Topic 5 Health and disease

How do you define good health?

a state of complete physical, mental and social well-being and not merely the absence of disease or infirmity

What are communicable diseases?

Communicable diseases are caused by **microorganisms** called **pathogens** which can spread between individuals or individuals and animals

What are some examples of communicable diseases?

* Tuberculosis
* Influenza
* HIV/AIDS
* Malaria

What are non communicable diseases?

Non communicable diseases are **not caused by pathogens** and **cannot be passed on** between individuals

What are some risks that increase your chance of developing a non-communicable disease?

* Smoking - lung disease, lung cancer and cardiovascular disease
* Obesity caused by a bad diet- Type 2 diabetes
* Consuming alcohol- Liver disease

What is susceptibility?

If an individual suffers from one disease they are more likely to be susceptible to other diseases. This is because the immune system may be compromised in some way or the different types of disease may interact in ways that negatively affect the health of an individual.

What is a pathogen?

A **pathogen** is any microorganism that **causes disease** in another organism (e.g. in plants or animals)

What can a pathogen be?

* Bacteria
* Fungi
* Protists (protoctists)
* Viruses

What are some properties of pathogenic bacteria?

* Pathogenic bacteria do not always infect the host of cells , they remain within body cavities or spaces
* Toxins produced by bacteria also damage cells
* They are small and can reproduce very quickly

What are some properties of pathogenic Fungi?

* Fungal diseases are much more common in plants than animals
* Fungi can be **single-celled** or **multicellular**
* The **spores** they produce allow them to infect other organisms

What are some properties of pathogenic protists?

* Protists are a diverse group of eukaryotic organisms
* They are **parasites** which mean they need a **host** In order to survive
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What are some properties of a virus?

* Viruses are **not considered to be alive**
* they are small particles
* They are parasitic and **can only reproduce inside living cells**
* They infect **every type of living organism**
* They have no cellular structure but have a **protein coat** and contain either **RNA** or **DNA**.

What are some examples of Viruses?

* HIV
* Influenza virus
* Ebola virus

What are the two pathways of reproduction of a virus ?

* the lytic pathway
* the Lysogenic pathway

What are the steps of the Lytic pathway?

1. the virus infects the host cell and injects it’s DNA into the cytoplasm
2. Next, the virus uses proteins and enzymes within the host cell to produce new virus particles
3. Finally, the cell bursts, releasing the virus particles into the host organism to infect more cells

What are the steps of the Lysogenic pathway?

1. The virus injects its DNA into the host cell and the DNA becomes incorporated into the host DNA
2. As the host cell replicates, the viral DNA replicates also, but no new viral particles are made during this time, the virus is dormant
3. Changes in the environment (e.g. a Chemical trigger) cause the viral DNA to move to the Lytic pathway to make new virus particles

What are some common infections caused by bacteria?

* tuberculosis
* Cholera
* stomach ulcers
* chlamydia

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What are some common infections caused by fungi?

* Chalara ash dieback

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What are some infections caused by protists?

* Malaria

What are some infections caused by viruses?

* Ebola virus
* HIV virus

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How does the HIV virus work?

* The virus infects a certain type of lymphocyte in the body’s immune system
* Normally lymphocytes seek out and destroy pathogens entering the body producing antibodies that attach to pathogens, enhancing phagocytic activity
* However HIV avoids being recognised and destroyed by lymphocytes by changing its protein coat
* it then infects a certain type of lymphocyte and uses the cells’ machinery to multiply
* this reduces the number of lymphocytes of the immune system, and also the number of antibodies that can be made
* this decreases the body’s ability to fight off infections. eventually leading to AIDS

in what ways are diseases spread?

* Airborne- droplets travelling in the air ( maybe as a result of wind or sneezing or coughing) that lead to infections
* Waterborne- pathogens that live in dirty water are transmitted to organisms that come into contact with it
* Oral transmitted- pathogens are ingested and transmitted to the host
* Body fluids and sexual transmission- Exchange of saliva, blood or semen can carry pathogens from one host to another
* Animal vectors- Animals carry pathogen between hosts

What’s some information about Tuberculosis? (Symptoms, mechanism of transmission, Methods to prevent transmission)

* **Symptom**s= Cough, bloody mucus, lung damage
* **Mechanism of Transmission**= Airborne, through coughing
* **Method to prevent/ reduce transmission**= Avoid crowded areas, maintain good hygiene, Ventilate workplace/home

What’s some information about Cholera? (Symptoms, mechanism of transmission, Methods to prevent transmission)

* **Symptom**s=Diarrhoea, vomiting, leg cramps
* **Mechanism of Transmission**= Waterborne, in contaminated water sources
* **Method to prevent/ reduce transmission**= Avoid dirty water, good sanitation, Give access to clean water

What’s some information about Stomach Ulcers ? (Symptoms, mechanism of transmission, Methods to prevent transmission)

* **Symptom**s= can be symptomless or cause abdominal pain, loss of appetite, bloating and nausea
* **Mechanism of Transmission**= Oral transmission, consumption
* **Method to prevent/ reduce transmission**= Ensure access to clean water

What’s some information about Chlamydia? (Symptoms, mechanism of transmission, Methods to prevent transmission)

* **Symptoms**= Can be symptomless or cause painful urination, discharge and bleeding after sex
* **Mechanism of Transmission**= Sexually transmitted in body fluids
* **Method to prevent/ reduce transmission**= Use a condom, screening after unprotected sex, limiting sexual partners

What’s some information about Chalara Ash Dieback ? (Symptoms, mechanism of transmission, Methods to prevent transmission)

* **Symptoms**= Dark patches on leaves, early leaf loss and lesions in bark
* **Mechanism of Transmission**= Airborne, carried in the wind
* **Method to prevent/ reduce transmission**= Remove infected trees immediately and replace with another species. Limit imports from countries known to carry the disease

What’s some information about Malaria ? (Symptoms, mechanism of transmission, Methods to prevent transmission)

* **Symptoms**= Blood and liver damage, chills, fever, fatigue in some severe cases, death.
* **Mechanism of Transmission**= Animal borne, carried by mosquitos
* **Method to prevent/ reduce transmission**= Use insect repellent, mosquito nets, prevent reproduction in mosquitos

What’s some information about Ebola virus ? (Symptoms, mechanism of transmission, Methods to prevent transmission)

* **Symptoms**= Headaches, high temperatures, joint and muscle pains, diarrhoea, haemorrhagic fever.
* **Mechanism of Transmission**= Body fluids
* **Method to prevent/ reduce transmission**= Isolate infected individuals, sterilise infected areas.

What’s some information about HIV virus ? (Symptoms, mechanism of transmission, Methods to prevent transmission)

* **Symptoms**= Headaches, high temperatures, joint and muscle pains, AIDS associated illness
* **Mechanism of Transmission**= Sexually transmitted, body fluids
* **Method to prevent/ reduce transmission**= Wear condoms, limit sexual partners, Avoid sharing needles, Screening after potential exposure, Education, Medication can stop the spread

What are some plant chemical barriers to infection?

Plants have chemical adaptations to prevent herbivores from eating them:

* Antiseptics or antimicrobial enzymes
* Chemical poisons to deter pests that might be eating them
* Mechanisms to attract other insects as biological control

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What are some plant physical barriers to infection?

* the cellulose cell wall provides support for the plant and but also protection from microorganisms
* the waxy cuticle of the leaf and stems acts as a barrier to microbes from entering the plant, the only place they can enter in the leaf is through the stomata
* Bark provides a tough layer around the stem of the plant to prevent pathogens from entering
* Thorns or Hairy stems also makes it more difficult for pests to access the plant tissue to feed
* As deciduous trees loose leaves in the winter the infections can be taken with them

What are some symptoms of disease in plants?

* stunted growth
* Spots on leaves
* Areas decaying/rotting
* Visible pests
* Discolouration of the leaves
* Growths
* Malformed leaves and stems

What are the steps to detecting and identifying a disease in a plant?

1. When a symptom of a disease is detected , it is important to determine wether it is due to the proposed disease or rather an environmental issue


1. assessing the distribution of the infected plants may also help you asses whether the disease is pathogen caused or rather a natural factor
2. If no environmental factors are detected then a more detailed assessment of the pathogen may be needed


1. ecologists may take cuttings of plant and to return to the laboratory for a chemical analysis


1. culturing the pathogen from the sample taken may lead to accurate identification
2. DNA analysis in the laboratory will help identify specific pathogens

What are some human physical barriers to infection?

* Skin
* Hairs and mucus in the nose
* Mucus and cilia in the trachea and bronchi

How does skin work as a physical barrier to infection in humans?

Skin- covers almost all parts of your body to prevent infections from pathogens. If it is cut or grazed, it immediately starts to heal itself usually forming a scab

How does Hairs and mucus in the nose work as a physical barrier to infection in humans?

hairs and mucus in the nose- these make it difficult for pathogens to get past them further up the nose so they are not inhaled into the lungs

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How does Mucus and cilia in the trachea and bronchi work as a physical barrier to infection in humans?

pathogens get trapped in the mucus produced by cells in the in the airways of the lungs. Other cells lining the trachea and bronchi have cilia (microscopic hair-like structures) that waft mucus up to the back of the throat so it can be removed from the body (by coughing, swallowing down to the stomach to be destroyed in the stomach acid, blowing the nose ect.)

What are chemical barriers to infection? (definition)

Substances produced by the body cells to trap or kill pathogens before they can get further into the body and cause disease

What are human chemical barriers to infection? (examples)

* stomach acid
* Lysozymes
* Natural bacterial flora in the gut and vagina
* Sebum

How does stomach acid act as a chemical barrier to infection in humans?

contains hydrochloric acid which is strong enough to kill any pathogen that has been caught in mucus in the airways and then swallowed or have been consumed with food or water

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How do Lysozymes act as a chemical barrier to infection in humans?

enzymes produced by the eyes and released in tears will breakdown and kill any bacteria around the eye

How does Natural bacterial flora in the gut and vagina act as a chemical barrier to infection in humans?

protect against infection from pathogenic bacteria by outcompeting the pathogen

How does Sebum work as a chemical barrier to infection?

Sebum on the surface of the skin- kills bacterial and fungal pathogens

What cells produce mucus to capture pathogens?

Goblet cells

What cells sweep mucus up to the throat to be swallowed?

Ciliated Epithelial cells

What are Phagocytes and what to they do?

Phagocytes are white blood cells that carry out phagocytosis and are part of the body's immune response.

* phagocytes carry out phagocytosis by engulfing and digesting pathogens
* Phagocytes have a sensitive cell surface membrane that can detect chemicals produced by pathogenic cells
* Once they encounter the pathogenic cell they will engulf it and and release digestive enzymes to digest it
* This is a non specific immune response and is the same for all pathogens

What are Lymphocytes and what do they do?

B-Lymphocytes produce antibodies.

* Antibodies are Y-shaped proteins with a shape that is specific (complimentary) to the antigens on the surface of the pathogen
* This is a specific type of immune response as the antibodies produced will only fit one type of antigen on a pathogen
* Antibodies attach to the antigens and agglutination (clumping together)
* this means that the pathogenic cell cannot move very well
* At the same time chemicals are released to signal to the phagocytes that there are pathogenic cells that should be killed

What are the stages of the immune system’s response to infection?

1. the pathogen enters the blood stream and multiplies
2. A release of toxins (in case of bacteria) and infection to body cells causes symptoms in the patient
3. Phagocytes that encounter the pathogen recognise that it is an invading pathogen and engulf and digest (non specific response)
4. Eventually the pathogen encounters a B- lymphocyte which recognises its antigens
5. The lymphocyte begins to produce specific antigens to counter that pathogen
6. the lymphocyte also clones itself to produce lots of lymphocytes (all producing the specific antibodies)
7. Antibodies cause agglutination of pathogens
8. phagocytes engulf and digest the agglutinated pathogens
9. After the patient has recovered they retain antibodies specific to the disease as well as memory cells (lymphocytes that recognise the pathogen)
10. if the patient encounters the same pathogen again it will trigger a secondary immune response
11. Memory cells can produce much larger quantities of the desired antibodies In a much shorter amount of time to fight off the pathogen before the patient suffers any symptoms

What is an antigen?

A molecule found on the surface of a cell

What is an antibody?

a protein made by lymphocytes that is complimentary to an antigen and when when attached clumps them together and signals the cells they are on for destruction

Why are vaccines used?

Vaccines are used to induce immunity to infectious diseases

How do vaccines work?

A vaccine contains a harmless version of a pathogen.

* A vaccine may be administered orally , nasally or via injection

Once in the bloodstream a vaccine can trigger an immune response in the following ways
* Lymphocytes recognise the antigens in the blood stream
* the activated lymphocytes produce antibodies specific to the antigen encountered
* memory cells and antibodies subsequently remain circulating in the blood stream
* future infection by the same pathogen will trigger a much faster and larger immune response
* Due to the rapid response to the pathogen it is not able to cause any disease or any symptoms

What are some advantages to vaccination?

* Diseases that were once common are now fairly rare due to widespread vaccinations (for example: polio, measles)
* Epidemics can be prevented if a large number of the population are vaccinated

What are some disadvantages to vaccines?

* Vaccines don’t always give immunity
* There can be side effects to the vaccine, (for example: swelling or a rash and in some more severe cases seizures)

What are the two types of medication an individual can take when treating a disease and what do they do?

* Medication which treats the symptoms of a disease (e.g. painkillers)
* Medication which treats the cause of the disease (e.g. antibiotics)

What are antibiotics?

Antibiotics, such as Penicillin, are medicines which help to cure bacterial disease by killing infective bacteria inside the body. Only certain antibiotics will work on certain diseases.

How do antibodies work?

Antibodies work by inhibiting the processes in the bacterial cells such as the production of cell walls.

Antibiotics will not work against viruses, as viruses reproduce inside cells. it is difficult to produce drugs that will kill viruses without damaging the host’s tissue

What are the steps to Uncontaminated culture preparation?

1. Whenever working aseptically, all work should be carried out in front of a lit Bunsen burner with a yellow flame - The flame creates a convection current above the bench, preventing the contamination of any microorganisms in the air
2. Hot agar jelly is poured into a sterilised Petri dish. The agar is left to cool and set- The Petri dish and culture medium are heated to a high temperature to kill any potential microorganisms that could contaminate the experiment
3. An innoculating loop is passed through a hot flame before it is used to transfer bacteria to the culture medium - any microorganisms on the loop are killed
4. The lid of the Petri dish should be lifted as little as possible, at the side facing the Bunsen burner- reduces the risk o f contamination from the air
5. The lid of the Petri dish should be secured with tape

How can the effectiveness of antibiotics be determined from the results of Practical: investigation of Bacterial growth

The effectiveness of different antibiotics, antiseptics or disinfectants, can be determined by calculating the area of an inhibition zone around a disc of the substance being tested. Area = πr^2

what are the steps to the Practical in investigating bacterial growth?

1. Make sure your hands and workplace are clean
2. Use a permanent marker to divide the bottom of the plate into sections
3. carefully place antibiotic disks onto set agar plate making sure your working next to a Bunsen burner
4. close and seal the lid

Why use a control variable in the practice?

* It is vital that one of the paper disks In the practical is not soaked in antiseptic or antibiotic but rather sterile water
* This is to be sure that any differences in bacterial growth were caused by the presence of the antibiotic and not some other factor (such as the paper discs themselves)

where does the drug digitalis originate from and what does it help?

Foxglove, helps strengthen the heartbeat

Where does the drug aspirin originate from and what does it do?

willow bark, painkiller fever and inflammation

Who discovered Penicillin?

Alexander Flemming (1928)

How did Alexander Flemming discover penicillin?

He left some Petri dishes that had been contaminated with mould and found that bacteria would not grow near the mould. He discovered that the mould released a chemical called penicillin that killed the bacteria surrounding it.

What are all new drugs tested for in development?

* **Toxicity-** does it have harmful side effects
* **Efficiency**- does to drug work?
* **Dose**- what dose is the lowest that can still be used and still have an effect?

What is preclinical testing?

Preclinical testing is done in a laboratory using cells, tissues and live animals.

What is clinical testing?

Clinical trials use healthy volunteers and patients

What are double blind trials.

In double blind trials some patients are given a placebo, this is to test the legitimacy of the results.

What are the three stages of drug development?

* Preclinical testing
* Whole organism testing
* Clinical trials

What is the purpose of the stage of Preclinical testing in developing of new drugs?

Preclinical testing is the first stage in developing new drugs:

* The drug is tested on cells in the lab
* Computer models may also be used to simulate the metabolic pathways that may be taken by the drug
* Efficacy and toxicity are also tested at this stage

What is the purpose of the stage of Whole organism testing in developing of new drugs?

Whole organism testing is the second stage in developing new drugs:

* the drug is tested on animals to see the effect in a whole organism- all new medicines in the UK have to have tests on 2 different animals by law
* Efficacy, toxicity and dosage are tested at this stage

What is the purpose of the stage of Clinical trials in developing of new drugs?

Clinical trials is the third stage development of new drugs:

* The drug is tested on human volunteers first, generally with a ver low dosage then increased. This is to make sure it is safe in a body functioning normally
* The next stage is test on patients with the condition. Patients are usually split into two groups; one given the drug and the other given a placebo. This is called a double blind test as neither the doctor nor the patient knows if the patient if the patient is getting the placebo or the active drug
* Once the drug is found to be safe then the lowest effective dose is tested at this stage

What are monoclonal antibodies?

Monoclonal antibodies are antibodies that are made by identical immune cells, these identical immune cells are clones of the parent cell

How are monoclonal antibodies produced?

They are produced by stimulating mouse lymphocytes to make a particular antibody by exposing them to an antigen

Why are tumour cells used In the production of antibodies?

Tumour cells can divide repeatedly

What are some uses of monoclonal antibodies?

* In **pregnancy tests** - monoclonal antibodies with **blue beads** attached bind to the **HGC** hormone
* To **diagnose certain diseases** - in laboratories to measure the **levels of hormones and other chemicals In blood**
* To treat some diseases- for cancer the monoclonal antibody can be bound to a radioactive substance that can stop cells from dividing
* **To locate blood clots-** radioactively labelled monoclonal antibodies are used to **bind to proteins** in a blood clot. Then a special radioactivity detecting camera can be used to see where the clot is.

How are monoclonal antibodies used in pregnancy tests?

The monoclonal antibodies are specific to a hormone produced in pregnancy, **human chronic gonadotrophin (HCG)** They will bind to a hormone if present and trigger a colour change.

How are monoclonal antibodies used in the diagnosis of disease?

The monoclonal antibodies are **specific** to **antigens** found on the surface of **pathogens, blood clots** or **cancer cells** they also contain markers that help doctors find them. It is used in the test for prostate cancer.

How are monoclonal antibodies used for Measuring and Monitoring?

They can be used to detect not only the presence of a chemical or pathogen but also the quantity

How are monoclonal antibodies used in research?

Monoclonal antibodies with a fluorescent dye attached can be used by scientists to detect specific molecules In a cell or tissue

How are monoclonal antibodies used for treating disease?

Monoclonal antibodies can be used in 3 ways when treating cancer:

* Use of monoclonal antibodies to trigger immune cells to destroy them
* using monoclonal antibodies to block receptors, which stops them growing and dividing
* carry toxic drugs, or radioactive substances for radiotherapy to the site of the tumour

What are some advantages to using monoclonal antibodies?

* They only bind to specific molecules on diseased or damaged cells - they do not affect healthy cells
* Highly specific so can be produced to treat a range of diseases
* hoped to be a cheaper procedure and a tried and tested method of treating conditions

What are some disadvantages of monoclonal antibodies?

* Caused more side effects than first expected. The use of mice antibodies caused complications.
* It is an expensive process at the moment
* ethical issues of using mice

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What are risk factors?

Risk factors can increase the chance of developing many **non-communicable** diseases.

What are some examples of non-communicable diseases?

* cardiovascular diseases
* cancer
* lung and liver diseases
* obesity and malnutrition

What are some associated risk factors?

* lifestyle choices- alcohol, drugs
* Environmental exposure- pollution, noise and asbestos
* Unavoidable factors- age, gender and genetics

What are the diseases linked to the risk factor smoking and how are they correlated?

Lung disease, Lung cancer and cardiovascular disease; Chemicals in cigarette smoke (such as tar and nicotine) damage the alveoli in the lungs and the endothelial lining of the arteries

What are the diseases linked to the risk factor obesity caused by a poor diet and how are they correlated?

Type 2 diabetes; Excess consumption of sugar as a result of a poor diet reduces the body’s sensitivity to insulin

What are the diseases linked to the risk factor Consuming alcohol and how are they correlated?

Liver disease and impaired brain function; the breakdown of alcohol by cells of the liver produces substances which can be toxic to the liver cells in high concentrations. The neurones of the brain are also damaged by alcohol, reducing brain function.

What are the diseases linked to the risk factor carcinogens and how are they correlated?

cancer; Exposure to ionising radiation (e.g. X rays) or certain chemicals can damage DNA in cells leading to uncontrolled cell devision, causing cancer.

What are the diseases linked to the risk factor smoking and consuming alcohol when pregnant and how are they correlated?

Poor development of foetus (unborn baby); Carbon monoxide in cigarette smoke reduces the amount of oxygen transported around the mother’s body, reducing the oxygen delivered to the foetus. Substances in alcohol can impair the development of the brain in a foetus.

What causes malnutrition?

Eating fever calories than we burn, or having an unbalanced diet can lead to malnutrition.

What can malnutrition lead to?

Malnutrition can lead to may different outcomes depending on the nutrient that Is lacking, for example:

* Brittle bones may result if calcium levels are low
* Anaemia may result from low iron levels

What is BMI? (definition)

Body Mass Index (BMI) is a simplistic measurement which uses data about the weight and height of an individual to determine their health status.

What is the equation for BMI?

Weight in kilograms/height in m^2

What is the cause of liver disease?

Liver disease can result from an excessively high intake of alcohol for a prolonged period of time

What is Cardiovascular disease?

Cardiovascular disease includes and long term condition of the heart as a result of high cholesterol levels and the build up of fatty deposits leading to the development of atherosclerosis

What are the categories of CVD?

* Coronary heart disease- Angina, heart attacks and heart failure all disrupt the blood flow to the heart
* strokes- Disruption of blood to the brain
* Peripheral arterial disease- Blockages to (peripheral) arteries in the limbs
* Aortic Disease- Conditions associated with the aorta