Inflammation and tissue repair

Question 1

What is inflammation?

Answer 1

Inflammation is the body’s response to damage/ injury, creating an environment for repair and restoration. it is a non-specific immune response, occuring in connective tissues

Question 2

What are the 2 types of inflammation?

Answer 2

acute & chronic

Question 3

What is the difference between chronic and acute inflammation?

Answer 3

Acute inflammation tends to be beneficial in repairing and restoring damage, lasts for a couple of days, at most a week
Chronic inflammation is a prolonged tissue response lasting from weeks to months, it includes inflammation, tissue necrosis and tissue repair all occurring simultaneously

Question 4

Why is chronic inflammation dangerous?

Answer 4

It can cause harm to healthy cells as well as unhealthy cells, it can contribute to diseases such as cancer, diabetes, and heart disease. Chronic inflammation is more likely to occur in those who suffer autoimmune conditions, e.g., rheumatoid arthritis

Question 5

Causes of chronic inflammation?

Answer 5

Prolonged exposure to toxic agents e.g., carcinogens
repeated episodes of acute inflammation
autoimmune conditions e.g., type 1 diabetes
persistent infection from bacteria

Question 6

Factors that may induce inflammation

Answer 6

Toxins
viruses
bacteria
Funghi
allergies
stress
Highly processed food e.g., fast food, high refined sugars / carbs

Question 7

What is the function of inflammation?

Answer 7

It limits the spread of pathogens and kills them
It prepares tissue for repair
It removes any dead cells/pathogens from tissue
It alerts the immune system to a threat of infection

Question 8

What are the 4 signs of inflammation

Answer 8

Redness
Pain
Swelling
Heat

Question 9

Why does inflammation create heat?

Answer 9

Heat (hyperemia) is caused by increased blood flow to the site of damage, this is important as the temperature rise increases the rate of enzyme activity within cells, it also inhibits the growth and spread of bacteria. This speeds up the repair process

Question 10

Why does inflammation cause redness?

Answer 10

As the blood flows closer to the skin surface, the sit of damage, the blood vessels vasodilate, widening the diameter, it brings more WBC and chemicals to site of infection

Question 11

Why does inflammation cause swelling?

Answer 11

Swelling (odema) is a build-up of fluid, this is because the capillaries become more permeable causing fluid to leak out into surrounding tissues. swelling limits the movement of infection from spreading, keeping it in one location aids in the speed of repair

Question 12

Why does inflammation cause pain?

Answer 12

Chemicals such as histamines are released which stimulate the nerve endings creating a sensation of pain. If something is painful we are more likely to rest which aids in the speed of recovery, as it prevents movement from site of injury

Question 13

Technical 5th sign of inflammation

Answer 13

Loss of function, created by swelling and pain sensation, limiting the movement aids in repair and restoration

Question 14

Explain Step 1 in the inflammation response

Answer 14

A tissue suffers damage which causes mast cells to release chemical e.g., histamines and cytokines.
Which diffuse into blood vessels. This causes the blood vessels to become leaky, causing the movement of fluid out of capillaries into surrounding tissues causing swelling. Vasodilation also causes the redness and heat associated with inflammation. This slows down transmission of any bacteria

Question 15

Explain stage 2 of inflammation

Answer 15

In acute inflammation neutrophils/phagocytes flood the site of damage and engulf and digest bacteria, macrophages appear 8-12 hours later due to maturing from monocytes.
Phagocytosis occurs
WBC release cytokines which attracts more WBC to site of infection (positive feedback mechanism)

Question 16

Explain stage 3 in inflammation

Answer 16

Enzymes break down histamine, which causes phagocytes to no longer be attracted to the site of infection. WBC and platelets undergo cell division to repair tissue

Question 17

Explain the process of phagocytosis

Answer 17

When bacteria is present it will release chemicals that are detected.
The phagocytes are attracted to these chemicals, engulfing the bacteria in it’s vacuole, forming a phagosome. The phagosome then combines with lysosomes within the cell creating a phagolysosome, the lytic enzymes in the lysosomes are involved in the digestion of the bacteria. Any useful products are absorbed by the cell e.g., glucose, proteins, the rest are excreted out of the cell via exocytosis

Question 18

Function of histamine

Answer 18

A signaling chemical involved in infections. allergies and anaphylactic shock. Histamine increases the permeability of blood vessels (vasodilation)

Question 19

Function of kinins

Answer 19

increases permeability of blood vessels (vasodilation)

Question 20

Function of prostaglandins

Answer 20

Intensify kinins and histamine effect

Question 21

Function of complement

Answer 21

They circulate the blood, become active when they leave the capillaries, and interact with bacteria, capable of damaging bacteria cell membrane, aid in making neutrophils more effective

Question 22

Function of leukotrienes

Answer 22

Vasodilation and phagocytic attachment

Question 23

Define leukocytosis

Answer 23

A process that occurs to increase WBC count in blood, it occurs due to inducing factors being released from damaged cells, stimulating production of neutrophils from bone marrow

Question 24

Define margination

Answer 24

This refers to the action of phagocytes clinging to the inner wall of capillaries, Inflamed tissue releases CAMS (cell adhesive molecules), which act as a guide for phagocytes, leading them to the damage, incoming neutrophils bind to the tissue and become activated, neutrophils release further CAMS allowing more to bind

Question 25

Define diapedesis

Answer 25

Involves chemical signaling, allowing neutrophils to flatten and squeeze through gaps in capillaries, through gaps in endothelial cells

Question 26

Define chemotaxis

Answer 26

chemotactic agents have been released which signal neutrophils and other WBC to move to damaged tissue

Question 27

What is pus?

Answer 27

Can be created by phagocytes, a mixture of dead cells, debris and dead WBC

Question 28

What is a monocyte?

Question 29

What is a macrophage?

Answer 29

A mature form of monocyte, involved in phagocytosis

Question 30

Name the 4 steps in tissue repair

Answer 30

Haemotoma, scab formation, granulation phase & regeneration

Question 31

Explain stage 1 in tissue repair

Answer 31

Day O, tissue is damaged, which stimulates inflammation and early haemostasis. A clot is formed to minimise blood loss and act as a physical barrier. Vasospasm occurs reducing blood loss, collagen fibres become activated and release clotting factors. Soluble fibrinogen is converted to insoluble fibrin via activation of thrombin enzyme. Fibrin fibres interlink to stabilize blood clot

Question 32

Explain stage 2 in tissue repair

Answer 32

Scab formation occurs day 0-3, Stabilizing of blood clot continues. Inhibitor of clots control the size of clot. Neutrophils and macrophages start to clear debris and invading pathogens, Blood clot dries to rid of pathogens and moisture. where there is a lot of phagocytic activity pus may form

Question 33

Explain stage 3 in tissue repair

Answer 33

Granulation phase: day 4-14, clot is replaced by granulation tissue, this contains new capillaries which supply a blood flow. Fibroblasts (mesenchymal cells) are activated and secrete a matrix, local growth factors and collagen fibres to replace clots. Fibroblasts pull edges of wound together to form cross-bridges of collagen fibres to stabilise the area

Question 34

Explain stage 4 in tissue repair

Answer 34

Occurs from day 14 onwards, regeneration stage. Fibroblasts become inactive or undergo apoptosis. New epithelium forms, causing the scab to detach, This new tissue will contain a different arrangement of blood vessels and collagen fibres, this is why scar tissue looks different, looks like a white line on skin surface