Heart Test #2 Flashcards
What does cardiac output measure?
a measure of how hard the heart is working?
What is cardiac output?
the volume of blood ejected from the left ventricle, into the aorta each minute
What is the formula for cardiac output (CO)?
CO = SV (stroke volume) x HR (heart rate)
Stroke volume unit of measure
SV : stroke volume (ml/beat)
Heart rate unit of measure
HR : heart rate (beats per minute)
The Franklin-Sterling Law states….
The more the heart is stretched (i.e. filled with blood), the harder it will contract, forcing more blood out
Cardiac output
Venous return
Affects stroke volume
What is venous return?
rate of blood flow back to the heart
What regulates the heart rate?
- autonomic control and chemical regulation
Where is the autonomic control center located?
the medulla oblongata
What does the autonomic control center/medulla oblongata receive messages from?
Proprioceptors (body position)
Chemoreceptors (O2 , CO2 , pH)
Baroreceptors (blood pressure)
Chemoreceptors detect what?
changes in the chemical composition of the blood
What are the two branches of the autonomic nervous system?
- parasympathetic nervous system
- sympathetic nervous system
Sympathetic nerves run from _______________ _______________ to the _____________
medulla oblongata, SA node
What neurotransmitter is used by the sympathetic nervous system?
norepinephrine
What is norepinephrine’s effect on heart rate?
- increases the amount depolarization occurs (more “+”)
- decreases the amount of times repolarization occurs
- thus increasing the heart rate
- increases Ca+2 entry, increasing the force of contraction
The vagus nerve (X) acts as what for the parasympathetic nervous system?
the main component of the PSNS/contains the main nerves of the PSNS
What neurotransmitter does the parasympathetic nervous system release?
acetylcholine (ACh)
What is acetylcholine’s effect on heart rate?
Hyperpolarization of SA node (more “-“)
-takes longer to depolarize
thus heart rate slows