Chap 7 Ischemia Reperfusion

Question 1

What is the main cause of injury during ischemia?

Answer 1

From hypoxia/anoxia and stasis in microcirculation

Question 2

Describe how ischemic injury occurs.

Answer 2

Mitochondria without O2 cannot produce ATP by oxidative phosphorylation
ATP falls, with ADP and AMP rise.
Glycolysis stimulated but insufficient for the cell
Lactic acid builds up making intracellular pH decrease, this then inhibits glycolysis
To compensate ion pumps are supposed to pump H ions out however there is pump dysfunction as no O2. Intracellular Ca rises are a consequence
This leads to eventually cell memebrane damage and cell death
During process reactive O2 species produced and accum in mitochondria
Increase ROS and Ca causes cell necrosis

Question 3

What are the main causes of injury during reperfusion?

Answer 3

Metabolic, thrombotic, inflammatory

Question 4

Describe reperfusion injury.

Answer 4

Burst of ROS production, increased Ca uptake into mito, shift of pH towards enutral
Mitochondrial oxidative damage leads to cell death through apoptosis and necrosis
Increased ROS during ischemia and reperfusion initiated apptosis and necrosis

Elicits inflamm response dependent of complement
Imflamm mediators delivered to reperfused tissue (mac, lumphocytes, neutrophils, mast cells and plt)
Edema

Question 5

List clinical manifestations of reperfusion injury.

Answer 5

myocardial stunning
arrhthmia
tissue edema
multi-organ dysfunction
compartmenet syndrom
bacterial translocation
RF 
ARDS
no reflow phenomena

Question 6

Describe myocardial stunning.

Answer 6

Reversible, decreased ATP resunthesis, coronary spasm, cytotoxic injury

Question 7

Describe arrhythmia.

Answer 7

Rapid and sudden changes in ions concentration

Question 8

Describe tissue edema.

Answer 8

Disruption to blood brain barrier can cause increased ICP

Question 9

Which organ most injured in multi-organ dysfunction.

Answer 9

Lungs most frequently injured

Question 10

How long before nerve ischemia is permanent in CS.

Answer 10

12-24 hours

Question 11

What causes bacterial translocation.

Answer 11

increased intestinal permeability.

Question 12

What is no reflow phenomena?

Answer 12

Downstream microembolization of plt, neutrophils, thrombus, and atheroma particles cause occlusion. absence of obstruction in named arteries