Chapter 9 - Transport in animals

Question 1

What is the circulatory system?

Answer 1

The circulatory system is a system of blood vessels with a pump and valves to ensure one-way flow of blood.

Question 2

What type of circulation do fish have?

Answer 2

Fish have a two-chambered heart and a single circulation. This means that for every one circuit of the body, the blood passes through the heart once.

Question 3

What type of circulation do mammals have?

Answer 3

Mammals have a four-chambered heart and a double circulation. This means that for every one circuit of the body, the blood passes through the heart twice. The right side of the heart receives deoxygenated blood from the body and pumps it to the lungs through the pulmonary artery. The left side of the heart receives oxygenated blood from the lungs and pumps it to the body through the aorta.

Question 4

What is the difference between the pulmonary circuit and the systemic circuit?

Answer 4

The pulmonary circuit travels through the heart and lungs and the systemic circuit travels through the heart and the body.

Question 5

What are some advantages of double circulation?

Answer 5

Advantages of double circulation include the blood being able to increase its pressure again after travelling through the small capillaries in the lung so it can efficiently supply cells with oxygen and glucose, they the need for respiration faster and more frequently.

Question 6

Where do the right and left sides of the heart receive and pump blood from and to?

Answer 6

The right side of the heart receives deoxygenated blood from the body through the vena cava and pumps it to the lungs through the pulmonary artery. The left side of the heart receives oxygenated blood from the lungs through the pulmonary vein and pumps it to the body through the aorta.

Question 7

What vessel carries blood away from the heart?

Answer 7

Blood is pumped away from the heart in arteries

Question 8

What vessel brings blood towards the heart?

Answer 8

Blood returns to the heart in veins

Question 9

What separates the two sides of the heart?

Answer 9

The two sides of the heart are separated by a muscular wall called the septum.

Question 10

What are the functions of valves?

Answer 10

Valves prevent blood from flowing backwards. The valves are pushed open when the atria contract but when the ventricles contract, they are pushed shut to prevent blood from flowing back into the atria.

Question 11

What supplies nutrients and blood to the heart and removes waste?

Answer 11

The heart is made of cardiac muscle tissue which are supplied with blood and nutrients and remove waste products by the coronary arteries.

Question 12

How can the activity of the heart be monitored?

Answer 12

The activity of the heart can be monitored using an ECG, measuring the pulse rate or listening to the sounds of valves closing using properly a stethoscope.

Question 13

How do you investigate the effects of exercise on heart rate?

Answer 13

To investigate the effects of exercise on heart rate, record the pulse rate at rest for one minute. Immediately after they do some exercise, record the pulse rate every minute until it returns to resting rate. This experiment will show that during exercise, the heart rate increases and may take several minutes to return to normal.

Question 14

What effect does physical activity have on heart rate and breathing rate?

Answer 14

Increased physical activity results in an increased heart rate and breathing rate. This allows the muscles to be provided with enough nutrients and oxygen for increased respiration. This also allows waste products to be removed at a faster rate. The heart continues to beat after exercise is finished to allow extra oxygen to be delivered to the muscle cells to break down and remove lactic acid from anaerobic respiration.

Question 15

What happens if a coronary artery becomes blocked?

Answer 15

If a coronary artery becomes partially or completely blocked by fatty deposits called ‘plaques’ (which are mainly formed by cholesterol) it can lead to coronary heart disease.

Question 16

What six factors increase the risk of developing coronary heart disease?

Answer 16

Poor diet, stress, smoking, genetic predisposition, age and gender

Question 17

How does a poor diet increase the risk of developing coronary heart disease?

Answer 17

Eating more saturated fat increases cholesterol levels, increasing the chance of the build up of fatty plaques.

Question 18

How does stress increase the risk of developing coronary heart disease?

Answer 18

When under stress, hormones produced can increase blood pressure, increasing the chance of a blockage in the coronary arteries.

Question 19

How does smoking increase the risk of developing coronary heart disease?

Answer 19

Nicotine in cigarettes will cause blood vessels to become narrower, increasing blood pressure which will cause the build-up of fat globules. If this occurs in the coronary artery, this will cause coronary heart disease.

Question 20

How does genetic predisposition increase the risk of developing coronary heart disease?

Answer 20

Studies show that people with a history of coronary heart disease in their family are more likely to develop it themselves, suggesting it partly has a genetic basis.

Question 21

How does age increase the risk of developing coronary heart disease?

Answer 21

The risk of developing coronary heart disease increases as you get older.

Question 22

How does gender increase the risk of developing coronary heart disease?

Answer 22

Males are more likely to develop coronary heart disease than females.

Question 23

How can you reduce the risks of developing coronary heart disease?

Answer 23

Reducing the risks of developing coronary heart disease can be achieved by quitting smoking, reducing the amount of animal fats you eat and eating more fruits and vegetables which will reduce cholesterol levels in the blood and help with weight loss if overweight and exercising regular as this will help with weight loss, decrease blood pressure and cholesterol levels and help reduce stress.

Question 24

What is the function of arteries?

Answer 24

Arteries carry blood away from the heart at high pressure. The walls of the arteries are thick and muscular and contain elastic fibre and they have a narrow lumen. This allows them to withstand the high pressure of blood and maintain blood pressure as it recoils after the blood has passed through.

Question 25

What is the function of veins?

Answer 25

Veins carry blood towards the heart at a low pressure. The walls of veins are thin, they have a wide lumen, and they contain valves to prevent backflow. This keeps blood pressure low.

Question 26

What is the function of capillaries?

Answer 26

Capillaries carry blood to the cells of the tissues. The walls of capillaries are one cell thick and contain gaps to allow fluid to leak out. They have a very narrow lumen. This allows easy diffusion for substances and the leaky walls allow blood plasma to leak out and form tissue fluid surrounding cells.

Question 27

Diagram of the blood vessels in the circulatory system

Answer 27

Question 28

What is the function of red blood cells?

Answer 28

Red blood cells are biconcave discs containing no nucleus but plenty of the protein haemoglobin. They transport oxygen which binds to haemoglobin around the body from the lungs to cells which require it for aerobic respiration.

Question 29

What is the function of white blood cells?

Answer 29

White blood cells are large cells containing a big nucleus, different types have slightly different structures and functions. They defend the body against infection by pathogens by carrying out phagocytosis and antibody production.

Question 30

What is the function of platelets?

Answer 30

Platelets are fragments of cells. They are involved in helping the blood to clot. Blood clotting prevents blood loss and the entry of pathogens.

Question 31

What is the function of plasma?

Answer 31

Plasma is a straw-coloured liquid which holds all the other components. It is important for the transport of carbon dioxide, nutrients, urea, mineral ions, hormones and heat energy.

Question 32

Diagram of the blood components

Answer 32

Question 33

What is the function of phagocytes?

Answer 33

Phagocytes are a type of white blood cell. They carry out phagocytosis by engulfing and digesting pathogens. Phagocytes have a sensitive cell surface membrane that can detect chemicals produced by pathogenic cells. Once they encounter the pathogenic cell, they will engulf it and release digestive enzymes to digest it. they can be easily recognised under the microscope by their multi-lobed nucleus and their granular cytoplasm.

Question 34

What is the function of lymphocytes?

Answer 34

Lymphocytes produce antibodies to destroy pathogenic cells and antitoxins to neutralise toxins released by pathogens. They can easily be recognised under the microscope by their large, round nucleus which takes up nearly the whole cell and their clear, non-granular cytoplasm.

Question 35

How does blood form a clot?

Answer 35

Platelets are fragments of cells. They are involved in helping the blood to clot. Blood clotting prevents blood loss and the entry of pathogens. When the skin is broken, platelets arrive to stop the bleeding. A series of reactions occur within the blood plasma. Platelets release chemicals that cause soluble fibrinogen proteins to convert into insoluble fibrin and from an insoluble mesh across the wound, trapping red blood cells and therefore forming a clot. The clot will eventually dry to form a scab to protect the wound from bacteria entering.