P2- Injury, Healing and Repair Flashcards Preview

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Flashcards in P2- Injury, Healing and Repair Deck (46)
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1

Name the causes of cellular / tissue injury.

-Physical - mechanical , thermal ,electric , Barotrauma
-Chemical - drugs , metabolic , hypoxia , nutrition
-Infectious - cytolysis , toxins , immune response
-Immunological -may contribute to other categories
-Genetic -may contribute to other categories

2

What can. cause cellular injury?

many agents

3

Describe mechanics by which cell injury manifest , at a cellular level.

Mechanisms by which cell injury is manifest may be very similar for different causal agents

4

what are the different phases of cellular injury?

-reversible
-irreversible

5

what is cellular injury recognised by?

-morphological / Structural features
-biochemical features

6

what does severe damage in cellular injury lead to?

cell death

7

What are the vulnerable intracellular systems of mechanics of cellular injury?

-Cell Membrane Integrity
-Aerobic Respiration
-Protein Synthesis :
Enzymes
Structural Proteins
-Genomic Integrity

8

what is closely related in mechanisms of cellular injury?

structural and biochemical aspects

9

what are types of mechanics of cellular injury?

-deficiency of metabolite (o2)
-impaired metabolism (respiration and syntheis e.g of proteins)
-Membrane damage (structural -physical/chemical, functional- failure of ion pumps , calcium ion homeostasis )
-DNA damage or loss (radiation, drugs, free radicals)

10

describe disruptions to membrane integrity.

-Mechanical disruption
Physical trauma, osmotic, freezing, complement, cytotoxic proteins in Tc cells
-Functional disruption
Depletion of ATP, alterations to lipids and protein in the cell membranes e.g. cross linking induced by free radicals
-CSM and internal membranes.

11

Describe impaired metabolism.

Respiration:
-Lack of oxygen e.g blood supply, CO
-Block mitochondrial respiratory chain e.g. cyanide binding to cytochrome oxidase
Protein synthesis;
-Ricin blocks translation at ribosome
-Decreased ATP will contribute

12

Describe DNA damage / loss.

-May not be immediately apparent
-Dividing cells particularly affected – or when there is a growth stimulus
-Non-lethal damage may introduce heritable abnormality that can lead to disease in daughter cells e.g. neoplasia
-Free radicals
Highly reactive and chemically unstable species

13

Describe metabolite deficiency.

Any essential metabolite:
Oxygen:
-Aerobic metabolism
-Anaerobic pathways induce acidosis
-Ischaemia and infarction
-Reperfusion injury

Glucose
-Some cells have high requirements and sensitive to deficiency.
-Diabetes mellitus - poor utilisation - absolute or relative deficiency of insulin

Hormones
-Lack of trophic hormones leads to target cell atrophy

14

what does the severity of damage and the effects on the cells and tissues depend on?

-Type, magnitude and duration of injury
-The type of tissue affected
-The proportion / numbers and types of cells affected
-The effect on the connective tissue scaffold
-The effect on other tissues and structures e.g. blood vessels

15

what are the stages of cellular insult?

-Normal cell
-cellular insult
-adaptive response
-reversible cell injury (loops to adaptive response and normal cell)
-irreversible cell injury
-cell death

16

what occurs in reversible damage?

-Reduced aerobic respiration
-Increased anaerobic respiration
-Membrane pumps fail
-Cell swelling
-Accumulation of lipids

17

what is the recognition of cell injury?

Cell swelling (Hydropic change) :
-Cytoplasm pale and swollen
-Accumulation of fluid
-Function of membranes and membrane pumps affected
-Hypoxia and chemical poisons

Fatty change :
-Accumulate lipid droplets
-Uncoupling of lipid and protein metabolism
-Liver commonly affected
-May see many small vacuoles or one large vacuole
(Both of these events are usually reversible )

18

what is irreversible damage characterised by?

-Severe damage to cell membranes
-Severe damage to mitochondria
-Leakage of enzymes
-Nuclear changes

19

what happens in irreversible damage?

ATP Depletion

Cell Membrane Damage;
-Progressive Loss of Phospholipids (Increased Degradation, Reduced Synthesis)
- Lipid Breakdown Products

20

what are the 2 types of cell death?

Apoptosis : pre-programmed (decides itself)
Necrosis : pathological cell death

21

Describe features of apoptosis.

-Physiological or
Pathological

-Affects scattered cells: Cells shrink , Apoptotic bodies form, No inflammation

Energy dependent:
Stereotyped sequence of events , Biochemical regulation (Inducers /Inhibitors)

22

Describe features of necrosis.

-Always pathological

-Affects sheets of cells : Cells swell , Dissolution of organelles, Inflammation

-Not energy dependent

-Descriptive terms : Coagulative, Colliquitive Caseous , Fibrinoid

23

what is involved in apoptosis?

-inhibitors
-inducers
-Molecular mediators and regulators
-increased apoptosis (AIDS)
-decreased apoptosis (Neoplasia)

24

what is the outcome of complete repair after injury and damage?

Regeneration Restitution

25

what is the outcome of incomplete repair after injury and damage?

repair scarring

26

what is the outcome of cell injury affected by?

The type of cell affected:
-Adaptive capability of cell affected
-Pre-existing disease

The damaging agent:
-Duration / Severity of exposure
-Damage that affects structures required for healing eg blood vessels with radiation

Other host factors

27

what are the classifications of cell types?

Labile :
GI Tract, Bone Marrow
Stable:
Hepatocytes, Endothelium
Permanent:
Neurones, Skeletal Muscle

28

what are cells that are lost replaced by?

a pool known as stem cells

29

where are stem cells located?

in discrete compartments

30

what does the integrity of stem cell compartment determine?

the regenerative capacity of the tissue