Chapter 8 - Transport In Humans

Question 1

Why do we need a transport system?

Answer 1

We are multicellular and complex. Most of our cells are far away from body surface. Our large body also has reduced surface area to volume ratio. Thus, diffusion is inadequate and we need a transport system.

Question 2

What does blood contain?(4)

Answer 2

1) plasma
2) red blood cells
3) white blood cells
4) platelets

Question 3

After centrifugation, what is the order of substances? (Densest to least dense)

Answer 3

Red blood cells, white blood cell and platelets, plasma

Question 4

What is the function of plasma? (6)

Answer 4

It transports

1) proteins
2) mineral salts
3) digested food substances (from intestines to other parts of the body. Excess to kidneys for excretion)
4) metabolic waste products (kidneys or lungs for CO2)
5) hormones (glands to target organs)
6) heat (respiring body tissues to all parts of body)

Question 5

What are 3 characteristics of red blood cells?

Answer 5

1) produced in bone marrow
2) destroyed in spleen
3) limited lifespan of 120 days

Question 6

What is the process of absorbing oxygen in lungs and transporting of oxygen to cells? (5)

Answer 6

1) Haemoglobin in red blood cells has an affinity (attraction) for oxygen.
2) The one cell thick alveolar wall that separates the blood capillaries from alveolar air is permeable to oxygen and carbon dioxide.
3) since alveolar air contains a higher concentration of oxygen than the blood, oxygen dissolves in the moisture lining the alveolar walls and then diffuses into the blood capillaries.
4) haemoglobin combines loosely with oxygen to form oxyhaemoglobin, giving the blood a bright red color. It is then transported to other parts of the body.
5) As blood passes through tissues with very little oxygen, oxyhaemoglobin releases its oxygen. Oxygen diffuses in solution into the tissue cells, giving haemoglobin a purplish red color.

Question 7

Why do people at high altitudes have larger number of red blood cells in their bodies?

Answer 7

At high altitudes, concentration of oxygen is low. More red blood cells are needed to compensate for the lack of oxygen. This process is called acclimatization.

Question 8

Why do runners train at high altitudes?

Answer 8

It triggers the body to produce more haemoglobin. With an increased number of red blood cells and increased volume of blood, more oxygen and glucose will be brought to muscles for aerobic respiration. More energy is released

Question 9

What are 7 characteristics of a white blood cell?

Answer 9

1) larger than red blood cells but lesser than red blood cells
2) produced in bone marrow
3) destroyed in spleen
4) colorless as they do not contain haemoglobin
5) irregular in shape and contains nucleus
6) mobile: able to move, change shape and squeeze through walls of thinnest blood capillaries.
7) lifespan of a few days though they have nucleus

Question 10

What are the differences between lymphocytes and phagocytes?(3)

Answer 10

1) lymphocytes have large rounded nucleus while phagocytes have lobed nucleus.
2) lymphocytes have small around of non-granular (not grainy) cytoplasm while phagocytes have a granular cytoplasm.
3) lymphocytes produce antibodies against microorganisms while phagocytes extend cytoplasm, ENGULF and INGEST foreign particles by phagocytosis.

Question 11

What is the function of lymphocytes?(1)

Answer 11

produce antibodies to presence of foreign particles or toxin in the blood, where toxin is produced by disease causing germs in the blood.

Question 12

What are 3 functions of antibodies?

Answer 12

1) act as antitoxins to neutralise the poisonous effects of toxins.
2) kills bacteria in the blood by attaching to them and causing bacterial surface membrane to rupture(break).
3) causes agglutination, where foreign particles clump together so that they can be easily engulfed and ingested by phagocytes.

Question 13

What is the function of phagocytes? (2)

Answer 13

1) Engulf and ingest foreign particles like bacteria by phagocytosis.
2) After engulfing and ingesting the foreign particles, they send out chemical messages to nearby lymphocytes to produce antibodies to neutralize them.

Question 14

What is tissue rejection?

Answer 14

Transplanted organs may be treated as foreign by the body. Thus, lymphocytes would produce antibodies to attack the transplanted organ. This is tissue rejection.

Question 15

How to prevent tissue rejection? (3)

Answer 15

1) tissue match: donor and recipient must be genetically as close as possible
2) use of drugs to inhibit immune system, the system that produces lymphocytes
3) x-ray radiation to bone marrow to inhibit production of blood cells, slowing down rejection process.

Question 16

What are 3 characteristics of blood platelets?

Answer 16

1) not true cells
2) fragments of cytoplasm which are membrane bound
3) important for clotting of blood.

Question 17

Describe the process of blood clotting. (5)

Answer 17

1) damaged tissues and platelets produces thrombokinase, an enzyme
2) thrombokinase and calcium ions convert inactive prothrombin into active thrombin.
3) active thrombin then converts fibrinogen into insoluble fibrin threads.
4) insoluble fibrin threads entangles blood cells and forms a clot.
5) clots seal wounds to prevent excessive blood loss and bacteria from entering the body to cause more infections

Question 18

What causes clumping of red blood cells?

Answer 18

Plasma contains natural antibodies which recognise and binds to specific antigens on red blood cells. When two blood groups of different types are mixed, antibodies in the plasma of the recipient binds to the antigen on red blood cells of the donor’s blood, causing agglutination to occur.

Question 19

What antigen and plasma does blood type A have?

Answer 19

Antigen A and antibody b.

Question 20

What antigen and plasma does blood type B have?

Answer 20

Antigen B and antibody a

Question 21

What antigen and plasma does blood type O have?

Answer 21

No antigen, but have antibodies a and b

Question 22

What antigen and plasma does blood type AB have?

Answer 22

Antigens A and B but no antibodies

Question 23

What are 3 protective functions of blood?

Answer 23

1) blood clotting
2) phagocytosis
3) production of antibodies

Question 24

Define phagocytosis.

Answer 24

The process of engulfing and ingesting foreign particles with phagocytes

Question 25

Define an artery.

Answer 25

Blood vessels that carry blood AWAY from the heart. Aorta to arteries, then to arterioles.

Question 26

Define veins.

Answer 26

United venules forming the veins which carry blood TOWARDS the heart.

Question 27

What does arterial blood contain?(2)

Answer 27

1) oxygen

2) glucose

Question 28

What does venous flood contain?

Answer 28

1) carbon dioxide

2) metabolic waste products

Question 29

What is the function of an artery?

Answer 29

transport oxygenated blood from heart to other organs of the body.

Question 30

How are arteries adapted for their function?(2)

Answer 30

1) they have thick and elastic muscular walls to support blood coming from the heart, which is higher in pressure. This pushes the blood along.
2) muscles contract and relax to cause constriction and dilation of the artery respectively. Constriction allows less blood to flow through while dilation allows more blood to flow through.

Question 31

How are veins adapted for its function? (3)

Answer 31

1) they have relatively thin walls with less elastic tissue as the flow of blood is slower. Hence, the blood pressure is lower compared to arteries.
2) they have valves to prevent blood from flowing backwards due to gravity.
3) since movement of blood along veins is assisted by the action of the skeletal muscles, exercising the muscles increases pressure exerted on the veins and moves blood along more quickly.

Question 32

What is the function of the vein?

Answer 32

Transport deoxygenated blood back to the heart.

Question 33

What are 5 adaptations of capillaries?

Answer 33

1) endothelium (capillary walls) consists of a single layer of flattered cell walls for faster exchange of substances between blood and cells.
2) it is highly branched. It increases surface area and total cross sectional area for more efficient exchange of substances between blood and cells.
3) Increased total cross sectional area also lowers the blood pressure, slowing down the flow of blood, giving more time for exchange of substances.
4) partially permeable endothelium allows only smaller molecules to pass, not the larger ones
5) narrow lumen slows down blood flow to provide more time for exchange of substances

Question 34

What are tissue fluids?

Answer 34

Colorless fluid found in tiny spaces between cells.

Question 35

How are substances transferred between capillaries and tissue cells? (2)

Answer 35

1) useful materials and oxygen move into blood capillaries, then tissue fluids, then into cells by diffusion.
2) metabolic waste products released by cells move into tissue fluid by diffusion, then through capillary walls, then into blood, then carried to excretory organs for removal.

Question 36

What is double circulation?

Answer 36

Blood passes through the heart twice as it moves from pulmonary (lungs) circulation to systematic circulation.(round the body)

Question 37

What are the advantages of double circulation?(2)

Answer 37

1) blood entering lungs is at a lower pressure compared to blood leaving the heart. This ensures that blood flows more slowly through the lungs, allowing sufficient time for blood to be fully oxygenated before returning to the heart.
2) heart pumps oxygenated blood at high pressure to the rest of the body, ensuring that oxygenated blood is quickly distributed to all the tissues in the body.

Question 38

What is the structure of the heart? (4)

Answer 38

1) roughly conical shape
2) lies between lungs and behind chest bone
3) surrounded by pericardium (two layers of membrane with a fluid in between the membranes to reduce friction when the heart is beating)
4) consist of four chambers: 2 ventricles and 2 atria

Question 39

What is the adaptation of the left ventricle?

Answer 39

It has thicker muscular walls than the right ventricle as it has to pump blood into the systematic circulation, which requires it to withstand higher pressure.

Question 40

What is the adaptation of the right ventricle?

Answer 40

It has relatively thick muscular walls, but thinner than left ventricle, to move blood into pulmonary circulation, which requires it to withstand lower pressure.

Question 41

What is the adaptation of the atria?

Answer 41

They have relatively thinner walls compared to ventricles to force blood into the ventricles.

Question 42

What is the function of the median septum?

Answer 42

Divide left and right ventricles to prevent oxygenated and deoxygenated blood from mixing, so as to provide more oxygen for the body.

Question 43

What should you do now?

Answer 43

Read tb and identify parts of the heart. (Set as 3)

Question 44

Describe the pathway of blood through the heart.(7)

Answer 44

1) Right atrium muscles relax, lowering the pressure of the right atrium. Deoxygenated blood returns to the right atrium via vena cava. Blood from head, neck and arms return to the right atrium via superior vena cava, while blood from other parts of the body (excluding lungs) return via inferior vena cava. Tricuspid valve is closed as it is receiving blood.
2) The right atrium muscles then contracts. Its pressure increases, opening the tricuspid valve to allow blood to pump into the right ventricle, which is relaxed and has lower pressure than the right atrium.
3) When the right ventricle muscles contract, the pressure closes the tricuspid valve to prevent backflow of blood into the atrium. The pressure is higher than the atria and pulmonary artery. Blood leaves the right ventricle through the pulmonary arch, which will divide into 2 pulmonary arteries, one to each lung.
4) The blood in the pulmonary arteries is at lower pressure than blood in the aorta.This slows down the rate of blood flow to give more time for gas exchange in the lungs.
5) The left atrium muscles relax, allowing oxygenated blood from the lungs to flow in via pulmonary veins. The bicuspid valve is closed as it is receiving blood, and the pressure is low.
6) The left atrium muscles contracts. The pressure becomes higher than the left ventricle. This causes the bicuspid valve to open and blood enters the left ventricle. The left ventricle muscles are relaxed.
7) The left ventricle muscles contracts. Its pressure becomes higher than the aorta, opening the semi-lunar valves, which allows blood to pump into the aorta. Blood is then pumped to the rest of the body.

Question 45

What is ventricular diastole?

Answer 45

Relaxation of ventricles

Question 46

What is ventricular systole?

Answer 46

Contraction of ventricles

Question 47

What is coronary heart disease and what happens?

Answer 47

It is the buildup of fatty substances on inner surfaces of the coronary arteries, causing the lumen to narrow. The narrower lumen requires increased pressure to pump blood through the artery, which might cause blood clots to form in arteries. This reduces blood flow to the heart, and when heart muscle cells received reduced oxygen supply, it may lead to a heart attack.

Question 48

What are 4 causes of coronary heart disease?

Answer 48

1) high fat diet rich in cholesterol and saturated animal fats
2) emotional stress
3) smoking
4) sedentary lifestyle (Not enough exercise)

Question 49

How can coronary heart disease be treated?

Answer 49

Drugs and surgery. Minor surgery is called Balloon Angioplasty, and the major surgery is called Heart bypass.

Question 50

What are 4 preventive measures against coronary heart disease?

Answer 50

1) a healthy diet with reduced intake of animal fats which can be replaced with polyunsaturated plant fats&rich in vegetable and fruits
2) manage stress in an appropriate way
3) avoid smoking
4) exercise regularly

Question 51

How is tissue fluids formed?

Answer 51

Arteries have higher blood pressure than veins. Higher blood pressure at arterial end forces plasma out of through the capillary walls to form tissue fluids. Red blood cell, platelets and large molecules like proteins remain in capillaries. Phagocytes can squeeze through capillary walls. Pressure will decrease sharply at the venule end as capillary offers resistance to blood flow. osmotic pressure increase (water potential decrease) because of proteins present in small volumes of plasma. Hence, fluid reenters blood capillary at the venule end.

Question 52

State 4 differences between structure of arteries and structure of veins.

Answer 52

1) Arteries have thicker muscular tissue while veins have thinner, less muscular tissue.
2) Arteries have narrow lumen while veins have wide lumen.
3) Arteries have no valves while veins have valves.
4) Arteries have more elastic tissue while veins have less elastic tissue.

Question 53

What is the function of coronary artery?

Answer 53

Transport oxygen and nutrients to the heart muscles