Cardiovascular 3 (Topic 16) Flashcards
(46 cards)
what is cardiac output (CO)
the volume of blood ejected by each ventricles per one minute
how do you calculate CO? (cardiac output)
HR (bpm/mins) x SV (ml/beat)
what is the stroke volume?
the volume of blood ejected by each ventricles per beat (ml/beat)
in a resting adult male, stroke volume averages about 70ml/beat, and the average HR is about 75 bpm/min. - 1. Calculate the total cardiac output pumped per ventricles
2. what is the Cardiac output ejected from right ventricle? left ventricle?
CO= 75 hr (Bpm/min) x 70 SV (ml/beat)
= 5250 mL/min pumped per ventricle
CO= 5.25L from right ventricles
CO = 5.25L from left ventricles
what is the total blood volume usually in the body?
5L (4-6L)
the total blood volume in the body is usually 5L or (4-6L) what does this mean?
the volume of blood in the body is 5L which means that the entire blood content in the body passes through the entire circulatory system (both systemic and pulmonary)
during exercise, explain what happens to the cardiac output.
CO may increase up to 5x or more during exercise
the basic heart rate is set by what portion of the conduction system?
the SA node
explain how modifiers, such as extrinsic and intrinsic factors, affect and modify the heart rate
- any changes to the HR will not change the action potential because the SA node is an intrinsic factor - its built in- and its the natural pacemaker of the heart. But the heart rate will change if there is a change in the pacemaker potential
what are the 2 factors that contribute and or /affect Heart rate
- Autonomic nervous system:
- SNS
-PSNS - Hormones
how does the sympathetic nervous system affect the heart rate
- thru the thoracic nerves (cardiac accelerator nerves) extend to the SA and AV node and most of the myocardium
- Na+ channels that make the pacemaker potential open wider which increases the Na+ permeability at the SA node
- this results in an increased in the slope of the pacemaker potential which makes threshold reach faster and in turn increases the heart rate
explain how the PSNS affect the heart rate
- thru the Vagus nerve which extends to the SA node, AV node, and the atrial myocardium (there’s less innervation to the ventricular myocardium)
- keeps resting HR slower than the pace set by SA node
- leads to an increased in K+ permeability at the SA node which makes the membrane potential more negative during repolarization
- as a result, threshold is reach more slowly
what hormones increase heart rate
- epinephrine and norepinephrine
how do epinephrine and norepinephrine increase hHR
they both mimic the effect of SNS
explain how Thyroid hormone affects heart rate
it has a slow but direct effect on increasing HR which usually occur over days. It also increases the number of epinephrine receptors which in turn increases the sensitivity of cells to epinephrine
what are other factors that contribute to heart rate?
Ions
Fever
Age
Fitness
explain how Ions such as, K+, have an affect on heart rate
-High K+ in the ISF causes a membrane potential that’s higher than normal
- which causes the Na+ channels for the pacemaker potential to not open
- so repolarization is slow and heart rate decreases may occur = cardiac arrest
how does fever affect heart rate?
increased temp = increase HR due to the increased speed of AP firing from the SA node
How does age affect heart rate
newborns have a very high heart rate = higher than 120 bpm
how does fitness affect heart rate
increased fitness leads to a decreased heart rate
what is the average stroke volume?
70ml/beat
what is END DIASTOLIC VOLUME? (EDV)
The volume of blood in each ventricle at the end of the ventricular diastole (right before contraction)
EDV is also known as?
Preload
what is the maximum ventricular volume in EDV
120 ml
