Biology 3 Unit 2
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What is the function of the circulatory system?
To transport blood around the body
What does the circulatory system consist of?
- Blood vessels
- The heart
What is the heart and what is its function?
The heart is a muscular organ that pumps blood around the body
What is the difference between the left and right side of the heart?
- Right - forces deoxygenated blood to the lungs where it picks up oxygen and loses carbon dioxide
- Left - pumps oxygenated blood around the body
What are the upper and lower chambers in the heart called, and what are their functions?
- Upper chambers - Atria: right receives blood from the vena cava, left from the pulmonary vein. They contract and force blood into the ventricles
- Lower chambers - Ventricles: they contract and force blood out of the heart, into the pulmonary artery from the right, into the aorta on the left
What is the function of the valves in the heart?
Valves in the heart ensure that blood flows in the correct direction
Describe the structure of arteries and their function
- Arteries have thick walls containing muscle and elastic tissue
- They carry blood away from the heart
describe the structure of veins and their function
- Veins have thinner walls that arteries
- Often have valves to prevent back-flow of blood
Describe the structure of capillaries and their function
- Capillaries have narrow thin-walled vessels
- The carry the blood through the organs and allow the exchange of substances with all the living cells in the body
What happens if blood vessels are blocked or are too narrow?
If blood vessels are too narrow the blood will not flow efficiently. This means organs will be deprived of nutrients and oxygen
What happens if there are leaky valves?
- Leaky valves means that blood could flow into the wrong direction
- Artificial or animal valves can be inserted to replace damaged valves
When and why are stents used?
If arteries begin to narrow and restrict blood flow, stents are used to keep blood vessels open
What is blood?
Blood is a tissue and consists of a fluid calls plasma. Plasma contains red blood cells white blood cells and platelets
What does Blood plasma transport?
- Blood plasma transports:
- Carbon dioxide from the organs to the lungs
- Soluble products of digestion from the small intestine to other organs
- Urea from the liver to the kidney
What are red blood cells and their function?
- Red blood cells:
- Are biconcave discs which do not have a nucleus
- Contain the red pigment haemoglobin
- Use their haemoglobin which combines with oxygen to form oxyhaemoglobin in the lungs
- Carry the oxygen to all organs where the oxyhaemoglobin splits into haemoglobin and oxygen
What are white blood cells and their function?
- They have a nucleus
- Form part if the body's defence system against microorganism
What are platelets and their function?
- Are small fragments of cells
- Do not have a nucleus
- Help blood to clot at the site of a wound
What is the function of xylem?
Xylem tissues transports water and mineral ions from the roots to the stem and leaves
What is the transpiration stream?
Transpiration stream is the movement of water from the roots through the xylem and out of the leaves
What is the function of phloem?
Phloem tissue carries dissolved sugars from the leaves to the rest of the ant including the growing regions and the storage organs
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