Flashcards in Circulatory System Deck (21):
What is blood composed of?
Red blood cells, white blood cells, plasma and platelets.
What is the function of red blood cells?
Red blood cells transport oxygen to the muscles from the lungs.
How are red blood cells adapted for their function?
They have a biconcave disc shape which increases their surface area : volume; they contain haemoglobin which binds easily to oxygen; they don't have a nucleus which increases their capacity to carry oxygen.
What are white blood cells used for?
They form part of the immune system and attack foreign microbes such as pathogens which can be harmful.
What are platelets?
They are small fragments of cells which encourage blood to clot at the sites of wounds.
What is the function of the plasma?
It transports dissolved food molecules, carbon dioxide and urea around the body, and it has blood cells suspended in it.
What is an artery like?
It has a thick wall of muscle and elastic fibres; it also has a small lumen; arteries carry blood away from the heart to the organs of the body.
What is a vein like?
It has thin walls and often contains valves to prevent the back flow of blood; it has a large lumen; veins carry blood towards the heart which is usually deoxygenated.
What is a capillary like?
Very thin walls for a short diffusion distance; relatively large lumen; capillaries link the arteries and veins.
How can capillaries become narrower?
By fatty deposits building up on the walls of the capillaries.
How do doctors solve narrowed blood vessels?
A mesh stent and balloon is placed in the blood vessel; the balloon is inflated and the mesh stent holds the vessel open and blood will flow freely.
What supplies the heart with oxygen?
The coronary arteries.
What substances does the circulatory system transport?
Oxygen, glucose and carbon dioxide.
What is special about the human circulatory system?
It is a double circulation, bringing deoxygenated blood to the heart to be pumped to the lungs and oxygenated blood to be pumped around the body.
What are the advantages / disadvantages of using mechanical replacement valves?
They last for a very long time; you have to always take medicine to stop blood from clotting; mechanical valves are made from polymers or titanium.
What are the advantages / disadvantages of using replacement biological valves?
They work very well and the patient doesn't need any medication; they only last for around 15 years; biological valves are based on valves taken from pigs or cattle.
What are perfluorocarbons (PFCs)?
They are a form of artificial blood; they are non-reactive chemicals that can carry dissolved gases around the body.
What are the advantages / disadvantages of PFCs?
They do not contain cells so can carry oxygen into swollen tissues of a damaged body; they work for a long time and don't carry disease; they don't dissolve in water so it's difficult to get them into the blood; they can cause severe side effects.
What are the advantages/ disadvantages of blood transfusions?
They can replace blood lost to extend your life; the donor and patient must match blood group; there's often a shortage of blood donors; blood can only be stored for a limited time.
What are the advantages/ disadvantages of haemoglobin-based artificial blood?
The haemoglobin used carries more oxygen than normal blood; it doesn't need to be refrigerated always; it is broken down very quickly; it doesn't clot or fight disease and has caused severe problems.