Cardiac output Flashcards
What are the determinants of caridac output
Stroke volume * heart rate determines cardiac output
measured, L/min
When does blood pressure rapidly drop in the vascular system
When arteial blood reaches the arteriols, capillarys and veins, blood pressure is low
What are the two heamodynamic equasions for the vasuclar system
MAP = CO * TPR
CO = SV * HR
How is blood pressure maintains by the cardiac system
The volume of blood in the arterys determines BP
Volume of blood is determined by the blood inflow from the heart
Volume = Flow in - flow out
How is flow in and out of arterys determined
In = ventricular contractions
Out = arteiral resistance
How can we increase CO, what does this do and when is it done
Increased cardiac output through increase SV or increasing HR
Increases the VO2 max, increased during excersise
How does an unhealthy heart keep CO constant
By increasing HR due to a fall in the SV
How is pressure of the arteial system measured and where is this located and why
Barrow receptors detect strech of the arterys, send constnat information about strech which corrosponds to the vessles pressure
Locations:
- Caroted arterys - blood flow to brain
- Aortic arch - flow from heart
How is arteial homeostasis controled when arterial BP falls (hypotention)
Increase BP: Sympathetic cardiac nerves increase HR - acellorator
controled by the sympathetic trunk ganglion
- Signal SA node to increase, AV node to decrease pasue
- Signals to heart walls, stimulates ventricular myocytes to increase Ca++ release for stronger contractions
How is arteial homeostasis controled when arterial BP rises (hypertention)
Decrease BP: Vegus nerve (parasympathetic) break
- Signals to SA node to decrease activity
- Signals to AV node to increase pause time
What is the barrow response
When standing up:
SV falls due to gravity -> increase in HR = small drop CO Change
to prevent MAP change increase TPR
How do barrow receptors signal to the brain when there is a change in BP
Rate of signals recived by barrow receptors indicates pressure
- Hypertention = increased rate of signaling = more streach
- Hypotention = decreased rate of signaling = less streach = VERY BAD
