1B - Cell Injury, Hypoxia, Free Radicals

Question 1

Severe changes in environment lead to: (3)

Answer 1

Adaptation
Cell injury
Cell death

Question 2

The degree of injury depends on: (3)

Answer 2

Type of injury
Severity of injury
Type of tissue

Question 3

Cell injury is part of a continuum.
Physiological ——————> Harmful
_________? _________? _________? _________?

Answer 3

Physiological ———————> Harmful

Homeostasis, Cellular Adaptation, Cellular Injury, Cell death

Question 4

Causes of cell injury: (7)

Answer 4

1) Hypoxia
2) Toxins
3) Physical agents (direct trauma, temp extremes, pressure changes, electric currents)
4) Radiation
5) Microorganisms
6) Immune mechanisms
7) Dietary insufficient Ines and deficiencies; dietary excess

Question 5

Types of hypoxia: (4)

Answer 5

Hypoxaemic hypoxia
Anaemic hypoxia
Ischaemic hypoxia
Histocytic hypoxia

Question 6

Description and cause of hypoxaemic hypoxia:

Answer 6

Arterial content of oxygen is low

Due to:
Reduced inspired pO2 at altitude
Reduced absorption secondary to lung disease

Question 7

Description and cause of anaemic hypoxia:

Answer 7

Decreased ability of haemoglobin to carry oxygen

Due to:
Anaemia
Carbon monoxide poisoning

Question 8

Description and cause of ischaemic hypoxia:

Answer 8

Interruption to blood supply

Due to:
Blockage of vessel
Heart failure

Question 9

Description and cause of histocytic hypoxia:

Answer 9

Inability to utilise oxygen in cells due to disabled oxidative phosphorylation

Due to:
Cyanide poisoning

Question 10

Hypoxia: neurones and fibroblasts damage occurs after ______ and ______ respectively

Answer 10

Neurones: damage occurs after a few minutes (very sensitive)
Fibroblasts: damage occurs after a few hours

Question 11

By which reactions does the immune system damage the body’s cells? (2)

Answer 11

Hypersensitivity reactions

Autoimmune reactions

Question 12

What happens in hypersensitivity reactions?

Answer 12

The host tissue is injured secondary to an overly vigorous immune reaction e.g. urticaria (hives)

Question 13

What happens in autoimmune reactions?

Answer 13

The immune system fails to distinguish self from non-self e.g. Grave’s disease of thyroid

Question 14

Which 4 cell components are most susceptible to injury?

Answer 14

1) Cell membranes - plasma membranes, organelle membranes
2) Nucleus - DNA
3) Proteins - structural (enzymes)
4) Mitochondria - oxidative phosphorylation

Question 15

Hypoxia: the REVERSIBLE injury mechanism:

Answer 15

1) Ischaemia
2) Reduced oxidative phosphorylation (Mitochondria)
3) Reduced ATP
4a) Reduced Na pump
5a) Increased influx of Ca2+, H2O, Na+ and increased efflux of K+
6a) Cellular swelling, Loss of microvilli, Blebs, ER swelling, Myelin figures
4b) Increased glycolysis
5b) Reduced pH and reduced glycogen
6b) Clumping of nuclear chromatin
4c) Other effects
5c) Detachment of ribosomes
6c) rescued protein synthesis
7c) Lipid deposition