Immunity and Infection

Question 1

What is communicable (infectious) disease?

Answer 1

Communicable diseases are diseases that can pass from person to person. The pathogens that cause these diseases can spread in various ways, such as through the air, contact with contaminated substances or surfaces, or from animal and insect bites.

Question 2

Top five infectious diseases

Answer 2

Tuberculosis - 1.7 M
Measles - 544,000
Meningitis - 456,000
Tetanus - 222,000
Pertussis (Whooping cough) - 131,000

Question 3

Causes: Pathogens types of them:

Answer 3

1. Bacteria: Most abundant living organisms
   Pneumonia, Meningitis, Strep throat, TB, Tetanus, Pertussis
2. Viruses: Lack function to grow & reproduce by themselves = parasites take what they need from host cells they invade.
   E.g. Common cold, Influenza, Hepatitis, Chicken Pox, Measles, Mumps, Rubella, Cervical cancer, HIV/AIDS, Polio
3. Fungi: Organisms (moulds, yeast) that absorb food from organic matter.
4. Protozoa: Single-celled organisms  developing countries. e.g. malaria
5. Parasitic Worms: e.g. tapeworm

Question 4

Chain of infection

Answer 4

1. Infectious agent(pathogen)
2. Reservoirs - where the pathogen lives
3. Portal of exit - salava. blood. air, coaghing
4. Means of transmission Direct/Indirect - direct, caughing, touching, blood touching, sex. Indirect - animals, food, water, objects
5. Portal of Entry -direct contact, skin, wound, eyes
6. Susceptible host - how strong is the host aganist pathogen, amount of pathogens
   Repeat

Question 5

How to stop the spread of pathogens?

Answer 5

Handwashing

Question 6

Defence against pathogens

Answer 6

1st Defence: Physical & Chemical Barriers
2nd Defence: Immune System
3rd Inflammatory Response

Question 7

1st Defence: Physical & Chemical Barriers

Answer 7

Body’s largest organ? -skin
Prevents many micro-organisms from entering body – even if many bacteria & fungal organisms live on surface, few can penetrate
Mouth: mucous membranes; Also tears, saliva, vaginal secretions high in antibodies & enzymes that destroy invading micro-organisms
Respiratory tract: mucous membranes + cells with cilia; cough

Question 8

2nd Defence: Immune System

Answer 8

Body has been invaded  response system activated
The defenders: White blood cells (continuously produced in bone marrow)
Neutrophils, macrophages, NK cells, dendritic cells, lymphocytes
 Attack, ingest, devour, eat, destroy [AIDED]
 Congregation in lymph nodes
2 types of lymphocytes: T cells, B cells
1st encounter of invader  some reserved as memory T cells & memory B cells

Question 9

2 types of lymphocytes

Answer 9

T cells, B cells

Question 10

lymphocytes

Answer 10

Remarkable feature of lymphocyte defenders: Ability to distinguish “self” from “non-self”.
Lymphocytes capable of great destruction
Autoimmune disorders: Lupus, rheumatoid arthritis
All cells in your body: cell markers “self”
Foreign invaders: also markers

Question 11

= Antigens:

Answer 11

Non-self markers that trigger immune response
Antibody-Antigen “Lock & Key

Question 12

Inflammatory Response

Answer 12

Histamine + other substances released by special cells in area of invasion or injury, cause blood vessels to dilate & fluid to flow out of capillaries to injured tissue
Heat, swelling, redness
White blood cells attack invaders
Pus: Dead white blood cells + debris from battle

Question 13

Incubation period:

Answer 13

Viruses/bacteria actively multiplying in body before immune system responds – might not have symptoms, but might be contagious.
Symptoms appear after incubation period – unless host has acquired immunity
Many symptoms due to immune response, not invading organisms: Fever, runny nose, fatigue

Question 14

Antibiotic treatment

Answer 14

Bacterial infections only
Interrupt new bacteria production by damaging reproductive cycle or causing faulty parts
Bacteria become resistant – e.g. 1 strain of TB is resistant to 7 different antibiotics
Frequency that bacteria encounter antibiotics…

Question 15

Important tips to know when taking antibiotics

Answer 15

Don’t take antibiotics every time “sick”
Use as directed, never stop early
Never take without Rx- doctors perscription

Question 16

Immunity

Answer 16

Survival from infection  Immunity = infected person will never get same illness again
Memory cells circulate for years, sometimes life

Question 17

Immunization

Answer 17

Based on immune system’s ability to remember
Manipulate immune system with vaccine: preparation of killed (e.g. flu) or weakened (e.g. measles, mumps, rubella) pathogens given to stimulate immune response; body produces antibodies to prevent serious infection if ever exposed to disease organism itself.

1.5M people, including 700,000 children, die each year from vaccine-preventable diseases.

Question 18

Immunity flow chart

Answer 18

Immunity
innate(inborn) genetic factors acquired
Active (ownantubodies) Passive (ready-made antibodies)
Natural (exposure to infectious agent Artificial immunizatio Natural(maternal antibodies) Artificial (antibodies from

other sources

Question 19

Immunization

Answer 19

Vaccination works on premise of Herd Immunity

http://www.health.harvard.edu/herd-immunity-animation

95% vaccination

Question 20

Allergies

Answer 20

Result of hypersensitive & overactive immune system.
Immune system mounts a response to a harmless substance.
Allergy symptoms result from immune response
Allergens: Substances that provoke allergic response.
Special antibody: Immunoglobulin E (IgE) produced at initial exposure; subsequent exposure allergen binds to IgE, histamine released.

Question 21

3 phases of the immune system fighting off a virus

Answer 21

1. Viruses invade and take over the body cells to replicate
2. hellper cells trigger the productuin of killer T cells and B cells

Question 22

Herd Immunity

Answer 22

for the protection of other people (the population)

IF you are around people who are vactinated and you are not vactiated you cannot he infected.