Body defence

Question 1

What’s the function of the immune system?

Answer 1

1. To deal with threats to normal function

2. To restore homeostasis

Question 2

What is the immune system split up into?

Answer 2

External barrier (e.g. skin, mucous membrane, nasal hair)
Internal protection, which is split into first and second line defence.

Question 3

How does the immune system deal with threats?

Answer 3

It provides protection from pathogens (found in air, food and water- micro-organisms that cause disease)
It also detects antigens (toxins or other foreign substances which induce specific immune responses, especially the production of antibodies)

Question 4

List some of the exterior defences

Answer 4

Saliva
Skin
Stomach acid
Good gut bacteria
Mucus linings
Tears

Question 5

How does the skin assist in the defence against pathogens?

Answer 5

It provides a barrier to entry

Question 6

How does saliva assist in the defence against pathogens?

Answer 6

There are antibacterial enzymes in saliva

Question 7

How does stomach acid assist in the defence against pathogens?

Answer 7

Low pH kills harmful microbes

Question 8

How does good gut bacteria assist in the defence against pathogens?

Answer 8

They out-compete harmful bacteria

Question 9

How do mucus linings assist in the defence against pathogens?

Answer 9

They trap dirt and microbes

Question 10

How do tears assist in the defence against pathogens?

Answer 10

There are antibacterial enzymes in tears

Question 11

Name the primary lymphoid organs

Answer 11

Bone marrow and the thymus gland

Question 12

Why are the thymus gland and bone marrow primary lymphoid organs?

Answer 12

Primary lymphoid organs are where lymphocytes are formed and mature. They provide an environment for stem cells to divide and mature into B- and T- cells.

Question 13

Name the secondary lymphoid organs

Answer 13

Lymph nodes, tonsils, spleen, Peyer’s patches, and mucosa associated lymphoid tissue (MALT).

Question 14

What happens in secondary lymphoid organs?

Answer 14

Secondary lymphoid tissues are arranged as a series of filters monitoring the contents of the extracellular fluids. Secondary lymphoid tissues are also where lymphocytes are activated.

Question 15

What is lymph?

Answer 15

A colourless fluid containing white blood cells, which bathes the tissues and drains through the lymphatic system into the bloodstream.

Question 16

Name the immunological protection organs

Answer 16

Tonsils, lymph nodes, thymus, spleen, Peyer’s patches, appendix, bone marrow

Question 17

What is the lymphatic system?

Answer 17

The lymphatic system is a system of lymph vessels and lymph nodes that run throughout the body. It also plays a role in:
fighting bacteria and other infections
destroying old or abnormal cells, such as cancer cells

Question 18

What is the first line of defence?

Answer 18

The exterior non-specific defence

Question 19

What’s the second line of defence?

Answer 19

The interior non-specific defence

Question 20

What does the interior non-specific defence include?

Answer 20

Phagocytic white blood cells
Antimicrobial proteins
Inflammatory response

Question 21

What’s the third line of defence?

Answer 21

The specific defence

Question 22

What does the specific defence include?

Answer 22

Lymphocytes

Antibodies

Question 23

Which is the innate defence system?

Answer 23

The non-specific defence (interior)

Question 24

Which is the adaptive defence system?

Answer 24

The specific defence

Question 25

Which is faster, the innate immunity or adaptive immunity?

Answer 25

The innate immunity because it can respond to anything

Question 26

Cells that mediate the innate immunity

Answer 26

Macrophages
Natural killer cells
Neutrophils
Basophils

Question 27

Cells that mediate the adaptive immunity

Answer 27

B cells

T cells eg CD4, CD8 T cells

Question 28

Briefly describe neutrophils

Answer 28

Most abundant WBC (70%)
Important in fighting early phases of bacterial infections
Engulf and destroy microbes at infected sites

Question 29

Briefly describe macrophages

Answer 29

Important in long-lasting infections
Pseudopodia, migration and phagocytosis
Largest phagocytes, long lived
Clean up dead neutrophils and tissue debris
Eg. lung alveolar; brain microglial cells; histiocytes in connective tissues, red pulp of spleen

Question 30

Briefly describe natural killer cells

Answer 30

Not as differentiated
Involved in killing virus-infected cells, transplanted bone marrow cells and malignant tumour cells
Attack cells with surface membrane change (loss of MHC I molecule)
Pore insertion (perforin)
Cell lysis

Question 31

When does the specific body defence develop?

Answer 31

It develops shortly after birth and during first months in response to pathogens you encounter

Question 32

Why is it called the adaptive immune system?

Answer 32

Its responses are specific and targeted against particular pathogen

Question 33

What are antigens?

Answer 33

A toxin or other foreign substance which induces an immune response in the body, especially the production of antibodies.

Question 34

How are antibodies produced?

Answer 34

B cell binds to antigen via membrane antibodies
Activated lymphocyte, assisted by helper T cells
Transforms into plasma cell (larger)
Secretion of antibodies into circulation

Question 35

What are the different classes of immunoglobulin?

Answer 35

IgG (72%)
IgA (8%)
IgM (15%)
IgD (1%)
IgE (4%)

Question 36

Active naturally acquired immunity

Answer 36

This comes from infection/ contact with a pathogen

Question 37

Passive naturally acquired immunity

Answer 37

This comes antibodies that pass from mother to child via placenta/ breast milk

Question 38

Active artificially acquired immunity

Answer 38

This comes from being vaccinated

Question 39

Passive artificially acquired immunity

Answer 39

This comes from an injection of immune serum