Carbohydrates
Amino Acids
Lipids
Vitamins
Define haematopoiesis
The production of all blood cells in red bone marrow from pluripotent stem cells.
During the first two months of gestation, the embryonic yolk sac performs this function. From months 2-9, the liver and spleen of the foetus take over this role.
Name two other locations in the body where haematopoiesis takes place
In the red bone marrow inside vertebrae, ribs, sternum, skull, sacrum, pelvis and proximal long bones (mostly femur)
Describe how the structure of RBCs supports oxygen transport.
Erythrocytes are bi-concave and have no nucleus, giving the cells a larger surface area to transport oxygen.
Describe the structure of haemoglobin (Hb)
Each erythrocyte has 280million Hb molecules. One haemoglobin molecule consists of four polypeptide chains (globin) and each chain is bound to a pigment called ‘haem’ which contains iron. Each haem group can carry an oxygen molecule, which means each haemoglobin can carry four oxygen molecules.
What is ‘haematocrit’ and why is this value smaller in females?
It is the percentage of blood volume occupied by erythrocytes and in females, it is roughly 42% while in males it is roughly 47%. The reason for this is menstrual blood loss in women and the fact that androgens, of which men have more, stimulate RBC production
Why is the colour of blood red?
The chemical bond between iron and oxygen reflects red light.
What is the main difference between adult and foetal haemoglobin?
Adult haemoglobin molecules are composed of two alpha and two beta sub-units.
Foetal haemoglobin is composed of two alpha and two gamma sub-units.
What nutrients are required for erythropoiesis?
Vitamin B12
Folate (B9)
Iron
List two triggers of erythropoiesis
Hypoxia (stimulates kidneys to produce erythropoietin which stimulates erythropoiesis in bone marrow)
High altitude
Blood loss
Pregnancy
Why do premature newborns often exhibit anaemia?
Partly due to inadequate EPO (erythropoietin) and during the first weeks of life, the liver produces EPO but is less sensitive to hypoxia than the kidneys
What is erythropoietin?
A hormone secreted by the kidneys (in adults and children) which stimulates the formation of erythrocytes in red bone marrow.
Explain what is meant by:
a. Rhesus positive
b. Rhesus negative
a. Erythrocytes have Rhesus antigens on the surface
b. Erythrocytes do not have Rhesus antigens on the surface
Inheritance of the Rhesus factor is via a rhesus _________ gene. Anti-rhesus antibodies are produced in rhesus ________ individuals only if they come into contact with the rhesus ________. They could come into contact in ________ or incompatible blood infusion.
recessive
negative
antigen
pregnancy
List two key functions of leukocytes
Defends the body from microbes and foreign particles. Plays an important role in immunity
Describe the difference between granulocytes and agranulocytes
Granulocytes have secretory granules in their cytoplasm and agranulocytes do not.