Ischaemia & Infarction 1

Question 1

Describe ischemia.

Answer 1

Ischemia is a relative lack of blood supply to a tissue or organ, leading to inadequate oxygen supply to meet the needs of that tissue or organ, resulting in hypoxia.

Question 2

What are the different types of hypoxia mentioned in the content?

Answer 2

The different types of hypoxia mentioned are hypoxic hypoxia, anemic hypoxia, stagnant hypoxia, and toxic hypoxia.

Question 3

Define anemic hypoxia.

Answer 3

Anemic hypoxia occurs when the blood itself is abnormal, lacking enough hemoglobin to transport oxygen, despite a normal inspired oxygen level.

Question 4

How does stagnant hypoxia occur?

Answer 4

Stagnant hypoxia occurs when there is a normal inspired oxygen level, but abnormal delivery of oxygen, which can be localized (e.g., vessel occlusion) or systemic (e.g., during shock).

Question 5

Describe toxic hypoxia.

Answer 5

Toxic hypoxia happens when there is a normal inspired oxygen level, but the tissue cannot utilize the oxygen being delivered to it.

Question 6

What factors affect oxygen supply according to the content?

Answer 6

Factors affecting oxygen supply include a normal inspired oxygen level, adequate pulmonary function, normal blood constituents, maintained blood flow, and integrity of the vasculature.

Question 7

What factors affect oxygen demand according to the content?

Answer 7

Factors affecting oxygen demand include the specific tissue requirements, activity of the tissue above baseline value, and conditions like ischemic heart disease, coronary artery atheroma, cardiac failure, pulmonary disorders, anemia, or previous myocardial infarction.

Question 8

Describe the process of atheroma formation in arteries.

Answer 8

Atheroma formation involves the accumulation of lipid and fibrous tissue in the intima of arteries, leading to a narrowing of the lumen.

Question 9

What are the clinical consequences of atheroma in coronary arteries?

Answer 9

Clinical consequences may include stable angina (chest pain on exertion), unstable angina (chest pain at rest), myocardial infarction, and other conditions.

Question 10

Define myocardial infarction.

Answer 10

Myocardial infarction refers to the death of heart muscle tissue due to a lack of blood supply, commonly known as a heart attack.

Question 11

How does atherosclerosis in the aorta lead to aneurysm formation?

Answer 11

Atherosclerosis in the aorta can lead to aneurysm formation due to weakening of the arterial wall, potentially resulting in a bulge or rupture.

Question 12

Describe the relationship between atheroma, thrombosis, and myocardial infarction.

Answer 12

Atheroma can cause thrombosis, leading to a blockage in the coronary arteries and subsequent myocardial infarction (heart attack).

Question 13

What are the differences between stable and unstable angina in relation to atheroma?

Answer 13

Stable angina causes chest pain on exertion but not at rest, while unstable angina results in chest pain at rest, indicating a more severe condition.

Question 14

Explain the impact of a ruptured abdominal aortic aneurysm on health.

Answer 14

A ruptured abdominal aortic aneurysm can have severe consequences, including internal bleeding, shock, and potentially fatal outcomes if not treated promptly.

Question 15

How does a cerebral infarct differ from a myocardial infarction in terms of location and consequences?

Answer 15

A cerebral infarct occurs in the brain due to a lack of blood supply, leading to brain tissue damage, while a myocardial infarction affects the heart muscle, potentially causing heart failure.

Question 16

Describe the findings in the Enfamil renal aneurysm identification zone.

Answer 16

Severe formation, thrombosis, perforation, and retroperitoneal hemorrhage from a ruptured abdominal aortic aneurysm.

Question 17

What is the relationship between a change in vessel wall and thrombosis according to the content?

Answer 17

A change in vessel wall can cause thrombosis.

Question 18

How does a change in vessel radius affect blood flow according to the content?

Answer 18

Reducing the vessel radius leads to a decrease in blood flow, oxygen supply, causing ischemia and infarction.

Question 19

Define ischemia based on the content.

Answer 19

Ischemia is when the blood and oxygen supply fails to meet the demand, leading to functional effects.

Question 20

What are the functional effects of ischemia mentioned in the content?

Answer 20

Functional effects include acute or chronic onset, acute events on chronically ischemic tissue, and biochemical effects.

Question 21

How is glucose metabolized in normal aerobic metabolism according to the content?

Answer 21

Glucose is converted into ATP, carbon dioxide, and water in normal aerobic metabolism.

Question 22

Describe the process of anaerobic metabolism.

Answer 22

Anaerobic metabolism is much less efficient than aerobic metabolism, producing a small amount of ATP and lactate which needs to be removed, leading to potential cell death.

Question 23

What are the effects of ischaemia on different tissues?

Answer 23

Different tissues have variable oxygen requirements, making cells with high metabolic rates more greatly affected than those with lower rates.

Question 24

Define infarction.

Answer 24

Infarction is ischemic necrosis within a tissue or organ in the living body, caused by occlusion of the arterial supply or venous drainage.

Question 25

How does infarction occur?

Answer 25

Infarction occurs when there is a stoppage of blood and oxygen flow, often due to factors like thrombosis, embolism, or mechanical strangulation.

Question 26

Do specialized cells like neurons or heart muscle cells have high or low metabolic rates?

Answer 26

Specialized cells like neurons or heart muscle cells have high metabolic rates, making them more susceptible to the effects of ischaemia.

Question 27

Describe the clinical effects of ischaemia.

Answer 27

Ischaemia can lead to dysfunction in various organs, such as causing arrhythmias in the heart or myocardial pain known as angina.

Question 28

Describe the factors that determine the scale of damage in ischaemia or infarction.

Answer 28

The scale of damage in ischaemia or infarction is dependent on factors like the length of time of ischaemia, the affected tissue or organ, the blood supply (usually a single artery), and any previous infarction.

Question 29

What type of necrosis typically occurs in the heart and lungs during infarction?

Answer 29

Coagulative necrosis is the type of necrosis that typically occurs in the heart and lungs during infarction.

Question 30

How does anaerobic metabolism in infarction lead to tissue breakdown?

Answer 30

Anaerobic metabolism in infarction causes the liberation of enzymes and breakdown of tissue, leading to cell death.

Question 31

Define colliquative necrosis and in which organ does it typically occur?

Answer 31

Colliquative necrosis is a type of necrosis where the tissue is broken down into small pieces, typically occurring in the brain.

Question 32

Describe the timeline of myocardial dysfunction and cell changes during ischaemia.

Answer 32

During ischaemia, myocardial dysfunction begins with anaerobic metabolism and ATP depletion within seconds, followed by myocardial contractility loss in under two minutes, and structural changes like myofibrillar relaxation and mitochondrial swelling after a few minutes.

Question 33

What happens after 20 to 30 minutes of severe ischaemia in terms of damage?

Answer 33

After 20 to 30 minutes of severe ischaemia, irreversible damage is most likely to occur, leading to myocyte necrosis and leakage of macromolecules from cells to extracellular tissue.