Microcirculation Flashcards
Capillaries have the greatest cross-sectional area due to what?
Their extensive branching
Which vessel is the slowest velocity vessel?
Capillaries
Where are continuous capillaries typically found?
Fat
Muscle
Nervous system
Where are fenestrated capillaries typically found?
Intestinal villi
Endocrine glands
Kidney
What is the difference between transcellular and paracellular transport?
Transcellular - solutes transported by a cell through a cell, involves transcytosis
Paracellular - solutes transported via gaps in capillary wall
Large proteins are too large to pass via transcellular transport. What mechanism are they transported by?
Paracellular
Bulk flow is a method of paracellular transport. True or false?
True
Most blood vessels are permeable to proteins. True or false?
False - impermeable
Protein concentration in plasma is higher than interstitial fluid. True or false?
True
What are starling forces?
The pressures that drive fluid into and out of capillaries
Describe how water flows from interstitial fluid into plasma.
High protein content in plasma drives osmosis
Hydrostatic pressure pushes water out of the capillary into the interstitial fluid
Oncotic pressure pushes water from the interstitial fluid back into the plasma
Roughly 4/L of fluid a day leaves the blood and goes to tissues. True or false?
True
What is the role of the lymphatic system?
Drains excess fluid
Lymph nodes have phagocytic cells. True or false?
True
Oedema is caused by bulk flow from the capillaries into interstitial fluid. True or false?
True
Oedema is a symptom of liver or kidney failure. What is the cause of the imbalance in Starling forces?
Low colloid osmotic pressure as less protein synthesis in liver and kidneys due to failure. This leads to water leaving into interstitial fluid
What is macular oedema due to?
leakage of proteins from retinal microcirculation
What are the four starling forces?
Capillary hydrostatic pressure
Capillary osmotic pressure
Interstitial fluid hydrostatic pressure
Interstitial fluid osmotic pressure
What is meant by capillary hydrostatic pressure?
The pressure exerted by the blood inside capillaries on the capillary wall
What is meant by capillary osmotic pressure?
The pressure exerted on the capillary walls by proteins in plasma
Pulmonary oedema is a symptom of left ventricular failure and pulmonary embolism. What is the mechanism?
Capillary pressure too high
