Blood Vessels And Blood Flashcards
How many types of blood vessels are there and what are they called?
3.
Arteries, veins, capillaries
Describe the structure of arteries and where are they carrying blood to?
Arteries are muscular tubes with thick walls. They are under considerable pressure from the force of the pumping action of the heart. They carry blood away from the heart
What are the smallest kind of arteries called?
Arterioles
Describe the structure of veins and where they carry blood to
Unlike the arteries, veins have thin walls and have little ability to contract.
They carry blood to the heart
What are the smallest veins called?
Venules
Why don’t arteries have valves?
They aren’t needed because of the pressure at which the blood is travelling away from the heart
How is blood prevented from flowing in the wrong direction in the veins?
Veins contain one way Valves along their length
Describe the capillaries
Capillaries are thin-walled networks of tiny blood vessels at the ends of the arterioles and venules. They are the smallest of the blood vessels, and are scattered with smooth muscle fibres.
How do capillaries control the blood flow?
They contain valve like rings of muscle (precapillary sphincters)
What is the function of the capillaries and how is this different in the lungs?
In most tissues, capillaries allow:
Oxygen to be transferred from the blood to the tissues
Carbon dioxide and other waste products to be absorbed
The capillaries in the lungs do the opposite. They:
Transfer oxygen from the lungs to the blood
Pass carbon dioxide to the lungs to be exhaled
What is the name of the method by which blood pressure forces fluid and small solutes like nutrients and oxygen out of the capillaries and into the surrounding tissue, while preventing larger molecules like proteins from passing through
Filtration
What are the components of blood?
Around 45% of blood volume is composed of red and white cells and platelets, which all originate in bone marrow. The remaining 55% is a yellowish liquid called plasma.
Describe the function of red blood cells
Red cells give blood its colour. The principal function of red blood cells is to carry oxygen from the lungs to feed the tissues.
What is haemoglobin? and what determines its amount carried by red blood cells?
The protein which transports oxygen to the tissues. The amount is determined by the level of iron in the body
What is the function of white blood cells?
To destroy bacteria, to remove diseases or injured tissue
What is the job of platelets?
They prevent bleeding after an injury by promoting clotting
