Response to cell and tissue damage

Question 1

What is sublethal injury?

Answer 1

The loss of homeostasis and it is reversible but if uncorrected leads to cell death.

Question 2

What are the two major types of sublethal injury?

Answer 2

Hydropic/oncosis (where the cell retains too much water)

Fat changes- steatosis (where there is a change in energy balance to the cell accumulates fat)

Question 3

What is autophagy?

Answer 3

Where the cell walls off areas to be ‘eaten’

Question 4

What is atrophy?

Answer 4

where the cell shrinks

Question 5

What is the nature of injury determined by?

Answer 5

Whether it is acute or chronic, mild or severe and the cell type affected

Question 6

what is necrosis?

Answer 6

Death of tissue following bioenergetic failure and a loss of plasma membrane integrity. It induces inflammation and repair

Question 7

Name some causes of necrosis

Answer 7

Ischaemia, metabolic and trauma.

Question 8

Name the different types of necrosis

Answer 8

Coagulative (necrosis in tissue),
Colliquative (necrosis in the brain),
Caseous (necrosis seen in tuberculosis),
Gangrenous (necrosis with rotting tissue),
Fibrinoid (necrosis in a microscopic feature of arterioles),
Fat necrosis (may follow trauma)

Question 9

Describe Apoptosis?

Answer 9

Where individual cells are killed in a control manner and does not trigger inflammation. The cell is broken down into smaller membrane bound fragments which are then destroyed.

Question 10

What are some variations of programmed cell death?

Answer 10

Pyroptosis
Ferroptosis
Necroptosis

Question 11

What does reduced apoptosis cause?

Answer 11

Neoplasia, autoimmune disease and viral infections

Question 12

what does increased apoptosis cause?

Answer 12

Neurodegenerative disorders, HIV infection of T lymphocytes.

Question 13

Describe the differences between apoptosis and necrosis

Answer 13

Apoptosis - physiological or pathological, affects single cells, energy dependant fragmentation of DNA, membrane integrity is maintained, cells shrunk and broken into fragments, no inflammatory response triggered and the cells are phagocytosed.
Nercrosis - pathological, whole cell groups are effected, there is abnormal homeostasis, membrane integrity is lost, cell swells, inflammatory response triggered and its phagocytosed by inflammatory cells

Question 14

Describe coagulative necrosis

Answer 14

Most common type which involves coagulation of cellular proteins.

Question 15

Define coagulation

Answer 15

Where a liquid turns into a semi-solid gel

Question 16

Describe colliquative

Answer 16

Liquefaction with formation of a cystic space in the brain.

Question 17

Describe Caseous

Answer 17

Characteristic of tuberculosis, it is dead tissue with inflammation.

Question 18

Describe Gangrenous

Answer 18

Necrosis with dead tissue

Question 19

Describe Fibrinoid

Answer 19

Fibrin deposited in blood vessel walls

Question 20

what is pyroptosis?

Answer 20

Part of apoptosis then necrosis. It is associated with samonella

Question 21

Define labile, stable and permanent cells

Answer 21

Permanent - have a very limited capacity to replaced (neurons and skeletal muscles)
Stable - Not constantly turning over cells but do have the ability to regenerate if needed. (kidney and liver)
Labile - Always turning over cells so have a large capacity to regenerate (blood, gut and skin)

Question 22

Describe healing by the first intention in the first week

Answer 22

1. Limited cell death
2. Basement membrane disrupted
3. Incision space fills with blood
4. Scab forms
5. Neutrophils move towards clot
6. Epidermis thickens at its cut edges
7. epidermal cells migrate along cut margins of dermis
8. Epithelial cells fuse in the mid line beneath the surface of the scab.
9. Day 3 neutrophils largely replaced by macrophages
10. Day 5 granulation tissue invades incision space
11. Collagen fibres bridge the incision
12. Epidermis recovers to normal thickness.

Question 23

Describe first intention in the second week

Answer 23

During the second week, there is proliferation of fibroblasts, collagen accumulates and leucoytes infiltrate and oedema reduces. Vasculatarity virtually disappears.

Question 24

Describe first intention by the end of 1 month

Answer 24

Scar consists of cellular connective tissue. Tensile strength now increases.

Question 25

Describe healing by secondary intention

Answer 25

Occurs when there is extensive cell loss and there is a large tissue defect that must be filled. This results in more fibrin, more necrotic tissue and the inflammatory response is more intense. Wound contraction reduces size of defect, this can be characterised by the presence of myofibroblasts.

Question 26

Describe briefly bone repair

Answer 26

Haematoma occurs at the break site, a callus is formed and then lamellar bone is laid down.

Question 27

factors that influence bone healing are?

Answer 27

Systemic; age, nutrition, metabolism, circulatory status and hormones
Local; infection, mechanical factors, foreign bodies, size and location and the type of wound

Question 28

Poor scar formation can occur why?

Answer 28

Due to dehiscence (wound bursts open) and ulceration (where there is not enough circulation)

Question 29

What occurs when there is an excessive formation of repair components?

Answer 29

Keloid scar - excessive fibroblast proliferation and collagen production