Tissue response to injury

Question 1

Discuss the difference between acute and chronic inflammation

Answer 1

Acute inflammation
• It is a coordinated host response to injury
• Pre-programmed
• Results in vascular changes that are local, but can be systemic
• Has evolved to protect against the most common threat from acute injury; bacteria. Thus, the PMN presence

Chronic inflammation
• If injury persists, the it progresses to chronic inflammation
• Chronic inflammation is a long standing injury associated with a long standing response
• What happens is that injury and repair occurs simultaneously
• There is often the appearance of chronic inflammatory granulation tissue

Question 2

Identify the classical signs of acute inflammation.

Explain rubor and calour

Answer 2

• Tumour: swelling
• Dolour: pain
• Rubor: redness
• Calour: heat

Rubor and Calor:
• Caused by vascular dilation
• This results in blood being brought to the surface of the body and thus increases surface temperature LOCALLY
• Neutrophil emigration

Question 3

What are the morphological types of acute inflammation?

Answer 3

Morphological types of acute inflammation
• Suppurative acute inflammation: pus formation
• Serous acute inflammation: clear fluid produced
• Fibrinous acute inflammation: fibrin deposited on a surface

Question 4

What are patterns of chronic inflammation?

Answer 4

Patterns of chronic inflammation

1. Suppuration: formation of pus
2. Chronic inflammatory granulation tissue (new connectivetissueand microscopic blood vessels that form on the surfaces of a wound during the healing process) with fibrosis (excess collagen)
3. Granulomatous: macrophage and lymphocytes predominated

Question 5

Explain what causes tumour in relation to Starlings forces.

Answer 5

• There are two factors involved in the production of swelling: hydrostatic pressure and oncotic/ osmotic pressure
• The relationship between the two is known as starlings forces
• Hydrostatic pressure: pressure a liquid exerts on its surroundings. It pushes fluids outside the capillaries.
• When blood is coming from arteries, the hydrostatic pressure is high. Thus, fluids seeps out from the arterial end of the capillary
• As fluid seeps out from the blood, the solute concentration becomes higher at the venule end of the capillary. Thus, fluids seep back into the blood via osmosis
• Oncotic pressure: blood contains a large number of plasma proteins which displaces the water content in blood. Thus, water tries to diffuse back into the blood via osmosis. It pulls fluids back into the capillaries

Question 6

What are the two types of wound healing?

Answer 6

Regeneration
• Replaces tissue with original tissue
• Very limited in humans
• Only the liver is capable of this

Repair
• Blood clot/ necrotic tissue
• Replaced with granulation tissue (new connectivetissueand microscopic blood vessels that form on the surfaces of a wound during the healing process)
• Matures to scar/ adipose tissue