Lecture Two

Question 1

What is the immune system?

Answer 1

• a collection of organs, vessels, cells and molecules
• a system in constant motion and change (not static)
• a system with access to virtually every part of the body

Question 2

What does the immune system do?

Answer 2

• monitors molecular shapes within body
• distinguishes between self and nonself antigens
• protects us from infection
• speeds up recovery from infection
• helps us maintain adequate relationship with environment we live in

Question 3

What does the immune system respond to?

Answer 3

Molecular shapes. Either

1. Because they are strange shapes
2. Because they are familiar shapes in strange contexts

Question 4

What are antigens?

Answer 4

Molecular shoes the immune system recognises

Question 5

List some sources of antigens

Answer 5

Viruses,
Bacteria,
Parasites
Dust particles,
Cells From other people

Question 6

What can function as an antigen?

Answer 6

Anything big enough and greater than a certain complexity

Question 7

What is innate immunity?

Answer 7

• Non specific immunity
• first line barrier
• not improved by repeated antigen exposure
• consists of physical barriers and biochemical barriers
• if breeched, stimulates adaptive immunity

Question 8

What are some biophysical barriers to microbes?

Answer 8

Skin

Cilia

Question 9

What are some biochemical barriers to microbes?

Answer 9

Lysozyme in tears,

HCl in stomach

Question 10

What are commensal organisms and what is their purpose?

Answer 10

• Organisms that live in harmony with its host.
• bacteria in gut, vagina
• compete with foreign microbes for resources so they don’t survive
• component of innate immunity

Question 11

What does the innate system do when surface barriers are breeches?

Answer 11

• local innate immune factors (phagocytes and complement system) will inhibit microbe multiplication
• attempt to limit damage it causes

Question 12

What are phagocytes ?

Answer 12

• Neutrophils
• sometimes called polymorphonuclear leukocyte s
• ingest and digest foreign material
• have surface receptors that recognise common cell wall components of many types of bacteria

Question 13

Explain phagocytosis

Answer 13

• the process of phagocyte ingesting and digesting foreign material

1. Neutrophil comes into contact with bacteria and adheres to it
2. Adherence activates neutrophil to fold membrane around bacterium
3. Bacterium is taken into a vesicle inside neutrophil
4. Phagosome is formed
5. Neutrophil releases packets of digest enzymes
6. Bacteria is digested
7. Neutrophil releases degraded products

Question 14

What is the complement system?

Answer 14

• component of innate immunity
• a series of ~20 blood proteins which can diffuse out of the bloodstream into tissue spaces of our bodies to limit infections (particularly bacterial)

Question 15

Describe the process of the complement system

Answer 15

1. First complement components bind to bacterial antigen
2. Activates other complement components
3. Other complement components increase vascular permeability, opsonate bacteria, lyse bacterial cell walls, and release chemicals

All which aim to facilitate phagocytosis

Question 16

What does increasing vascular permeability do?

Answer 16

Helps white blood cells get to site of infection quicker

Question 17

What does the release of chemicals do?

Answer 17

Attracting neutrophils to the site

A.k.a chemotaxis

Question 18

What is opsonisation?

Answer 18

Coating the foreign material

Question 19

What does opsonisation do?

Answer 19

Makes foreign material more readily phagocytosed

Question 20

What does lysis do?

Answer 20

Breaches integrity of bacterial cell walls

Question 21

How does immune system recognise antigens?

Answer 21

• immune system has molecular recognition structures
• called receptors
• act as hands
• immune system uses receptors to sense outside world

Question 22

Where are receptors found?

Answer 22

On the surface if cells of immune system (cell surface receptors)

Question 23

Where are soluble receptors found?

Answer 23

In the fluids of the body

Question 24

What are the most common class of soluble receptors called?

Answer 24

Antibodies

Question 25

What is immunological memory

Answer 25

Immune system has adapted to a certain antigen in such a way that it will respond much more rapidly and vigorously if it meets the same antigen

Question 26

What is adaptive immunity

Answer 26

- Specific immunity | - Immunity which is improved my repeated exposure

Question 27

What is acquired immunological tolerance

Answer 27

The state of induced antigen specific immunological unresponsiveness

Question 28

What are the two fundamental processes that living, a process, conserves?

Answer 28

1. Autopoiesis, generating self. All living things continue to build themselves somewhere, 2. Adaptation. They maintain their relationship with things outside themselves

Question 29

Name the two types of receptors

Answer 29

Soluble receptors cell surface receptors

Question 30

What are soluble receptors

Answer 30

(antibodies) binding of antibody to virus allow other molecules in the body to recognise. Cells are neutralised.

Question 31

What are cell surface receptors

Answer 31

the cell machinery is used by the virus. Proteins are made and some will appear on the surface of the cell. When cytotoxic lymphocyte binds to that virus infected cell, it will kill it and kill itself. Reduced the possibility of other cells being infected.

Question 32

List some biophysical barriers to infectious agents. Give examples

Answer 32

1) skin - most infectious agents cannot penetrate - importance of this barrier particularly seen in patients with serious burns - sweat and sebacceous secretions e.g. Lactic acid, fatty acid, generate direct inhibitory effects and low pH 2) cilia - lining nasopharynx, wafts dust particles and infectious agents out ? 3) mucous in nose - traps microbes 4) acid lining stomach - acidic environment kills microbes

Question 33

List some biochemical barriers to infectious agents. Give examples

Answer 33

1) Lysozyme in most secretions e.g. Tears,saliva - enzyme is a bactericide - causes bacteria to fall apart 2) sebaceous gland secretions - oil to generate direct inhibitory effects 3) commensenal organisms in gut and vagina - compete with microbes (for resources etc so foreign microbes don't survive) 4) spermine in semen. - bacteriacide

Question 34

What are the components of the adaptive immunity

Answer 34

* Antibodies, complement cytokines | * Lymphocytes, monocytes, antigen presenting cells

Question 35

What are the components of innate immunity

Answer 35

* Lysozyme complement, acute phase proteins, interferon * Phagocytes, natural killer cells. * Lysozyme complement, acute phase proteins, interferon * Phagocytes, natural killer cells. * Lysozyme, complement, acute phase proteins, interferon * Phagocytes, natural killer cells.

Question 36

How does a phagocyte know what to eat?

Answer 36

Phagocyte can recognise what to ingest due to the complement system A Series of 20 proteins that diffuse from blood stream to tissue spaces in our body act to limit infections ( particularly bacterial) and causes an amplifying enzymatic cascade. 1. VASODILATION- change vascular permeability to facilitate neutrophil access to site of infection 2. CHEMOTAXIS- attracting neutrophils to site 3. OPSONIZATION - coating foreign material spot make it more readily phagocytised (bacteria more easily recognised) 4. LYSIS - breaching integrity of bacterial cell walls.

Question 37

What is an epitope

Answer 37

part of an antigen molecule where an antibody attaches itself

Question 38

What is a receptor

Answer 38

Molecular recognition structure to recognise antigens

Question 39

Outline the relationship between primary contact, secondary contact ahd immunological memory

Answer 39

* Primary contact with a nonself antigen stimulates immune response * Immune system builds up memory * Secondary contact with same antigen leads to better immune response (before symptoms are noticed