OCR F212 - Health and Disease Revision/Flash cards

Revision notes for health and disease , i made them for myself so there are bound to be spelling mistakes

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  • Created by: kath
  • Created on: 28-05-13 18:26

causes and means of transmission of malaria

  • If the host already has malaria, the female anopheles mosquito will **** the parasite gametes into its own stomach
  • The gametes fuse and the zygotes develop in the mosquito's stomach
  • Infective stages are formed and these move to he mosquito's salivary glands
  • when the mosquito bites another person it injects a little saliva as an anticoagulant
  • the siliva contains the infective stanges 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
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Define the terms HEALTH and DISE

HEALTH - A state of mental, physical and social wellbeing

DISEASE - A departure from good health caused by am malfunction of the mind or body

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Define the terms PARASIE and PATHOGEN

PARASITE - An organism that lives on or in another living thing causing harm to its st

PATHOGEN - An organism that causes disease

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Causes and means of transmission og HIV/AIDS

Virus enters the body by :

  • exchange of bodily fluids e.g. blood to blood contact
  • unprotected sexual intercourse
  • unscreened blood transfusions
  • use of unsterilised surgical equipment
  • sharing hypodermic needles
  • across placenta during childbirth
  • accidents e.g. 'needlestick'

can remain unactive in body for may years. once virus is active it attacks and destroys T helper cells in the immune system, effectively rendeing immune system useless

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Causes and means of transmission of TB

Bacteria are contained in the tiny droplets of liquid which are released when an infected person coughs, sneezes or talks

Takes close contact with an infected person over a long period of time to contract disease

Number of conditions which make contraction of the disease more likely:

  • Overcrowding
  • poor ventilation
  • poor health - particularly people with HIV/AIDS
  • poor diet
  • homelessness
  • living or working with people who are migrated from areas where TB is more common

Can also be contracted from the milk or meat of cattle

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What parasite causes Malaria?

PLASMODIUM - eukaryotic single-celled parasite (protoctist)

transported by the FEMALE ANOPHELES MOSQUITO

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Name the bacterium that causes TB

MYCOBACTERIUM TUBERCULOSIS

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Define the terms; IMMUNE RESPONSE, ANTIGEN, ANTIBO

IMMUNE SYSTEM - The specific response to a pathogen which involves the action of lymphocytes and the production of antibodies

ANTIGEN - Molecules that stimulate an immune response

ANTIBODY - Protein molecules that can identify and neutralise antigens

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Global impacts of Milaria, HIVAIDS and TB

All are common in sub-Sahara Africa and other developing countries

This is because :

  • there is limited access to good healthcare - drugs are not always available, people are less likely to e diagnosed and treated, blood donations aren't always screened for infectious diseases and surgical equipment isn't always sterile
  • there's a limited health education to inform people how to avoid infectious diseases - e.g. fewer people know about the transmission of HIV  and that it can be prevented by safe-sex practices e.g. using condoms
  • there's limited equipment to reduce the spread of infections - e.g. fwere people have mosquito nets to reduce the spread of infection with malaria
  • there are overcrowded conditions - this increases the risk of TB infection by droplet transmission

the prevalence of malaria,HIV and TB in developing countries, like sub-Suharan Africa, slows down social and economic development because these diseases increase death rates, reduce productivity (fewer people able to work) and result in high healthcare costs

studying global distribution of these disease is important::

  • info used to find out where pople are most at risk
  • ddata collected used to predict where epidemics are most likey
  • research
  • provide aid
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What are the bodies primary defences?

SKIN -  acts as a physical barrier, blocking pathogens from entering the body. also acts as a chemical barrier by producing chemicals that are antimicrobial and can lower pH, inhibiting the growth of pathogens

MUCOUS MEMBRANES - Protect body openings that are expose to the envisronment (e.g. mouth, nostrils, ears, genitals and ****). Some membranes secrete mucus - a trasps pathogens and contains antimicrobial enzymes

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Structure of antibodies

  • Four polypeptide chains held together by disulfie bridges
  • Y shaped
  • constant region - same in all antibodies, this enables the antibody to attach to the phagocytic cells and helps the process of phagocytosis
  • variable region - specific shape differs from one type of antibody to the next. It ensures that the antibodycan attach only to the correct antigen
  • Hinge regions - flexibility - allow the branches to move further apart to allow attachment to more than one antigen

(http://ts1.mm.bing.net/th?id=H.4919233208387600&pid=1.7)

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There are four main stages involved in immune resp

1. Phagocytes engulf pathogens

2. Phagocytes Activate T lymphocytes

3. T lymphocytes activate B lymphocytes, which divide into plasma cells

4. plasma cells make moe antibodies to a specific Antigen

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Explain the roll of phagocytes in immune respone

Phagocytes carry out phagocytosis.

They're found in the blood and in tissues and are first cells to respond to a pathogen inside the body

How they work...

  • 1. phagocyte recognises the antigens on a pathogen
  • 2. the cytoplasm of the phagocyte moves round the pathogen, engulfing it.
  • 3. the pathogen is now contained in  phagocytic vacuole in the cytoplasm of the phagocyte
  • 4. A lysosome (an organelle that contains digestive enzyme) fuses with the phagocytic vacuole. the enzyme breaks down the pathogen.
  • 5. the phagocyte then presents the pathogen's antigens. It puts the antigens on its surface to activate other immune system cells

(http://2.bp.blogspot.com/_LjI7TbwK5dY/SYdLXU1HauI/AAAAAAAAACI/O8pTOAouuEI/s320/Phagocytosis.bmp)

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Explain the roll of phagocytes in immune respone

Phagocytes carry out phagocytosis.

They're found in the blood and in tissues and are first cells to respond to a pathogen inside the body

How they work...

  • 1. phagocyte recognises the antigens on a pathogen
  • 2. the cytoplasm of the phagocyte moves round the pathogen, engulfing it.
  • 3. the pathogen is now contained in  phagocytic vacuole in the cytoplasm of the phagocyte
  • 4. A lysosome (an organelle that contains digestive enzyme) fuses with the phagocytic vacuole. the enzyme breaks down the pathogen.
  • 5. the phagocyte then presents the pathogen's antigens. It puts the antigens on its surface to activate other immune system cells

(http://2.bp.blogspot.com/_LjI7TbwK5dY/SYdLXU1HauI/AAAAAAAAACI/O8pTOAouuEI/s320/Phagocytosis.bmp)

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Activation of T Lymphocytes

1. A T lymphocyte is another type of white blood cell

2. Their surface is covered with receptors

3. The receptors bind to antigens presented by the phagocytes

4. Each T lymphocyte has a different receptor on its surface

5. When the receptor on the surface of a T lymphocyte meets a complementary antigen, it binds to it - so each T lymphocyte will bind to a different antigen.

6. This activates the T lymphocyte  the process is called clonal selection

7. The T lymphocyte then undergoes clonal expansion - it divides to produce clones, which then differentiate into different types of T lymphocytes that carry out different functions

  • some activated T lymphocytes  (called Helper T cells) release substances to activate B lymphocytes
  • some attach to antigens on a pathogen and kill the cell (killer T cells)
  • some become memorary cells
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Activation of B lymphocytes

B lymphocytes are activated by T lymphocytes and can divide to make plasma cells

1. B lymphocytes are another type of white blood cell

2. They are covered in proteins called antibodies

3. Antibodies bind to antigens to form an antigen-antibody complex

4. Each B lymphocyte has a different shaped antibody on its surface

5. When the antibody on the surface of a B lymphocyte meets a complementary shaped antigen, it binds to it - so each B lymphocyte will bind to a different antigen

6. This, together with substances released from helper T cells activates the B lymphocyte. This process is another example of clonal selection

7. The activated B lymphocyte divides by mitosis, into plasma cells and memory cells. This another example of clonal expansion

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Cell signaling in immune response

1. Cell signaling is basically how cells communicate

2. A cell may release (or present) a substance that binds to the receptors on another cell - this causes a response of some kind in the other cell.

3. Cell signalling is really important in the immune response because it helps to activate all the different types of white blood cells that are needed.

4. FOR EXAMPLE - helper T cells release substances that bind to receptors on B lymphocytes. This activates the B lymphocytes - the helper T cells are signalling to the B lymphocytes that there's a pathogen in the body.

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The role of plasma cells

1. Plasma cells are clones of the B lymphocyte

2. They secrete loads of antibody, specific to the antigen, into the blood

3. These antibodies will bind to the antigens on the surface of the pathogen to form lots of antigen-antibody complexes

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Action of Antibodies

Agglutinating pathogen- each antibody has 2 binding sites, so an antibody can bind to 2 pathogens, at the same time - the pathogens become clumped together. Phagocyte then bind to the antibodies and phagocytose a lot of pathogens all at once.

Neutralising toxins - antibodies can bind to the toxins produced by pathogens. This prevents the toxins from affecting human cells, so the toxins are neutralised. The toxin-antibody complexes are also phagocytosed.

Preventing the pathogen binding to human cells - when antibodies bind to the antigens on pathogens, they may block the cell surface receptors that the pathogens need to bind to the host cells. This means the pathogen can't attch to or infect the host cells

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Memory cells

Circulate the body for a number of years, so that if a pathogen presenting the same antigens returns, the memory cells can stimulate the production of plasma cells and antibodies much more quickly

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Primary and secondary immune response

Primary response - when the infecing agent is first detected, the immune system starts to produce antibodies, but it takes a few days before the number of antibodies in the blood rises to a level that can fight the infection.

Secondary response - The immune system recognises the pathogen if the body is infected again, so the immune system can swing into action more quickly. The production of antibodies rises sooner and reaches a higher concentration

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Clonal selection and expansion

(http://home.comcast.net/~john.kimball1/BiologyPages/C/ClonalSelection.jpg)

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Natural and artificial immunity

 Natural - passive

  •  Antibodies provided via the placenta or breast milk. This makes the baby immune to diseases that the mother is immune to. It is very useful in the first year of the baby’s life, when the immune system is developing

Artificial - passive

  • Immunity provided by injection of antibodies made by another individual

Active - natural

  • Immunity provided by antibodies made as a result of infection. A person suffers from disease once and is then immune (e.g. chicken pox)

Active- Artificial

  • 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
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Vaccines and controlling disease

1. While your B lymphocytes are busy dividing to build up theur numbers to deal with a pathogen, you suffer from the disease. Vaccination can help avoid this.

2. Vaccines contain antigens that cause your body to produce memory cells against a particular pathogen, without the pathogen causing disease. This mean you become immune without getting any symptoms

3. If most people in a community are vaccinated, the disease becomes extremely rare. This means that even people who haven't been vaccinated are unlikely to get the disease, because there's no one to catch it from. This is called herd immunity.

4. Vaccines always contain antigens - these may be free or attahed to a dead or attenuated (weakened) pathogen.

5. Vaccines may be injeted or taken orally. The disadvanatge of taking a vaccine orally are that it it could be broken down by enzymes in the gut or the molecules of the vaccine may be too large to be absrobed into the blood.

6. Sometimes booster vaccines are given later on to make sure that memory cells are produced.

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Influenza Vaccines

1. the infkuenza virus causes flu

2. Proteins on the surface of the influenza virus acta as antigens, triggering the immune system

3. these antigens can change regularly, froming new strains of the virus.

4. memory cells produced from vaccination with one strain of flu will not recognise other strains with different antigens.

5. Every year there are different strains of the influenza virus circulating in the population, so a different vaccine has to be made.

6. Labs collects samples of these different strains and organisations, such as WHO and CDC, test the effectivness of different influenza vaccines against them.

7. New vaccines are developed and one is chosen every year that is the most effective against the recently circulating flu virus

8. Govenments and gealth authorities then implement a programme of vaccination using the most suitable vaccine. This is a good example of how society uses science to inform decision making

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Possible sources of medicine that need to be prote

1. Many medicinal drugs are manufactured using natural compounds found in plants, animals or microorganisms. E.g. penicillin is obtained from a fungus, some cancer drugs are made using soil bacteria, and daffodils are now grown to produce a drug used to treat Alzheimer's disease.

2. Only a small proportion of organisms have been investigated so ar, so it is possible that plants or microorgansims exist that conatin compounds that could be used to treat currently incurable diseases, such as AIDS.

3. Possible sources of drugs need to be protected by maintaining the biodiversity on Earth. If we don't protect them, some species could die out before we get a chance to study the.

4. Even organisms that have already been studied could still prove to be useful sources of medicines as new techniques are developed for identifying, purifying and testing compounds.

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Atherosclerosis

1. When damage occurs to the lining of an artery, white blood cell move into the area

2. Over time white blood cells, lipids and connective tissue build up and harden to form a fiberous plaque at the site of damage - an atheroma.

3. The atheroma partially blocks the lumen of the artery, and restricts blood flow.

4. Atherosclerosis is the hardening of arteries due to the formation of atheromas.

5. Cgerette smoke contains nicotine, which causes an increase in blood pressure. Increased blood pressure can cause damage to the arteries, leading to the formation of more atheromas.

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Coronary Heart Disease (CHD)

1. CHD is when the coronary arteries (supply blood to the carica muscle) have lots of atheromas in them. This restricts blood flow to the heart.

2. A reduction in blood flow reduces the amount of oxygen an area of the hert gets. This can cause angina or a heart attac.

3. Smoking increases the risk of CHD because carbon monoxide irreversibly binds with haemoglobin reducing the amount of oxygen transported in the blood, which reduces the amount of oxygen available to tissues, including the heart.

4. Nicotine in cigerette smoke makes platelets sticky, increasing chance of blood clots forming. If clotting happens in the coronary arteries it could cause a heart attack.

5. The presence of atheromas also increases the risk of blood clots forming.

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Stroke

1. A stroke is a rapid loss of brain function due to a disruption in the blood supply to the brain.

2. This can be caused by a blood clot in an artery leading to the brain, which reduces the amount of blood, and therefore oxygen, that can reach the brain.

3. Nicotine increases the risk of a stroke because it increases the rick of clots forming

4. Carbon monoxide also increases the risk of stroke because it reduces the amount of oxygen available to the brain by combining with Hb

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Lung cancer

1. Cigarette smoke contains many carcinogens

2. These carcinogens may cause mutations in the DNA of lung cells, which could lead to uncontrolled cell growth and the formation of a malignant tumour

3. This decreases gas exchange and leads to a shortness of breath - body is struggling to take in enough oxygen

4. Tumour uses lots of neutriants and energy to grow - causes weight loss

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Chronic Bronchitis

1. inflamation of the bronchi

2. The upper respiratory tract is lined with goblet cells that produce mucus to trap microorganisms. The tract is lined with cilia that'beat' to move the mucus towards the throat to be swallowed

3. Cigarette smoke damages the cilia and causes the goblet cells to produce more mucus.

4. The mucus accumulates in the lungs, which causes increased coughing, to ttry and shitf the mucus

5. Microorganisms multiply in the mucus and cause lung infections that lead to inflamation, which decreases gas exchange.

6. Chronic Bronchitis is a type of chronic obstructive pulmonary disease (COPD). COPD is a group of diseases that involve permanent airflow reduction.

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Emphysema

1. Emphyysema is a lung disease caused by smoking or long-term exposure to air pollution - foreign particles in the smoke become trapped in the alveoli.

2. This causes inflamation, which encourages phagocytes to the area. The phagocytes produce n enzyme (elastase) that breaks down elastin

3. The alveoli walls are destroyed and the elasticity of the lungs is lost - unable to expell air from the alveoli so they burst

4. This reduces the surface area of the  alveoli - rate of gas exchange decreases

5. symptoms include:

  • shortness of breath
  • wheezing
  • increased breathing rate -> trying to increase amount of air reaching their lungs
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Cholesterol

Lipid but not triglyceride

Important

  • component of cell membrane - fluidity
  • synthesis of steriod hormones
  • synthesis of vit D
  • synthesis of bile

Non-polar

  • Transported in blood as lipoproteins

increasing proportion of protein, HDLs

  • lots of protein relative to lipid

LDLs

  • lots of lipids relative to proteins
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Role of HDLs and LDLs

High level of cholesterol in diet less of a concern because liver will adjust how much it makes according to how much is taken in in diet - degree of saturated fat is more important

If diet is high in saturated fats, these

  • enter blood
  • enter liver cells
  • cause reduction in production of LDL receptors on cell surface membrane of liver cells
  • more LDLs in blood which deposit cholesterol in walls of arteries

If diet is high in polyunsaturated fats, these

  • enter blood
  • enter liver cells
  • cause an increase in number of LDL receptors on csm of liver cells
  • more LDLs removed from blood
  • Fewer LDLs in blood
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Evidence linking cigarette smoking to disease and

Epidemiological

  • the study of patterns of disease in population (in order to work out what are the causes of diseases and how they might spread)
  • more studies have shown a correlation between
  •     - Number of cigarettes smoked and number of cases of lung cancer
  •     - Number of cigarettes smoked and number of deaths from lung cancer
  •     - An inverse correlation between number of cigarettes smoked and lifespan

Epidemeology shows that the two are associated, but not that smoking causes cancer

Experimental evidence

  • Tumors developed in animals exposed to cigarette smoke
  • Dogs smoking using filter have some protection
  • Benzopyrene is found in tar - painted onto skin of mice -> develop tumours
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