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 is single circulation?

Answer 2

the blood passes through a single circuit – where blood is pumped by the heart to the gills for oxygenation, after which the blood flows to the rest of the body and back to the heart.

Question 3

How does single circulation work in fishes?

Answer 3

They have a two-chambered heart comprising an atrium and a ventricle. In fishes, the heart pumps out the deoxygenated blood which undergoes oxygenation in the gills. In gills, blood receives oxygen and releases carbon dioxide, a process facilitated by the thin walls of gill capillaries allowing efficient gas exchange. The oxygenated blood is then passed to the body parts from where the deoxygenated blood is returned to the heart.

Question 4

What is double circulation?

Answer 4

Double circulation means that the blood flows through two circuits – one low-pressure circuit and one high-pressure circuit.

Question 5

What is the double circulation of a mammal?

Answer 5

Mammals have a four chamber heart (two atria and two ventricles) and double circulation. Double circulation means that the blood flows through two circuits – one low-pressure circuit and one high-pressure circuit. The right low-pressure circuit is when the deoxygenated blood travels from the heart, to the lungs where it becomes oxygenated, and back. This is also known as the pulmonary circuit. The left high-pressure circuit, or systemic circuit, is when oxygenated blood flows from the heart to the rest of the body, and back. This is higher pressure because the blood has to travel further, so the heart applies a greater force on this blood, this is why the left side of the heart has a thicker muscle wall.

Question 6

What are the advantages of double circulation?

Answer 6

• Blood travelling through the small capillaries in the lungsloses a lot of pressurethat was given to it by the pumping of the heart, meaning itcannot travel as fast. By returning the blood to the heart after going through the lungs itspressure can be raised againbefore sending it to the body, meaningcellscan be supplied with theoxygen and glucosethey need for respirationfaster and more frequently
• Double circulation also helps keep the oxygenated and deoxygenated blood separate and prevents their mixing – this allows a highly efficient supply of oxygen to the body.

Question 7

Why is single circulation inefficient?

Answer 7

Single circulation is inefficient because there lower blood pressure after passing through gills, leading to a slower rate of flow to body tissues and less efficient due to the mixing of blood and the single loop system resulting in reduced oxygenation efficiency.

Question 8

Which side is the heart’s left?

Answer 8

YOUR RIGHT

Question 9

Which blood vessel pumps blood away from the heart?

Answer 9

Arteries

Question 10

Which blood vessel returns blood to the heart?

Answer 10

Veins

Question 11

What supplies the heart with blood?

Answer 11

Coronary arteries

Question 12

What are the parts of the heart at the top?

Answer 12

Left and right atrium

Question 13

Why do ventricles have thicker muscle walls than the atria?

Answer 13

they are pumping blood out of the heart and so need to generatea higher pressure

Question 14

Why does the left ventircle have a thicker muscle wall than the right ventricle?

Answer 14

it has to pump blood at high pressure around theentire body, whereas the right ventricle is pumping blood at lower pressure to thelungs

Question 15

What does the septum do?

Answer 15

separates the two sides of the heart and soprevents mixing of oxygenated and deoxygenated blood

Question 16

What is the function of valves?

Answer 16

to prevent backflow of blood

Question 17

Where are the atrioventricular valves located?

Answer 17

between the atria and ventricles on both sides of the heart

Question 18

What is the atrioventricular valve on the hearts right?

Answer 18

tricuspid valve

Question 19

What is the atrioventricular valve on the hearts left?

Answer 19

bicuspid valve also called the mitral valve

Question 20

What is the function of the atrioventricular valves?

Answer 20

These valves are pushedopen when the atria contractbut when theventricles contract they are pushed shutto prevent blood from flowing back into the atria

Question 21

Where are the semilunar valves located?

Answer 21

In the two blood arteries that come out of the top of the heart. They are unusual in that they are theonly two arteries in the body that contain valves

Question 22

What is the semilunar valve located in the aorta?

Answer 22

aortic semilunar valve

Question 23

What is the semilunar valve located in the pulmonary artery?

Answer 23

pulmonary semilunar valve

Question 24

What is the function of the semilunar valves?

Answer 24

These valvesopen when the ventricles contractso blood squeezes past them out of the heart, but then shut to avoid blood flowing back into the heart

Question 25

How can you monitor the activity of the heart?

Answer 25

ECG, pulse rate and listening to sounds of valves closing

Question 26

Experiment to investigate effect of exercise on hear rate

Answer 26

- Breathing rate can be measured by counting the number of breaths per minute, while heart rate can be measured by taking a pulse - This can be done by pressing two fingers down on the inside of their wrist, between the bone and the tendon on their thumb side. You should be able to feel pulses. This is because, during ventricular systole, blood is forced down the arteries, so they expand slightly. Using a stopwatch, count the number of pulses in 30 seconds, and multiply by two to gain the pulse rate per minute. - Either can be measured before and after an activity is performed and the results plotted on a bar chart - It is important that the time over which breathing rate and pulse rate are measured is consistent, and that individuals fully recover (rest) before starting a new activity

Question 27

What does increased physical activity result in?

Answer 27

Increased physical activity results in an increased heart rate and breathing rate. Heart rate remains high for a period of time after physical has stopped, there is a gradual return to resting heart rate

Question 28

Why does physical activity increase heart rate?

Answer 28

- Physical activity increases heart rate. This is because physical activity increases the body’s need for energy, increasing the rate of respiration and thus the demand for oxygen. This means the heart needs to pump blood around the body faster, to deliver oxygen faster to the needy tissues, so the heart rate increases. If the heart rate increases, the number of ‘pulses’ of blood pushed out by the ventricles per minute also increases, so the pulse rate increases. - The heart rate rises during exercise so that sufficient blood is taken to the working muscles to provide them with enough nutrients and oxygen for increased respiration. An increase in heart rate also allows for waste products to be removed at a faster rate

Question 29

Why does the heart continue to beat fast after exercise?

Answer 29

- Following exercise, the heart continues to beat faster for a while to ensure that all excess waste products are removed from muscle cells. - It is also likely that muscle cells have been respiring anaerobically during exercise and so have built up an oxygen debt. This needs to be ‘repaid’ following exercise and so the heart continues to beat faster to ensure that extra oxygen is still being delivered to muscle cells - The extra oxygen is used to break down the lactic acid that has been built up in cells as a result of anaerobic respiration

Question 30

What happens if a coronary artery is blocked?

Answer 30

- The blood is supplied by the coronary arteries. If a coronary artery becomes partially or completely blocked by fatty deposits called ‘plaques’ (mainly formed from cholesterol), the arteries are not as elastic as they should be and therefore cannot stretch to accommodate the blood which is being forced through them - leading to coronary heart disease - Partial blockage of the coronary arteries creates a restricted blood flow to the cardiac muscle cells and results in severe chest pains called angina - Complete blockage means cells in that area of the heart will not be able to respire and can no longer contract, leading to a heart attack

Question 31

What are the risk factors for coronary heart disease?

Answer 31

Poor diet- Eating more saturated fat increases cholesterol levels, increasing the chance of the buildup of fatty plaques Stress- When under stress, hormones produced can increase blood pressure, increasing the chance of a blockage in the coronary arteries Smoking- Nicotine in cigarettes causes blood vessels to become narrower, increasing blood pressure which causes the buildup of fat globules. If this occurs in the coronary artery, it could cause coronary heart disease Genetic predisposition- Studies show that people with a history of coronary heart disease in their family are more likely to develop it themselves Age- The risk of developing coronary heart disease increases as you get older Gender- Males are more likely to develop it than females

Question 32

How can you reduce risk for coronary heart disease?

Answer 32

- Quit smoking - Diet: reduce animal fats and eat more fruits and vegetables - this will reduce cholesterol levels in the blood and help with weight loss if overweight - Exercise regularly: again, this will help with weight loss, decrease blood pressure and cholesterol levels and help reduce stress

Question 33

Why is the septum important?

Answer 33

The septum is a vital part of the heart because it separates the left and right sides, preventing the mixing of oxygenated and deoxygenated blood. This separation is crucial for the efficiency of our circulatory system. Oxygenated blood is pumped from the left side of the heart to the rest of the body, providing essential oxygen to our cells for energy production. Meanwhile, deoxygenated blood returns to the right side of the heart and is pumped to the lungs for re-oxygenation. Without the septum, these two types of blood would mix, reducing the efficiency of oxygen delivery to the body's tissues.

Question 34

How does blood move through the heart?

Answer 34

Deoxygenated blood coming from the body flows into the right atrium via the vena cava. Once the right atrium has filled with blood the heart gives a little beat and the blood is pushed through the tricuspid (atrioventricular) valve into the right ventricle. The walls of the ventricle contract and the blood is pushed into the pulmonary artery through the semilunar valve which prevents blood flowing backwards into the heart. The blood travels to the lungs and moves through the capillaries past the alveoli where gas exchange takes place (this is why there has to be low pressure on this side of the heart – blood is going directly to capillaries which would burst under higher pressure). Oxygen-rich blood returns to the left atrium via the pulmonary vein. It passes through the bicuspid (atrioventricular) valve into the left ventricle. The thicker muscle walls of the ventricle contract strongly to push the blood forcefully into the aorta and all the way around the body. The semilunar valve in the aorta prevents the blood flowing back down into the heart

Question 35

Arteries characteristics

Answer 35

- Carry blood at high pressure away from the heart (dangerous to cut as blood will spurt out) - Carry oxygenated blood (other than the pulmonary artery) - Have thick muscular walls containing elastic fibres to withstand the high pressure of blood and maintain the blood pressure as it recoils after the blood has passed through - Can stretch as blood is forced through them and return to original shape. This is felt as a pulse. - Have a narrow lumen to maintain high blood pressure - Speed of flow is fast

Question 36

Veins characteristics

Answer 36

- Carry blood at low pressure towards the heart - Carry deoxygenated blood (other than the pulmonary vein) - Have thin walls - Have a large lumen as blood pressure is low - Contain valves to prevent the backflow of blood as it is under low pressure - Blood is squeezed back towards the heart by the action of the skeletal muscles - Speed of flow is slow

Question 37

Capillaries characteristics

Answer 37

- Carry blood at low pressure within tissues - Forms a huge network linking arteries to veins (allowing blood to access every cell in our body) - Carry both oxygenated and deoxygenated blood - Have walls that are one cell thick so substances can easily diffuse in and out of them - Have ‘leaky’ walls so that blood plasma can leak out and form tissue fluid surrounding cells - Speed of flow is slow

Question 38

What do the superior and inferior vena cava do?

Answer 38

The superior vena cava collects blood from the head and upper parts of the body and empties it into the right atrium. The inferior vena cava collects blood from the rest of the body and empties it into the right atrium. (They are veins and carry the blood to the heart)

Question 39

What does the aorta do?

Answer 39

The aorta takes blood from the left ventricle to the rest of the body.

Question 40

What does the pulmonary artery do?

Answer 40

The pulmonary artery carries deoxygenated blood from the right ventricle of the heart to the lungs.

Question 41

What does the pulmonary vein do?

Answer 41

The pulmonary veins carry oxygenated blood from the lungs to the left atrium of the heart.

Question 42

What carries oxygenated blood to the kidneys? What carries deoxygenated blood away from the kidney?

Answer 42

renal artery and renal vein

Question 43

What do the hepatic artery and vein do?

Answer 43

- The hepatic artery brings oxygenated blood from the heart to the liver - The hepatic vein brings deoxygenated blood from the liver back to the heart

Question 44

What does the hepatic portal vein do?

Answer 44

The hepatic portal vein transports deoxygenated blood from the gut to the liver (nutrient-rich blood)

Question 45

What are the four components of blood?

Answer 45

Red blood cells, plasma, platelets, white blood cells

Question 46

Red blood cells function and appearance

Answer 46

- Biconcave discs containing no nucleus but plenty of the protein haemoglobin - Function is to transport oxygen around the body from the lungs to cells which require it for aerobic respiration

Question 47

White blood cells appearance and function

Answer 47

- Large cells containing big nucleus, different types have slightly different structures and functions - Function is to defend the body against infection by pathogens by carrying out phagocytosis and antibody production - There are two main types, phagocytes and lymphocytes

Question 48

What does a phagocyte's function?

Answer 48

engulfing pathogens by phagocytosis

Question 49

How do phagocytes engulf pathogens?

Answer 49

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.

Question 50

What is the function of lymphocytes?

Answer 50

antibody production

Question 51

Why do lymphocytes produce antibodies?

Answer 51

Produce antibodies to destroy pathogenic cells and antitoxins to neutralise toxins released by pathogens

Question 52

How can you recognise phagocytes and lymphocytes in the microscope?

Answer 52

- Phagocytes can be easily recognised under the microscope by their multi-lobed nucleus and their granular cytoplasm - Lymphocytes 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 53

What are platelets?

Answer 53

Platelets are fragments of cells which are involved in blood clotting and forming scabs where the skin has been cut or punctured

Question 54

What is plasma?

Answer 54

- Straw coloured liquid - Involved in transport of blood cells, ions, nutrients, urea, hormones and carbon dioxide

Question 55

What is the role of blood clotting?

Answer 55

Role is to prevent blood loss and the entry of pathogens

Question 56

What happens when skin is broken?

Answer 56

When the skin is broken (i.e. there is a wound) platelets arrive to stop the bleeding and stimulate blood clotting. A series of reactions occur within the blood plasma. Platelets release chemicals that cause soluble fibrinogen proteins to convert into insoluble fibrin and form an insoluble mesh across the wound, trapping red blood cells and therefore forming a clot. The clot eventually dries and develops into a scab to protect the wound from bacteria entering.