Infection and Responce

• Communicable diseases can be spread from person to person by pathogens, such as bacteria, viruses, and fungi. e.g. mumps, measles, chicken pox, influenza, HIV
• Non-communicable diseases are diseases that cannot be spread from person to person e.g. cancer, coronary heart disease or diabetes
• Health is defined as a state of complete physical, mental, and social well-being and not merely the absence of disease or infirmity.
• Ill health can be caused by both communicable and non-communicable diseases
• People with a defective immune system are much more likely to suffer from infectious disease
• HPV is harmless but can cause cervical cancer
• Some diseases can be triggered by the immune system e.g. allergies such as asthma or dermatitis
• Communicable diseases are spread by pathogens
• Pathogens are microorganisms that cause infectious diseases in humans or animals. They include: bacteria, viruses, protists and fungi
• Once inside the human body bacteria reproduces very rapidly
• Bacteria can release harmful chemicals called toxins
• Toxins damage cells and tissues causing disease symptoms
• Viruses cannot reproduce on their own, they need a host cell to reproduce in.
• First, the virus invades the host cell and then the virus makes copies of itself inside the host cell, it is very damaging to the cell, when the virus leaves it can cause the cell to burst open and die
• Pathogens can be spread via the air/water droplets (influenza), water (cholera), or direct contact (chicken pox)
• To reduce the spread of pathogens you can: practice basic hygiene e.g. washing hands before eating, providing people with clean water, or using protection during intercourse
• Measles is a highly infectious disease caused by a virus that spreads through the air. The first symptoms are a fever and a red rash.
• Most children are vaccinated against measles at a very young age
• HIV is a virus that attacks the immune system and can lead to AIDS. The first symptom is flu-like illness, after a certain point the patients immune system becomes so severely damaged it cannot fight off any other diseases
• Antiretroviral drugs stop HIV from multiplying inside the patient, people who take these drugs often do not develop AIDS and can go off living a very normal life
• Antiretroviral drugs are not a cure for HIV or AIDS
• Bacteria can be killed by antibiotics whereas viruses cannot
• Salmonella can be caused by food being infected by being prepared in unhygienic conditions
• Salmonella symptoms include: a fever, stomach cramps, vomiting and diarrhoea
• Salmonella can be found in poultry such as chicken, in the UK all chickens are vaccinated against Salmonella, this controls the spread of the disease
• Gonorrhoea is an STD caused by bacteria that can be spread through sexual contact, symptoms include: a thick yellow/green discharge from the penis or vagina and pain when urinating
• Gonorrhoea was treated by the antibiotic penicillin. However, antibiotic-resistant strains are now common
• Stop the spread of gonorrhoea by: Using condoms and avoiding sexual contact with infected partners
• The immune system has a vital role: It protects your body from harmful substances, germs and cell changes that could make you ill
• The malaria pathogen is an example of a protist
• People with malaria experience repeated bouts of fever. Malaria can be fatal
• First, the infected person is bitten by a mosquito, the malaria pathogen passes into the mosquito, the mosquito then bites a different person and passes the malaria pathogen to them
• The mosquito is a vector as it carries the pathogen from one person to another
• Ways to stop malaria: stop the vector (mosquito) from breeding by draining out areas of still water (their breeding area), spray still water with insecticide to kill the mosquitos, and sleep under a mosquito net to stop the mosquitos from biting you (spray the net with insecticide)
• The body has two defence systems against diseases: the non-specific defence system and the immune system
• The non-specific defence system prevents pathogens from entering the human body
• 4 parts of the non-specific defence system: skin, nose, lungs, stomach
• Skin: the outer layer of the skin contains dead cells, which are difficult for the pathogens to penetrate, skin also produces an oily substance called sebum which can kill bacteria, when the skin is damaged it can make it easier for pathogens to enter, to stop it the skin scabs over
• The nose contains hair and mucus which trap the pathogen before it can enter the breathing system, if they do make it past the nose the trachea and bronchi are covered in tiny hairs called cilia, cilia is covered in mucus which traps pathogens
• The stomach contains hydrochloric acid which kills bacteria and pathogens before they can make there way to the digestive system