16 Questions
What is ischemia?
Cut off arterial blood supply
What is the main difference between acute and chronic ischemia?
Duration of ischemia
What can cause acute ischemia?
All of the above
What is a factor that affects the fate of ischemia?
All of the above
What is the result of chronic ischemia?
Degeneration and fibrosis
What is oedema?
Abnormal accumulation of fluid in tissue or serous membranes
What is an effect of ischemia on CNS tissues?
They are sensitive to hypoxia and rapidly undergo necrosis
What can worsen the effect of ischemia?
Anemia
What is the primary cause of localized oedema in cases of venous obstruction?
Increase in hydrostatic pressure
What is the effect of increased aldosterone level on oedema?
It promotes Na and water retention
What is the term for the fluid that accumulates in localized inflammatory oedema?
Exudates
What is a common cause of decreased osmotic pressure?
All of the above
What is the term for oedema that occurs due to lymphatic obstruction?
Lymphatic oedema
What is a common cause of generalized oedema?
Right sided heart failure
What is the term for oedema that occurs due to increased capillary permeability?
Inflammatory oedema
What is the cause of localized oedema due to compression from outside by gravid uterus and tumors?
Obstructive venous oedema
Study Notes
Ischemia
- Ischemia is a cut off of arterial blood supply
- Types of ischemia:
- Acute ischemia: sudden and complete obstruction of an artery
- Chronic ischemia: gradual and incomplete occlusion of an artery
- Causes of acute ischemia:
- Atherosclerosis
- Thrombus
- Embolus
- Surgical ligature
- Ergot poisoning leading to arterial spasm
- Twisting of vessels
- Forest bite
- Compression from outside (e.g. enlarged lymph node, gravid uterus, and tumors)
- Causes of chronic ischemia:
- End arteritis obliterans (e.g. in syphilis)
- Factors affecting the fate of ischemia:
- Type of ischemia (acute or chronic)
- Degree of organ vascularity (number of arterial blood supply and efficiency of collaterals and anastomosis)
- Vulnerability of tissue to hypoxia (e.g. CNS tissues are very sensitive to hypoxia)
- Oxygen concentration in blood (e.g. anemia)
Oedema
- Oedema is an abnormal accumulation of fluid in tissue or serous membranes
- Mechanism:
- Increased hydrostatic pressure
- Decreased osmotic (oncotic) pressure
- Increased capillary permeability
- Lymphatic obstruction
- Na and water retention
- Causes of oedema:
- Increased hydrostatic pressure:
- Localized: venous obstruction
- Generalized: right-sided heart failure
- Decreased osmotic (oncotic) pressure:
- Decreased protein intake
- Liver diseases
- Proteinuria
- Increased capillary permeability:
- Inflammation
- Hypoxia
- Exposure to toxins and certain chemicals
- Lymphatic obstruction:
- Congenital lymphatic hypoplasia
- Inflammatory (e.g. filariasis) or nonspecific lymphadenitis and lymphangitis
- Fibrosis (post-inflammatory or post-irradiation)
- Tumor emboli
- Compression from outside (e.g. tumors)
- Surgical removal of lymphatics (e.g. modified radical mastectomy)
- Na and water retention:
- Increased aldosterone level (e.g. right-sided heart failure)
- Increased hydrostatic pressure:
- Types of oedema:
- Generalized:
- Renal
- Cardiac
- Nutritional
- Localized:
- Inflammatory
- Venous
- Lymphatic
- Generalized:
This lecture covers the types of ischemia, including acute and chronic ischemia, and their causes such as atherosclerosis and thrombus. It is taught by Dr. Fatma Samir at the Faculty of Medicine, Menoufia University.
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