Circulation I Flashcards
What are the four causes of edema?
- Increased intravascular hydrostatic pressure
- Decreased serum oncotic pressure
- Increased permeability of vessel walls
- Lymphatic obstruction or destruction
Explain the mechanism underlying increased intravascular hydrostatic pressure as a cause of edema. Give an example.
Pushes fluid out of vessels, not enough is reabsorbed
Example: heart failure, venous obstruction
Explain the mechanism underlying decreased serum oncotic pressure as a cause of edema. Give an example.
Not enough oncotic pressure to reabsorb fluid that leaks into interstitium
Example: low/absent protein synthesis, protein loss
Explain the mechanism underlying increased permeability of vessel walls as a cause of edema. Give an example.
More fluid leaks out than can be reabsorbed or carried away
Example: burns, inflammation, chemical injury
Explain the mechanism underlying lymphatic obstruction or destruction as a cause of edema. Give an example.
Lymph no longer able to carry away fluid that leaks into interstitium
Example: neoplasia, post-surgery, parasites
Distinguish a transudate from an exudate.
Transudate: fluid of low protein content (not from inflammation)
Exudate: fluid of high protein content (infectious, like pus)
Define hyperemia. Distinguish between active and passive hyperemia.
Congestion; increased volume of blood within a specific vascular bed
Active: increased flow into the area
Passive: decreased outflow from the area
Define hemorrhage. What morphological change would it cause?
Flow of blood FROM the vascular compartment
Change: see blood no longer contained in heart or in lumen of blood vessel
Name six local and two systemic causes for hemorrhage.
Local:
- Trauma
- Infection
- Inflammation
- Tumor
- Vascular malformation
- Focal tissue necrosis
Systemic:
- Coagulopathy
- Vascular defects (vasculitis)
Name the three factors determining the clinical significance of a hemorrhage.
- Volume of blood: larger amount worse than smaller
- Rate of bleeding: rapid worse than slow
- Site where hemorrhage occurs: including whether it leaves body or accumulates as a hematoma
Distinguish petechiae, purpora, hematoma, and ecchymosis.
Petechiae: minute hemorrhages in skin, mucous membranes, or serosal surfaces
Purpora: splotches of hemorrhage on surfaces
Hematoma: pool of extravascular blood trapped in tissues
Ecchymosis: large hemorrhages of surfaces deeper within tissue, normally with a known cause
Define anemia.
Reduction in number and/or volume of erythrocytes per unit volume of blood
What are the two major causes of anemia?
- Decreased production of RBCs
2. Increased loss of RBCs: slow blood loss, increased desctruction
Distinguish ischemia from infarction.
Ischemia: reduction or loss of the blood supply to a tissue or organ
Infarction: death of cells, a tissue, or an organ due to insufficient or absent blood supply
Describe the morphology of an infarct of the heart. (5 factors/stages)
- Muscle necrosis
- Neutrophil infiltration
- Macrophages
- Fibroblasts and capillaries
- Increased collagen (with healing) -> scar formation
Distinguish a thrombus from a clot.
BOTH are coagulated blood
Thrombus = “white clot,” composed of coagulation factors, always in vasculature
Clot = “red clot,” composed of clotted blood, normally outside of vasculature or in vasculature after death
Define edema.
The presence of excessive fluid in the tissues or body cavities
Fluid in cavities = effusions
Define anasarca.
Very severe generalized edema, especially of subcutaneous tissue
Define dependent edema.
Distribution by gravity
Define pitting edema.
Finger pressure leaves a depression
Define ascites.
Excessive peritoneal fluid
Define hydrothorax.
Excessive pleural fluid
Define hydrarthrosis.
Excessive joint fluid
List the gross (2) and microscopic (2) morphological changes associated with edema.
Gross:
- -Organ or tissue swells
- -Increased mass of the tissue due to an influx of fluid
Microscopic:
- -Separation of tissue elements by pale, pink, protein-containing fluid
- -No new cellular elements in the tissue (all interstitial)
