Pathology Week 3 Flashcards
Edema is…
characterized by an increase in intercellular fluid
What are the mechanisms of edema?
- Increased hydrostatic pressure
- Decreased plasma osmotic pressure
- Lymphatic obstruction
- Increased sodium (increased hydrostatic pressure due to expansion of intravascular volume and reducing plasma osmotic pressure)
- Inflammation
Relating to edema what are the causes of: Increased hydrostatic pressure
- Systemic: CHF
- Regional: Deep venous thrombosis
- venous obstruction, Iatrogenic fluid overload
Relating to edema what are the causes of: Decreased plasma osmotic pressure
- low albumin: nephrosis, liver disease
Relating to edema what are the causes of: Lymphatic obstruction
- surgery, tumor, radiation, filaria
Relating to edema what are the causes of: Increased sodium
- renal disorders; secondary to CHF
Relating to edema what are the causes of: Inflammation
- Acute, chronic, angiogenesis
Describe subcutaneous edema:
Subcutaneous edema may be diffuse but tends to accumulate preferentially where body positioned greatest distance below heart (hydrostatic pressure highest there) and most pronounced in legs when standing and sitting when recumbent (termed dependent edema)
Describe pitting edema:
Pitting edema: finger shaped depression in subcutaneous tissue
Describe pulmonary edema:
lungs 2-3x normal weight, sectioning reveals frothy, sometimes blood tinged fluid consisting of air, edema fluid and extravasated red cells.
Describe brain edema:
Localized or generalized depending on nature and extent of pathologic progress or injury
- Generalized edema, show narrowing of sulci while gyri are swollen and flattened against the skull
What is hyperemia?
It is an active process (exercise, inflammation) that increases blood volume through arteriolar dilation.
What is congestion?
Congestion is a passive process (local obstruction, CHF) that increases blood volume through capillary engorgement (decreased outflow) with possible associated cyanosis.
Explain edema’s relationship to congestive heart failure
- Right heart failure, increased hydrostatic pressure in venous circuit
- Additionally, decreased renal perfusion causes kidneys to hold onto water
- Creates vicious circle because heart can’t handle more water
What is hemostasis?
The balance between coagulation and anticoagulation, forming a hemostatic plug when needed in response to vascular injury.