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Bio paper 1
Infectious diseases
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Hamza Patel
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Communicable diseases
Diseases that can be spread from person to person
Communicable diseases
Spread by pathogens such as bacteria or viruses
Non-communicable diseases
Diseases that cannot be passed from person to person
Diseases can cause ill health, which is defined as the state of physical and mental well-being
Ill health can be caused by communicable and non-communicable diseases, poor diet, high levels of stress, and other life situations
People with a defective immune system (e.g. those with HIV)
Are much more likely to suffer from infectious diseases
(e.g.
tuberculosis
)
Infection with the human papilloma virus (HPV)
Can cause cervical cancer
Infection with a pathogen
Can trigger an allergy (e.g. certain cases of asthma or dermatitis)
Physical illness (e.g. arthritis)
Can trigger a mental illness (e.g. depression)
Pathogen
Microorganisms that cause infectious disease
Types of pathogens
Bacteria
Viruses
Protists
Fungi
Bacteria
Reproduce very rapidly under ideal conditions
Can divide every 20 minutes
Release harmful chemicals called toxins that damage tissues and make us feel ill
Viruses
Cannot be produced by themselves
Can only reproduce inside a host cell
Invade host cell, reproduce inside, then cause the cell to burst open and die
Ways pathogens are spread
Airborne (e.g. influenza)
Waterborne (e.g. cholera)
Direct contact (e.g. HIV)
Reducing the spread of pathogens
1. Practicing basic hygiene (e.g. handwashing)
2. Providing clean drinking water
3. Reducing direct contact (e.g. using condoms)
4. Isolating highly infectious patients
5. Vaccination
Around 300,000 people in the UK get food poisoning from a type of bacteria every year
Many bacterial diseases can kill us
Viruses are very damaging to host cells, causing them to burst open and die
Viruses
Pathogens that cannot be killed by antibiotics
Measles
Highly infectious disease
First symptom is fever
After 3 days, develops red skin rash
Virus spread through coughing/sneezing droplets
Can cause complications and be fatal
HIV
First symptom is flu-like illness
Attacks immune system cells
Immune system becomes severely damaged
Can lead to other infections and cancer
Treated with antiretroviral drugs but not cured
Transmitted through exchange of bodily fluids
Most children are vaccinated
against measles when young
Antiretroviral drugs stop HIV from
multiplying
and prevent
AIDS
development
HIV can be spread through
unprotected sex
and sharing
infected needles
Communicable disease
A disease that is passed from person to person by a pathogen
Malaria is a very common disease in certain parts of the world and it causes over 400,000 deaths every year
Malaria
A communicable disease spread by a pathogen
Malaria pathogen
An example of a protist
Malaria
is a very serious disease, people with
malaria
experience repeated bouts of
fever
and in some cases it can be
fatal
Life cycle of malaria
1.
Infected person is bitten by a mosquito
2.
Malaria pathogen passes into the mosquito
3.
Mosquito bites a different person and passes the malaria pathogen to them
Mosquito
A vector that carries a pathogen from one person to another person
Preventing the spread of malaria
1. Stop the vector (mosquito) from breeding
2. Drain areas of still water where mosquitoes breed
3. Spray areas of still water with insecticide
4. Prevent mosquitoes from biting humans by using mosquito nets
It is virtually impossible to kill all mosquitoes
Nonspecific defense system
The body's first line of defense against pathogens, preventing them from entering the body
Parts of the nonspecific defense system
Skin
Nose and mucus
Trachea and bronchi (cilia)
Stomach (hydrochloric acid)
Skin
Forms a protective layer covering the body
Outer layer of dead cells difficult for pathogens to penetrate
Produces sebum which can kill bacteria
Can scab over when damaged to prevent pathogen entry
Nose and
mucus
Contains
hair
and
mucus
to trap
pathogens
before they enter the breathing system
Trachea and bronchi
Covered in tiny hair-like structures called
cilia
Cilia are covered in
mucus
which traps and moves pathogens upwards towards the
throat
to be swallowed
Stomach
Contains
hydrochloric
acid
which kills
pathogens
before they can enter the digestive system further
Even with the nonspecific defense systems, pathogens can still get into the human body and cause serious disease
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