Physiology of Circulation Flashcards
Circulation is primarily influenced by what?
tissue needs
3 characteristics of arteries?
1) transport blood under high pressure
2) strong vascular walls
3) rapid blood flow
4 characteristics of arterioles?
1) final small branches of arterial system
2) act as control conduits - blood released into capillaries
3) strong muscular walls that vasoconstrict/dilate
4) innervated by SNS only
4 characteristics of capillaries?
1) exchange site for nutrients, wastes, electrolytes, fluid
2) very thin walls
3) contain small capillary pores
4) permeable to small molecular substances, H2O
3 characteristics of venules?
1) gathers low oxygenated blood
2) collects blood from capillaries
3) gradually merge into larger veins
Major function of veins?
- serve as a blood reservoir (64% of total blood volume)
- transport blood from tissues to heart
Distribution of blood volume?
- veins = 64%
- arteries = 15%
- capillaries = 5%
- pulmonary = 9%
- heart = 7%
What is the volume of blood flowing through a vessel, an organ, or the entire, circulation in a given period (ml/min)?
blood flow
What is the force per unit area exerted on a vessel wall by the contained blood (mmHg)?
blood pressure
What is the opposition to flow; amount of friction blood meets when passes through the vessels?
resistance
Blood flow is affected by what 2 factors?
- pressure gradient
- vascular resistance
What is the calculation of flow through a vessel?
Ohm’s law:
blood flow = change in pressure between 2 ends of vessel/ resistance
What is the normal adult overall blood flow?
5,000 ml/min = cardiac output
What are the two descriptions of blood flow?
- laminar
- turbulent
What is known as the measure of blood flow through a vessel for a given pressure difference? Also known as the reciprocal of resistance?
conductance
What plays the greatest role in determining rate of blood flow?
diameter