Week 3 - Lesson 1 (Part 2) Flashcards
What does the sympathetic nervous system do? (2)
- Increase the rate of cardiac contraction
2. Force of cardiac contraction
What does the parasympathetic nervous system do? (2)
- Reduces the heart rate
2. Force of contraction
What do the sympathetic and parasympathetic systems respond to?
Many stimuli
What does an increased heart rate yield?
An increased volume of blood to the tissues
What is necessary to move fluid from one point to another in a closed system?
Energy gradient
How does blood move in the case of the arterial tree?
A pressure gradient
How is pressure situated in the heart in order to create a necessary pressure gradient?
The left side has higher pressure and the right side has lower pressure
Blood pressure
Force exerted by the blood against the arterial walls when the heart contracts
What is blood pressure an important indicator of? (3)
- Current cardiovascular function
- Risk indicator of future cardiovascular morbidity
- Risk indicator of future mortality
What do capillary beds consist of? (3)
- Arterioles
- Capillaries
- Venules
How much does each heart beat approximately eject from the ventricle to the arterial tree?
70cc
Why must a considerable portion of the heart’s output must be stored during systole?
Because the small capillary network is unable to transmit large volumes of blood with each heartbeat
- passed on later during diastole
What is oscillatory flow in the arterial tree initiated by?
Each beat of the heart
- which behaves like a flow generator with an ejected pulse
How much blood is pumped every 5 minutes approximately?
5L
When does pressure build in the heart?
At the beginning of each cardiac contraction as the pressure in the left ventricle rapidly rises
What happens when the pressure in the left ventricle increases and it exceeds the pressure in the ascending aorta?
It forces the aortic valve open
Why does the mean pressure gradually decrease as it goes through the body?
Because of its loss in total fluid energy
What happens when the mean pressure decreases?
Systolic pressure begins to increase again
What is the wave propagation phenomenon due to?
Increasing stiffness of the vessel walls toward the periphery and the reflected waves which are enhanced by increasing peripheral resistance
What kind of arterial reservoir is there in the circulatory system? (2)
- High pressure
2. High energy
What kind of venous reservoir is there in the circulatory system? (2)
- Low pressure
2. Low energy
What do the elastic walls of the conducting arteries do?
They store excess volume by stretching during systole and relaxing during diastole
Where is energy stored during diastole?
In the stretched elastic walls of the arteries
What is the energy stored in the stretched elastic walls of the arteries during diastole used for?
To propel blood forward through the peripheral resistance vessels
- therefore flow is constant throughout the cardiac cycle
