Disorders of Circulation Flashcards
What are some differences between hyperemia and congestion?
Hyperemia is an active process resulting from arterial dilatation and increased blood flow. Congestion is a passive process resulting from impaired outflow of venous blood from a tissue.
Hyperemia makes tissues look “redder.”
Congestion gives tissues a “red-blue” color.
What is a commonality between hyperemia and congestion?
Both refer to increased intravascular blood volume in a tissue, organ or body part
What are two examples of hyperemia?
Sites of inflammation
Exercising skeletal muscle
What is an example of congestion?
Right CHF leads to hepatic congestion
Explain how CHF leads to ischemia and necrosis in the liver?
Blood is backed up at the central vein.
The sinusoids become engorged with blood, squeezing nearby hepatocytes –> ischemia
Thus, the impeded outflow leads to necrosis of hepatocytes around the central vein
What causes edema?
Fluid moving out of capillaries into the interstitial space exceeds the body’s lymphatic drainage capacity
Five reasons for edema:
- Increased hydrostatic pressure
- Decreased oncotic pressure due to reduced plasma albumin
- Lymphatic obstruction
- Increased vascular permeability
- Na+ retention
What could increase hydrostatic pressure?
a. Systemic - heart failure
b. Local - impaired venous return post DVT
What 5 things could decrease plasma albumin (overlap with pharm)
Renal failure - excretion
Liver failure - not making enough albumin
Burns - protein leaks out into interstitial space
Cystic fibrosis
Pregnancy
Malnutrition
What could obstruct the lymphatics?
a neoplasm
What could cause increased vascular permeability?
inflammation
What could cause sodium retention?
Renal failure
What are the three pathophysiological categories for edema?
Heart failure
Renal failure
Malnutrition, decreased hepatic synthesis, nephrotic syndrome
How does heart failure cause edema?
It increases capillary hydrostatic pressure, as there is a significant venous backup.
Because the heart’s not pumping much blood, there is decreased blood flow to the kidneys. This results in activation of the renin-ang.-aldo. system and retention of sodium and water.
How does renal failure cause edema?
Sodium and H2O retention, increasing blood volume
How do malnutrition, liver disease and nephrotic syndrome cause edema?
They decrease plasma albumin and, thus, oncotic pressure
What causes transudate leakage?
High hydrostatic pressure, low oncotic pressure
What causes exudate leakage?
Increased vascular permeability (inflammation)
Vasodilation and stasis
f. Explain the pathogenesis, pathology and pathophysiology of HEMORRHAGE.
Pathology - Flow of blood from a ruptured blood vessel into tissue, into a body cavity or outside the body
Pathogenesis - Bleeding occurs when blood vessel is disrupted by either a mechanical force or a pathologic process, such as (congestion, inflammation, neoplastic erosion of vessel)
Pathophysiology - Abnormal hemostasis causes a predisposition to bleeding
What could cause a thrombus?
- Endothelial injury
- Altered blood flow
- Hypercoagulable state
What would cause endothelial injury?
inflammation, advanced therosclerosis
What would cause altered blood flow?
Turbulence, via atherosclerotic vessel narrowing, or stasis (a-fib, bed rest, scarred tissue on a heart doesn’t pump)
What would cause a hypercoagulable state?
Predisposition to easy clot formation (inherited protein C deficiency, contraceptives and smoking, metastatic cancer, obesity)
What factors influence the clinical outcomes of thrombosis?
- Degree of occlusion of vessel lumen, collaterals, size of infarct
- Survival of patient is determined by size and location of infarct as well as collateral circulation
