Responses to cell and tissue injury

Question 1

What is pyroptosis and ferropotosis ?

Answer 1

Both show early features that appear to be Apoptosis then finish by Necrosis

Pyroptosis - Salmonella bugs live in an inflammatory cell like a macrophage, they initiate what looks like apoptosis (genetically programmed and requires energy) then the cell bursts (part apoptosis then necrosis)

Ferroptosis - In the context of oxygen free radicals, oxygen species which could be toxic, then the cell bursts (iron dependant)

Question 2

Define labile, stable and permanent cells ?

Answer 2

Labile cells are always turning over and have a huge capacity for regeneration (blood, skin, gut)

Stable cells aren’t constantly turning over but if required can slowly repopulate (Kidney a nd liver (you can give half of a liver as a transplant and it grows back in 6 weeks).

Permanent cells cannot be replaced once lost (neurones, skeletal muscle)

Question 3

Describe the outcomes of cell and tissue injury ?

Answer 3

Any injury leads to a loss in cellular homeostasis – the consequences of this is what disease is

Question 4

Define the differences between healing and repair?

Answer 4

Healing is a complete resolution – repair is the second closest match to healing

Question 5

Describe the differences between healing by primary and secondary intention ?

Answer 5

Primary intention healing;

• The edges of the wound can be brought together, and healing made
• In skin
• Will have some inflammation as some tissue necrosis will occur due to lethal injury and cells spilling their contents
• Some tissue damage
• Some haemorrhage
• Prevents a big scar and give skin regeneration

Secondary intention healing;

• Tissue is missing so skin cannot be brought together
• May have dirt in the wound that could lead to an abscess
• The base which is damaged has inflammation and haemorrhage, new vessels and granules (granulation tissue) will gradually fill in the gap and restoration occurs with a scar.
• Can prevent abscess formation if clean but will cause scarred tissue

Question 6

What is the definition of an Atrophy?

Answer 6

Cell shrinks as it has lost specialised function or organelles

Question 7

What is the definition of an Atrophy?

Answer 7

Cell shrinks as it has lost specialised function or organelles

Question 8

What is lethal injury?

Answer 8

Lethal cell injury is when the cell will fail to exclude sodium and water, consequentially swelling. until it bursts

Question 9

What happens if the hydronic change is too high in lethal cell injury?

Answer 9

If the hydropic change is too high then too much water will come into the cell, making the cell inefficient and unable to generate enough ATP to increase the function of the sodium potassium pump, causing the cell to burst (necrosis).

Question 10

What is Necrosis?

Answer 10

Necrosis is the death of tissues following a bioenergetic failure. and loss of plasma membrane integrity

Question 11

What does Necrosis cause?

Answer 11

Necrosis;

• promotes inflammation and repair
• Causes Ischaemia (a restriction in blood vessels)
• Causes Metabolic issues
• Causes Trauma

Question 12

What is Colliquative necrosis?

Answer 12

Necrosis of the brain; the. dead area is liquified

Question 13

What is Coagulative necrosis?

Answer 13

Necrosis in most tissues; looks like a firm pale area, with ghost outlines on microscopy

Question 14

What is Caseous necrosis?

Answer 14

Caseous necrosis is seen in Tuberculosis; there is a place yellow semi-solid material (causes an inflammatory response that damages cells)

Question 15

What is Gangrenous necrosis?

Answer 15

Gangrene is necrosis with putrefaction (decaying or rotting body parts); it occurs after vascular occlusion (blockage) or certain infections and appears as black

Question 16

What is Fibrinoid necrosis?

Answer 16

Fibrinoid necrosis is a microscopic feature in arterioles in malignant (very virulant) hypertension

Question 17

What is Fat necrosis?

Answer 17

Fat necrosis may follow trauma and cause a mass, or may follow pancreatitis; Visible as multiple white spots.

Question 18

What is Fat necrosis?

Answer 18

Fat necrosis may follow trauma and cause a mass, or may follow pancreatitis; Visible as multiple white spots.

Question 19

What is Apoptosis ?

Answer 19

Apoptosis is a specific, discrete response that doesn’t promotes an inflammatory response and targets cells

• Cell death that removes a cell discretely
• It removes individual cells instead of groups or tissues

Question 20

What makes apoptosis a better form of cell destruction than necrosis?

Answer 20

Apoptosis is much more controlled and all of the broken up contents is kept within the cell membrane whereas in necrosis the cell membrane is also destructed which is more harmful.

Question 21

What is the the role and features of granulation tissue?

Answer 21

Granulation tissue is responsible for the formation of new blood vessels, fibroblasts and odemedous tissues (watery intercellular spaces)

It is a repair phenomenon and has loops of capillaries which are supported by myofibroblasts.

Inflammatory cells may be present

It actively contracts to reduce the wound size

Question 22

Give the steps for wound healing by first intention and how long each section takes?

Answer 22

1) . Limited cell death
2) . Basement membrane disrupted
3) . Incisional space fills with blood
4) . Scab forms
5) . Neutrophils move towards clot
6) . Epidermis thickens at its cut edges
7) . Epidermal cells migrate along the margins of dermis
- This happens within 24 hours

8) . Epithelial cells fuse in the midline beneath the surface scab
9) . Day 3 - neutrophils largely replaces by macrophages
10) . Day 5 - granulation tissue invades incision space
11) . Collagen fibres bridge the incision
12) . Epidermis recovers to normal thickness
- This part of the process takes 3-7 days

Question 23

What type of healing occurs in bone healing?

Answer 23

Bone healing undergoes both primary and secondary healing as on top of the granulation tissue the collagen scar (secondary) has bone cells that lay down osteoid which becomes calcified and remodels the bone.