Pathogens
Disease-causing organisms
Transmissible Diseases
Pathogens that can be passed or transmitted from one host to another
Mechanical Barriers
Physical barriers between the body and pathogens. Examples:
- The dead outer layers of the skin that form a barrier to entry
- the hairs in the nose that trap larger particles when you breath in
Chemical Barriers
Barriers that destroy pathogens in entry ways.
Examples:
- Hydrochloric acid in the stomach which kills pathogens in food
- Cells that line the airways which make mucus. They can take pathogens up to the throat and into the stomach acid.
Examples of Transmission
- Through the air
- In contaminated food and drink
- Direct contact from infected people
- Insects
- Body fluids
- Intimate activity
Examples of diseases caused by transmission
- Influenza, tuberculosis, common cold
- cholera, typhoid
- athlete’s foot
- dengue fever, malaria
- HIV/AIDS, hepatitis
- HIV/AIDS, non-specific urethritis (NSU), chlamydia
Antigens
A protein chemical on the surfaces of all pathogens, used by the lymphocytes to get rid of the pathogens.
Ways Antibodies can Eliminate Pathogens
- They can cause the pathogens to stick together in a group, making it easier for phagocytes to absorb them.
- Some bacteria have a flagella which could be held by the lymphocyte to prevent movement, allowing the phagocytes to absorb them.
- Some pathogens release toxins. Lymphocytes can create certain anti-bodies called “anti-toxins” to neutralise them.
- Antibodies can ‘punch’ holes into the pathogen’s cell membrane and cause them to burst through osmosis.
Immune Response
A defensive response of the body due to an invasion of pathogens.
‘Lock and Key Method’ but with Antibodies
Antibodies only attach to certain pathogens which can be determined through their antigens. They are completely unique and can not be used for other pathogens.
Active Immunity
The process of defence against a pathogen by antibody production. Can be attained by catching the transmissible disease, vaccine or natural way.
Memory Cells
They hold the ‘code’ to the specific anti-body production needed for the specific pathogen, making it faster to respond. They are retained after a invasion by the pathogen. They are not permanent but stay for a long period of time and are found in the blood and lymphatic system.
Vaccination
When a weakened or small amount of a pathogen with antigens is purposely added into the body. These antigens trigger an immune response by the lymphocytes to produce antibodies. These are remembered and start the production of memory cells. It is an artificial way to gain active immunity.
Passive Immunity
short-term defence against a pathogen by antibodies acquired from another individual, e.g. mother to infant. It is efficient for a short time as it will not cause a production of memory cells.
Passive immunity examples
Passive immunity can be given through the placenta of a mother to a child, the breast milk of a mother to a child, an injection from tetanus to prevent muscle paralysis, anti-venom for a snake bite,
Autoimmune Diseases
The body could sometimes determine their own cells to be foreign, attacking it by mistake. This can cause diseases known as autoimmune diseases.
Examples of Autoimmune Diseases
Rheumatoid Arthritis, multiple sclerosis, type 1 diabetes. etc.
Type 1 Diabetes
When the body attacks the pancreas preventing the production of insulin.
Insulin
A peptide hormone in the body that controls the concentration of glucose in the blood. It helps store glucose as glycogen in the liver and muscles.
Type 1 Diabetes symptoms
- Weight loss as the cells use protein and fat as sources of energy instead.
- Thirst as the increased in concentration of glucose in the blood that lowers the water potential causes water to not be transported properly.
- Tiredness as there is a lack of glycogen that could be converted to glucose between meals.
Indicator of Type 1 diabetes
Glucose being found in urine
Personal Hygiene
When an individual cleans themselves to prevent the spread of pathogens.
Examples of Good Personal Hygiene
- Washing your hands after the toilet and before eating.
- Washing your hair to prevent spread of head lice and dandruff
- Brushing one’s teeth; dental hygiene
- Cuts and bruises should be cleaned to prevent infection.
Examples of Good Food Preparation
- Food should be covered to keep flies away
- Kitchen surfaces to be cleaned to kill bacteria
- Food should be cooked thoroughly to kill pathogens
- Cooked food should be kept away from raw food to prevent the spread of pathogens
- Water used for cooking/ drinking should be sterilised or boiled
