B4 - Organising Animals And Plants (animals) Flashcards
What is the function of blood?
Any 3 from:
Protect the body from pathogens
To carry oxygen to the body’s cells
Carries carbon dioxide away
To carry waste product urea to be excreted by kidneys
To carry nutrients to the cells for function and growth
What are the components of blood?
Blood is composed of plasma, which carries red blood cells, white blood cells and platelets
What are the characteristics of a red blood cell?
They are biconcave discs, which increases the surface area : volume ration for diffusion.
They are packed haemoglobin that binds to oxygen.
They have no nucleus so there is more space for haemoglobin
What are the characteristics of white blood cells?
Much bigger compared to red blood cells but they are scarcer
They are part of the body’s defence system
Some of them form antitoxins and antibodies ; some engulf bacteria
What are the function of platelets
They help blood to clot
They coagulate at the site of a wound to form a jelly-like clot to prevent bleeding
They harden to form a scab
What is the function of arteries and how are they adapted?
They carry oxygenated blood away from the heart to the organs of the body. They have thick walls containing muscle and elastic fibres - this makes the artery able to withstand a lot of pressure because the blood is under a lot of pressure. They have small lumens
What are the functions of veins and how are they adapted?
They carry deoxygenated blood away from the organs toward the heart. Veins don’t have a pulse unlike arteries and have valves to prevent the back-flow of blood. They have much thinner walls and large lumens compared to an artery.
What are the functions of capillaries and how are they adapted?
They form a huge network that link the arteries and veins. Capillaries are narrow with very thin walls (one cell thick). This allows substances to easily diffuse out of blood and into cells and vice versa. They have narrow lumens
What is the use of a stent?
A stent can be used to open a blocked artery. They are metal meshes placed in arteries to solve the problem of coronary heart disease. A tiny balloon is inflated to open up the blood vessel and the stent - the balloon deflates, leaving the stent
What are statins used for?
Doctors prescribe statins to those at risk of heart disease. They reduce blood cholesterol levels, which slows down the rate at which fatty material is deposited in the coronary arteries
What are pacemakers used for?
Inserted in the chest through surgery, pacemakers send electrical impulses that stimulate the heart in order to correct irregularities in heart rate.
How are coronary heart diseases caused?
In coronary heart diseases, layers of fatty material build up inside of the coronary arteries, making them narrower. This means there is a reduced flow of blood through the coronary arteries, resulting in a lack of oxygen for the heart muscle
What issues do faulty heart valves cause?
Faulty heart valves stop the valve from fully opening. This would cause problems for the blood flow and the pumping of blood within the heart.
