Oedema and Infarction Overview

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What occurs as a primary response of mononuclear phagocytes to lipopolysaccharide (LPS)?

Decreased adherence of leukocytes

Suppression of inflammatory responses

Production of prostaglandins

Release of TNF, IL-1, and IL-6 (correct)

What systemic effect is caused by the release of high levels of TNF and IL-1?

Stimulation of acute phase reactants (correct)

Reduced body temperature

Improved myocardial contractility

Increased platelet count

How does high-dose LPS affect endothelial cell production?

Stimulates myocardial contractility

Reduces production of tissue factor pathway inhibitor (TFPI) (correct)

Increases nitric oxide levels

Enhances production of thrombomodulin

What major condition may develop as a consequence of high levels of cytokines during septic shock?

Multi-organ system failure Signup and view all the answers

What is one of the consequences of systemic vasodilation due to high cytokine levels?

Diminished perfusion to organs Signup and view all the answers

What shape do most infarcts tend to exhibit?

Wedge-shaped Signup and view all the answers

How are infarcts classified based on color?

Red and white Signup and view all the answers

What is the dominant histologic characteristic of infarction?

Ischemic coagulative necrosis Signup and view all the answers

What condition is known as cardiovascular collapse?

Shock Signup and view all the answers

Which of the following can lead to systemic hypoperfusion?

Severe hemorrhage Signup and view all the answers

What occurs initially during shock?

Hypotension Signup and view all the answers

What can occur as a result of persistent shock?

Cellular hypoxia Signup and view all the answers

When can an infarct be converted into an abscess?

Following the fragmentation of a bacterial vegetation Signup and view all the answers

What type of shock results primarily from myocardial pump failure?

Cardiogenic shock Signup and view all the answers

What is a common cause of hypovolemic shock?

Severe burns Signup and view all the answers

Which type of shock is most commonly associated with gram-negative infections?

Septic shock Signup and view all the answers

What characterizes neurogenic shock?

Loss of vascular tone and peripheral pooling Signup and view all the answers

What is a key feature of anaphylactic shock?

Generalized IgE-mediated hypersensitivity Signup and view all the answers

What serious condition can develop in the kidneys due to shock?

Acute tubular necrosis Signup and view all the answers

What is septic shock primarily caused by?

Systemic microbial infection Signup and view all the answers

How do endotoxins contribute to septic shock?

They enhance the elimination of bacteria by activating macrophages. Signup and view all the answers

Which of the following is a cause of reduced plasma oncotic pressure?

Nephrotic syndrome Signup and view all the answers

What is a common indicator of subcutaneous edema?

Pitting edema Signup and view all the answers

Which mechanism is least likely to cause an infarction?

Increased hydrostatic pressure Signup and view all the answers

What type of edema is characterized by swollen lungs and a foamy fluid upon sectioning?

Pulmonary edema Signup and view all the answers

What is a typical cause of lymphatic obstruction leading to lymphedema?

Neoplastic obstruction Signup and view all the answers

Which of the following is the primary cause of infarcts?

Embolic events Signup and view all the answers

Which condition typically involves narrowing of the sulci and distention of the gyri in the brain?

Cerebral edema Signup and view all the answers

What type of shock is specifically associated with infections and requires understanding of pathophysiology?

Septic shock Signup and view all the answers

Study Notes

Oedema

Oedema signifies increased fluid in interstitial tissue spaces
Categorized based on pathophysiological mechanisms:
- Increased hydrostatic pressure (e.g., deep vein thrombosis (DVT), congestive heart failure)
- Reduced plasma oncotic pressure (e.g., nephrotic syndrome, cirrhosis)
- Lymphatic obstruction (e.g., cancer, parasitic infections)
- Sodium retention (e.g., kidney failure)
- Inflammation

Morphology of Oedema

Microscopically, oedema manifests as subtle cell swelling and separation of extracellular matrix elements.
Oedema is easily identified macroscopically.
- Subcutaneous oedema: finger pressure creates a pitting depression.
- Periorbital oedema: swelling around the eyes.
- Pulmonary oedema: lungs are significantly heavier, sectioning reveals frothy, blood-tinged fluid.
- Brain oedema: brain appears swollen, with narrowed sulci and distended gyri.

Infarction

An infarct is an area of ischemic necrosis due to blood supply blockage.
Almost all infarcts (99%) are caused by thrombotic or embolic events involving arterial occlusion.
Other causes include:
- Local vasospasm
- Extrinsic vessel compression (e.g., tumors)
Infarcts are often wedge-shaped. If the base is a serosal surface (tissue lining body cavities like the lungs), sometimes an overlying fibrinous exudate is present. The lateral margins can reflect the pattern of vascular supply.
Initially, infarcts are poorly defined and mildly hemorrhagic. Over time, margins become better defined, and eventually, the area is replaced by scar tissue.
Different infarcts may be characterized based on colour (red vs. white) or presence of infection (septic vs. bland).

Morphology of Infarcts

Wedge-shaped, with the base on the periphery and the apex towards the hilus (often showing the point of blockage in the tissue).
Replaced by scar tissue; depressed on surface.

Classification of Infarcts

Colour: Red (hemorrhagic) or white (anemic). Hemorrhagic infarcts occur with venous blockage, areas with dual blood circulation or reperfusion, or in organs with sluggish venous outflow. Anemic infarcts occur with arterial blockages in solid organs, with end arteries, where the tissue limits the amount of hemorrhage from neighbouring tissues.
Infection: Septic (infected) or bland (not infected)

Septic Infarcts

Develop when embolization of bacteria from a heart valve occurs, or when microbes seed a necrotic area.
Converted to an abscess in these circumstances.

Histology of Infarcts

The dominant characteristic of an infarct is ischemic coagulative necrosis.
Most infarcts are ultimately replaced by scar tissue.
The brain is an exception; ischemic injury often results in liquefactive necrosis in the central nervous system.

Shock

Shock, or cardiovascular collapse, often results in potentially lethal clinical events.
Causes often include hemorrhage, extensive trauma/burns, massive myocardial infarction, or massive pulmonary embolism.
Can result from microbial sepsis.
Shock characterizes systemic hypoperfusion (reduced blood flow to tissues) due to blood volume loss.
Ultimately resulting in hypotension (low blood pressure), tissue perfusion impairment and cellular hypoxia, which often leads to organ failure.

Types of Shock

Cardiogenic: myocardial pump failure
- Intrinsic myocardial damage (infarct)
- Ventricular arrhythmias
- Extrinsic compression (e.g., cardiac tamponade)
- Outflow obstruction (e.g., pulmonary embolism)
Hypovolemic: blood or plasma volume loss (hemorrhage, fluid loss, trauma)
Septic: systemic microbial infection
- Most often from gram-negative bacteria (endotoxin production)
- Occurs when bacteria invade bloodstream.
Neurogenic: loss of vascular tone (anesthesia, spinal injury)
Anaphylactic: hypersensitivity response. Leading to systemic vasodilation and increased vascular permeability. Characterized by blood pooling in peripheral vessels

Morphology of Shock

Cellular and tissue changes from shock are related to hypoxic/ischemic injury.
Changes can occur in any tissue. For example:
- Heart: focal or widespread coagulation necrosis
- Kidneys: extensive tubular ischemic injury (acute tubular necrosis)
- Gastrointestinal tract: patchy mucosal hemorrhage and necrosis
- Lungs: diffuse alveolar damage (shock lung)
- Liver: fatty changes; central hemorrhagic necrosis.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

This quiz covers key concepts related to oedema and infarction, including their pathophysiology and morphological characteristics. Learn about the different types of oedema, their causes, and how they can be identified both microscopically and macroscopically. Explore the implications of these conditions in the context of medical health.