Ch 10 - (Diseases & Immunity) Flashcards
What are 2 ways pathogens can be passed on from one host to another?
- Direct Contact
- Indirect Contact
Describe direct contact
pathogens can be passed on by body fluids such as blood or semen.
Define indirect contact
by contaminated, food, water, surfaces and animals.
what are 2 body defences
- Mechanics barriers
- Chemical barriers
- Cells
Define mechanical barriers.
Structures that make it difficult for pathogens to get past them into the body.
What are the examples mechanical barriers?
- Skin - covers all parts of the body
- Hair in the nose - makes it difficult for pathogens to get further up the nose.
Define chemical barriers.
Substances produced by the body that traps/kills pathogens before they can enter the body.
What are examples of chemical barriers?
a) mucus - made in many parts of the body. Pathogens get trapped in mucus and can be removed by (coughing, blowing nose, swallowing)
b) Stomach acid - contains HCl which kills pathogens that have been swallowed or have been consumed in food or water.
Define cells barrier.
Different types of White blood cells work to prevent pathogens reaching areas of the body they can replicate.
what are examples of cell barriers?
a) Phagocytosis - engulfing and digesting pathogenic cells
b) by producing antibodies - clump pathogenic cells so they can’t move easily (agglutination) and releasing chemicals that signal to the other cells that they must be destroyed.
What are the ways in which the spread of diseases can be controlled?
a) clean water supply
b) Hygienic food preparation
c) good personal hygiene
d) waste disposal/sanitation
e) sewage treatment
how does hygienic food preparation work?
- Keep food cold so bacteria and fungi don’t reproduce.
- wash hands before cooking and clean surfaces
- cook food at High temp (to kill any bacteria)
- cover food to prevent flies landing on it
- use seperate utensils for uncooked meat
How does personal hygiene work?
- washing hands with soap, traps pathogens as well as
- use tissue to catch sneeze or coughs
- dispose sued tissue to ensure alive pathogens are disposed
How does waste disposal work?
- waste food should be disposed in closed container to prevent flies from transmitting pathogens
- rubbish bins should be covered
- all rubbish should be sorted before collection, away from human habitat.
How does sanitation work?
- houses should have plumbing and drains to safely remige faeces
- raw sewage should be treated to remove solid waste and kill bacteria before being released.
Define active immunity
The defence against a pathogen by antibody production in the body.
- Helps in developing memory cells for future response.
- Slow acting but long lasting immunity
what are the 2 ways in which active immunity works?
- when body is infected by pathogen, the lymphoycytes go through the process of making antibodies specific to the pathogens.
- vaccination
Define antigens
Antigens are molecules present on the cell membrane.
What happens when lymphocytes recognizes a foreign antigen?
- Lymphocytes make antigens that are complementary to the shape of antigens on the pathogenic cells
What is the role of antibodies?
- Attach to antigens and cause agglutination of pathogens (pathogenic cells cannot move around easily)
- Chemicals are released that signal the presence of pathogens to phagocytes
- Phagocytes move towards the site of an infection where they engulf and destroy pathogens.
What happens to the immunity when encountered with pathogen?
- Initial response will make us sick
- Lymphocytes give rise to memory cells that retain the instruction of making specific antibodies
- in case of reinfection, same type of pathogen, antibodies cab be made very quickly in greater quantities, so pathogens are destroyed and people become immune.
Define antitoxin
protein that neutralises toxins produced
What does vaccination do?
Gives protection against specific diseases and boosts the body defense against infection from pathogens
What happens in the body when you are vaccinated?
- dead or altered form of the disease-causing
- pathogens cannot cause illness but can provoke an immune response.
- lymphocytes produce complimentary antibodies for the antigens.
- antibodies target the antigen and attach themselves to create memory cells
- memory cells remain in the blood
- immunity is long lasting
Define herd immunity.
A ledge percentage of population is vaccinated, it provides protection for the entire population, because there are very few places for the pathogens to breed.
What does herd immunity prevent?
epidemics and pandemics from occurring
What happens in passive immunity?
It does not make it’s own antibodies or memory cells.
Describe the process of cholera in the small intestine.
- Bacteria attaches to the wall of small intestine
- They produce a toxin
- Toxin stimulates the cell lining of the intestine to release chloride ions from inside the cells into the lumen of the intestine.
- Chloride ions accumulate in the lumen of the small intestine and lower the water potential
- Once the water potential is lower than the cells of the linings, water starts to move out of the cells by osmosis.
- Large quantities to water is lost by faeces.
- Blood contains too little chloride ions and water.
