Infarction and Shock Flashcards
What is infarction?
Ischemic necrosis within a tissue or organ
What is infarction most often caused by?
Thrombotic or embolic occlusion
What is white infarct?
Ischemic; turns pale, classic wedge shape
What is red infarct?
Hemorrhagic; bleeding into tissue or organ
What are the determining factors of clinical significance for infarction?
- Nature of vascular supply
- Rate of development of occlusion
- Vulnerability of tissue to hypoxia
If an occlusion has a very quick development, what is the likely result?
Necrosis
If an occlusion develops over years, what is the likely result?
Tissue atrophy
What tissues are vulnerable to hypoxia?
Heart, nerve, brain
Infarction has margins lined by rim of…
hyperemia/inflammation
The surface of an infarct is covered by…
fibrinous exudate
Heart attack/myocardial infarction leads to what type of necrosis?
Coagulative necrosis
What is the most common shape of an infarct?
Wedge-shaped
What is shock?
Hypoperfusion of tissues
What are five major subtypes of shock?
- Cardiogenic
- Hypovolemic
- Septic
- Anaphylactic
- Neurogenic
Myocardial infarction and myocarditis lead to what type of shock?
Cardiogenic
Cardiac tamponade and pulmonary embolus lead to what type of shock?
Cardiogenic
Hemorrhage leads to what type of shock?
Hypovolemic
Diarrhea and dehydration lead to what type of shock?
Hypovolemic
Burns lead to what type of shock?
Hypovolemic
A severe infection will lead to what type of shock?
Septic
Type 1 hypersensitivity reactions lead to what type of shock?
Anaphylactic
Brain damage and/or spinal cord injury lead to what type of shock?
Neurogenic
What are three results of myocardial pump failure?
- Decreased blood volume
- Increased vasodilation
- Increased vascular permeability
What happens during cardiogenic shock?
Heart fails as a pump
After myocardial infarction, necrotic tissue will appear ___ and scar tissue will appear ___
necrotic tissue = dark
scar tissue = pale/white
What is cardiac tamponade?
Survival of heart attack leads to tear in myocardium and bleeding into pericardial sac; atria will collapse
Is cor pulmonale acute or chronic?
Acute
What is cor pulmonale?
Right ventricular dilation (fills with blood that can’t leave) and hypertrophy
Cor pulmonale is an extension of…
what happens with embolized deep vein thrombosis: saddle embolus
What is hypovolemic shock?
Not enough blood due to blood loss
What are potential causes of cardiogenic shock?
- Myocardial infarction
- Cardiac tamponade
- Cor pulmonale
What are potential causes of hypovolemic shock?
- Hemorrhage
- Severe trauma
- Extensive burns (2nd and 3rd degree)
How does an extensive burn lead to hypovolemic shock?
Blisters are filled with edema fluid which is derived from blood plasma, thus decreasing blood volume
What is septic shock?
Sock due to blood borne infection
septic shock
Endotoxins are released from gram ___ bacteria (role of LPS)
gram negative bacteria
septic sock
Endotoxins stimulate release of ___
cytokines (IL-1, 6, and 8, TNF)
septic shock
Cytokines trigger the release of…
PAF, NO, bradykinin, complement, prostaglandins, and leukotrienes
septic shock
What is the result of released PAF, NO, bradykinin, complement, prostaglandins, and leukotrienes by cytokines?
Systemic vasodilation
What are the stages of shock?
- Non-progressive stage
- Progressive stage
- Irreversible stage
What is the non-progressive stage of shock?
Compensatory mechanisms are maintaining blood pressure: SNS, RAA axis, autoregulation
What is the progressive stage of shock?
Tissue hypoxia and metabolic acidosis but the tissue is not dying yet
What is the irreversible stage of shock?
Enzyme leakage and organ shutdown over a short time course
If increased BUN, creatinine, and decreased GFR are found in the blood, what is the likely cause?
Irreversible stage of shock due to kidney failure
If increased troponin, pancreatic lipase, and amylase are found in the blood, what is the likely cause?
Irreversible shock
