Transport in Humans Flashcards
What is the function of plasma?
Transport proteins, mineral salts, food, excretory products and hormones around the body.
What is the function of red blood cells?
It transports oxygen from the lungs to the rest of the body.
How is the red blood cell adapted for its function?
Haemoglobin combines reversibly with oxygen -> allows red blood cells to perform its function
Circular biconcave shape -> increased surface area to volume ratio -> absorb and release oxygen faster
No nucleus -> more haemoglobin -> more oxygen
Elastic -> squeeze through capillaries
What is the function of white blood cells?
It keeps the body healthy by fighting diseases.
What are the physical characteristics of a lymphocyte?
A lymphocyte has a large rounded nucleus and a relatively small amount of non granular cytoplasm. They are nearly round in shape and only show limited movements.
What are the physical characteristics of a phagocyte?
A phagocyte has a lobed nucleus and a granular cytoplasm.
What is the function of platelets?
They play a part in the clotting of blood.
What happens when blood vessels are damaged?
When blood vessels are damaged, damaged tissues and blood platelets release thrombokinase. Thrombokinase converts prothrombin into thrombin under the presence of calcium ions. Thrombin catalyses the conversion of fibrinogen into fibrin. Fibrin threads entangle blood cells, forming a clot. The clot seals the wound and prevents entry of microorganisms.
How does phagocytosis work?
Phagocytosis is the process of engulfing or ingesting foreign particles, such as bacteria, by white blood cells. Phagocytes engulf bacteria by flowing over them, enclosing them and digesting them.
How do antibodies protect our body?
They act by destroying the bacteria (e.g. attaching to them and causing their membrane to rupture), agglutinating the bacteria for easier ingestion, or neutralising the toxins produced by bacteria.
How is tissue rejection prevented?
The tissues of the donor and recipient must be as genetically close as possible. Either that, or immunosuppressive drugs could be used to inhibit the responses of the immune system. However, the latter method requires the recipient to take the drugs for the rest of their life, and live with a weakened immune system.
How are arteries adapted for its function?
Thick muscular walls -> withstand immense pressure of blood
Elastic -> Allows the walls to stretch and recoil -> blood can be pushed in spurts along the artery
How are veins adapted for its function?
Semilunar valves -> prevent backflow of blood
How are substances transferred between capillaries and tissue cells?
Dissolved food substances and oxygen diffuse from the blood in the blood capillaries into the tissue fluid, then into the cells. Metabolic waste products diffuse from the cells into the tissue fluid, then through the blood capillary walls.
How does blood travel from the body to the heart?
Deoxygenated blood from various parts of the body is returned to the right atrium. Blood from the head, neck and arms is returned via the superior vena cava. Blood from other parts of the body is brought back via the inferior vena cava.
