Cell Injury

Question 1

Hypoxaemic hypoxia

Answer 1

Arterial content of oxygen is low

• reduced inspired pO2 from atmosphere
• reduced absorption secondary to lung disease

Question 2

Anaemia hypoxia

Answer 2

Reduced ability of the haemoglobin to carry oxygen e.g. sickle cell anaemia

Carbon monoxide poisoning

Question 3

Ischaemic hypoxia

Answer 3

Interruption to the blood supply

• heart failure
• blockage of blood supply

Question 4

Histiocytic hypoxia

Answer 4

Inability to utilise oxygen in cells due to disabled oxidative phosphorylation enzymes e.g. cyanide poisoning

Question 5

Time taken for hypoxia in neurones

Answer 5

Few minutes

Question 6

Time taken for hypoxia in fibroblasts

Answer 6

Few hours

Question 7

Prolonged hypoxia

Answer 7

• Normally the intracellular free calcium is low but the breakdown of mitochondria and endoplasmic reticulum causes calcium to increase intracellularly
• NCX is reversed and activates enzymes such as ATPases, phospholipase, proteases and endonucleases
• decreases ATP, phospholipids and disrupts the membrane and cytoskeleton proteins and nucleic chromatin damage which is irreversible

Question 8

When are free radicals produced?

Answer 8

1. During normal metabolic reactions such as oxidative phosphorylation
2. Oxidative burst in neutrophils
3. Radiation converts H20 into OH-
4. Fenton reaction - contact with unbound metals within the body e.g. iron and copper
5. Drugs and chemicals e.g paracetamol metabolism in the liver

Question 9

Ceruloplasmin

Answer 9

Storage proteins for copper

Question 10

How to diagnose cell death

Answer 10

Dye exclusion technique - if the dye enters the cell the cell membrane is permeable therefore the cell is dead

Question 11

Coagulative necrosis under a microscope

Answer 11

Increased neutrophils
No nucleus in cells
Ghost outlines

Question 12

Causes of infection other than thrombosis and embolism

Answer 12

Torsion e.g. twisted bowel on mesentery or testicular torsion

Question 13

Where are white infarcts found

Answer 13

Solid organs such as the heart kidney and spleen

Question 14

Where are red infarcts found

Answer 14

In the lungs and liver due to a dual blood supply

Intestines due to numerous anastomoses

Question 15

Tumour lysis syndrome

Answer 15

Killing cancer cells releases potassium which can cause an arrhythmia

Question 16

Three phases of apoptosis

Answer 16

Initiation
Execution
Degradation and phagocytosis

Question 17

Initiation of apoptosis

Answer 17

Activation of caspases:

• enzymes that control and mediate apoptosis
• causes cleavage of DNA and proteins of the cytoskeleton

Question 18

Intrinsic pathway of initiation

Answer 18

• Initiating signal comes from within the cell

Triggered by:

• irreparable DNA damage
• withdrawal of growth factors or hormones
• P53 protein is activated which results in the outer mitochondrial membrane becoming leaky
• cytochrome C is released from the mitochondria, causing activation of caspaces

Question 19

Extrinsic pathway of initiation

Answer 19

• Initiated by extracellular signals
• triggered by cells in danger e.g. tumour cells or by vitally infected cells
• TNF alpha is secreted by T killer cells and binds to cell membrane receptors (death receptor)
• activates caspaces

Question 20

Mallory’s hyaline

Answer 20

Damage keratin filaments seen in alcoholic liver disease

Question 21

Causes of hypercalcaemia

Answer 21

Increased secretion of parathyroid hormone resulting in bone resorption:

• primary - parathyroid hyperplasia or tumour
• secondary - renal failure with increased retention of phosphate
• ectopic - secretion of PTH related proteins by malignant tumours

Destruction of bone tissue

• primary tumours of the bone marrow such as leukaemia or multiple myeloma
• diffuse skeletal metastases
• Paget’s disease - accelerated bone turnover - immobilisation

Question 22

In a hepatic acinar, which zone is more susceptible to ischaemic damage?

Answer 22

Zone 3 - near the terminal hepatic venue as it’s further away from the portal triad