Inflammation and wound healing

Question 1

Inflammation

Answer 1

non specific protective response of the body to threats. Involves specialized cells, mediators and inflammatory enzymes which work together to destroy or contain foreign bodies
May be acute or chronic

Question 2

Acute inflammation

Answer 2

occurs over seconds, minutes, hours or days

rapid response and results in increased blood flow to affected area

Question 3

Chronic inflammation

Answer 3

occurs over long periods

can occur when acute inflammation does not resolve

Question 4

Five cardinal signs of inflammation

Answer 4

ruber (redness)
calor (heat)
tumor (swelling or oedema)
delor (pain)
functio laessa (loss of function)

Question 5

Acute inflammation involves several constituents of the immune and vascular systems

Answer 5

Infection
Physical injury
Radiation
Chemical exposure
Thermal burns
Tissue necrosis
Foreign antigens
Immune responses

Question 6

Inflammatory response process

Answer 6

vasodilation ( increased blood flow)
increased vascular permeability ( capillaries allow fluid and proteins to leak into the tissue)
migration of blood borne leukocytes (neutrophils/ polymorphs) into the tissue

Question 7

How the inflammatory response works

Answer 7

Acute inflammation results in increased blood flow to the affected region. The blood capillaries become more permeable and fluid, inflammatory mediators and leukocytes enter the tissue. Vasodilation and vascular permeability are brought about by the action of histamine, serotonin and other chemical mediators. The fluid that leaks out of the blood vessels generally contains proteins and is therefor called exudate. This fluid will eventually return to the circulatory system via the lymphatic system.

Question 8

Inflammatory mediators

Answer 8

soluble molecules that act locally. Interleukin 1 (IL-1), interleukin 6 (IL-6) and tumor necrosis factor are important inflammatory mediators that induce the acute inflammatory response

Question 9

How do neutrophils leave the blood vessels and enter the tissue>

Answer 9

Presence of a number of mediators including TNF alpha induce endothelial cells to increase synthesis of surface adhesion molecules called selectins
The selectins then interact with the neutrophil polymorphs causing the neutrophil polymorphs to roll along the vessel wall
The rolling polymorphs express integrins which bind to intracellular adhesion molecules. This binding stimulates the move through the wall of the blood vessel by pseudopodal movement
Once out of the blood vessels the neutrophil polymorphs move following a chemokine (e.g. C5a ) concentration gradient to the area of damage. C5a also activated the neutrophils causing them to increase in size and synthesize additional toxic granules. The neutrophil polymorphs along with macrophages, phagocytose microbes tagged with C3b , an opsonin and kill them

Question 10

Neutrophil polymorphs are recruited to the tissue via these steps

Answer 10

Migration-polymorphs lie along the inner wall of the blood vessels
Rollin- polymorphs roll along the vessel wall
Adhesion- polymorphs stick to the vessel wall by means of adhesion molecules
Emigration and chemotaxis- polymorphs move from the vessels into the surrounding tissues and from there to the source of the damage, following a chemokine gradient
Activation- polymorphs become enlarged and armed to kill invaders
Phagocytosis- organism is engulfed in phagosome and this is fused with the lysosome
Killing- phagocytized bacteria are killed

Question 11

Yellow exudate

Answer 11

pus

Question 12

4 possible outcomes of acute inflammation

Answer 12

complete resolution ( no permanent damage)
scarring
abscess formation accumulation of pus, bacteria contained but not killed ( pimple)
progression to chronic inflammation

Question 13

Main cells in acute and chronic inflammation

Answer 13

acute- neutrophil polymorphs

chronic- T lymphocytes, B lymphocytes and antigen presenting cells including macrophages

Question 14

Two main conditions under which chronic inflammation develops

Answer 14

viral infection

autoimmune reactions

Question 15

Chronic suppurative inflammation

Answer 15

factors that cause acute inflammation don’t resolve in a few days
is a persistent acute inflammation typified by infiltration with neutrophils and formation of pus

Question 16

Examples of suppurative inflammation

Answer 16

persistent bacterial infection
abscess formation
sequestration of acute inflammation

Question 17

Granulomatous inflammation

Answer 17

special type of chronic inflammation that occurs when a piece of inert foreign material or an infectious agent is present that cannot be digested

Question 18

Granulomas

Answer 18

collections of epithelioid macrophage cells that have stuck together these are the main infiltrating cells along with some fibroblasts and lymphocytes

Question 19

Causes of granulomatous inflammation

Answer 19

infection by certain pathogens
foreign material
drugs that cause liver granulomas
autoimmune diseases
some tumors
sarcoidosis

Question 20

Tuberculosis

Answer 20

caused by the bacterium Mycobacterium tuberculosis
most people are asymptomatic
Primary infection usually occurs when the infectious droplets are inhaled and lodge in the lung alveoli
When in the lungs the bacilli are engulfed by the alveolar macrophages but the macrophages are incapable of digesting bacterium. The bacilli multiply inside the macrophages and form lesions. The macrophages then surround the foci of infection and form granulomas which wall of the infection

Question 21

Structure of the granuloma

Answer 21

central area- contains multinucleated giant cells containing bacilli
midzone- contains epithelioid cells
outer zone- consists of fibroblasts lymphocytes and monocytes
center- undergoes caseous necrosis and the granulomas break down releasing infected matter into the lungs. This causes patient to cough

Question 22

Inside the granulomas most bacilli die from?

Answer 22

acidosis and anoxia

some become dormant and can be reactivated later

Question 23

miliary distribution

Answer 23

distributed to all organs

Question 24

Wound healing

Answer 24

complex process in which the body’s tissues repair themselves after injury

Question 25

Effective healing requires

Answer 25

adequate blood supply
nutrients
vitamins
immobilization of healing tissue
absence of infection
viable cells

Question 26

The healing process

Answer 26

first few minutes after injury platelets aggregate and fibrin and fibronectin leak out of the site of injury. This results in formation of a scab which controls bleeding.

Question 27

Wound healing may be primary or secondary intention. Explain

Answer 27

Primary intention occurs when the wound edges are neat and can be brought together. It leaves minimal scarring
Secondary intention leaves scarring

Question 28

Healing may be imperfect and result in

Answer 28

scarring
keloid formation
abscess or empyema formation
wound breakdown
malunion/ fibrous union
traumatic neuroma

Question 29

What is a haematoma

Answer 29

localised gathering of blood within the tissue outside the blood vessels. It is due to damage of blood vessels which release blood into the subcutaneous tissue

Question 30

Different infective agents include

Answer 30

bacteria
virus
fungi
protozoa
helminths

Question 31

Illness is not always spread from obviously sick individuals but also:

Answer 31

carriers
some diseases contagious during incubation
others are acquired from animals or environmental sources

Question 32

Routes of transmission include

Answer 32

direct contact
indirect contact
air, food, water borne transmission
animal vectors
transplacental

Question 33

Most common portals of entry include

Answer 33

gastrointestinal
urinary 
genital
damaged skin
respiratory tract