Unit 2.2 Food And Health Flashcards
(150 cards)
1
Q
Why is good nutrition important? (Name 5 reasons)
A
It will:
- Provide better health
- Ensure a stronger immune system
- Help you learn more effectively
- Mean that you become ill less often
- Make you stronger
- Make you more productive
2
Q
What are the 7 components in a balanced diet?
A
Carbohydrates Proteins Fats Vitamins Minerals Water Fibre/roughage
3
Q
Why is fibre needed in the diet?
A
It is essential for healthy functioning of the digestive system, because it is indigestible
4
Q
How can you calculate BMI?
A
(Mass in kg) / (height in m)^2
5
Q
Why is excess salt in your diet bad?
A
- It will decrease the water potential of your blood
- So more water is held in the blood and the blood pressure increases
- This can lead to hypertension
6
Q
What is hypertension?
A
- A condition in which the blood pressure, and particularly the diastolic pressure, is maintained at a level that is too high
- This can damage the inner lining of the arteries
7
Q
Which are healthier; saturated or unsaturated fats?
A
Unsaturated fats
8
Q
Where is cholesterol made?
A
In the liver from saturated fats
9
Q
How is cholesterol used in the body?
A
- In cell membranes
- In the skin
- To make steroid sex hormones
- To make bile
10
Q
How is cholesterol transported around the body?
A
In the blood, in the form of lipoproteins (tiny balls of fat combined with protein)
11
Q
What are high-density lipoproteins (HDLs) made from, and what do they do?
A
- They are a combination of unsaturated fats, cholesterol and protein
- They tend to carry cholesterol from the body tissues back to the liver
- The liver uses the cholesterol for cell metabolism, to make bile
- Or the cholesterol is broken down
12
Q
Why are HDLs good?
A
They are associated with reducing blood cholesterol levels:
- They reduce deposition in the artery walls by atherosclerosis
- May help to remove the fatty depositions of atherosclerosis
Since they use unsaturated fats, these are thought to be more beneficial to health than saturated fats
13
Q
What are low-density lipoproteins (LDLs) made from, and what do they do?
A
- They are a combination of saturated fats, cholesterol and protein
- They tend to carry cholesterol from the liver to the tissues
- The tissue cells have receptor sites that allow LDLs to bind to their cell surface membranes
14
Q
What happens if too much saturated fat and cholesterol is consumed in the diet?
A
The concentration of LDLs in the blood will rise
15
Q
Why is a high blood concentration of LDLs bad?
A
It causes deposition in the artery walls
16
Q
How do saturated fats affect the LDL receptors?
A
- Decrease the activity of the LDL receptors
- So as blood LDL conc rises, less is removed from the blood
- This results in higher concs of LDL in the blood and they are deposited in the artery walls
17
Q
How do polyunsaturated fats affect the LDL receptors?
A
- They increase the activity of the LDL receptors
- So they decrease the concentration of LDL in the blood
18
Q
How do monounsaturated fats affect the LDL receptors?
A
They seem to help remove LDLs from the blood
19
Q
What is atherosclerosis?
A
The deposition of fatty substances in the walls of arteries
20
Q
What is coronary heart disease (CHD)?
A
The deposition of fatty substances in the coronary artery walls (atherosclerosis)
21
Q
Why is CHD bad?
A
- Deposition in the coronary artery walls narrows the size of the lumen
- This restricts blood flow to the heart muscle
- This can cause oxygen starvation
22
Q
How can we make food production (plants) more efficient?
A
- Improve the growth rate of crops
- Increase the size of yield from each plant
- Reduces losses of crops due to diseases and pests
- Make harvesting easier by standardising plant size
- Improve plant responses to fertilisers
23
Q
How can we make food production (animals) more efficient?
A
- Improve the rate of growth
- Increase productivity
- Increase resistance to disease
24
Q
What is selective breeding?
A
Where humans select the individual organisms that are allowed to breed according to chosen characteristics
25
What do fertilisers do?
- They replace the minerals in the soil
- These minerals may have been removed by previous crops
- They increase the rate of growth and the overall size of the crops
26
What is a pesticide?
A chemical that kills pests
27
What is a fungicide?
A chemical that kills fungi
28
What is an antibiotic?
A chemical that kills or prevents reproduction in bacteria
29
What are the 3 stages of selective breeding?
- Isolation
- Artificial selection
- Inbreeding or line breeding
30
What is selection pressure?
An external pressure that drives evolution in a particular direction
31
How can microorganisms spoil our food?
- Visible growth of microorganisms on food
- Their presence in food can cause infection
- The bacterium Clostridium botulinum produces a toxin called botulin, which is extremely toxic
- Microorganisms use an external digestion process: they release enzymes into the food and absorb the nutrients released by breakdown of the food molecules, which eventually turns the food to mush
32
How can we prevent food spoilage?
By using food quickly
Or by preventing spoilage:
- By killing microbes already on the food
- Or preventing the microbes from reproducing
- The food must then be packaged to prevent further contamination with microbes
33
What methods are there for killing microorganisms/preventing their reproduction on food?
- Cooking
- Pasteurising
- Drying, salting and coating in sugar
- Smoking
- Pickling
- Irradiation
- Cooling and freezing
34
How can you prevent food from further contamination with microbes?
- Canning (the food is heated and sealed in airtight cans)
- Vacuum wrapping (air is excluded so microbes can't respire aerobically)
- Any plastic or paper packaging
35
How does cooking kill microorganisms/prevent their reproduction on food?
The heat denatures the enzymes + other proteins
| It also kills the microorganisms
36
How does pasteurising kill microorganisms/prevent their reproduction on food?
- Involves heating to 72°C for 15 seconds and then cooling rapidly to 4°C
- This kills harmful microorganisms
37
How do drying, salting and coating in sugar kill microorganisms/prevent their reproduction on food?
These process dehydrate any microorganisms:
| - Water leaves them by osmosis
38
How does smoking kill microorganisms/prevent their reproduction on food?
The food develops a hardened, dry outer surface
| Smoke contains antibacterial chemicals
39
How does pickling kill microorganisms/prevent their reproduction on food?
An acid pH is used to kill microorganisms by denaturing their enzymes and other proteins
40
How does irradiation kill microorganisms/prevent their reproduction on food?
Ionising radiation kills the microorganisms by disrupting their DNA structure
41
How does cooling/freezing kill microorganisms/prevent their reproduction on food?
They don't kill microorganisms, but retard enzyme activity so their metabolism, growth and reproduction is very slow
42
What is a mycoprotein?
A protein made by a fungus
43
What are the advantages of using microorganisms to manufacture protein (single-cell protein) that is used directly as food?
- Production of protein can be many times faster than that of animal or plant protein
- Production can be increased + decreased according to demand
- There are no animal welfare issues
- They provide a good source of protein for vegetarians
- The protein contains no animal fat or cholesterol
- SCP production could be combined with removal of waste products
44
What are the disadvantages of using microorganisms to manufacture protein (single-cell protein) that is used directly as food?
- Many people do not want to eat fungal protein or food that has been grown on waste
- Isolation of the protein: the microorganisms are grown in huge fermenters and need to be isolated from the material on which they grow
- The protein has to be purified to ensure it is uncontaminated
- Infection: the conditions needed for useful microorganisms to grow are also ideal for pathogenic organisms, so care must be taken to ensure the culture isn't infected with the wrong organisms
- Palatability: the protein does not have the taste or texture of traditional protein sources
45
Definition of health
A state of mental, physical and social wellbeing, not just the absence of disease
46
Definition of disease
A departure from good health caused by a malfunction of the mind or body
47
What is a parasite?
An organism that lives in or on another living thing, causing harm to its host
48
How do parasites cause harm to their host?
By taking nutrition from the host
| They may cause damage that allows other organisms to invade the host and cause secondary infections
49
What are internal parasites?
Parasites that live in their host
50
What are pathogens?
Organisms that cause disease
| They live by taking nutrition from their host, but also cause damage in the process
51
How can the presence of bacteria cause disease?
- They can damage cells
- They can release waste products that are toxic to us
They multiply rapidly in the human body
52
What bacterium causes tuberculosis?
Mycobacterium tuberculosis and mycobacterium bovis
53
How can fungus cause disease?
- The fungus lives in the skin
- When it sends out reproductive hyphae, these grow to the surface of skin to release spores
- This causes redness and severe irritation
54
How do viruses cause disease?
- They invade cells and take over the genetic machinery + other organelles of the cell
- They then cause the cell to manufacture more copies of the virus
- The host cell eventually bursts, releasing many new viruses
55
How do protoctista cause disease?
They enter host cells and feed on the contents as they grow
56
In order to cause a disease, what must a pathogen be able to do?
- Travel from one host to another
- Get into the host's tissues
- Reproduce
- Cause damage to the host's tissues
57
What are the most common forms of transmission?
- By means of a vector
- By physical contact
- By droplet infection
58
Malaria is caused by a eukaryotic organism from the genus Plasmodium. There are a number of different species. What is the name of the most widespread?
Plasmodium falciparum
59
How is malaria spread?
By a vector
60
Where do malarial parasites live and what do they feed on?
- They live in the red blood cells of the human host
| - They feed on the haemoglobin
61
How do mosquitoes get the malarial parasite?
- If they bite someone who already has malaria, they will suck the parasite gametes into its stomach
- The gametes fuse and the zygotes develop in the mosquito's stomach
- Infective stages are formed
- These move to the mosquito's salivary glands
62
How does a mosquito (that is already carrying the malarial parasite) infect another person with malaria?
- When it bites another person, it injects a little saliva as an anticoagulant
- This saliva contains the infective stage of the parasite
- In the human host, the infective stages enter the liver, where they multiply before passing into the blood again
- In the blood they enter the red blood cells, where the gametes are produced
63
How can HIV be transmitted?
- Exchange of body fluids (e.g. Blood-to-blood contact)
- Unprotected sex
- Unscreened blood transfusions
- Use of unsterilised surgical equipment
- Sharing hypodermic needles
- Accidents (e.g. 'Needle-stick')
- Across the placenta or during childbirth
- From mother to baby during breast feeding
64
What is HIV/AIDS caused by?
The human immunodeficiency virus
65
What happens when the human immunodeficiency virus becomes active?
It attacks and destroys T helper cells in the immune system, which reduces the ability to resist infection
66
How is TB transmitted?
By droplet infection
67
It is not that easy to contract TB - it usually takes close contact with an infected person over a prolonged period. But what conditions make contraction and spread more likely?
- Overcrowding
- Poor ventilation
- Poor health
- Poor diet
- Homelessness
- Living or working with people who have migrated from areas where TB is more common
68
What aspects may contribute to the poor health of the people in less economically developed countries?
- Poverty
- Lack of proper shelter
- Lack of purified water
- Poor nutrition
- Poor hygiene
- Lack of investment by the government
- Poor or inadequate health services
- Civil unrest or warfare
- Inadequate education about the causes of disease and how they are transmitted
- Inadequate transport facilities that prevent people reaching medical assitance
69
What is epidemiology?
The study of patterns of disease and the factors that influence their spread
70
Why is epidemiology useful?
It allows us to:
- identify the cause of a disease
- identify risk factors associated with a disease
- determine the incidence of a disease
- determine the prevalence of a disease
- determine the mortality
- determine the morbidity
- study how quickly it is spreading
- identify a disease as endemic, epidemic or pandemic
- identify countries at risk
- identify which parts of a population are at risk
- check how well control programmes are working
71
What are primary defences?
Defences that attempt to prevent pathogens from entering the body
72
How is the skin adapted to be a primary defence?
- The outer layer of the skin is called the epidermis
- The epidermis consists of layers of cells
- Most of these cells are called keratinocytes
- These cells are produced by mitosis at the base of the epidermis
- They then migrate to the surface of the skin
- As they migrate, they dry out and the cytoplasm is replaced by the protein keratin (keratinisation)
- This takes about 30 days
- By the time the cells reach the surface, they are no longer alive
- The keratinised layer of dead cells acts as an effective barrier to pathogens
73
Name 3 primary defences, other than the skin
- Mucous membranes
- The eyes are protected by antibodies in the tear fluid
- The ear canal is lined by wax, which traps pathogens
- The vagina is protected by maintaining relatively acidic conditions
74
Definition of immune response
The specific response to a pathogen, which involves the action of lymphocytes and the production of antibodies
75
What is the role of phagocytes?
To kill pathogens that have entered the body, before they reproduce and cause the symptoms of a disease
76
What are the 2 types of phagocytes that are found in the body?
- Neutrophils
| - Macrophages
77
Where are neutrophils found?
- They are manufactured in the bone marrow
- They travel in the blood and often squeeze out of the blood into tissue fluid
- May also be found on epithelial surfaces, such as the lungs
78
What are the differences between neutrophils and macrophages?
```
Neutrophils = multilobed nucleus, released in large numbers as a result of an infection, short lived - die after digesting a few pathogens
Macrophages = larger cells, travel in the blood as monocytes
```
79
How do macrophages develop?
- They are manufactures in the bone marrow
- They travel in the blood as monocytes
- They tend to settle in the body organs, particularly in the lymph nodes
- Here they develop into macrophages
80
How do phagocytes work?
They (neutrophils) engulf and destroy pathogenic cells:
- When a pathogen invades the body, it is recognised as foreign by its antigens (which are specific to the organism)
- Our own cells have antigens, but these are recognised as our own and do not produce a response
- Antibodies in the blood attach to the foreign antigens
- Phagocytes have membrane-bound proteins that act as receptors
- The receptor binds to the antibodies already attached to the pathogen (sometimes assisted by other proteins called opsonins)
- Once the phagocyte is bound to the pathogen, it will envelop the pathogen by folding its membrane inwards
- The pathogen is trapped inside a vacuole called a phagosome
- Lysosomes fuse with the phagosome and release enzymes called lysins into it, which digest the bacterium
- The end products are harmless nutrients that can be absorbed into the cytoplasm
81
What is the role of macrophages?
- Infected cells release chemicals such as histamine, which attracts neutrophils to the area
- Histamine also causes a response that makes the capillaries more leaky
- As a result, more fluid leaves the capillaries in the area of infection, causing swelling and redness
- It also means that more tissue fluid passes into the lymphatic system
- This leads the pathogens towards the macrophages waiting in the lymph nodes
- The macrophages act like phagocytes to engulf and digest the pathogen, but they do not fully digest it
- They separate out the antigens and incorporate them into a cell surface molecule
- This is exposed on the surface of the macrophage, which becomes known as an antigen-presenting cell
- Its function is to find the lymphocytes that can neutralise that particular antigen
82
What are antigens?
- Molecules that stimulate an immune response
- They are usually large molecules
- They have a specific shape
- Usually a protein or glycoprotein in or on the plasma membrane
83
What are antibodies?
Protein molecules that can identify and neutralise antigens
84
What is specificity? (For antibodies/antigens)
An antibody is specific to a particular antigen because of the shape of the variable region. Each type of antibody has a differently shaped variable region.
85
What produces antibodies?
B-lymphocytes or plasma cells
86
What is the structure of antibodies?
They are Y-shaped, large proteins, with 2 distinct regions:
- 4 polypeptide chains held together by disulfide bridges
- A constant region, which is the same in all antibodies
- A variable region, which has a specific shape and differs from 1 type of antibody to another
- Hinge regions, which allow a certain degree of flexibility
87
What is another name for antibodies?
Immunoglobulins
88
What is the role of the constant region in an antibody molecule?
- It enables the antibody to attach to phagocytic cells
| - Helps in the process of phagocytosis
89
What is the role of the variable region in an antibody molecule?
- It ensures that the antibody can attach only to the correct antigen
- The shape of the variable region is complementary to that shape of the antigen, and can bind to that antigen
90
What is the role of the hinge regions in an antibody molecule?
They allow the branches of the Y-shaped molecule to move further apart in order to allow attachment to more than 1 antigen
91
How do antibodies work?
- By attaching to the antigens on a pathogen
- The pathogen may have another use for this molecule
- E.g. It may be a binding site, which would be used to bind to the host cell
- If the antibody blocks this binding site, the pathogen cannot bind to its host cells (neutralisation)
92
What is agglutination?
- A large antibody (several Y-shaped molecules attached together) has many specific variable regions
- Each variable region can act as a binding site to bind an antigen on a pathogen
- If it has a number of binding sites, it may be able to attach to a number of pathogens at the same time (agglutination)
- When the pathogens are stuck together, they cannot enter host cells
93
What happens if the body is infected a second time by the same pathogen? (Secondary immune response)
- The antibodies do not stay in the blood after the first infection, so they need to be made again
- But the production of antibodies starts sooner and is much more rapid
- So the conc of antibodies rises sooner + reaches a higher conc
94
What is cell signalling?
The communication between cells that allows effective coordination of a response
95
How does cell signalling work for the immune response?
- Through cell surface molecules and through the release of hormone-like chemicals called cytokines
- In order to detect a signal, the target cell must have a cell surface receptor
- B lymphocytes and T lymphocytes have receptors that are complementary in shape to the foreign antigen
- The antigen may be an isolated protein, it may be attached to a pathogen, or it may be on the surface of a host cell
- When the antigen is detected, the lymphocyte is activated or stimulated
- Chemical signals are also detected by their target cells using specialised cell surface receptors
96
How are distress signals communicated?
- When a body cell is infected by a pathogen, it is usually damaged in some way
- The internal cell organelles will attempt to fight the invader
- As a result, a number of pathogen cells are damaged
- Parts of the pathogen often end up attached to the host plasma membrane
- These act as a distress signal and can be detected by cells from the immune system
- They can also act as markers to indicate that the host cell is infected - T killer cells can recognise that the cell is infected and must be destroyed
97
How do cytokines work?
- There are a range of cytokines released by cells
- These chemical signals act as instructions to their target cells
- They generally act over short distances at very low conc
- They act by binding to specific membrane-bound receptors on the target cell
- This alters the cell's behaviour through gene expression
98
What are lymphocytes?
- White blood cells
- They have a large nucleus and specialised receptors on their plasma membranes
- They circulate around the body in the blood and lymph
99
What are memory cells?
- Cells that circulate in the blood after an immune response
| - They speed up the response to a subsequent attack by the same pathogen
100
What is clonal selection?
The selection of the correct B and T lymphocytes
101
What is clonal expansion?
- When the lymphocytes found by clonal selection increase in numbers, so that they can become effective in fighting the pathogen
- The lymphocytes divide by mitosis a number of times (they are cloned)
102
Where do B lymphocytes (B cells) mature?
In the bone marrow
103
Where do T lymphocytes (T cells) originate and mature?
- They originate in the bone marrow
| - They mature in the thymus gland
104
What is the role of T helper cells?
They release cytokines that stimulate the B cells to develop and stimulate phagocytosis by the phagocytes
105
What is the role of T memory cells?
They remain in the blood
106
What is the role of T killer cells?
To attack and kill infected body cells
107
What is the role of plasma cells?
They flow around in the blood, manufacturing and releasing the antibodies
108
What is the role of B memory cells?
They remain in the body for many years and act as the immunological memory
109
What is a vaccination?
A deliberate exposure to antigenic material that has been rendered harmless, which activates the immune system to make an immune response and provide immunity.
110
What forms can the antigenic material used in vaccines take?
- Whole, live microorganisms (usually ones that are not as harmful as those that cause the real disease)
- A harmless or attenuated version of the pathogenic organism
- A dead pathogen
- A preparation of the antigens from a pathogen
- Some harmless toxin
111
What is herd vaccination?
- Using a vaccine to provide immunity to all or almost all of the population at risk
- Once enough people are immune, the disease can no longer spread
112
What is ring vaccination?
- Used when a new case of a disease is reported
| - Involves vaccinating all the people in the immediate vicinity of the new case
113
What is active immunity?
- The immunity that is achieved by activation of the immune system
- Lymphocytes in the body manufacture antibodies and release them into the blood
- This form of immunity can usually last for many years or even a lifetime
114
What is passive immunity?
- Immunity provided by antibodies that have not been manufactured by stimulating the recipient's immune system
- E.g. Antibodies may be provided by a mother across the placenta
- This form of immunity is usually short-lived
115
What is natural immunity?
- Immunity that is gained in the normal course of living processes
- It may be gained as a result of an infection that stimulates an immune response
116
What is artificial immunity?
Immunity gained by deliberate exposure to antibodies or antigens
117
How does tar restrict the flow of air to the alveoli?
- The presence of many chemicals in the tar lying on the surface of the airway may cause an allergic reaction
- This causes the smooth muscles in the walls of the airways to contract
- The lumen of the airway gets smaller
118
How does tar delay the diffusion of oxygen into the blood, and CO2 out of the blood?
- Tar is a combination of chemicals
- These chemicals settle on the lining of the airways and alveoli
- This increases the diffusion distance
- So diffusion takes longer
119
How does tar block the bronchioles?
- It paralyses or destroys the cilia on the surface of the airway
- This means that they are unable to move the layer of mucus away and up to the back of the mouth
- The tar also stimulates the goblet cells and mucus-secreting glands to enlarge and release more mucus
- Bacteria and viruses that become trapped in the mucus are not removed
- They can multiply in the mucus
- Eventually a combination of mucus and bacteria may block the bronchioles
120
Why are smokers more likely to catch diseases such as influenza?
- The lungs are more susceptible to infection
| - Because of the presence of bacteria and viruses
121
Why do smokers cough?
They are attempting to shift the bacteria-laden mucus that collects in the lungs
This results from:
- the irritation of the airways by the mucus and bacteria
- the need to clear the airways in order to get air down into the alveoli
122
Why is a smoker's cough bad?
It can damage the delicate lining of the airways and alveoli:
- The lining will eventually be replaced by scar tissue
- This is thicker and less flexible
- The layer of smooth muscle in the wall of the bronchioles also thickens
- This reduces the lumen of the airway
- So the flow of air is permanently restricted
123
How does smoking damage the lining of the airways?
- The presence of bacteria and viruses in the mucus causes frequent infections
- These inflame, and damage, the lining of the airways
- In particular, it damages the layer of epithelium
124
How does smoking damage the elastic tissue in the lining of the lungs?
- Frequent infections caused by the presence of bacteria and viruses in the mucus attracts white blood cells
- They are brought in to deal with the pathogenic microorganisms
- They have to make their way out of the blood + into the airways
- So they release enzymes, which digest parts of the linings of the lungs in order to pass through the air spaces
- In particular, the enzyme elastase is used
- This damages the elastic tissue in the lining of the lungs
125
What effect does loss of elastic tissue have?
It can reduce the elasticity of the alveolus wall:
- During exhalation, the alveolus walls do not recoil to push the air out
The bronchioles collapse, trapping air in the alveoli:
- This can cause the alveoli to burst as pressure in the lungs increases
126
How can tar cause lung cancer?
It contains lots of carcinogenic compounds
- These enter the cells of the lung tissue
- They enter the nucleus of these cells
- They have a direct effect upon the genetic material
- Any change to the genetic material is called a mutation
- If the mutation affects the genes that control cell division, then uncontrolled cell division may take place (cancer)
127
What diseases are associated with smoking?
Chronic bronchitis
Emphysema
Lung cancer
Chronic obstructive pulmonary disease
128
What is chronic bronchitis?
- The inflammation of the lining of the airways
| - This is accompanied by damage to the cilia and the overproduction of mucus, so that mucus collects in the lungs
129
What is emphysema?
The loss of elasticity in the alveoli, which causes the alveoli to burst
- The lungs have a reduced surface area as larger air spaces are formed
- This means that there is less surface area for gaseous exchange
- The loss of elasticity makes it harder to exhale
A person with emphysema will be often be short of breath
130
What is chronic obstructive pulmonary disease?
A combination of diseases that include chronic bronchitis, emphysema and asthma
131
What effects can nicotine have on a smoker?
- It causes addiction
- It mimics the action of transmitter substances at the synapses between nerves, which makes the nervous system more sensitive and the smoker feel more alert
- It causes the release of the hormone adrenaline
- It causes constriction of the arterioles leading to the extremities of the body
- It can make platelets sticky, increasing the risk that a blood clot or thrombus may form
132
What effects can carbon monoxide from cigarette smoke have?
- It can enter the red blood cells and combine with haemoglobin, forming carboxyhaemoglobin, because it combines much more readily than oxygen. This reduces the oxygen-carrying capacity of the blood.
- It can also damage the lining of the arteries
133
What is a stroke?
- The death of a part of the brain tissue
| - It is caused by the loss of blood flow to that part of the brain and subsequent oxygen deficiency
134
When carbon monoxide damages the lining of the arteries, what effect does this have?
- It damages the endothelium of the arteries
- The damage is repaired by the action of white blood cells
- These encourage the growth of smooth muscle and the deposition of fatty substances (atherosclerosis)
- The build up of the deposits (atheromas) occurs under the endothelium, in the wall of the artery
- It may grow enough to break through the inner lining of the artery
- The atheroma eventually forms a plaque, which sticks out into the lumen of the artery
- This leaves the artery wall rougher and less flexible than in a healthy artery, and it also reduces the size of the lumen of the artery, which reduces blood flow
135
What are cardiovascular diseases?
Diseases that affect the heart and circulatory system
136
Why do people with a cardiovascular disease have high blood pressure and hypertension?
- The deposition of atheroma narrows the artery lumen
- This increases the friction between the blood and the artery wall
- The heart pumps against this increased friction, raising the blood pressure
137
What is arteriosclerosis?
- The hardening of the artery walls, which makes them less flexible
- It is caused by the deposition of minerals in the walls and particularly in the atheromas
138
What factors increase the risk of coronary heart disease? Name 7.
```
Age (risk increases as you get older)
Gender (men are more at risk)
Cigarette smoking
Obesity
High blood pressure
High blood cholesterol concentration
Physical inactivity
Diet (a high level of saturated fats)
A high salt intake
An absence of healthy fats (polyunsaturated fats)
An absence of antioxidants
Genetic factors/family history of cardiovascular disease
Diabetes
Stress
```
139
Describe how the mosquito transmits the malarial parasite to a human (3 marks)
Mosquito is a vector. The parasite is present in the mosquitoes salivary gland. The mosquito feeds on human and passes saliva into the blood as an anticoagulant.
140
Suggest why diets with a high red meat content are associated with high blood cholesterol.
Red meat contains saturated fat. Saturated fat is associated with an increased amount of LDLs.
141
Suggest why a hospital might use a multodisc to select the most suitable antibiotic for treating a patient.
(3 marks)
```
Cheap
Quick
Allowing earlier treatment of patient.
Compares antibiotics under the same conditions.
Prevent antibiotic resistance developing
```
142
Outline the role of LDLs in the formation of an atheroma. (2 marks)
Damage to endothelium.
LDLs are made from saturated fat.
LDLs collect at the sight of damage and are deposited under endothelium.
143
Explain how inserting a stent would reduce the symptoms of CHD. (4 marks)
It increases the size of the lumen which increases blood flow so more oxygen is supplied to the heart muscle which is needed for aerobic respiration.
144
Suggest two medical conditions that may be associated with increased blood cholesterol levels. (2 marks)
CHD
Stroke
Atheroscelorsis
Type 2 diabetes
145
Explain why food spoils faster at higher temperatures. (3 marks)
Bacteria reproduce faster, so there are more bacteria producing more toxins.
Enzymes work faster at higher temperatures because there is more kinetic energy so more enzyme substrate complexes form.
146
Name the vector for the malarial parasite.
female Anopheles
147
Suggest why adults who have survived malaria lose their immunity when they leave a malarial area (2 marks)
No repeat infections, so no secondary response.
| Limited life for memory cells.
148
State three reasons why it isn't possible to produce an effective vaccine for malaria. (3 marks)
Different types of malaria parasites
Different antigens due to mutuations.
Different stages in the life cycle, each with different antigens..
149
Suggest the meaning of the term chronic. (2 marks)
A lifelong condition that gets worse.
150
Suggest a reason why people choose not to get immunised. (1 mark)
Cost
Side effects
Fear of needles.
