Cell Death

Question 1

What are the 6 main methds of injury leading to cell death?

Answer 1

Energy failure - Lack of metabolites
Mechanical disruption - Trauma or osmotic pressure
DNA damage or loss - Chemo, ROS
Blockage of metabolic pathways - Interruption of protein synthesis
Membrane integrity failure - ROS, Toxins or damage to ion pumps

Question 2

What are the 2 forms of cell death?

Answer 2

Apoptosis - Planned

Necrosis - Unplanned

Question 3

What happens during apoptosis?

Answer 3

Enzymatic pathways are activated to degrade the cellular DNA
Cells fragment and wrap the organelles in plasma membranes (apoptotic bodies)
Phagocytosis of the apoptotic bodies occurs (if the contents leak then an inflammatory response will occur)

Question 4

What do Pyknosis and Karyorrhexis mean?

Answer 4

Pyknosis - Nucleus shrinking

Karyorrhexis - Nucleus fragmenting

Question 5

What are the pro-apoptotic members of the BCL-2 family?

Answer 5

Bax, Bak and Bok

Question 6

What are the anti-apoptotic members of the BCL-2 family?

Answer 6

Bcl-2 and BCL-XL

Question 7

What happens in the extrinsic apoptotic pathway?

Answer 7

Fas ligand binds to the TNF receptor initiating the caspase enzyme cascade

Question 8

What are the definitions of Ischaemia and Infarction?

Answer 8

Ischaemia - Inadequate blood supply to a tissue leading to a deprevation of nutrients
Infarction - Death if a tissue as a result of Ischaemia

Question 9

What happens during ischaemia?

Answer 9

Reduction or loss of O2
Membrane pumps fail - Osmoregulation loss, Increased Ca2+ in cell, cell death initiation
Lysosomal breakdown - ROS damage cell

Question 10

What are the 3 predispositions for thrombus formation?

Answer 10

Changes in the internal surface of the blood vessel
Changes in the pattern of blood flow
Changes in the blood constituents

Question 11

What are the conditions associated with thrombus formation?

Answer 11

Myocardial Infarction
Cerebral infarction
Pulmonary embolism

Question 12

How do thrombuses form?

Answer 12

Atheroma - Change in the vessel wall (lipid cells form bump)
Ulceration - Loss of the endothelial cells and exposure of the collagen
Platelet adherence - Platelets group at ulcer site
Thrombosis - Thrombus is formed of platelets, fibrin and RBCs

Question 13

Which cells are most at risk from ischaemia

Answer 13

Cells with high metabolic demand

Question 14

What causes reperfusion injury?

Answer 14

ROS