Overview Of The Immune System L07

Question 1

How does the body differentiate between self and non-self body cells

Answer 1

This is achieved through ‘self’ marker molecules associated with the surface of our body cells

Question 2

What size roughly are viruses

Answer 2

10-1000 nm

Question 3

What size roughly are bacteria

Answer 3

0.1-5 um

Question 4

What size roughly are protozoa

Answer 4

5-200 um,

Question 5

What size roughly are fungi

Answer 5

3-10 um

Question 6

How do viruses, bacteria, protozoa and fungi infect humans

Answer 6

Viruses : Intracellular infection (also extracellular)
Bacteria: Largely extracellular (some exceptions)
Protozoa: Intracellular and extracellular
Fungi: Extracellular

Question 7

What is the innate immune system

Answer 7

First line of defence consisting of physical barriers to prevent entry of pathogens, phagocytes to digest microorganisms and chemical mediators to trigger recruitment and activation of immune cells (inflammation)

Question 8

What is the adaptive immune system

Answer 8

Formed principally by lymphocytes (T and B cells) which contain specific receptors to recognise specific antigens associated with pathogens. Also retains memory of previous encounter with the pathogen

Question 9

T cells carry out …………. mediated responses

B cells carry out ………….. mediated responses

Answer 9

1) cell

2) antibody

Question 10

Examples of the innate immune system

Answer 10

Skin, acid in stomach, acidic skin secretion, mucus and cilia, lysozyme in tears and other secretions, flushing of urinary tract and theres many non-pathogenic microorganisms present on the external and internal surfaces competing for essential nutrients.

Question 11

What do Monocytes differentiate into

Answer 11

Macrophages

Question 12

How do phagocytes arrive at site of inflammation

Answer 12

Chemotaxis (response to a chemical stimulus)

Question 13

How is complement system activated

Answer 13

Recognition proteins bind to a wide range of structures including pathogens, or structures associated with cellular damage/debris, leading to a coordinated cascade of enzymatic cleavage events generating complement protein fragments

Question 14

What does the complement system do

Answer 14

The complement protein fragments: recruit phagocytes, enhance phagocytosis, membrane damage to foreign cells

Question 15

What do natural killer cells do

Answer 15

Nk cells are neither T or B cells, and they are specialised to kill virally infected cells and tumour cells

Question 16

What constitutes of the primary lymphoid tissue

Answer 16

Bone marrow and thymus where T and B cells differentiate into mature antigen recognising cells

Question 17

What happens in secondary lymphoid tissues

Answer 17

Lymphocytes are activated, proliferation and differentiation occurs

Question 18

What consists of the adaptive immune responses

Answer 18

Lymphocytes which have specificity and memory

Question 19

Describe the structure of an antibody

Answer 19

Antibodies are tetrameric polypeptide structures (immunoglobulin)
Consists of 2 identical (longer) heavy chains and 2 identical (shorter) light chains
The variable region is called Fab
The constant region is called Fc and interacts with cell surface receptors and activates complement

Question 20

What are the 5 antibody subclasses

Answer 20

IgA, IgA, IgM, IgD, IgE

Question 21

How does an antibody function

Answer 21

Binds directly to pathogens preventing them from entering/damaging healthy body cells
Neutralises bacterial toxins
Activate complement
Facilitate phagocytosis by opsonisation

Question 22

Dendritic cells affect what type of cell stimulation

Answer 22

T-cells

Question 23

Differences between the innate and adaptive system

Answer 23

Innate:

• rapid response
• Anatomic barriers, phgocytes, chemical mediators
• Non-specific
• No memory

Adaptive:

• Slow response
• B and T cells
• Highly specific
• Memory and maturation of response