the circulatory system and the heart
- humans have a circulatory system that consists of blood vessels, the heart and blood.
- the heart is a muscular organ that pumps blood around the body. it actually is two pumps held together.
- the right pump forces deoxygenated blood to the lungs where it picks up oxygen and loses carbon dioxide
- after returning to the heart the oxygenated blood is then pumped to the rest of the body by the left pump.
- the action of two sides of the heart results in a double circulation
- carry blood away from the heart
- have thick walls containing muscles and elastic tissue
- Have small passageways for blood
- Contain blood under high pressure
- have thinner walls than arteries
- often have valves to prevent back flow
- Carry blood to the heart (always de-oxygenated apart from the pulmonary vein which goes from the lungs to the heart)
- Contain blood under low pressure
- are narrow, thin-walled vessels
- carry the blood through organs and allow the exchange of substances with all the living cells
- Microscopic – one cell thick
- Very low blood pressure
keeping the blood flowing
If blood vessels are blocked with fat or too narrow the blood will not flow efficiently. then the organs will be deprived of nutrients and oxygen.
stents can be inserted to keep blood vessels open.
transport in blood
- Fluid part of blood
- Carries carbon dioxide, hormones and waste
- Red blood cells
- Contain haemoglobin which carries oxygen
- Made in the bone marrow. The more you train the more red blood cells are made.
- White blood cells
- An important part of the immune system, they produce antibodies and destroy harmful microorganisms
- Made in the bone marrow
- have a nucleus
- Clump together to form clots
- Protect the body by stopping bleeding
artificial or real?
- fake blood
- always available
- doesn't need to be kept in a fridge
- no matching needed.
- artificial blood is expensive
- does not carry as much oxygen as whole blood.
- some types are insoluble in water so do not mix well with blood.
- they also have unpleasant side-effects.
- no wait for a donor
- no tissue to match
- blood clots
- stay in hospital
transport system in plants
flowering plants have separate transport systems
xylem tissue transports water and mineral ions from the roots to the stem, leaves and flowers
the movement of water from the roots through the xylem and out of the leaves is called the transpiration stream
phloem tissue carries dissolved sugars from the leaves to the rest of the plants, including the growing regions and the storage organs.