transport in humans Flashcards
What are the four main components of blood?
- plasma
- red blood cells
- white blood cells
- platelets
Describe the structure of a red blood cell
Red blood cells are disc shaped and have a concave surface on each side.
This is to increases surface area for absorbing and transporting oxygen.
They don’t have a nucleus so that there is more room for haemoglobin which binds with oxygen for transportation.
What is a platelet and describe their role?
Platelets are fragments of cells produced by your body.
Their role is to initiate the clotting process in a wound. This blocks the injury in the blood vessel to limit blood loss until the wound has healed.
What is primary immune response?
It occurs after the first exposure to an antigen. It triggers the generation of memory cells from the lymphocytes.
What is secondary immune response
It occurs when you have been exposed to the same antigen for the second time. The body reacts faster leading to more antibodies being produced in a smaller amount of time.
What are the two types of white blood cells?
Phagocytes and Lymphocytes.
Describe the structure of phagocytes.
They have large nuclei because they are very active cells.
They can change shape which helps them get out of the blood and engulf microorganisms.
describe the role of lymphocytes.
They produce antibodies specific to the antigens on pathogens.
The antibodies attach to the antigens to clump them together and signal to the phagocytes for phagocytosis.
They also produce antitoxins which neutralise the toxins produced by bacteria.
They also change into memory cells to remember the antigens.
Describe the role of the heart in the body and how it works.
The main role of the heart is to pump blood around the body.
In humans and mammals it is part of a double circulatory system as it goes through the heart twice in its route around the body.
Its flows from the right side of the heart, to the lungs, to the left side of the heart, to the body.
The heart walls are mainly made out of muscle to contract constantly to pump the blood.
Describe the function of arteries.
They carry the blood at high pressures and so they have thick, elastic walls.
Describe the function of capillaries.
They are where exchange takes place and so are only one cells thick to minimise diffusion distance.
Describe the function of veins.
carries the blood back to the heart at a low pressure. They have thinner walls because of this and contain valves to stop the blood from flowing the wrong way.
What are the ventricles?
They are the larger chambers within the heart. The right ventricle pumps blood to the lungs and the left ventricle pumps blood to the whole body.
What are the atria?
They are the smaller chambers in the heart which pumps blood to the ventricles.
What is the aorta?
It is the artery leaving the left ventricle which branches off to supply every cell in the body with blood.
