Lecture 19 - Blood flow in microcirculation Flashcards
Describe the branching network of micro vessels.
The circulation of the blood in the smallest blood vessels.
The last station of the blood circulation system that provides
suitable conditions for the living tissues.
The arterioles, venules and capillaries are major parts of this
system.
The main functions of the microcirculation are the delivery of
oxygen and nutrients and the removal of carbon dioxide (CO2).
5% of circulating blood volume is present in the capillaries at
any given time.
Over 10 billion of capillaries with surface area of 500-700 square
meters
What are capillaries?
Tiny blood-containing structures that connect arterioles to venules. They are the smallest and most abundant form of a blood vessel in the body. Capillaries are small enough to penetrate body tissues, allowing oxygen, nutrients, and waste products to be exchanged between tissues and the blood.
How does exchange happen across capillary walls?
Simple Diffusion
Bulk Flow
What is bulk flow?
Bulk flow is used by small, lipid-insoluble solutes in water to cross the capillary wall. The movement of materials across the wall is dependent on pressure and is bi-directional depending on the difference.
What is interstitial fluid?
A thin layer of fluid which surrounds the body’s cells.
What is flow from blood vessel to interstitium called?
filtration
What is flow from interstitium to blood vessel called?
reabsorption
Two types of pressure in capillaries?
Osmotic pressure
Hydrostatic pressure
Types of capillaries?
(A) Continuous capillaries
(tight structure) reduce bulk flow
(B) Fenestrated capillaries
(perforated structure) increase bulk flow
(C) Discontinuous capillaries
(great intercellular gaps) enable bulk flow
blood pressure drop in arterioles? Poiseuille equation
delta p = {8muLQ}/pi*R^4
