3. Cell Injury And Death Flashcards Preview

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Flashcards in 3. Cell Injury And Death Deck (78)
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1

What is involved in the maintenance of cellular steady state?

- preservation of genetic integrity
- normal enzyme content
- intact membranes and transmembrane proteins
- adequate supply of substrates and oxygen

2

What happens when cellular steady state is not maintained?

Cell injury.

Biochemical and/or morphological changes that occur when the steady state is perturbed by adverse influences

3

What happens when normal cell homeostasis is disrupted?

The cell either adapts or becomes injured. Cell injury can be mild and transient and therefore reversible, or it can be severe and progressive and therefore irreversible

4

What does irreversible cell injury lead to?

Cell death

Either necrosis or apoptosis

5

Name three types of cellular adaptation

- increased cellular activity (hyperplasia, hypertrophy)

- decreased cellular activity (atrophy)

- change in cell morphology (metaplasia)

6

Define hypertrophy

Individual cells increase in size (since the cells cannot divide)

Eg. Size and thickness of left ventricle increase due to systemic hypertension etc, muscle gets bigger

7

Define hyperplasia

The cell number increases, cells divide

8

Define atrophy

Cells shrink in size or number due to decreased demand

9

What effect do steroids have on the body in terms of cellular adaptations?

When used for a long time, steroids cause the adrenal glands to become atrophic - this then creates a problem if the steroids are stopped suddenly, it is recoverable if you reduce steroids slowly

10

Explain metaplasia

When cells change their shape and morphology in response to a change in stimulus - change function

Can be physiological or pathological

Physiological example = cervix goes through change from columnar to squamous epithelium

11

Give a physiological and pathological example of atrophy

Physiological = organ formation in embryology

Pathological = loss of innervation leading to muscle atrophy

12

Give a physiological and pathological example of hypertrophy

Physiological = skeletal and heart muscle in athletes

Pathological = left ventricular hypertrophy in response to systemic hypertension

13

Give a physiological and pathological example of hyperplasia

Physiological = increase in bone marrow cells producing red blood cells at high altitude

Pathological = angiogenesis in wound repair

14

Give an example of metaplasia

Barrett's oesophagus = replacement of normal squamous epithelium with columnar glandular epithelium due to gastric acid reflux

15

Define hypoxia and anoxia

Hypoxia = reduction of oxygen to delivered to cells, often cause by ischaemia

Anoxia = complete loss of oxygen to cells

16

Define ischaemia

Lack of blood flow. Therefore a common cause of tissue hypoxia

17

Other than ischaemia, how else might tissue hypoxia arise?

There might not be enough oxygen in the blood to start off with, or the cells might not be able to use the oxygen (eg. Cyanide poisoning)

18

Explain reoxygenation

Reperfusion - generation of oxygen free radicals.

If an artery becomes infarct, and then the infarct artery becomes patent again (eg. In thrombolysis) some of the myocardium will be reperfused, this creates free radicals which can cause cell death.

So reperfusion is helpful but can also cause problems

19

How might a bullet shot affect tissues?

Tear small blood vessels over a large area leading to widespread devascularisation and subsequent ischaemic tissue death

The cavity also contains a vacuum and so dirt is sucked into the wound leading to infection

20

How does mechanical trauma cause cell injury?

Disrupts cell structure

Damages to walls of blood vessels leading to thrombosis and secondary ischaemic damage

21

Define hyperprexia

A fever with extreme elevation of body temperature greater than or equal to 41.5 degrees celcius

(Extreme temperature damage can be both internal or external)

22

Give examples of chemical agents that can cause cell injury

- alcohol
- tobacco smoke
- drugs
- poisons
- environmental
- occupational

23

What is the mode of action of chemical agents in terms of cell injury?

Different modes of action

Range from simple denaturation and breakdown of macromolecules (eg. Strong acids and alkalis)

To more subtle interferences will cellular metabolism (eg. Paracetamol poisoning)

24

Describe liver cirrhosis in terms of cell injury

Alcohol abuse causing long term cell injury and death, the liver tries to regenerate in a suboptimal way

25

What are the carcinogenic effects of asbestos?

Causes cancer of the bronchi and pleura.

Often happens 20 to 30 years after the exposure

Can also affect those living with the exposed person (on their clothes etc)

26

What are the two types of bacterial toxin?

Exotoxin = secreted from living bacterial cell eg. Pseudomembranous colitis

Endotoxin = secreted from the dead bacterium eg. E. coli

27

How do X-rays cause cell injury?

Generation of free radicals and direct damage to macromolecules

Free radicals are very reactive and cause bonds to form where they shouldn't, causing damage

28

Which organs are most sensitive to ionising radiation?

Those with a high turnover rate (high proliferation rate)

Eg. Bone marrow, gonads, intestines

29

Which organs are not as sensitive to ionising radiation?

Uterus

Pancreas

Adrenal glands

30

How does UV light cause cell injury?

Can induce an inflammatory response several hours after exposure

Eg. Sunburn