Health Science - Inflammation

Question 1

What is the purpose of inflammation?

Answer 1

Protection - to isolate, inactivate and remove both the causative agent and dmaged tissue so that healing can take place

Question 2

What is inflammation?

Answer 2

A non specific physiological response to tissue damage.
It is characterised by a series of local events at cellular and tissue level

Question 3

Causes of Inflammation

Answer 3

Microbes - bacteria, viruses, protozoa, fungi
Physical agents - heat, cold, mechanical injury, UV light, radiation
Chemical agents - organic agents such as weed killers, organic poisons. Inorganic agents such as acids or alkalis

Question 4

What is acute inflammation?

Answer 4

Immediate response to cell injury and is usually of short duration

Question 5

Signs of acute inflammation

Answer 5

Redness, heat, pain, swelling, loss of function

Question 6

5 events of acute inflammation

Answer 6

1. Increased blood flow
2. Accumulation of tissue fluid
3. Migration of leukocytes
4. Increased core temperature
5. Pain and suppuration (pus formation)

Question 7

How and why is blood flow increased in acute inflammation?

Answer 7

Dilation of blood vessels is caused by the release of a number of chemical mediators from damaged cells e.g. histamione and serotonin.

Increased blood flow provides more oxygen and nutrients for increased cellular activity that accompanies inflammation

Question 8

How and why is tissue fluid formation increased (swelling) in acute inflammation?

Answer 8

Swelling of tissues (oedema) is caused by fluid leaving local blood vessels and entering interstitial spaces.
This helps in walling off the inflamed area limiting the spread of any infection.
-Can be harmful sometimes

Question 9

How do neutrophils arrive at the site of injury and what is their function

Answer 9

Neutrophils adhere to blood vessel lining via cell adhesion molecules squeezing between the endothelial cells and enters the tissue
Main function is phagocytosis of foreign antigens

Question 10

What other leucocyte besides neutrophil migrates to the site of injury ans what is their function?

Answer 10

After 24 hours, macrophages (tissue monocytes) become the predominant cell type at inflamed site and they persist in the tissue if the situation is not revloved, leading to chromic inflammation

Question 11

Process of the inflammatory response

Answer 11

1. Chemical signals are released by activated macrophages and mast cells at the site of injury causing nearby capillaries to widen and become more permeable.
2. Fluid, antimicrobial proteins and clotting elements move from the blood to the site and clotting begins.
3. Chemokines released by various kinds of cells attract more phagocytic cells from the blood to the injury site
4. Neutrophils and macrophages phagocytose pathogens and cell devris at the site and the tissue heals

Question 12

What is pyrexia?

Answer 12

Increased core temperature in the body

Question 13

Why does body temperature rise in inflammation or especially in infection?

Answer 13

Body temp rises when certain chemicals called interleukins are released from macrophages and granulocytes in response to microbial infection or other causes of inflammation

Pyrexia increases metabolic rate of cells in the inflamed area thus need for increase in oxygen and nutrients - increase in blood flow

Question 14

How does pain occur in inflammation?

Answer 14

Occurs when local swelling compresses sensory nerve endings and is made worse by the chemical mediators of the inflammatory process e.g bradykinin, prostaglandins

Question 15

How can pain promote healing in acute inflammation?

Answer 15

Because it encourages the protection of the damaged site.

Question 16

What does pus consist of?

Answer 16

Dead phagocytes, dead cells, cell debris, fibrin, living and dead mircobes

Question 17

What are pyogenic microbes and what are examples of them

Answer 17

Pus forming microbes - Staphylococcus aureus and streptococcus pyogenes

Question 18

How does chronic inflammation occur?

Answer 18

Acute inflammation may become chronic if resolution (successful outcome) is not complete, i.e. if live microbes remain at the site, as in deep deated abscesses, wound infections and bone infections

Causative agent cannot be eliminated and antigenic persistenmce occurs - may be due to deficiencies in hosts immune response.

Question 19

What types of inflammatory cells are activated in chronic inflammation?

Answer 19

Mainly lymphocytes instead of neutrophils.
Fibroblasts are also activated

Question 20

What do fibroblasts do in chronic inflammation?

Answer 20

They lay down a layer of collagen and cause fibrosis

Question 21

What may the body do if it is unable to clear the infection?

Answer 21

May try to wall it off and form granulomas which are a collection of defence cells

Question 22

Example of an infection that frquently becomes chronic and leads to granulomas forming

Answer 22

Tuberculosis

Question 23

What causes tuberculosis

Answer 23

Causative bacterium is Mycobacterium tuberculosis - resistant to body defences and so pockets of organisms are sealed up in granulomas within the lungs

Question 24

When is fibrous tissue formed?

Answer 24

During healing process when there is a loss of tissue or the cells that are destroyed do not regenerate

Question 25

Process of fibrosis

Answer 25

Begins with formation of granulation tissue, over time new capillaries and inflammatory material afre removed leaving only collagen fibres secreted by large flat cells known as fibroblasts

Question 26

Damaging effects of fibrosis

Answer 26

1. Adhesions - consist of fibrous tissue and may limit movement
2. Fibrosis of infarcts - blockage of blood vessel by a thromus causes an infarction -tissue death - organ damage
3. Tissue shrinkage - as fibrous tissue ages