Food and Health Flashcards
1
Q
what are the 7 categories of nutrients constituting a balanced diet?
A
carbohydrates, fats, proteins, fibre, water, vitamins and minerals
2
Q
what is malnutrition?
A
the consumption of an unbalanced diet, resulting in many health problems
3
Q
how to calculate body mass index (BMI) :
A
weight(Kg) / height(m2)
4
Q
when may obesity occur?
A
- when the energy intake (e.g. from fats and carbs) exceeds the energy requirements
- genetically e.g. genes controlling metabolic rate are not as efficient
- sedentary lifestyle
5
Q
What are 3 health problems obesity increases the risk of?
A
- hypertension (high blood pressure)
- CHD (coronary heart disease) and myocardial infarction (heart attack)
- maturity onset diabetes (insufficient insulin)
6
Q
Describe low density lipoproteins - composition and effect
A
consist of less protein and more lipids
more likely to be deposited in artery walls as atheromas, which can cause CHD as they carry cholesterol from the liver to the tissues
7
Q
Describe high density lipoproteins - composition and effect
A
consist of more protein and less lipids.
Carry cholesterol from tissues (including artery walls) to liver so are protective against CHD.
8
Q
how is cholesterol transported in the blood and why?
A
Transported in the blood bound to protein, forming lipoproteins because it is insoluble in water.
9
Q
what is a pathogen compared to a parasite?
A
Pathogen - a disease-causing organism.
Parasite - organism that lives in/on another living organism (host) causing some harm
10
Q
What is the name of the protozoan that causes malaria?
A
Plasmodium
11
Q
Describe the transmission of malaria - what is the vector?
A
vector-borne: female Anopheles mosquito carries it. Blood containing Plasmodium is sucked from an infected person by the mosquito, where it multiplies asexually in its salivary glands. Mosquito bites another person, transferring malaria parasites.
12
Q
What happens to the Plasmodium once in the body? (malaria)
A
Invades the liver cells and reproduces asexually. Some parasites leave the liver and invade red blood cells - symptoms begin when these burst out, releasing toxins.
13
Q
What are some ways in which Malaria can be controlled?
A
- diagnosis via blood samples
- anti-malarial drugs
- insecticides to kill mosquitoes
- mosquito nets at night
- insect repellents on skin to deter mosquitoes from biting
- drainage of marshes/ditches - mosquitoes lay eggs in water
14
Q
Why is prevention of Malaria by vaccine difficult?
A
At each stage, (mosquito—> liver cells –> blood cells) Plasmodium has different antigens, and a vaccine would need to incorporate them all to trigger antibodies against all stages
15
Q
What is the name of the bacterium tuberculosis is caused by?
A
Myobacterium tuberculosis
16
Q
Transmission of TB?
A
air-borne: spread by droplet infection
17
Q
Where is TB most easily spread/which factors increase the risk of an individual contracting it
A
- in developing countries especially among malnourished people and urban centres: spreads more easily in overcrowded conditions
- in areas where HIV infection is common: it is an AIDS related disease/weakened immune system
- can also be spread from drinking untreated milk from infected cattle
- not vaccinated against TB ;
- homelessness ;
- (lifestyle) e.g. poor diet / lack of protein / malnourished / smoking / alcoholism ;
close contact with people from / visiting, area where TB is common ;
18
Q
What are some ways in which TB can be controlled?
A
- diagnosis via sputum samples to identify TB bacteria
- treatment of TB with antibiotics over a long period of time to kill the large bacterial population
- screening via chest x-ray shows grey/white patches of scar tissue
- pasteurisation of milk to kill TB bacteria
- TB testing of cattle and slaughtering infected individuals
- provide better housing conditions for individuals living in crowded housing conditions
19
Q
what is meant be ‘health’?
A
a state of complete physical, mental and social well-being and not merely the absence of diseases or infirmity.
20
Q
what is meant be ‘disease’?
A
when 1 or more parts of the body are functioning inefficiently due to temporary or permanent damage
21
Q
Briefly discuss the global impact of malaria, TB and HIV? in terms of incidences&mortality per year.
A
Malaria - endemic in the tropics. Incidences: about 500mill of the population each year, mortality about 1 million a year.
TB - Incidences: 9mill. Motality: 3mill. prevalent in developing countries.
AIDS: worldwide, most common in Africa/Southeast Asia. Precise figures impossible due to the long incubation period & few people being tested.
22
Q
What is AIDS caused by?
A
Human Immunodeficiency Virus
23
Q
What is the retrovirus AIDS is caused by? why is it described as a retrovirus?
A
Human Immunodeficiency Virus
Has RNA as its genetic material, inside a protein coat
24
Q
What is the effect of HIV on the body upon transmission?
A
infects T-lymphocytes of the immune system
25
Describe the transmission of HIV + some examples
found in body fluids e.g. blood, semen, vagina mucus, breastmilk.
- sexual transmission: highest risk is anal intercourse as rectal lining is thin and easily ruptured (also transmitted in vaginal intercourse and oral intercourse especially if mouth ulcers/bleeding gums)
- Sharing of needles by intravenous drug users
- mother-to-baby: blood squeezed across placenta at birth/breast-feeding
26
What are some ways in which HIV can be controlled?
- diagnosis via blood tests to identify antibodies against HIV
- anti-viral drugs - very expensive
- use of condoms for all types of sexual intercourse
- needle exchange systems in areas where there is a high incidence of injection of drugs
- caesarian sections & advice against breast-feeding for HIV positive pregnant women
27
What are some ways in which HIV can be controlled?
- diagnosis via blood tests to identify antibodies against HIV
- anti-viral drugs - very expensive
- use of condoms for all types of sexual intercourse
- needle exchange systems in areas where there is a high incidence of injection of drugs
- caesarian sections & advice against breast-feeding for HIV positive pregnant women
28
How does the skin provide primary defence against pathogens and parasites?
- impermeable to most pathogens: natural barrier
- harmless bacteria live on the skin to help prevent infections by pathogens
- acid secretions from sweat and sebaceous glands kill most pathogens
- mitotic division when skin is damaged by cuts to seal over the wound so that pathogens cannot enter
29
How does the blood provide primary defence against pathogens and parasites?
Clotting: soluble protein fibrinogen in platelets is turned into insoluble fibrin to trap blood cells.
30
How do the bodily fluids provide primary defence against pathogens and parasites?
Tears and saliva contain lysozyme enzyme which destroys many bacteria.
Stomach secretes HCl which kills ingested bacteria
Mucus in vagina/airways traps pathogens
31
How does the epithelium in digestive and respiratory systems provide primary defence agains pathogens and parasites?
Contains goblet cells which secretes mucus to act as a barrier to prevent bacteria contacting cells as well as trapping particles/pathogens.
In the respiratory system, ciliated epithelial cells move the mucus to the back of the throat to be swallowed.
32
What is an antigen?
proteins on the surface of a pathogen/toxin produced by a pathogen that are specific to it.
33
What are the two types of phagocytes? where are they made, where are they later found and describe structure?
Neutrophils: made in the bone marrow from stem cells, circulate in the blood and can squeeze through pores in capillary walls. Multi lobed nucleus & granular cytoplasm due to many lysosomes.
Macrophages: made in the bone marrow from stem cells, accumulate in the organs. Kidney shaped nucleus and clear cytoplasm.
34
How do neutrophils destroy pathogens?
Engulf bacteria via endocytosis of bacteria into a phagosomes & destroy them by fusing phagosome with lysosomes and releasing lysin enzymes into phagosome to ingest the trapped bacteria.
35
How do macrophages destroy pathogens?
engulf them but only partially digest them, leaving the antigens intact. These antigens are then placed on the outer surface of the macrophage's cell membrane to aid recognition by other cells of the immune system in antigen presentation.
36
Where are lymphocytes made? structure?
made in the bone marrow from stem cells. White blood cells with a large, round nucleus and clear cytoplasm.
37
What are the 2 types of lymphocytes? name their respective responses
B-lymphocytes: humoral response
| T-lymphocytes: cell-mediated response
38
Where us the site of production of B and T lymphocytes, and where do they mature?
Both made from stem cells in the bone marrow, B-lymphocytes also mature here but T-lymphocytes mature in the thymus gland
39
How are B and T lymphocytes different in terms of antigen recognition?
Each B cell have receptors that are complementary to one specific antigen, as it is programmed to produce one specific antibody type.
T cells only recognise antigens when they are present on the cell membrane of another cell and specific to the T-cell receptors on their cell membranes
40
Describe the sequence of events in the primary immune response - HUMORAL
1. Macrophages engulf & partially ingest some pathogens, leaving antigens
2. Antigen presentation occurs - antigens from CSM of pathogen are attached to cell membranes of macrophages 3. Clonal selection occurs and B-cells and T-helper cells bind with their complementary receptors to the presented antigens - the T-helper cells secrete cytokines stimulating the correct B-cells which have come into contact with the pathogen's antigens and have complementary receptors to...
4. Clonal expansion - divide by mitosis creating many clones of the B-cell all with complementary receptors
5. Clonal differentiation - some B-cell clones differentiate to form plasma cells, others memory cells. Plasma cells will produce millions of specific shaped antibodies that attach to the complementary shaped foreign antigen & destroy by agglutination/neutralisation. Memory provide immunological memory of the specific antigen, helpful for later..
41
Describe the sequence of events in the secondary immune response
Memory cells remain in the blood and can recognise the same foreign antigen. They divide rapidly to form more plasma cells which secrete the correctly shaped antibodies. This response is much faster and so the pathogen is destroyed quickly with no disease symptoms.
42
Describe the structure in relation to function of antibodies
2 identical long heavy chains and 2 identical short light chains.
- Each chain has a variable region of different amino acid chains that form the antigen binding site, which is specific for a particular antigen
- The constant region is identical in each antibody and these bind to specific receptors on the cell membrane of phagocytes
- The hinge region allows some flexibility when binding.
- 2 binding sites allow agglutinate and neutralise pathogens
- disulphide bridges maintain stability
43
what are the three ways in which antibodies can destroy pathogens?
1. Neutralising toxins
2. Agglutinating pathogens
3. preventing pathogens from binding to human cells
44
Describe neutralisation of pathogens by antigens
Antibodies bind to toxins (metabolic waste) produced by pathogens preventing them from affecting human cells - they are effectively neutralised.
45
Describe the agglutination of pathogens by antibodies
Antibodies have 2 binding regions - they bind to 2 pathogens simultaneously causing them to clump togethers o they are less mobile and can be phagocytosed in bulk
46
How can antibodies prevent the pathogen from binding to human cells?
Block the cell surface receptors so it cannot bind to cells/tissues
47
what is natural immunity compared to artificial?
natural: due to natural processes, artificial: medical intervention
48
Describe passive natural immunity and the nature of the immunity it provides
Ready made antibodies pass from mother to child via breast milk/placenta. Provides only short-lived immunity as the antibodies are eventually broken down in the liver and child has no memory cells.
49
Describe active natural immunity and the nature of the immunity it provides
Production of antibodies and memory cells as a result of the person contracting a disease.
Provides long-term immunity to the disease as memory cells are formed.
50
Describe passive artificial immunity and the nature of the immunity it provides
Injection of ready made antibodies from another person/animal. Gives short-term immunity until antibodies are destroyed in the liver
51
Describe active artificial immunity and the nature of the immunity it provides
injection (/oral dose) of killed/weakened form of a pathogen. Stimulates immune system to produce antibodies and memory cells against the particular antigens in the injection. Long term immunity.
52
describe herd immunity? ring immunity?
herd: vaccination of almost a whole population to prevent contraction of/spreading of the disease (80-85%)
ring: vaccination of all the species in/surrounding a particular area where there is a high incidence/risk of disease
53
How do vaccines work?
weak/killed pathogen is injected/orally administered. Vaccine antigens are recognised by lymphocytes, clones of plasma cells made secreting antibodies & memory cells made. Booster dose sometimes given
54
Why is influenza so hard to control?
New strains often arise due to mutations.
These have different surface antigens, so a person immune to one flu virus is unlikely to be immune to other strains.
Spreads rapidly via droplet infection.
55
What are some government responses to new strains of influenza?
- isolation of infected people
- travel restrictions into/out of infection countries
- production of new vaccines
- vaccination of susceptible people e.g. elderly
- research and development of new anti-viral drugs
56
How might microorganisms be useful sources of new medicines?
Bacteria and fungi produce antibiotics against competing bacteria. Sponges secrete toxic chemicals to protect them from other animals.
57
How might plants be useful sources of new medicines?
Plants produce chemicals to protect them from herbivores. . About 7000 drugs are obtained from 3000 plant species thus far, 70% of which grow in tropical rainforests. It is therefore important to maintain biodiversity & conserve habitats.
58
What are some effects of smoking on the gaseous exchange system?
- heat from the smoke can paralyse cilia
- tar and smoke particles stick to cilia preventing them from beating away mucus efficiently causing mucus, tar and particles to slide down the air passageways and accumulate in alveoli: this increases the risk of respiratory infections (bacteria/pathogens not wafted away) and cause coughing
- prolonged coughing can damage alveoli and surrounding blood capillaries
- tar is carcinogenic so can cause cancers e.g. lung cancer
- damaged alveoli repair with thicker scar tissue, increasing the distance for gaseous exchange and reducing elasticity
59
What are symptoms of chronic bronchitis, caused by long-term smoking?
- persistant coghing especially after exertion
- breathlessness
- fatigue
- coughing up bacteria-filled mucus
- rattling of air in congested air passageways heard via a stethoscope
- grey/white patches of scar tissue shown on an x-ray
60
What is emphysema?
mucus blocks terminal bronchioles causing air to become trapped in alveoli. The high pressure created within alveoli during expiration can therefore burst the alveoli and surrounding blood capillaries. alveoli repair themselves, but their number is reduced and thick scar tissue formed. Lungs become less elastic as elastic fibres around alveoli are destroyed. Phagocytic white blood cells also release elastase to digest elastin to reach bacteria in lungs.
61
What are symptoms of emphysema?
- severe breathlessness
- persistant coughing
- forced expirations, rapid breathing rate
- barrel-shaped chest as lungs enlarge to try to compensate for decreased surface area
- death and loss of peripheral tissue such as finger joints due to lack of oxygen
62
what is the effect of lung cancer caused by long-term smoking?
Carcinogenic tars cause genes controlling mitosis to mutate into oncogenes. Epithelial cells therefore divide more frequently and lose their specialised structure. Cancer cells form a tumour which is supplied with blood and lymph vessels and so cancer cells can break off and enter the blood or lymph systems and spread to other parts of the body forming secondary cancers.
63
Symptoms of lung cancer?
- breathlessness
- coughing
- chest pain
- loss of appetite and rapid weight loss
- grey/white area on chest in x-ray
64
What are the effects of nicotine absorbed into bloodstream via alveoli from the tobacco smoke?
- addiction
- releasee of adrenaline
- increased heart rate and blood pressure
- blood platelets become sticky increasing risk of atherosclerosis
- constriction of coronary arteries
- increased blood LDL cholesterol
- increased breathing rate
65
What is the effect of carbon monoxide from tobacco smoke on the cardiovascular system?
CO absorbed into blood stream and binds irreversibly with haemoglobin forming carboxyhemoglobin, reducing the oxygen-carrying capacity of the blood.
66
What is atherosclerosis? why does smoking increase the risk
The thickening of the artery walls with deposits of LDL cholesterol, reducing the size of their lumen and decreasing their elasticity. Cholesterol deposits are more likely to form where the walls are roughened by high blood pressure and where platelets are cluttered - both of these factors are exacerbated by nicotine.
Can lead to CHD and strokes.
67
Describe how CHD occurs and why smoking increases the risk
Narrowing/blocking of coronary arteries with cholesterol deposits. This deprives the heart muscle of oxygen so less respiration occurs in cardiac muscle cells so their is less ATP for contraction of the heart. Cardiac muscle cells deprived of O2 die and are replaced by scar tissue.
Severe lack of O2 to the heart may cause a heart attack/myocardial infarction.
Especially likely to be fatal of the blockage of the coronary artery is near the top as this will deprive most of the heart muscle of oxygen.
Nicotine and CO increase this risk. (affect atherosclerosis likelihood and oxygen availability)
68
Describe how strokes occur. Effects?
- Cerebral thrombosis (blood clot in carotid artery)
OR
- cerebral haemorrhage (rupturw and bleed from carotid artery)
BOTH of which can be due to atherosclerosis as this increased the risk of an internal blood clot and raises the blood pressure.
This deprives part of the brain with blood and so brain cells die from lack of O2. Damage is permanent, causing loss of speech, memory, paralysis of 1 side of the body.
69
Compare epidemiological and experimental evidence.
Epidemiological: statistics comparing disease incidences/ deaths e.g. between non-smokers and smokers
Experimental: direct studies on animals/people/tissues
70
Discuss the epidemiological evidence linking smoking to disease and early death. Knowledge of exact statistics is not required.
Strong positive correlation between consumption of cigarettes and deaths from lung cancer. Smokers are 18x more likely to develop lung cancer. 98% of people with emphysema are smokers. Incidence of CHD decreases in people who give up smoking. Death rates from CHD are higher in heavier & long-term smokers
71
Discuss the experimental evidence linking smoking to disease and early death
Animals made to inhale cigarette smoke developed lung cancers compared to control animals who did not.
Tars extracted from cigarette smoke painted onto mice as well as human skin in culture caused skin cancers.
Heart rate, blood pressure and blood cholesterol all increase in humans after just 1 cigarette.
72
How is consumption of a diet high in saturated fats e.g. butter, red meat and cheese linked to CHD?
Easily converted into LDL cholesterol and deposited in artery walls, especially the coronary arteries as they are initially narrow. This results in atherosclerosis and hypertension, putting the heart under strain as it has to pump harder and faster. Can result in a heart attack (myocardial infarction) due to lack of O2 to the cardiac muscle.
73
Why is the consumption of polyunsaturated fat e.g. in plant oils and oily fish better for you than consumption of saturated fats?
Polyunsaturated fats form HDL cholesterol and help to lower the level of LDL cholesterol.
Saturated form LDL cholesterol which can lead to atheromas ---> hypertension & atherosclerosis --> CHD
74
How is a diet high in salt intake linked to CHD?
excess salt lowers the water potential of the blood causing movement of water from the body cells into the blood. This increases the blood volume and therefore the blood pressure, increasing strain on the heart. (hypertension)
75
How can a diet high in fibre and vitamins A C and E decrease the risk of CHD?
High fibre (cellulose) can bind to saturated fats in the gut so less are absorbed. Vitamins A C and E lower the blood LDL cholesterol level.
76
What are 3 ways in which humans can selectively breed crop plants to their advantage? e.g.?
1. Production of high yields - e.g. wheat variety with less waste (shorter stem) crossed with a higher yielding variety, allowed to self-pollinate, seeds taken from the best plants and repeated for 10 generations.
2. Production of disease resistance - e.g. search for wheat varieties with a genetic resistance to rust fungus in an attempt to cross breed and produce new varieties with more resistance genes than previous varieties.
3. Production of pest resistance - e.g. to develop new varieties of wheat with resistance to aphids thus reducing the amount of expensive pesticides used
77
What are some ways in which cattle have been selectively bred? e.g. which characteristics, how achieved...
Individuals with more muscle, high milk yield, disease resistance crossed to produce offspring with 2 or more of these characteristics. Best offspring chosen for breeding each generation.
Semen can be collected from bulls, frozen and stored and then used via artificial insemination of cows.
However, cattle with high yields of meat/milk need more food to allow increased productivity.
78
How do fertilisers increase crop yields?
Inorganic fertilisers such as ammonium nitrate provides NH4+ and NO3- ions needed for plants to make proteins.
79
What 2 factors must be true if fertilisers are to increase yields economically?
What are some problems arising from excessive use of fertilisers?
1. Appropriate amounts are used
2. The cost of fertilisers is less than the profit from extra yield.
Excess fertilisers can cause pollution if they run off into streams/ rivers. Eutrophication - they cause excessive growth of surface algae which shade submerged plants which cannot photosynthesise to die and are decomposed by aerobic bacteria which use up oxygen in the water. Lack of O2 kills fish and other animals.
80
Why are biodegradable pesticides better than broad-range insecticides?
They are broken down in soils and in the bodies of organisms so do not poison non-pest organisms and are less likely to be present in foods. Broad-range are toxic to a wide range of insects, not just pests. Useful pollinating insects e.g. bees are killed.
Pests may develop resistance to pesticides via mutations.
81
How are antibiotics used in food production? what may be a problem with their excessive use?
Kill bacteria so protect animals reared intensively from bacterial diseases. Pigs and chickens are dosed with antibiotics routinely to increase growth rates and productivity,
Resistance is more likely to evolve in bacteria as they are used more, reducing the effectiveness of antibiotics to treat bacterial diseases, including in humans.
82
What are some ways in which microorganisms are used for food production?
Used to fermenr milk and make yoghurt and cheese- both keep longer than milk and have different tastes and textures.
Mycoprotein (quorn) can be made from a fungus (fusarium) in large fermenters. The fungus is provided with glucose, ammonium sulphate for nitrogen, a suitable temp., pH and oxygen. The fungus grows as hyphae which are separated from the culture and used to make food products e.g. vegetarian sausages.
83
What are the advantages and disadvantages of using microorganisms for food production?
```
advantages:
- cheaper than animals or plants
- grown in smaller areas
- do not need particular climates, can be grown all year
- use waste materials as food sources
- high protein, low fat food
disadvantages:
- less tasty/interesting food
- specialist laboratory facilities needed
- high initial start up costs
```
84
how does salting prevent food spoilage?
It's added to meat or fish to lower the water potential of the food. Thus water is lost from microorganisms via osmosis, killing them or at least stopping their reproduction
85
how does adding sugar prevent food spoilage?
added to jams and fruits to lower the water potential of the food. Thus water is lost from microorganisms via osmosis, killing them or at least stopping their reproduction
86
how does pickling prevent food spoilage?
vinegar has a low PH so denatures proteins of mircrobes, killing them. used for veg
87
how does freezing prevent food spoilage?
keeping food at -10 dgrees freezes the water inside the cells of microbes, preventing their growth. the organisms are not killed and will grow when the food is thawed.
88
how does heat treatment prevent food spoilage?
cooking food thoroughly will kill microbes, as their enzymes are denatured.
89
example of heat treatment and how it works
Pasteurised milk has been heated to 63 degrees c for 30 mins and then rapidly cooled to 4 degs c. this kills harmful bacteria without changing the flavour of the milk.
90
UHT milk- stands for? and describe.
ultra heat treated (UHT) milk has been heated above boiling point at high pressure to kill all bacteria- keeps for much longer.
91
how does irradiation prevent food spoilage?
gamma radiation kills microbes without changing the flavour or texture of food. this is used for soft fruits that tend to spoil rapidly.
92
Describe the sequence of events in the CELL-MEDIATED immune response
1. virus invades host cell
2. antigen presentation - non-self antigens are presented on the CSM of infected host cell
3. clonal selection -T-cells with complementary receptors bind to the non-self antigens on infected cell
4. clonal expansion - T-cell becomes sensitised and is triggered to divide by mitosis to form clones.
5. clonal differentiation - clones differentiate into T-supressor, T-killer, T-helper and T-memory cells
93
How do T-killer and T-helper cells respectively aid the immune response?
T-killer: produce performs which make holes in the CSM of infected host cell causing it to burst, killing it
T-helper: activate T-killer cells to destroy foreign antigens. Release cytokines that stimulate B-cells to divide and differentiate into plasma/memory cells
attract phagocytes
94
how are phagocytes able to pass from blood to tissue fluid during infection?
- lobed nucleus allows flexibility - cells can change shape ;
- can squeeze through pores in walls of capillaries ;
- histamine makes capillary walls / endothelium leaky - more permeable
