Path: Adaptation, Injury, Death (Part 3) Flashcards
Define Infarction
Ischemic necrosis of an organ or tissue
Define necrosis
The appearance a dead organ or tissue takes on in a person who remains alive
Define autolysis
The morphology all of the organs and tissues take on when a person dies. (Differs from Necrosis)
Which of the two, autolysis or necrosis, elicits an acute inflammatory response?
Necrosis
How would you characterize autolysis on a cellular level?
gradual fading of the components of every cell, all at the same rate
What is the #1 cause of infarction to an organ or tissue?
occlusion of the vessel by thrombus or thromboembolus.
List the 4 factors that have influence on whether reversible ischemia becomes irreversible infarction.
1- Vulnerability of the tissue
2- rate of ischemic development
3- alternative blood supply
4- blood oxygenation
How quickly do ischemic neurons begin dying?
In as little as 4 minutes
How quickly do ischemic cardiac myocytes begin dying?
In as little as 20 mins
Slowly progressive ischemia gives the body time to grow ________________ into the ischemic area.
new collateral arteries
What is claudication?
The pain of ischemia
What is a positive effect of claudication?
It stimulates the body to undergo angiogenesis, to get around the ischemia, alleviating the disease.
Why in the case of the lungs, mesentery and liver, does ischemia less commonly lead to infarction?
Collateral blood supplies
Any disease that impairs blood oxygenation in the lungs or blood oxygen-carrying capacity, makes ischemia anywhere in the body more or less likely to cause infarction?
MORE
“White anemic” infarcts are typical of solid organs with ______ ________ circulation, such as the heart, the spleen and the kidneys.
End-arterial
“Red hemorrhagic” infarcts have several (3) different mechanisms. Name them.
1- venous occlusion
2- dual or anastomosing blood supply
3- reperfusion
Briefly describe red hemorrhagic infarcts.
When tissue infarcts, the blood vessels start breaking down and this causes hemorrhage into the dead tissue.
True or false: In many organs, infarcts tend to be central, capsular and circularly-shaped. If false, give correct description.
False.
Peripheral, subcapsular and wedge-shaped
If a cerebral artery is occluded, leading to ischemic necrosis, the cerebral infarction tends to develop ________ necrosis, that is the solid tissue turns to ______ and drains away.
Liquefactive necrosis; turns to liquid
Why does liquefaction occur in the brain following infarct/during necrosis?
Microglial cells transform into debris eating macrophages within a cerebral infarction and the cells that make collagen and convert infarcts in other organs into scars tend to be excluded by the blood-brain barrier (BBB).
Reperfusion can render a cerebral infarction ________ (bad).
hemorrhagic
Injury to cardiac myocytes sufficient to kill them causes the release of their _______ contents into the bloodstream in a characteristic temporal pattern.
Enzyme
_______ ___________ is an enzyme that catalyzes the transfer of phosphate from creatine phosphate to ADP, creating ATP.
Creatine phosphokinase (CPK) or creatine kinase for short
CPK is concentrated in what two organs in particular?
Brain and muscle
CPK is composed of ___ and ___ dimers.
M & B
The ____ fraction (dimer) of CPK is released into blood with myocardial necrosis.
MB
MB serum levels will be elevated beginning ___ hrs after an MI and peak around ____ hrs, falling back to normal around ____ hrs after the myocytes died.
3hrs; 24hrs; 48hrs
AST serum levels will be elevated ___ hrs after MI, peak around ____ hrs and normalize around ___ days.
24hrs; 48hrs; 4 days
Following an MI, LDH serum levels will be elevated at ___ hrs, peak around ___ hrs and normalize around ___ days.
24hrs, 72hrs, 7 days
_______ are proteins that regulate calcium-mediated contraction of cardiac and skeletal muscle.
Troponins
What are the cardiac-specific versions of the Troponins?
Troponin-I and Troponin-T
Following an MI, cardiac troponins will be elevated after about ___ hrs, peaking around ___ hrs but not normalizing until around ___ days.
3hrs; 24hrs; 10 days
True or false: the sensitivity for MI of CK-MB and Troponin assays are both above 50%.
False, they are both at 35%
True or false: the specificity for MI of CK-MB and troponin assays are both over 90%.
False. 80% for CK-MB and 96% for troponin
The sensitivity of the troponin level for the Dx of acute MI improves to 90% if it is assayed ___ hrs after the onset of chest pain.
10 hrs
Why is it recommended to repeat troponin assay at least once 3-6 hrs after the initial level?
To rule in or out the Dx of acute MI, a second assay of troponin levels is recommended approx 10 hrs after the MI because of the increased (90%) sensitivity of the assay after 10 hrs.
For the Dx of acute MI, an elevated troponin needs to be combined with at least one of the following:
1- symptoms of ischemia
2- EKG evidence of ischemia
3- imaging evidence of ischemia
4- ID of an intracoronary thrombus by angiography or autopsy.
True or false: Highly sensitive troponin assays are very specific for the Dx of acute MI.
False. Highly sensitive troponin assays are POORLY specific for the Dx of acute MI, illustrating the inevitable tradeoff between sensitivity and specificity, and making it important to combine a positive test with other evidence of acute MI to make this Dx.
Gangrene is a distinctive form of ischemic necrosis characterized by _______ and ______, typically of distal extremity, but also sometimes of internal organs.
blackening and shrinkage
True or false: gangrene is primarily a term for micro-pathology.
False. Gross pathology
Treatment of gangrene is surgical or non-surgical?
Surgical. Amputation or excision of the affected tissue/organ.
______ necrosis is a distinctive form of necrosis grossly resembling cheeese, associated with TB, histoplasmosis and similar diseases.
Caseous necrosis
Caseous necrosis is a term describing gross or micro pathology?
Gross
Caseating necrosis is usually caused by ______ infections or infections caused by bacteria resembling ______.
Fungal; fungi (mycobacteria [Mycobacterium tuberculosis])
True or false: Mycobacteria and most fungi are fast growing and usually sensitive to the same abx used to treat acute bacterial infections.
False. Slow growing and are sensitive to different abx than the ones used to treat acute bacterial infections.
T/F: Ischemia leads to liquefication in tissues other than brain tissue.
False
What is an abscess?
A localized area of liquefactive necrosis.