Cardiovascular Physiology 25 Flashcards
When is blood pressure highest and lowest?
Pressure is highest when blood leaves the heart and pressure is lowest in the veins returning back to the atria
Why are pressures in the systemic circulation higher than pressures in the pulmonary circulation?
The systemic circulation has to pump blood throughout our entire body the pulmonary circulation only has to pump blood from the top to the bottom of the lungs
Where is the pressure drop greatest in the systemic circulation?
At the level of the arterioles
What are arterioles?
Small diameter blood vessels that extend and branch out from an artery and lead to capillaries
What do the walls of arterioles have?
An abundance of smooth muscle
What are the two important functions of Arterioles?
- Regulate blood flow to organs by regulating the amount of blood flow to capillary beds supplying that organ
- Determine Mean Arterial Pressure (MAP)
Why are Arterioles called resistance vessels?
Because they have a small enough radius to give considerable resistance to blood flow
What act as pressure reservoirs in the body?
The large arteries
What is the equation for Flow?
𝛥P/R=F
How do arterioles cause a large decrease in MAP?
They cause a high resistance to flow
What does the high resistance to flow of Arterioles cause?
A drop in blood pressure
How is resistance of Arterioles regulated?
By contraction or relaxation of arteriolar smooth muscle
What is the meaning of Arterioles having Intrinsic or Basal tone?
They are partially contracted in the absence of external factors such as neural or hormonal stimuli
What kind of factors can affect basal tone?
Extrinsic (nerves and hormones) and Intrinsic factors (local controls)
