Lecture 5- Microbes, immunity and disease

Question 1

A virus is?

Answer 1

A piece of nucleic acid with a protein coat.

Some have an envelope that contains some of the host cells.

Question 2

Flavivirus

Answer 2

RNA virus that cause a large range of diseases, often spread by mosquitoes.

Question 3

Antibody

Answer 3

immune protein that binds to an antigen

Question 4

Subclinical

Answer 4

infectious disease that triggers the immune system, but NO SYMPTOMS

Question 5

What can cause febrile infant symptoms?

Answer 5

It is not always the infectious agents, but often our bodies response to them (out inflammatory pathway/immune response)

Question 6

What determines recovery and why doesn’t everyone ‘catch it’

Answer 6

It’s our bodies individual responses/pathways that determine the length/intensity and whether we are vunerable

Question 7

What of viruses can be recognised?

Answer 7

virus capsid particles
cells damaged by infection
virus infected cells (bits of virus end up on the viral surface)

Question 8

What of bacteria/fungi can be recognised?

Answer 8

bacterial surface antigens
bacterial metabolites
cells damaged by infection

Question 9

What does bacteria release that makes it harmful

Answer 9

hexotoxins

Question 10

What of parasites can be recognised?

Answer 10

surface shapes
life cycle changes
cells damaged by infection

Question 11

What allows parasites to evade the immune system?

Answer 11

Their constantly changing life cycle

Question 12

What could be an issue is a child has had many attacks of an illness (eg- ‘cough and wheeze’)

Answer 12

This could indicate an ‘immunologic deficiency’

Question 13

Why are children more susceptible to illness then adults>

Answer 13

1) Lower exposure to pathogens/bacteria so immune system has a smaller ‘memory’
2) Lack of appreciation of symptoms (slower diagnoses)
3) Not through the vaccine regime

Question 14

What does a high temp and lymphadenopathy indicate?

Answer 14

The body is having an immune response that istriggering a physiological change.

Question 15

Steps of phagocytosis

Answer 15

adherence
membrane activation
phagosome formation
fusion and digestion
release of degraded products

Question 16

Two types of blood phagocytes?

Answer 16

1) Granulocytes (neutrophils- short lived)

2) blood monocytes (monocytes - longer lived)

Question 17

What is the complement system?

Answer 17

An alternative way to stimulate inflammation & promote phagocytosis. It does this by infections (bacterial) activating a cascade of blood-derived proteins

Question 18

Steps of the complement system?

Answer 18

1) 1st complement components (series of proteins) work together to form an ENZYME that recognises a surface antigen/shape on bacteria
2) this activates a cascade of other complement component proteins ‘complement activation cascade’
3) These activated parts help us to deal with tissue damage/infection

Question 19

What are the functions of the complement system/what do the activated CC do?

Answer 19

1) Opsonization – enhancing phagocytosis of antigens. C3b has most important opsonizing activity (by civalently binding to surface of bacteria)
2) Chemotaxis – attracting macrophages and neutrophils (by forming chemotactic gradient)
3) Vascular permeability - Changes the blood vessel permeability, making the leakier (redness, swelling)

Question 20

What of the complement system do neutrophils recognise for complement-mediated opsinisation?

Answer 20

C3b complement components

Question 21

What do neutrophils usually recognise?

Answer 21

Bacterial cell wall shapes

Question 22

Opsonization

Answer 22

Enhancing phagocytosis by coating the thing to be phagocytosed with molecules the phagocyte is able to bind to with a high affinity eg) C3b molecules

Question 23

What are phagocytes of the RES (reticuloendothelial system)

Answer 23

different types of macrophage like cells all derived from bone marrow stem cells.
These are strategically placed in areas that they will encounter particles (alveolar macrophages of the lungs)

Question 24

What is lymph?

Answer 24

Fluid that has leaked out of capillaries into surrounding tissue due to hydrostatic pressure. It completes its body circuit outside of the blood

Question 25

Why do you get more fluid movement from blood into tissues during infections?

Answer 25

immune response to tissue damage leads to acute inflammation, enhancing vascular permeability and leads to tissue swelling

Question 26

How does fluid move through the lymphatics system

Answer 26

it’s ‘pumped’ by the normal muscular acitivity of the body squeezing/dilating the lymphatic vessels. Backflow is prevented by one-way leaf valves.

Question 27

How does the lymphatics system control swelling?

Answer 27

It is a system that eventually returns the fluid back into the bloodstream, reducing swelling.

Question 28

Lymph nodes

Answer 28

Secondary lymphoid organs along lymphatic tree of the adaptive immune system. Major site of lymphocytes. Filter material from fluid and expose the immune system to it. Small broad-bean shaped

Question 29

How would the lymph nodes know about an infection in another distant area?

Answer 29

Fluid drained from the infected/damaged tissue is likely to carry material from the infectious agent or of cells damged.

Question 30

What happens if you block lymphatic vessels

Answer 30

they cannot drain, you get excessive swelling ‘lymphedema’ and eventually necrosis of tissue

Question 31

Secondary lymphoid organs

Answer 31

Organs that lymphocytes formed in primary organs migrate to.
Filter foreign matter from body fluids.
Where immune response take place.
eg) spleen, lymph nodes, tonsils, skin

Question 32

Primary lymphoid organs

Answer 32

Where lymphocytes are made.

1) Bone marrow ( makes B lymphocytes)
2) Thymus (makes T lymphocytes)

also fetal liver (source of stem cells and B cells)

Question 33

How were zika virus cases detected?

Answer 33

1) compatible symptoms
2) detection of virus RNA in blood by PCR
3) detection of immune AB specific for zika

Question 34

PCR is?

Answer 34

PCR (short for Polymerase Chain Reaction) is a relatively simple and inexpensive tool that you can use to focus in on a segment of DNA and copy it billions of times over. PCR is used every day to diagnose diseases, identify bacteria and viruses

Question 35

Endemic?

Answer 35

virus/disease alway present at a relatively stable level

Question 36

Epidemic

Answer 36

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