AS - Unit 2 - Food and health Flashcards
What is a balanced diet?
One that contains all the nutrients required for health in appropriate proprtions
What is obesity?
When a person is 20% or more heavier than the recommended weight for their height
Give 6 things that good nutrition will give you
Provide better health Ensure a stronger immune system You become ill less often Help you learn more effectively Make you stronger Make you more productive
What are proteins essential for?
Growth and repair of muscle and other body tissues
What is our main source of energy in our diet?
Carbohydrates
Why are fats important in our diet?
Important in:
Cell membranes
Waterproofing
Absorption of fat-soluble vitamins
Why are vitamins essential to our diets?
They play many important roles in the chemical processes taking place inside cells.
Why are minerals vital to our diets?
They are essential to the body’s normal function
Why is it important to be hydrated?
Water is used to transport many substances around the body
60% of the human body is water
Why is fibre and roughage important in our diets?
This is the indigestible part of our food, but it is essential for healthy functioning of the digestive system
How do you calculate BMI?
Mass in kg/ (height in m)2 (squared)
What is the average value of BMI for a healthy person?
18.5-25
Give 6 problems with the body which are caused by obesity
Cancer Cardiovascular disease Type 2 diabetes Gallstones Osteoarthritis High blood pressure (hypertension)
What can excess salt in your diet cause?
It will decrease the water potential of your blood
Bringing more water into the blood
The blood pressure increases
Putting the body into hypertension
What type of fats are beneficial to your diet and where can you find them?
Unsaturated fats are good for you, these are found in plants such as avocados
Olive oil is also a good source of unsaturated fat
What are lipoproteins?
A combination of lipid, cholesterol and protein used to transport fats and cholesterol around the body
Why is cholesterol in the blood?
Cholesterol is essential to the normal functioning of the body. It is found in cell membranes and in the skin
It is used to make steroid sex hormones and bile
Therefore cholesterol must be transported around the body.
Fats are not soluble in water so cholesterol has to find a way to be transported around the body
It is transported in the blood in the form of lipoproteins
These are tiny balls of fat combined with protein
What are the two forms of lipoproteins?
High-density lipoprotein (HDL)
Low-density lipoprotein (LDL)
What is high-density lipoprotein?
They are produced by the combination of unsaturated fats, cholesterol and protein.
They tend to carry cholestrol from the body tissues back to the liver
Liver cells have receptor sites that allow the HDLs to bind to their cell surface membranes
In liver, cholesterol is used in cell metabolism or broken down
Therefore, high levels of HDLs are associated with reducing blood cholesterol levels
What is low-density lipoprotein?
Produced by the combination of saturated fats, cholesterol and protein
These tend to carry cholesterol from the liver to the tissues
If too much saturated fat and cholesterol is consumed in the diet then the concentration of LDLs in the blood will rise
What does a high concentration of LDLs cause in the body?
Deposition in the artery walls
How do different fats affect the LDL receptors on tissue cells?
Saturated fats: Thought to decrease the activity of the LDL receptors. Therefore as blood LDL concentration rises, less is removed from the blood and they are deposited in the artery walls
Polyunsaturated fats: Increase the activity of the LDL receptors and so decrease the concentration of LDL in the blood
Monounsaturated fats: Seem to help remove LDLs from the blood
What increases the concentration of LDLs in the blood?
Eating a lot of saturated animal fats
What concentration of lipoproteins is it important to keep in the body?
Maintain a low proportion of LDLs in the blood
Maintain a high proportion of HDLs in the blood
What is selective breeding?
Humans select the individual organisms that are allowed to breed according to chosen characteristics
What are fertilisers?
Minerals needed for plant growth, which are added to soil to improve its fertility
What is a pesticide?
A chemical that kills pests
What is a fungicide?
A chemical that kills fungi
What is an antibiotic?
A chemical that kills or prevents reproduction in bacteria
How do most plants store energy?
As the carbohydrate starch
Give 5 ways we can make plant food production more efficient
Improve the growth rate of crops
Increase the size of yield from each plant
Reduce losses of crops due to diseases and pests
Make harvesting easier by standardising plant size
Improve plant responses to fertilisers
Give 3 ways animal food production can be more efficient
Improve the rate of growth
Increase productivity
Increase resistance to disease
What are the three stages to selective breeding?
Isolation
Artificial selection
Inbreeding or line breeding
How has cattle been bred to produce the best yield of desired products for human consumption?
They breed cattle for a high milk yield or for meat production. Dairy cows can produce over 40 litres of milk a day
How are salmon bred to produce the best yield of desired products for human consumption?
Farmed salmon have been selected to grow more quickly so that time-to-market has been cut by 30%.
The meat also has less fat content, better colour and texture
How have egg laying chickens been selectively bred for a better yield?
They have been selectively bred to produce over 300 eggs a year, while their unselected relatives will produce 20-30 a year
What four ways can microorganisms spoil our food?
Visible growth of microorganisms on food (mould)
Microorganisms that use external digestion (the food will be reduced to mush)
The bacterium Clostridium botulinum
Microorganisms that can cause infection (salmonella)
10 ways we can prevent food spoilage?
Cooking Pasteurising Drying, salting and coating in sugar Smoking Pickling Irradiation Cooling and freezing Canning Vacuum wrapping Plastic or paper packaging
What four foods are made by using microorganisms?
Yogurt
Cheese
Bread - yeast
Alcohol - yeast
Give 6 advantages of using microorganisms to produce food
Production of protein can be many times faster than that of animal or plant protein
Production can be increased or decreased according to demand
No animal welfare issues
Good source of proteins for vegetarians
Contains no animal fat or cholesterol
Single celled protein (SCP) production could be combined with removal of waste products
Give 5 disadvantages of using microorganisms to produce food
People might not want to eat fungal protein or food that has been grown on waste
Microorganisms are grown in huge fermenters and need to be isolated from the material on which they grow
Has to be purified to ensure it is uncontaminated
Infection - conditions used to produce the microorganism is the idea conditions for pathogenic organisms
does not have the taste or texture of traditional protein sources
What is health?
A state of mental, physical and social well-being, not just the absence of disease
What is disease?
A departure of good health caused by a malfunction of the mind or body
What is a parasite?
An organism that lives in or on another living thing, causing harm to its host
What is a pathogen?
An organism that causes disease
What 6 things to you need in order to be classed as healthy?
Free from disease Able to carry out all the normal physical and mental tasks expected in modern society well fed, with a balanced diet Usually happy, with a positive outlook Suitably housed with proper sanitation Well integrated into society
What is transmission?
The way in which a parasitic microorganism travels from one host to another
How can a pathogen cause disease?
Travel from one host to another
Get into the host’s tissues
Reproduce
Cause damage to the host’s tissues
What are the three most common forms of transmission?
By a vector
Physical contact
Droplet infection
How is malaria transmitted?
If the host already has malaria the mosquito will suck the parasite gametes into its stomach
Gametes fuse and the zygotes develop in the mosquito’s stomach
Infective stages are formed and these move to the mosquito’s salivary glands
Mosquito bites another person, injects a little saliva as an anticoagulant
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 red blood cells, where the gametes are produced
How can HIV be transmitted?
Exchange of body fluids such as blood-to-blood contact Unprotected sexual intercourse Unscreened blood transfusions Use of unsterilised surgical equipment Sharing hypodermic needles Accidents such as 'needle-stick' Across the placenta or during childbirth From mother to baby during breast feeding
How is tuberculosis transmitted?
Through droplet infection
Overcrowding
poor ventilation
Poor health - if someone already has HIV they are more likely to contract TB
Poor diet
Homelessness
Living or working with people who have migrated from areas where TB is more common
Why could people have bad health?
Poverty Lack of proper shelter Lack of purified water Poor nutrition Poor hygiene Lack of investment by the government Poor or inadequate health services Inadequate education about the causes of disease and how they are transmitted Civil unrest or warfare Inadequate transport facilities that prevent reaching medical assistance
What are primary defences?
Those that attempt to prevent pathogens from entering the body
What is an immune response/
The specific response to a pathogen, which involves the action of lymphocytes and the production of antibodies
Give 5 primary defences
The skin Mucous membranes Tear fluid in eyes Ear canal lined by wax Vagina protected by maintaining relatively acidic conditions
How is the skin effective in being a primary defence for the body?
Epidermis consists of layers of cells. Cells are called keratinocytes
These cells are produced by mitosis at the base of the epidermis
Migrate out to the surface of the skin
As they migrate they dry out and the cytoplasm is replaced by the protein keratin
Process called keratinisation
This takes about 30 days
They are no longer alive, eventually thedead cells slough off
the keratinised layer of dead cells acts as an effectife barrier to pathogens
How are mucous membranes adapted to being a primary defence for the body?
In the air ways the epithelial layer contains goblet cells which secrete mucus. It also has ciliated cells. The cilia are tiny, hair-like organelles that can move. They move in a coordinated fashion to waft the layer of mucus along. They move the mucus up to the top of the trachea, where it can enter the oesophagus. It is swallowed and passes down the digestive system. Most pathogens in the digestive system are killed by the acidity of the stomach, which can be pH1-2. This denatures the pathogen’s enzymes
Mucous membranes are also found in the gut, genital areas, anus, ears and nose
Give an example of a secondary defence
Phagocytes
What are the two types of phagocyte?
Neutrophils
Macrophages
What are neutrophils?
Phagocytes with a multilobed nucleus. 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.
They are short lived, but they will be released in large numbers as a result of an infection
What are macrophages?
Larger cells manufactured in the bone marrow. They travel in the blood as monocytes. Tend to settle in body organs, particularly in lymph nodes. Here they develop into macrophages. Play important role in the specific responses to invading pathogens.
How do phagocytes work?
Engluf and destroy pathogenic cells.
Pathogen recognised as foreign by chemical markers on outer membrane. Markers are called antigens
Proteins in blood, called antibodies, 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. This process may be assisted by other proteins called opsonins
Once the phagocyte is bound to the pathogen, it will envelop the pathogen by folding its membrane inwards. Pathogen is trapped inside a vacuole called a phagosome.
Lysosomes fuse with the phagosome to release enzymes into it. Enzymes are called lysins, these digest bacterium. End products are harmless nutrients that can be absorbed into the cytoplasm
Neutrophils are short-lived and die soon after digesting a few pathogens. They collect in an area of infection to form pus
What is the role of macrophages in the body?
Infected cells release chemicals such as histamine, which attracts neutrophils to the area. Histamine also causes a response that makes the capillaries more leaky.
Makes more fluid leave the capillaries in the area of the infection
Causes swelling and redness, but it also means that more tissue fluid passes into the lymphatic system. Leading the pathogens towards the macrophages waiting in the lymph nodes.
Macrophages initiate the specific response to a disease, this is known as the immune response. Also the activation of lymphocytes in the blood to help fight the disease
What are antigens?
Molecules that stimulate an immune response
What are antibodies?
Proteins molecules that can identify and neutralise antigens
Explain the structure of an antibody
Y-shaped with two distinct regions
Four polypeptide chains held together by disulfide bridges
A constant region, has a specific chape and differs from one type of antibody to another. This is as a result of its amino acid sequence, ensures that the antibody can attach only to the correct antigen.
Hinge regions, allow a certain degree of flexibility. These allow the branches of the Y-shaped molecule to move further apart in order to allow attachment to more than one antigen
How do antibodies work?
Most work by attaching to the antigens on a pathogen. Antigen is a molecules of the cell surface membrane of the pathogen. If the antibody blocks this pathogen, it cannot bind to its host cells. This is called neutralisation. Each variable region on the antibody can act as a binding site to bind to the antigen on a pathogen.
What is agglutination?
A large antibody can bind many pathogens together. The group of pathogens is too large to enter a host cell
What is the primary immune response?
When the number of antibodies in the blood rises to a level that can combat the infection in the first few days of being infected
What is the secondary immune response?
If the body is infected a second time, it is the immune system acting much more quickly that time round due to the body already knowing what antibody to produce for that particular pathogen.
The concentration of antibodies rises sooner and reaches a higher concentration.
What is cell signalling?
The communication between cells that allows effective coordination of a response
What are cytokines?
Hormone-like chemicals which are released through the cell surface molecules for communication amongst cells
What do B lymphocytes (B cells) and T lymphocytes (T cells) have in common?
They both have receptors that are complimentary 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 antigen is detected, the B or T lymphocyte is activated or stimulated.
Chemical signals are also detected by their target cells using specialised cell surface receptors
What happens in identification during cell signalling?
The pathogen carries antigens on its cells surface. These act as flags or markers that say ‘i am foreign’. These are detected by our body cells.
How does the body send a ‘distress signal’?
Pathogen invades a body cell, lysosomes attempt to fight it off. A number of pathogen cells are damaged. Parts of the pathogen often end up attached to the host plasma membrane.
These have two effect:
Act as a distress signal, can be detected by cells from the immune system
Can also act as markers to indicate the host cell is infected - T killer cells recognise the cell as infected and destroy it
How do macrophages help to protect the body?
They engulf the pathogen but don’t completely digest it, instead they take the antigens and incorporate them into a cell surface molecule.
This is now known as an antigen presenting cell.
How does communication using cytokines work?
Macrophages release monokines that attract neutrophils (by chemotaxis - the movement of cells towards a particular chemical)
Macrophages release monokines that stimulate B cells to differentiate and release antibodies
T cells, B cells and macrophages release interleukins, which can stimulate proliferation and differentiation of B and T cells
Many cells can release interferon, which can inhibit virus replication and stimulate the activity of T killer cells
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
What are lymphocytes?
White blood cells that circulate around the body in the blood and lymph. B cells mature in the bone marrow, while T cells originate in the bone marrow but mature in the thymus gland
What three different types of cell will T lymphocytes turn into?
T helper - release cytokines that stimulate the B cells to develop and stimulate phagocytosis by the phagocytes
T killer - attack and kill infected body cells
T memory cells
What two different types of cell will B lymphocytes turn into?
Effector/ plasma cells - flow around in the blood, manufacturing and releasing the antibodies
B memory cells - remain in the body for a number of years and act as the immunological memory
What is vaccination?
A deliberate exposure to antigenic material, which activates the immune system to make an immune response and provide immunity
What five different forms of antigenic material is used in vaccines?
Whole, live organisms - usually ones that are not as harmful as those that cause a real disease, must have very similar antigens
Harmless or attenuated version of the pathogenic organism
A dead pathogen
A preparation of the antigens from a pathogen
Some harmless toxin
What is herd vaccination?
Used to provide immunity to all or almost all of the population at risk
Once enough people are immune, the disease can no longer spread
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. This may mean vaccinating the people in the surrounding houses, or even the whole village or town. Used in many parts of the world to control the spread of livestock disease
What is active immunity?
Achieved by the activation of the immune system. Lymphocytes in the body can manufacture antibodies and release them into the blood. This form of immunity can usually last for many years or even a lifetime
What is passive immunity?
It is provided by antibodies that have not been manufactured by stimulating the recipient’s immune system. Antibodies may be provided by a mother across the placenta or via breast milk. Antibodies can also be provided by intravenous injection. This form of immunity is often short lived
What is natural immunity?
Gained in the normal course of living processes. It may be gained as a result of an infection that stimulates an immune response
What is artificial immunity?
Gained by the deliberate exposure to antibodies and antigens
Give an example of passive natural immunity
Antibodies provided via the placenta or via breast milk. This makes the baby immune to diseases that the mother is immune to. Very useful in the first year of the baby’s life, when its immune system is developing
Give an example of passive artificial immunity
Immunity provided by injection of antibodies made by another individual (e.g. tetanus injections)
Give an example of active natural immunity
Immunity provided by antibodies made in the immune system as a result of infection. A person suffers from the disease once and is then immune (e.g. immunity to chicken pox)
Give an example of active artificial immunity
Immunity provided by antibodies made in the immune system as a result of vaccination. A person is injected with a weakened, dead or similar pathogen, or with antigens, and this activates his/her immune system (e.g. immunity to TB and influenza)
Give 3 reasons why new drugs need to be developed
new diseases are emerging
many diseases for which there are no effective treatments
some antibiotic treatments are becoming less effective
Give 5 ways new drugs are discovered
By accident Traditional medicine Anaesthetics Observation of wildlife Modern research
Give three harmful substances in cigarette smoke
Tar
Carbon monoxide
Nicotine
What short-term harm does tar cause to your body if you smoke?
Tar settles on the lining of the airways and alveoli
This increases the diffusion distance for oxygen entering the blood and for carbon dioxide leaving the blood
It paralyses or destroys the cilia on the surface of the airway, so they are unable to move the layer of mucus up to the back of the mouth
Stimulates goblet cells to produce more mucus, collects in the airways
Bacteria and viruses becomes trapped in the mucus not removed, multiply in the mucus, eventually a combination of mucus and bacteria block the bronchioles
What long-term harm does tar cause to your body if you smoke?
Smokers cough
Delicate lining of the airways and alveoli can be damaged by smokers cough
Lining eventually replaced by scar tissue, thicker and less flexible
Layer of smooth muscle in the wall of the bronchioles thickens
Reduces the lumen of the airway, and the flow of air is permanently restricted
What are carcinogens?
Chemicals that cause cancer
What is Chronic obstructive pulmonary disease (COPD)?
A combination of diseases including chronic bronchitis and emphysema
What is chronic bronchitis?
The inflammation of the lining of the airways. Accompanied by damage to the cilia and the overproduction of mucus, so that the mucus collects in the lungs
What are the symptoms of chronic bronchitis?
Irritation in the lungs
Continual coughing
Coughing up mucus that is often filled with bacteria and white blood cells
It leads to an increased risk of lung infection
What is emphysema?
The loss of elasticity in the alveoli, which causes the alveoli to burst. Lungs have a reduced surface area as larger air spaces are formed. Means there is less surface area for gaseous exchange.
What are the symptoms of emphysema?
Often be short of breath, especially when exerting themselves
Loss of elasticity in the alveoli makes it harder to exhale
Breathing will become shallow and more rapid, blood is less well oxygenated and fatigue occurs
What is atherosclerosis?
The deposition of fatty substances in the walls of the arteries
What is cardiovascular disease?
A disease of the heart or circulatory system
What do nicotine and carbon monoxide in your body do to you?
It gives you an increased risk of cardiovascular diseases such as:
Atherosclerosis
Coronary heart disease
Stroke
What does nicotine in cigarette smoke do?
It causes addiction
Mimics the action of transmitter substances, making the nervous system more sensitive, and the smoker feels more alert
Causes the release of the hormone adrenaline
Causes constriction of the arterioles leading to the extremities, reduces blood flow and O2 delivery to the extremities
Makes platelets sticky, increasing the risk of blood clots or thrombosis
How does carbon monoxide affect the body?
Enters the red blood cells and combines with haemoglobin. Combines much more readily with oxygen and forms the stable compound carboxyhaemoglobin. Reduces the oxygen-carrying capacity of the blood
Smokers feel this when they exercise. The body will detect lower levels of oxygen and it may cause the heart rate to rise
carbon monoxide can also damage the lining of the arteries
What is coronary heart disease?
A disease of the heart caused by malfunction of the coronary arteries
What is stroke?
The death of the brain due to lack of blood flow to that part of the brain and subsequent oxygen deficiency
What are the symptoms of cardiovascular disease?
High blood pressure and hypertension CHD: More difficult to exercise Out of breath Angina Heart attack (begin as small pain often mistaken for indigestion to begin with)
What is the different between arteriosclerosis and atherosclorosis?
Arterio - hardening of the normally flexible walls due to loss of elasticity of the arterial musculature
Athero - arteries grow harder and thicker, become more resistant to blood flow, blood pressure rises. Deposition occurs under the endothelium in this
What are the symptoms of stroke?
Numbness of the face, arm or leg especially on one side of the body
Sudden confusion and difficulty speaking or understanding
Difficulty seeing in one or both eyes
Trouble walking
Sudden severe headache
What is a risk factor?
A factor that increases the chance or risk that a person will develop a disease
What factors increase the risk of CHD?
Age Gender Cigarette smoking Obesity High blood pressure (hypertension) High blood cholesterol concentration Physical inactivity Diet - high level of animal fats High salt intake Absence of healthy fats Absence of antioxidants such as vit A, C and E Genetic factors/family history of cardiovascular disease Diabetes Stress
What is epidemiology?
The study of the distribution of a disease in populations, and the factors that influence its spread
What can epidemiology identify?
Which countries may be at greater risk
Which age range of the population may be at greater risk
Which sex may be at greater risk
Which lifestyle factors may increase or decrease the risk
How can information from epidemiology be used?
To:
Help countries or organisations target further spending
Help target research at particular risk factors to find a cause or a cure
Help target screening procedures and find those at risk early
Help target advice and education at the parts of the population most at risk
Predict where a disease might become more prevalent in the future
Target geographical areas at risk, using preventative measures to prevent the disease spreading
Check how well campaigns and preventative measures are working
