CP1: Acute inflammation

Question 1

What is acute inflammation

Answer 1

response of the microcirculation to injury and it is an all purpose defence mechanism to contain and isolate the injury to achieve healing and repair

Question 2

Where do these inflammatory processes occur;

1. Hepatitis
2. Endocarditis
3. Cystitis
4. Dermatitis
5. Pleuritis (pleurisy)
6. Pneumonitis (pneumonia)

Answer 2

1. liver
2. heart
3. bladder
4. skin
5. lungs
6. lungs

Question 3

Give examples of exogenous causes of inflammation

Answer 3

Trauma, infection, chemicals, temperature, radiation

Question 4

Give examples of endogenous causes of inflammation

Answer 4

anoxia (caused by hypoxia), antigen-antibody complexes, body chemicals, metabolic products

Question 5

What are the macroscopic changes seen (cardinal signs)

Answer 5

• redness
• swelling
• heat
• pain
• loss of function

Question 6

What are the microscopic changes occuring

Answer 6

1. Initial constriction followed by immediate dilation of vessels thus causing redness
2. Increased blood flow to site
3. Increased permeability of vessels due to endothelial cells pulling together creating leaky vessels allowing WBCs to flow out and stimulate an immune response
4. Migration of leucocytes through wall causes oedema

Question 7

Why is there protein deposition in inflamation

Answer 7

This stops bleeding by creating a mechanical barrier (fibrin clot)

Question 8

What is extravasation

Answer 8

This is the movement of WBCs out of capillaries into the surrounding tissue

Question 9

How does extravasation occur

Answer 9

1. Margination = where WBCs gather at endothelial wall and there is rolling as the WBCs aren’t firmly attached
2. Pavementing is where there is stable adhesion and firm attachment to the endothelium
3. Transmigration (diapedesis) ; to the site of injury through the endothelium

Question 10

What is the first cell to arrive at the site of injury

Answer 10

Neutrophil polymorphs (6-24 hours)

• mobile, phagocytic, responds to chemotaxis
• segmented nucleus, granular cytoplasm

Question 11

What is the second cells to arrive at the site of injury

Answer 11

Eosinophils

• especially in allergy and helminth infections
• these are bilobed red granules larger than RBCs

Basophils/mast cells

• blue/purple cytoplasm
• degranulates with release of vasoactive amines

Question 12

What is the third cell to arrive at the site of injury

Answer 12

Monocytes/macrophages (after 24 hours)

• these circulate/ are in the tissue and are the second main cell of acute inflammation
• mobile, phagocytic, responds to chemotaxis
• bean shaped nucleus and copious cytoplasm

Question 13

What is chemotaxis

Answer 13

The movement of organisms in response to chemical changes this occurs in the presence of

• bacteria, fungi, immune complexes, toxins
• complement components, lipoxygenase products
• WBC breakdown products

Question 14

What are the two ways in which phagocytosis can be initiated in acute inflammation

Answer 14

1. Mechanical contact = immediate response
2. Opsonisation = opsinosins coat microbes that go unrecognised and this triggers phagocytes; opsinosins are non-specific to the foreign body

Question 15

What is a pseudopod

Answer 15

The cytoplasm of phagocytes that will extend around the pathogen to form a phagosome

• killing and degradation of the contents occurs via lysosomal activity

Question 16

What are the roles of mediators in the acute inflammatory response

Answer 16

To recognise when a threat is gone or to amplify the response by directing WBCs to the site of injury

Question 17

Where are mediators

Answer 17

These direct the WBCs to the site of injury and are released from the damaged tissues

1. Circulating in the plasma (made in liver)
2. Intracellularly (either preformed or synthesised once tissue damage has occurred)

Question 18

What are the clinical features of acute inflammation

Answer 18

• pyrexia
• drowsiness
• lethargy
  (all three are because much energy is used)
• leukocytosis (increased WBCs)
• decreased appetite (not enough energy for digestion)
• acute phase proteins

Question 19

How does acute inflammation result in resolution

Answer 19

• by clearance of injury
• clearance of inflammatory cells and mediators
• replacement of injured cells
• normal functioning resumed (this may require use of antibiotics)

Question 20

How does acute inflammation result in repair

Answer 20

some tissue lost may not be able to regenerate and so it is replaced by granulation tissue and fibrosis meaning it has less than ideal functioning

Question 21

How does acute inflammation result in chronic inflammation

Answer 21

This is when the injury cannot be dealt with and there has been repeated episodes

Question 22

How does acute inflammation result in suppurative inflammation

Answer 22

This is where an exudate is formed by WBC leakage

If the neutrophils, dead cells, bacteria and debris are walled off and surrounded by a fibrous rim, it will become an abscess (well defined radiolucent area) this will stop the spread of infection

Question 23

How does acute inflammation result in septicaemia

Answer 23

This is the worse outcome and could occur if someone is immunocompromised

= When organism gains access to lymphatics then the blood - this has high mortality and a heightened response

Question 24

What are the 5 fates of acute inflammation

Answer 24

1. resolution
2. repair
3. chronic inflammation
4. suppurative inflammation
5. septicaemia

Question 25

What is the purpose of acute inflammation

Answer 25

• all purpose defence mechanism
• produced to contain and isolate injury
• to destroy/neutralise injury
• ideally resolves injury
• achieves healing and repair
• can become chronic

Question 26

What results from permeable vessels (a microscopic change in acute inflammation)

Answer 26

This enhances the migration of cells and dilution of toxins: it stimulates lymphatics/immune response and the deposition of proteins (e.g. fibrin to form a mechanical barrier and stop bleeding)