Chapter 12. The blood circulatory system
1. a White cells can vary their shape. They have a nucleus. They do not contain haemoglobin.
b They are an important part of the immune system They can produce antibodies which
combat foreign substances which get into the bloodstream. Some of them can ingest bacteria
or damaged cells and other unwanted particles. White cells do not carry oxygen.
2. The lungs.
3. In all the living, respiring cells of the body.
4. If oxyhaemoglobin was a stable compound it would not readily break down to release its
oxygen where needed.
If a diet is deficient in iron an adequate supply of haemoglobin cannot be produced. Cellular
respiration would be reduced and the person would be anaemic.
1. a Both ventricles pump blood into the arteries.
b The bicuspid, tricuspid and semi-lunar valves prevent blood flowing the wrong way.
2. c Atria contract.
e Blood enters ventricles.
b Ventricles contract.
g Tri- and bicuspid valves close.
a Blood enters arteries.
f Semi-lunar valves close.
d Ventricles relax.
(You could start with d).
3. a The ventricles have to pump blood all round the body. The atria have only to pump blood
into the ventricles.
b The left ventricle has to pump blood all round the body (apart from the lungs). The right
ventricle has to pump blood only to the lungs.
4. The pulmonary veins are not shown.
5. If the heart valves do not function properly, some of the blood in the arteries can flow back
into the heart, so less blood is delivered to the body. This means that less oxygen reaches the
muscle cells and this impairs vigorous activity.
1. a Left Atrium.
i Left ventricle.
b Vena cava.
f Right atrium.
h Right ventricle.
e Pulmonary artery.
g Pulmonary vein.
2. The pulmonary artery carries deoxygenated blood.
The pulmonary vein carries oxygenated blood.
3. a Veins return blood to the heart. Arteries carry blood away from the heart.
b Veins are wider than arteries, less elastic with thinner walls and less muscle tissue.
Some of them have valves in their linings.
4. a Capillaries have ‘walls’ only one cell thick compared with the thick, muscular walls of
arteries and the thinner walls of veins. Capillaries are much smaller than veins or arteries. The
capillary walls allow exchange of oxygen, carbon dioxide and digested food substances
with the tissues.
b Capillaries penetrate all the tissues of the body and supply them with food and oxygen.
Arteries deliver blood to the capillaries and veins collect blood from the capillaries but do not
exchange substances with the tissues.
5. Blood pressure is needed to circulate blood round the body. It is a normal function of a
healthy blood circulatory system. Usually when people say they suffer from ‘blood pressure’
they mean a level of pressure which exceeds the normal range, i.e. ‘high blood pressure’.
1. Lymph consists of water, plasma proteins, salts (as ions), white blood cells and antibodies.
The lymphatics leaving the alimentary canal may contain lipid droplets.
2. The fat molecule has not been digested to fatty acids and glycerol so it will enter a lacteal in a
villus rather than a capillary. The lacteals empty their contents into lymphatic vessels which
eventually join up to form a lymphatic duct. The duct empties its contents into the left
subclavian vein which joins the vena cava before entering the left side of the heart. The left
ventricle will pump blood round the body and some of it will reach the liver in the hepatic
3. B lymphocytes (‘memory cells’) are retained in the lymph nodes. These cells produce
antibodies which attack bacteria and other harmful cells. The spleen produces lymphocytes
and antibodies. It removes bacteria from the blood. These are all immunological reactions.
||oxygen, glucose, water, urea, excess salts
| (ii) Lungs
||glucose, carbon dioxide, water vapour
|(iii) Active muscle
1. The phagocytes ingest harmful bacteria, the lymphocytes produce antibodies which act against
2. The inoculation promotes the production of antibodies against a disease. The body is ready to
‘fight’ the disease organisms when they arrive.
It is too late to do this once the disease organisms are present. The body will start making its
own antibodies but it will take time for them to build up to an effective level.
3. a Examples of diseases controlled by active immunity are measles, mumps, rubella, diphtheria
b An example of a disease controlled by passive immunity is tetanus.
4. The ‘universal donor’ is a group O person. The red cells have neither A or B antigens on their
surface and cannot be clumped by anti-A or anti-B antibodies.
5. If a person’s blood is clumped by the anti-B serum he could be group B or group AB. If the
blood fails to clump in anti-A serum, he cannot be group AB and must be Group B.
1. a Maintain a good level of regular exercise, reduce your stress levels..
b Don’t smoke, avoid an excess of fatty foods.
2. a If 95% of patients needing leg amputation are smokers there is clearly a correlation.
b Smoking cannot cause leg amputation but it might lead to conditions in which amputation
c Smoking is one of the causes of atheroma. If the atheroma occurs in the leg and cannot be
treated, it may necessitate amputation. (In fact there are many ways of treating atheroma in the
leg. Amputation is necessary only in extreme cases).
3. a Vigorous exercise increases the demand for oxygen and glucose for the higher rates of
respiration. These are met by increasing the blood flow which delivers these two substance
more rapidly to the muscles.
An increased respiration rate in active muscles produces CO2 which is removed by the faster
The arterioles supplying the muscle will widen and so increase the amount of blood reaching
the muscle. Increased ventilation in the lungs will hasten the supply of oxygen and the
removal of excess CO2.
b Stored glycogen in the muscles and liver will be converted to glucose. Lipids will be
released. The body temperature will rise leading to vasodilation in the skin and sweating (See
Levels of pyruvic and lactic acids may rise (See p. 20).
c The raised heart rate will increase the blood flow to all parts of the body, not just the
4. The first injection stimulates the lymphocytes in the immune system to produce antibodies
specific to the antigen in the vaccine. Some of the B lymphocytes are ‘memory’ cells. When
the second injection is received, the memory cells reproduce very rapidly and raise the level of
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Section 1, Chapters 1-5
Section 2, Chapters 6-9
Section 3, Chapters 10-12
Section 3, Chapters 13-17
Section 3, Chapters 18-20
Section 4, Chapters 21-24
Section 5, Chapters 25-27
Section 5, Chapters 28-29
Section 6, Chapters 30-34
Section 6, Chapters 35-37
Section 7, Chapters 38-39
Section 8, Chapters 40-41