Pathological Processes: Overall

Question 1

What can severe changes in the environment of a cell lead to?

Answer 1

Cell adaptation, injury or cell death

Question 2

Degree of injury to cell following severe changes in environment depends on what?

Answer 2

–Type of injury
–Severity of injury
–Type of tissue

Question 3

How is the cell injury response part of a continuum?

Answer 3

Stimulus: Physiological –> Harmful

Response: Homeostasis –> Cellular Adaptation –> Cellular Injury –> Cell death

Question 4

What kind of things can cause cell

injury? (7)

Answer 4

• Hypoxia
• Toxins
• Physical agents
• Radiation
• Micro-organisms
• Immune mechanisms
• Dietary insufficiency and deficiencies, dietary excess

Question 5

Give examples of physical agents that can cause cell injury (4)

Answer 5

– Direct trauma
– Extremes of temperature
– Changes in pressure
– Electric currents

Question 6

What is hypoxia?

Answer 6

Deficiency in the amount of oxygen reaching the tissues

Question 7

Define cyanosis

Answer 7

A bluish discoloration of the skin due to poor circulation or inadequate oxygenation of the blood

Question 8

What does frostbite most commonly affect?

Answer 8

Fingers, nose, toes

Question 9

What can frostbite often result in?

Answer 9

Gangrene

Question 10

What is cellulitis?

Answer 10

Inflammation of skin (subcutaneous connective tissue)

Question 11

How can the worsening/improving of cellulitis be tracked?

Answer 11

Draw around affected area

Question 12

What is the difference between hypoxia and ischaemia? Which is considered worse and why?

Answer 12

Hypoxia: Decreased oxygen supply
Ischaemia: Decreased blood supply

• Ischaemia deprives the cell of of oxygen but also many other things (e.g. sugars) that could impact metabolic processes.

Question 13

What are the four main causes of hypoxia?

Answer 13

– Hypoxaemic hypoxia – arterial content of oxygen is low
• Reduced inspired p02
at altitude
• Reduced absorption secondary to lung disease

– Anaemic hypoxia – decreased ability of haemoglobin to carry oxygen
• Anaemia
• Carbon monoxide poisoning

– Ischaemic hypoxia - interruption to blood supply
• Blockage of a vessel
• Heart failure

– Histiocytic hypoxia – inability to utilise oxygen in cells due to disabled
oxidative phosphorylation enzymes
• Cyanide poisoning

Question 14

Difference in sensitivity to hypoxia: brain vs skin

Answer 14

Neurones = few minutes 
Fibroblasts = few hours

Question 15

What is urticaria?

Answer 15

Hives

Question 16

How does the immune system damage the

body’s cells? (2)

Answer 16

• Hypersensitivity reactions - host tissue is
injured secondary to an overly vigorous
immune reaction, e.g., urticaria (= hives)
• Autoimmune reactions - immune system fails
to distinguish self from non-self, e.g., Grave’s
disease of thyroid.

Question 17

Which cell components are most

susceptible to injury? (4)

Answer 17

• Membranes
• Nucleus
• Proteins
• Mitochondria

Question 18

Why can different insults result in the same damage?

Answer 18

Sequence of events for other insults may be different
but as the cell has a limited responses to injury,
outcome often similar.

Question 19

Two types of injury that damage membranes primarily

Answer 19

• Extreme cold (e.g. frostbite)

- Free radicals

Question 20

• What is a free radical?
• What else is it often to referred to as?
• Comment on its reactivity.

Answer 20

• Single unpaired electron in an outer orbit
• Reactive oxygen species
• High reactivity: an unstable configuration hence react with other molecules, often producing further free radicals

Question 21

What are the three free radicals that are of particular biological significance in cells?

Answer 21

• OH• (hydroxyl): the most dangerous
• O2 (superoxide)
• H2O2 (hydrogen peroxide)

Question 22

What are the three free radicals that are of particular biological significance in cells?

Answer 22

• OH• (hydroxyl): the most dangerous
• O2- (superoxide)
• H2O2 (hydrogen peroxide)