Health Science - Immunity

Question 1

Function of immune system

Answer 1

To protect the body from overwhelming infections (pathogens)

Question 2

Examples of threats to the body

Answer 2

Bacteria, viruses, fungi, protozoa, cancer cells, parasites, non self cells

Question 3

Purpose of non specific defence mechanisms

Answer 3

First line of general defence- to prevent entry or minimise passage of microbes and foreign material into the body. Response occurs quickly and is non specific.

Question 4

Examples of non specific defence mechanisms

Answer 4

1. Defence at the body surfaces
2. Phagocytosis
3. Natural antimicrobial defences
4. Immunological surveillance (NK cells)
   5.Inflammatory response

Question 5

Examples of Defence at body surfaces

Answer 5

Skin and mucous membrane- physical barrier to invading microorganisms
Mucous-. traps microorganisms
Sweat - contains antibacterial and antifungal substances
Nasal hair - act as course filters

Question 6

What are the cells of innate immunity

Answer 6

Neutrophils, eosinophils, basophils and mast cells, monocytes in blood and tissue macrophages, natural killer cells

Question 7

What is Phagocytosis and what is its process?

Answer 7

Cell eating - phagocytic defence cells include macrophage(tissue monocyte) and neutrophils
Process involves binding, engulfing and digesting foreign cells and particles where enzymes within the phagocyte destroy the invading organism.

Question 8

What are cytokines and what is their function?

Answer 8

Chemicals secreted by macrophages whose function includes attracting other cells (like neutrophils) to the area required

Question 9

What is the major constituent of pus

Answer 9

dead neutrophils

Question 10

Note on Neutrophils

Answer 10

-Arrive quickly at site of inflammation to kill pathogens
-Attracted and migrate to site of infection by chemotaxis
-Phagocytosis allows neutrophils to engulf material to be destroyed

Question 11

Note on Monocytes

Answer 11

-Largest white blood cells
-Circulate in blood for 8 hours before moving into tissues where they differentaite into tissue macrophages - phagocytes
-Macrophages use phagocytosis - secrete cytokines and hydrolytic acid and bacterial substances into the extracellular space
-Macrophages act as antigen presenting cells (APC)

Question 12

Difference between basophils and mast cells

Answer 12

Have similar functions but found in different locations - Basophils are WBCs (found in blood) and mast cells reside in tissues.

Question 13

How do Mast Cells function?

Answer 13

By discharging their granule content whoich contains heparin, histamine, chemotactic factors and peroxidase

Question 14

Role of Mast Cells and Basophils

Answer 14

Role in allergic rxns e.g asthmatic attacks and rxns to peanuts

Question 15

Note on Eosinophils - what do their granules contain

Answer 15

-Important in defence against parasites and have role in allergic reacti
-Their granules contain; major basic protein, cationic protein, peroxidase.
-The peroxidase generates hydrochlorus acid
-The major basic protein damages the parasites outer surface
-The cathion protein acts as a neurotoxin, damaging the parasites nervous tissue

Question 16

Examples of Natural Antimicrobial Substances

Answer 16

-Hydrochloric acid
-Lysozyme - a bacterial enzyme in mucus, saliva, tears, sweat
-Saliva - slightly acidic medium is antibacterial
-Interferons - produced by T lymphocytes and cells inaded by virus - prevent viral replication within infected cells and the spread of viruses in healthy cells
-Cytokines - small proteins secreted by macrophages and T lymphocytes - have a role in both innate and adaptive immune response.
-Complement and acute phase proteins

Question 17

What are complement proteins?

Answer 17

A natural antimicrobial substance that is a protein present in plasma and plays a role in innate immunity.

Question 18

How do Complement proteins function?

Answer 18

1. Binding to and damaging the bacterial cell wall.
2. Complement binding also stimulates phagocytosis and further attracts more phagocytes by chemotaxis