iGCSE Biology Notes Transport in animals

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[h] iGCSE Biology Notes Transport in animals

• Animals have a circulatory system which transports blood around the body.
• It is a system of blood vessels to ensure a oneway flow of blood.
• Fish have a single circulatory system.
• This means the heart pumps deoxygenated blood to the gills (to become oxygenated) which then goes straight to the rest of the body, becomes deoxygenated then goes back to the heart. So there is just one loop.

[q] Let’s move on to animals! What is the circulatory system? 

How do animals transport things? 

[a] 

• Mammals like humans have a double circulatory system, this means that one side (the right) sends blood to the lungs and another side (the left) sends blood to the rest of the body.
• A double circulatory system is better because oxygenated blood can be delivered at higher pressure so glucose can be delivered faster, which is essential for mammals as we are warm blooded. This requires a lot of energy and therefore more respiration.

[q] What is the structure of the heart? 

How do we label the heart?

[a]

[q] How does the heart work? 

How does the heart pump blood?

[a] 

• Blood enters the heart through a vein.
• The blood with then go into an atrium.
• The muscles in the atria will then contract, sending the blood into the ventricles through the one-way valves.
• The muscles in the ventricles then contract, sending blood out of the ventricles into the arteries, out of the heart (again, through one-way valves).
• The septum is essential in separating oxygenated from deoxygenated blood.

[q] Muscle thickness? 

Why are different parts of the heart thicker or thinner? 

[a] 

• The left side has thicker muscle than the right side, why?
• Because the left side has to pump to the whole body, the right side only pumps to the lungs
• The ventricles have thicker muscles than the atria, why?
• Because the atria only have to pump to the ventricles, the ventricles have to pump much further.

[q] What causes coronary heart disease? 

What is coronary heart disease? 

[a] 

• Arteries can become blocked with fatty tissue, which slows blood flow.
• This can happen in the coronary arteries, the arteries which supply blood to the heart.
• This can mean less blood is supplied to the heart, so it doesn’t get enough glucose for respiration so it can’t get energy to contract.
• Smoking, obesity, stress, diet high in cholesterol, salt and saturated fat, being male, lack of exercise, old age and a genetic predisposition can increase chances.

[q] What makes your heart beat faster? 

Why would your heart beat faster? 

[a] 

• When you do exercise, you use more energy than normal.
• To compensate for this, your heart beats faster and you breath faster.
• This is so more oxygen and glucose is delivered to your body cells so that they can do more respiration to release more energy.

[q] How can we measure heart activity? 

How can we find the heart beat?

[a] 

• You can measure heart beat in 3 ways.
• You can simply listen to the heart valves using a stethoscope (lub-dub) to check it is functioning normally
• You can measure the pulse in the wrist or neck to check pulse rate.
• We can use an electrocardiogram (ECG) to detect the electrical impulses that control the heart beat to detect anything unusual.

[q] What blood vessels are there? 

What is different about each blood vessel? 

[a] 

• Arteries carry blood away from the heart.
• They then branch into arterioles and eventually capillaries where substances can be exchanged.
• Capillaries then collect into venules and eventually veins.
• Veins carry blood into the heart.

[q] What blood vessels are there? 

What is different about each blood vessel? 

[a] 

• Arteries carry blood away from the heart so the blood is at high pressure after the pumping.
• This is why arteries have thick, elastic muscular walls to withstand the high pressure.
• Veins carry blood to the heart from the body so the blood is at low pressure.
• This is why veins have thin walls and valves to prevent backflow.

[q] What blood vessels are there? 

What is different about each blood vessel?

[a] 

• Capillaries are where substances can actually move into and out of the blood.
• Their walls are one cell thick to allow fast diffusion
• They also have a huge surface area for fast diffusion
• Constant blood flow also maintains a concentration gradient for fast diffusion.

[q] What are the names of the major blood vessels? 

What are the names of specific blood vessels? 

[a] 

• The vessels that go to and from the lungs are called the pulmonary artery and the pulmonary vein.
• The vessels that go to and from the kidneys are called the renal artery and the renal vein.
• We also need to know the aorta, the artery that sends oxygenated blood from the heart to the rest of the body.
• And the vena cava, which sends the deoxygenated blood from the rest of the body back to the heart.

[q] What are the names of the major blood vessels? 

What are the names of specific blood vessels? 

[a] 

• You also need to know the vessels connecting to the liver
• The vessel from the heart carrying oxygenated blood is the hepatic artery.
• The vessel from the digestive system (small intestine mainly) to the liver is the hepatic portal vein.
• The vessel taking deoxygenated blood from the liver back to the heart is the hepatic vein.

[q] What is the blood made of? 

What are the parts of the blood? 

[a] 

• Blood is made up of 4 parts.
• The red blood cells which carry oxygen around the body with a substance called haemoglobin.
• They have no nucleus to fit more haemoglobin and therefore more oxygen in.
• They have a biconcave disc shape that increases surface area

[q] What is the blood made of? 

What are the parts of the blood? 

[a]

[q] What is the blood made of? 

What are the parts of the blood? 

[a] 

• Next are platelets.
• These clot the blood to prevent blood loss and prevent the entry of pathogens.
• Platelets start a reaction which turns fibrinogen (which is soluble and dissolved in the blood) into fibrin which is insoluble and joins lots of platelets together, forming a mesh.

[q] What is the blood made of? 

What are the parts of the blood? 

[a] 

• The plasma which is the liquid everything floats in, including the blood cells.
• Everything but oxygen is transported in the plasma (carbon dioxide, glucose, urea, hormones, ions etc.)

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