CB5 - Biology

Health

‘A state of complete physical, mental and social wellbeing’ (According to the world health organisation).

Mental wellbeing

How you view yourself

Social wellbeing

How well you get on with people

Physical wellbeing

Eating and sleeping well and being free from disease.

Disease

Have different causes. Can be either communicable or non-communicable

Communicable diseases

Can be passed from one person to another

Non-communicable diseases

Can’t be passed between people.

Pathogen

An microorganism which causes an infectious disease to plants and animals.

Features of a communicable disease

• Rapid variation in number of cases each time.

• Causes are often localised

• Caused by a pathogen

• Examples include: Malaria, Typhoid, Cholera.

Features of a non-communicable disease

• Number of cases change only gradually.

• Causes may be more widespread.

• Not caused by a pathogen

• Examples include: Cancer, Diabetes, Heart disease.

Human immunodeficiency viruses (HIV)

A pathogen which makes it easier for other pathogens to infect a person because of damage to the immune system.

Examples of pathogens

• Bacteria

• Viruses

• Fungi

• Protists

Features of bacteria

• They are smaller than human cells.

• They may release toxins (Poisonous substances).

• Some types invade and destroy body cells.

• They produce rapidly in warm, moist conditions that have a good supply of oxygen.

Features of viruses

• They are much smaller than bacteria.

•They reproduce rapidly in the body

• They take over a cell’s DNA which either:

• Make new toxins (poisonous substances)

• Cause damage when new viruses are released from cells

Features of fungi

• Eukaryotic organisms

• They are unicellular (have one cell) or multicellular organisms that each have bodies made up of hyphae (thread-like structures).

Features of protists

• Eukaryotic organisms

• Many are free living but some are pathogens.

• Sometimes they make us feel ill when they damage cells or change how they work.

•. Many of them are parasites meaning that they live inside other organisms by vectors (e.g. Mosquito).

Symptoms of cholera

Bacterium

• Watery, pale coloured diarrhoea often in large amounts (watery faeces).

Symptoms of malaria

Protist

• Fever (high temperature)

• Weakness

• Chills

• Sweating

Symptoms of HIV/AIDS

Virus

• Mild like flu symptoms may occur when first infected.

• Often no symptoms for a long time

• Eventually, there are repeated infections (e.g. Tuberculosis) that would not be a problem if the immune system was working properly.

Symptoms of tuberculosis

Bacterium

• Lung disease seen in blood speckled mucus

• Weight loss

• Fever and chills

• Night sweats

Symptoms of ebola

Virus

• Internal bleeding and fever (haemorrhagic fever).

• Severe headache

• Muscle pain

• Vomiting

• Diarrhoea (frequency watery faeces)

Symptoms of stomach ulcers

Bacterium

• Inflammation in stomach causing pain

• Bleeding in stomach

Symptoms of ash die-back

Fungus

• Leaf loss

• Bars lesions (damage)

• Dieback of top of tree (crown)

How spreading pathogens can help us determine

We can find ways to reduce of prevent the spread of the disease.

What the protist that carries malaria is caused by

A vector (the mosquito) They are not pathogens but do carry the pathogen.

How a malaria infection is carried out

1. The infected mosquito bites human and injects the protists that causes malaria.

2. The protist infects liver cells and red blood cells.

3. The mosquito becomes infected with parasite when it takes a blood meal.

4. The mosquito bites a second person and spreads malaria.

What HIV does to the body

1. HIV enters the blood and reproduces inside the white blood cells which results in their destruction,

2. Eventually, so many white blood cells are destroyed that the immune system doesn’t function properly. This stage is called AIDS.

3. The person with the disease becomes ill with a disease such ads tuberculosis, It wouldn’t be a problem if HIV didn’t affect them.

What the ebola virus does to the body

1. The virus infects humans from other infected people, animals or objects that had been in contact with the virus.

2. The virus infects either liver cells, cells from the lining blood vessels or white blood cells.

3. It multiplies these cells and destroys them causing symptoms such as severe pain.

Immuniastion

When a vaccine is given to prevent a person them becoming ill from a disease.

How vaccines work

• A vaccine contains antigens from the pathogen, often in the form of a weak or dead pathogen.

• The lymphocytes in the body produce antibodies and also memory lymphocytes.

• The memory lymphocytes will give a very rapid secondary response to the pathogen if the person is infected with the real pathogen. This makes them very unlikely for them to be ill.

Physical barriers

Ways to prevent or reduce the spread of cholera

• Boil the water before drinking it to destroy the bacteria

• Wash hands thoroughly after using the toilet to prevent the spread by touch.

Ways to prevent or reduce the spread of tuberculosis

• Ventalate building adequately to reduce the chances of breathing in bacteria in droplets of mucus coughed out by an infected person.

• Diagnose people promptly and give antibiotics to destroy tuberculosis bacteria.

Isolate infected people so they cannot pass the infection to others.

Ways to prevent or reduce the spread of malaria

• Prevent mosquito vectors biting people by killing mosquitos or keeping them off skin (e.g. by using a sleeping net).

Ways to prevent or reduce the spread of stomach ulcers

• Cook food thoroughly to kill bacteria.

• Wash hands thoroughly before preparing food to avoid.

Ways to prevent or reduce the spread of ebola

• Keep infected people isolated because the virus is easily spread.

• Wear fully protective clothing while working with infected people or dead bodies.

Sexually Transmitted Infection (STI)

Are spread by sexual activity.

How Chlamydia is transmitted

By contact with sexual fluid from an infected partner. An infected mother can also pass it to her baby during birth.

How HIV is commonly transmitted?

• Unprotected sex with an infected partner

• Sharing needles with an infected person

• From infected mother to fetus

• Infection from blood products

How the spread of STIs can be reduced or prevented

• Using condoms during sexual intercourse

• Screening people, including pregnant women

• Screening blood transfusions

• Supplying sterile needles to drug users

• Treating infections with antibiotics (for bacterial STIs like Chlamydia)

Two advantages of screening all pregnant women in the UK for HIV

• Doctors can treat the woman to stop HIV from worsening or passing to the baby.

• It provides data on HIV rates to help target awareness and education programs.

How the rate of Chlamydia infections in teenagers can be reduced

Through better health education in schools so students learn how it spreads and recognize symptoms, which encourages early treatment and prevention.

How a newborn baby’s eyes can become infected with Chlamydia

During birth, the baby's eyes and lungs may become contaminated with vaginal fluid containing the bacteria.

How using a condom during sex reduces the risk of STIs?

It prevents the exchange of sexual fluids, which may contain bacteria or viruses that cause STIs.