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ANIMAL NUTRITION Flashcards

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1
Q

Balanced diet

A

This is a diet that contains all the essential nutrients in the correct proportions to maintain good health. The nutrients needed are carbohydrate, fat, protein, vitamins, minerals, fibre and water

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2
Q

Ingestion

A

The taking of substances such as food and drink into the body through the mouth

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3
Q

Mechanical digestion

A

The breakdown of food into smaller pieces without chemical change to the food molecules

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4
Q

Chemical digestion

A

The breakdown of large insoluble molecules into small soluble molecules

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5
Q

Absorption

A

The movement of small food molecules and ions through the wall of the intestine into the blood

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6
Q

Assimilation

A

The movement of digested food molecules into the cells of the body where they are used, becoming part of the cells

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7
Q

Egestion

A

The passing out of food that has not been digested or absorbed, as faeces, through the anus

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8
Q

Dietary requirements CHILFREN

A

Your dietary requirements depend on your age, sex and levels of physical activity. The amount of energy needed is provided mainly by our carbohydrate and fat intake. While children are growing, they need more protein per kilogram of body weight than adults do.

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9
Q

Generally, males use up

A

more energy than females, and energy demand increases until we stop growing. Someone doing physical work will use up more energy than an office worker.

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10
Q

Pregnant women need

A

extra nutrients for the development of the fetus. Once the baby has been born, a breast-feeding mother will need more protein and minerals, e.g. calcium, in her diet to satisfy the baby’s requirements.

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11
Q

Malnutrition is the result of an unbalanced diet:

A

• Too much food – or too much carbohydrate, fat or protein – can lead to obesity. This can lead to coronary heart disease and diabetes (which can cause blindness). • Too much animal fat in the diet results in high cholesterol levels. Cholesterol can stick to the walls of arteries, gradually blocking them. If coronary arteries become blocked, the result can be angina and coronary heart disease. • Too little food can result in starvation. Extreme slimming diets, such as those that avoid carbohydrate foods, can result in the disease anorexia nervosa . • Constipation is caused by a lack of fibre in the diet. It can lead to bowel cancer. • Vitamin and mineral deficiency diseases are all the result of malnutrition. Scurvy is caused by a lack of vitamin C.

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12
Q

Carbohydrate

A

Source of energy Rice, potato, sweet potato, cassava, bread, millet, sugary foods (e.g. cake, jam, honey)

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13
Q

Fat/ oil (oils are liquid at room temperature but fats are solid)

A

Source of energy (twice as much as carbohydrate); used as insulation against heat loss, for some hormones, in cell membranes, for insulation of nerve fibres Butter, milk, cheese, egg yolk, animal fat, groundnuts (peanuts)

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14
Q

Protein

A

Growth, tissue repair, enzymes, some hormones, cell membranes, hair, nails. Can be broken down to provide energy Meat, fish, eggs, soya, groundnuts, milk, meat substitute (e.g. Quorn), cowpeas

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15
Q

Vitamin C

A

Needed to maintain healthy skin and gums Citrus fruits, blackcurrants, cabbage, tomato, guava, mango

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16
Q

Vitamin D

A

Needed to maintain hard bones. Helps in absorption of calcium from small intestine Milk, cheese, egg yolk, fish liver oil. Can be made in the skin when exposed to sunlight

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17
Q

Calcium

A

Needed to form healthy bones and teeth and for normal blood clotting Milk, cheese, fish

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18
Q

Iron

A

Needed for formation of haemoglobin in red blood cells Red meat, liver, kidney, eggs, green vegetables (spinach, cabbage, cocoyam, groundnut leaves), chocolate

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19
Q

FIBRE

A

This is cellulose. It adds bulk to undigested food passing through the intestines, maintaining peristalsis Vegetables, fruit, wholemeal bread

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20
Q

WATER

A

Formation of blood, cytoplasm, as a solvent for transport of nutrients and removal of wastes (as urine). Enzymes work only in solution Drinks, fruit, vegetables

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21
Q

Vitamins and minerals, although needed

A

in only small quantities, are important for maintaining good health. A shortage can result in a deficiency disease. You only need to know vitamins C and D, and the minerals calcium and iron. Fibre (roughage) is needed in much larger quantities. Do not forget that water is also a vital part of our dietary requirements.

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22
Q

A shortage of vitamin D

A

can lead to a deficiency disease called rickets. The symptoms are soft bones that become deformed. Sufferers may become bow legged. Exposure to moderate sunlight helps the body make vitamin D. Thus, a lack of exposure (because of climate or season or wearing clothing that acts as a barrier to sunlight) can result in the development of a deficiency.

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23
Q

A deficiency of iron

A

in the diet can lead to anaemia. The symptoms are constant tiredness and a lack of energy. Normally, as red blood cells in the body are broken down, the iron in the haemoglobin is recycled to make new red blood cells. However, if a woman has a heavy period (see Chapter 16) there is a lot of blood (and therefore iron) loss, which can result in anaemia.

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24
Q

Sometimes the balance of food

A

in the diet is wrong, e.g. too much carbohydrate and too little protein, such as when the bulk of the diet is starchy food, such as sweet potato or cassava. This can lead to kwashiorkor in young children. They lack protein, but other problems such as plant toxins can also play a role. The symptoms of kwashiorkor are dry skin, pot-belly, changes to hair colour, weakness and irritability.on.

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25
Q

Marasmus

A

is an acute form of malnutrition. The condition is caused by a very poor diet with inadequate carbohydrate intake and a lack of protein. The symptoms are emaciation, with reduced fat and muscle tissue. The skin is thin and hangs in folds.

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26
Q

Mouth

A

Food is ingested here. It is mechanically digested by cutting, chewing and grinding of teeth. Saliva is added

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27
Q

Salivary glands

A

Produce saliva, containing the enzyme amylase to begin the chemical digestion of starch. The water in saliva helps lubricate food and makes small pieces stick together

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28
Q

Oesophagus

A

Boluses (balls) of food pass through by peristalsis, from mouth to stomach

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29
Q

STOMACH

A

Muscular walls squeeze on food to make it semi-liquid. Gastric juice contains protease to chemically digest protein and hydrochloric acid to maintain an optimum pH (1– 2.5). The acid also kills bacteria

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30
Q

DUODENUM

A

This is the first part of the small intestine. It receives pancreatic juice containing protease, lipase and amylase. The juice also contains sodium hydrogencarbonate, which neutralises acid from the stomach, producing a pH of 7– 8

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31
Q

ILEUM

A

The second part of the small intestine. Enzymes in the epithelial lining chemically digest maltose and peptides. Its surface area is increased by the presence of villi, which allow the efficient absorption of digested food molecules.

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32
Q

PANCREAS

A

Secretes pancreatic juice into the duodenum for chemical digestion of proteins, fats and starch

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33
Q

LIVER

A

Makes bile, which is stored in the gall bladder. Bile contains salts that emulsify fats, forming droplets with a large surface area to make digestion by lipase more efficient. Digested foods are assimilated here. For example, glucose is stored as glycogen; surplus amino acids are deaminated

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34
Q

GALL BLADDER

A

Stores bile, made in the liver, to be secreted into the duodenum via the bile duction.

35
Q

COLON

A

The second part of the large intestine. Its main function is the reabsorption of water from undigested food. It also absorbs bile salts to pass back to the liver

36
Q

RECTUM

A

Stores faeces until they are egested

37
Q

ANUS

A

Has muscles to control when faeces are egested from the body.

38
Q

DIAORRHEA

A

Diarrhoea is the loss of watery faeces. It is sometimes caused by bacterial or viral infection, for example from food or water, resulting in the intestines being unable to absorb fluid from the contents of the colon or too much fluid being secreted into the colon. Undigested food then moves through the large intestine too quickly, resulting in insufficient time to absorb water from it. Unless the condition is treated, dehydration can occur. The treatment is called oral hydration therapy – drinking plenty of fluids (sipping small amounts of water at a time) to rehydrate the body.

39
Q

When cholera bacteria,

A

Vibrio cholerae, are ingested they multiply in the small intestine and invade its epithelial cells. As the bacteria become embedded, they release toxins (poisons) that irritate the intestinal lining and lead to the secretion of large amounts of water and salts, including chloride ions. The salts decrease the osmotic potential of the gut contents, drawing more water from surrounding tissues and blood by osmosis (see ‘Osmosis’ in Chapter 3). This makes the undigested food much more watery, leading to acute diarrhoea, and the loss of body fluids and salt leads to dehydration and kidney failure.

40
Q

TYPES OF TEETH

A
41
Q

STRUCTURE OF A TOOTH

A
42
Q

Bacteria are present on the

A

surface of our teeth. Food deposits and bacteria form a layer called plaque. Bacteria in the plaque respire sugars, producing acid. This acid dissolves enamel and dentine, forming a hole. Dentine underneath the enamel is softer – it dissolves more rapidly. If the hole reaches the pulp cavity, bacterial infection can get to the nerve. This results in toothache and, possibly, an abscess (an infection in the jaw).

43
Q

Food that we ingest

A

is mainly made up of large, insoluble molecules that cannot be absorbed through the gut wall. It needs to be changed into small, soluble molecules.

Chemical digestion involves breaking down large, insoluble molecules into small, soluble ones. Enzymes speed up the process. They work efficiently at body temperature (37 ° C) and at a suitable pH. The main places where chemical digestion happens are the mouth, stomach and small intestine.

44
Q

AMYLASE

A
45
Q

PROTEASE

A
46
Q

LIPASE

A
47
Q

the functions of hydrochloric acid in gastric juice

A
  • It gives an acid pH, which protease needs to work at its optimum.
  • It kills bacteria that may be present in food that has been ingested.
48
Q

Digestion of starch

A

Starch is digested in two places in the alimentary canal: by salivary amylase in the mouth and by pancreatic amylase in the duodenum.

Amylase works best in a neutral or slightly alkaline pH and converts large, insoluble starch molecules into smaller, soluble maltose molecules.

Maltose is a disaccharide sugar and is still too big to be absorbed through the wall of the intestine. Maltose is broken down to glucose by the enzyme maltase, which is present in the membranes of the epithelial cells of the villi.

49
Q

Digestion of protein

A

There are actually several proteases that break down proteins. One protease is pepsin, which is secreted in the stomach. Pepsin acts on proteins and breaks them down into soluble compounds called peptides. These are shorter chains of amino acids than proteins. Another protease is called trypsin. Trypsin is secreted by the pancreas in an inactive form, which is changed to an active enzyme in the duodenum (part of the small intestine). It has a similar role to pepsin, breaking down proteins to peptides.

50
Q

Hydrochloric acid in gastric juice

A

The hydrochloric acid that is secreted by cells in the wall of the stomach creates a very acid pH of 2.

This pH is important because it denatures enzymes in harmful organisms in food, such as bacteria (which may otherwise cause food poisoning), and it provides the optimum pH for the protein-digesting enzyme pepsin to work.

51
Q

Bile

A

Bile is made in the liver, stored in the gall bladder and transferred to the duodenum by the bile duct (Figure 7.2). It has no enzymes but does contain bile salts, which act on fats in a similar way to a detergent. The bile salts emulsify the fats, breaking them up into small droplets with a large surface area, which are more efficiently digested by lipase.

Bile is slightly alkaline, as it contains sodium hydrogencarbonate, and has the function of neutralising the acidic mixture of food and gastric juices as it enters the duodenum. This is important because enzymes secreted into the duodenum need alkaline conditions to work at their optimum rate.

52
Q

ABSORPTION

A

The small intestine has a very rich blood supply. Digested food molecules are small enough to pass through the wall of the intestine into the bloodstream. The small intestine and the colon are both involved in the absorption of water, but the small intestine absorbs the most.

53
Q

Role of villi in absorption

A

You need to be able to relate the structure of the small intestine to its function of absorbing digested food and describe the significance of villi in increasing the internal surface area.

Villi are present in the small intestine – these are finger-like projections that increase the surface area for absorption. If a section of small intestine was turned inside out, its surface would be like a carpet. The surface area of a villus is further increased by the presence of microvilli. Inside each villus are blood capillaries that absorb amino acids and glucose. There are also lacteals – these absorb fatty acids and glycerol.

54
Q

Food molecules are absorbed mainly

A

by diffusion. Figure 7.6 shows the features of a villus that increase the efficiency of diffusion. Molecules can also be absorbed by active transport (see Chapter 3). Epithelial cells contain mitochondria to provide energy for absorption against the concentration gradient.

55
Q

FOOD MOLECULE BY DIFFUSION

A
56
Q

Single circulation

A

Fish have a heart consisting of one blood-collecting chamber (the atrium) and one blood ejection chamber (the ventricle). It sends blood to the gills, where it is oxygenated. The blood then flows to all parts of the body before returning to the heart. This is known as single circulation because the blood goes through the heart once for each complete circulation of the body.

57
Q

Double circulation

A

Blood passes through the heart twice for each complete circulation of the body. The right side of the heart collects deoxygenated blood from the body and pumps it to the lungs. The left side collects oxygenated blood from the lungs and pumps it to the body. The double circulatory system helps to maintain blood pressure, making circulation efficient. Figure 9.1 shows the double circulatory system.

Blood passes through the heart twice for each complete circulation of the body. The right side of the heart collects deoxygenated blood from the body and pumps it to the lungs. The left side collects oxygenated blood from the lungs and pumps it to the body. The double circulatory system helps to maintain blood pressure, making circulation efficient. Figure 9.1 shows the double circulatory system.

Hayward, Dave. Cambridge IGCSE Biology Study and Revision Guide 2nd edition (Kindle Locations 1588-1591). Hodder Education. Kindle Edition.

58
Q
A
59
Q

STRUCTURE OF HEART

A

The heart is a pump made of muscle that moves blood around the body. The muscle is constantly active, so it needs its own blood supply, through the coronary artery, to provide it with oxygen and glucose. The heart has two sides. The right side receives deoxygenated blood from the body and then pumps blood to the lungs for oxygenation. The septum separates the left side from the right side. The left side receives oxygenated blood from the lungs and pumps it to the body.

60
Q

There are four chambers.

A

The right and left atria receive blood from veins and squeeze it into the ventricles. The right and left ventricles receive blood from the atria and squeeze it into arteries. Figure 9.2 shows the main parts of the heart. A surface view of the heart would also show the presence of coronary arteries on the surface of the ventricle muscle walls. For the Core paper, the valves in the heart do not need to be named. You only need to be able to identify where the valves are and understand that they allow the flow of blood only one way.

61
Q

HEART STRUCTURE DIAGRAM

A
62
Q

The wall of the left ventricle

A

is much thicker than the wall of the right ventricle because it needs to build up enough pressure to move the blood to all of the main organs. The walls of the atria are much thinner than those of the ventricles. This is because the contraction of the atria needs to be powerful enough only to move blood down into the ventricles, while the ventricles are moving blood around the body and through all of the organs. The septum divides the left side of the heart from the right side. This prevents the mixing of oxygenated and deoxygenated blood.

63
Q

Heart muscles in the atria contract

A

to build up sufficient pressure to move blood through the tricuspid (right side) and bicuspid valves (left side) into the ventricles. These valves then shut to prevent the backflow of blood. As the muscles in the ventricles contract, blood pressure builds up and the blood is forced through the semilunar valves into the pulmonary artery (right side) and aorta (left side). Once the pressure wave has passed, the semilunar valves close to prevent blood from the arteries being sucked back into the ventricles.

64
Q

Monitoring effect of heart

A

There are a number of ways by which the activity of the heart can be monitored: • Pulse rate: the ripple of pressure that passes down an artery as a result of the heartbeat can be felt as a ‘pulse’ when the artery is near the surface of the body. • Heart sounds can be heard using a stethoscope. This instrument amplifies the sounds of the heart valves opening and closing. • An ECG is an electrocardiogram. To obtain an ECG, electrodes, attached to an ECG recording machine, are stuck onto the surface of the skin on the arms, legs and chest. Electrical activity associated with heartbeat is then monitored and viewed on a computer screen or printed out.

65
Q

Effect of physical activity on pulse rate

A

A heartbeat is a contraction, each of which squeezes blood to the lungs and body. The heart beats about 70 times a minute, more if you are younger, and the rate becomes lower the fitter you are. This beat can be felt as a pulse in the wrist (radial artery) or neck (carotid artery). During exercise, pulse rate increases from the resting rate and stays high until physical activity slows down or stops. After exercise, the pulse gradually returns to normal.

During exercise, heart rate increases to supply the muscles with more oxygen and glucose. These are needed to allow the muscles to respire aerobically, so they have sufficient energy to contract.

Hayward, Dave. Cambridge IGCSE Biology Study and Revision Guide 2nd edition (Kindle Locations 1661-1663). Hodder Education. Kindle Edition.

66
Q

Coronary heart disease

A

Coronary heart disease (a heart attack) is caused by blockage of the coronary arteries. These supply the heart muscle with oxygen and glucose. Without these, the muscle cells stop contracting and die. The possible risk factors are shown in the following table.

67
Q

Prevention of coronary heart disease

A

Maintaining a healthy, balanced diet will lower the chance of a person becoming obese. The low intake of saturated fats that is part of a balanced diet reduces the chances of atheroma and thrombus formation. An obese person is less likely to take regular exercise. Regular, vigorous exercise can also reduce the chances of a heart attack. This may be because it increases muscle tone – not only of skeletal muscle, but also of cardiac muscle. Good heart muscle tone leads to an improved coronary blood flow and the heart requires less effort to keep pumping.

68
Q

coronary heart disease treatment

A

The simplest treatment for a patient who suffers from coronary heart disease is to be given a regular dose of aspirin. This prevents the formation of blood clots in the arteries, which can lead to a heart attack. Methods of removing or treating atheroma and thrombus formations include the use of angioplasty, a stent and, in the most severe cases, bypass surgery.

69
Q

angioplasty

A

Angioplasty involves the insertion of a long thin tube called a catheter into the blocked or narrowed blood vessel. A wire attached to a deflated balloon is then fed through the catheter to the damaged artery. Once in place, the balloon is inflated to widen the artery wall, effectively freeing the blockage. In some cases, a stent is also applied. This is a wire-mesh tube that can be expanded and left in place. It then acts as scaffolding, keeping the blood vessel open and maintaining the free flow of blood. Some stents can give a slow release of chemicals to prevent further blockage of the artery.

70
Q

by pass surgery

A

In bypass surgery, a section of blood vessel from a different part of the body, such as the leg, is removed. This is then attached around the blocked region of artery to bypass it, allowing blood to pass freely. This is a major, invasive operation because it involves open-heart surgery.

71
Q

ARTERIES

A

Arteries carry blood, at high pressure, away from the heart to organs of the body. Veins return blood, at low pressure, from organs towards the heart. Capillaries link arteries to veins. They carry blood through organs and tissues, allowing materials to be exchanged.

72
Q

ARTERY

A
73
Q

VEIN

A
74
Q

CAPILLARY

A
75
Q

Functions of arterioles, venules and shunt vessels

A

The arterioles, linking arteries to capillaries, have proportionately more muscle fibres than arteries. When the muscle fibres of the arterioles contract, they make the vessels narrower and restrict the blood flow (a process called vasoconstriction; see Chapter 14). In this way, the distribution of blood to different parts of the body can be regulated. Shunt vessels, linking the arterioles with venules, can dilate to allow the blood to bypass the capillaries in the skin. This helps to reduce heat loss. Venules return blood to veins.

76
Q

The lymphatic system

A

The lymphatic system is a collection of lymph vessels and lymph nodes. It has three main roles:

  • The return of tissue fluid to the blood in the form of lymph fluid. This prevents fluid build-up in the tissues.
  • The production of lymphocytes. These are made in lymph glands such as the tonsils, adenoids and spleen. The glands become more active during an infection because they are producing and releasing large numbers of lymphocytes.
  • The absorption of fatty acids and glycerol from the small intestine. Each villus contains a lacteal – a blind-ending lymph vessel.
77
Q

PLASMA

A

Plasma is a liquid that transports substances to cells and carries wastes away from cells. It acts as a pool for amino acids (these cannot be stored in the body) and contains blood proteins that are important in blood clotting. The following table shows the main substances carried by plasma..

78
Q

RBC

A

Oxygen is not included in the table above, as it is transported in red blood cells. Oxygen combines with haemoglobin to form oxyhaemoglobin. The oxygen is released from the red blood cells in capillaries where surrounding oxygen levels are low.

79
Q

LYMPHOCYTE

A
80
Q

PHAGOCYTE

A
81
Q

PLATELETS

A
82
Q

Functions of lymphocytes, phagocytes and platelets

A

Lymphocytes are involved in the production of antibodies, which are needed to fight disease (see Chapter 10). They can attach themselves to antigens (foreign proteins) and clump them together. Phagocytes have the ability to change their shape and move to engulf harmful bacteria by a process called phagocytosis. Platelets clump together when tissues are damaged and block the smaller capillaries. The platelets and damaged cells at the wound produce a substance that acts on a soluble plasma protein called fibrinogen. As a result, it is changed into insoluble fibrin, which forms a network of fibres across the wound. Red blood cells become trapped in this network and so form a blood clot. The clot not only stops further loss of blood, but also prevents the entry of pathogens (disease-causing organisms) into the wound.

83
Q

Transfer of material

A

Transfer of materials between capillaries and tissue fluid As blood enters capillaries from arterioles (small arteries), it slows down. This allows substances in the plasma, as well as oxygen from red blood cells, to diffuse through the capillary wall into the surrounding tissues (the capillary wall is thin and permeable). Liquid in the plasma also passes out. This forms tissue fluid, bathing the cells. Waste products from the cells, e.g. carbon dioxide, diffuse back through the capillary walls into the plasma. Some of the tissue fluid also passes back.

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