BIOL 4510 Lecture Notes - Atrioventricular Node, Paravertebral Ganglia, Purkinje Fibers

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scarletcat969

22 Nov 2012

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The amount of blood pumped by the heart per minute is given by: Cardiac output (l/min) = co = stroke volume (l/beat) x heart rate (beats/min) = sv*hr. For a typical human, sv ~ 70 mls and hr ~60 beats/min, therefore co ~ 4. 2litres/min. Heart rate (hr) is the major factor determining the cardiac output. Hr can vary by a factor of 3-4 in most people (although the ability to vary hr declines strongly with age). Since the beating in the heart is initiated by the sa node, to understand the regulation of hr we need to understand how the spontaneous firing rate of the sa node is regulated. When there is an increased demand for co, hr increases. This occurs primarily be altering autonomic nerve inputs to the heart. The autonomic nervous system is comprised of two parts: 1) the sympathetic nerve system and 2) the parasympathetic nerve system.

Related Questions

Rest activity

min volume 19700ml air/min 43400 ml air /min

breathing rate 13breat/min 21

heartrate 72beats/min 112 beats/min

blood pressure 118/70 158/88

% O2 inhaled air 20.94% (.)2094ml O2/ml air) same

% O2 exhaled air 18.94% (.1894 ml O2/ml air) same

a) claculate Tidal volume [ml air/breath]
b) calculate Oxygen consumption (VO2) [ ml O2 consumed/min] -
c) calculate Oxygen content of arterial blood (CO2a) [ml O2/mlblood] -
d) calculate Oxygen content of venous blood (CO2v) [ml O2/ml blood]-
You need to know that there is 13.3 g hemoglobin/100 ml blood, and1.3
ml O2 binds to each gram of hemoglobin. Assume arterial blood is100%
saturated with oxygen, whereas mixed venous blood is 60%saturated
when the subject is resting.
e) caluclate Cardiac Output (CO) [ ml blood/min ] -
f) caulculate Stroke Volume (SV) [ ml blood/beat] -

g) Tidal volume [ml air/breath]
h) Oxygen consumption (VO2) [ ml O2 consumed/min]
i) Stroke Volume (SV) [ ml blood/beat]
Assume change in stroke volume is the same as the change inpulse
pressure when going from rest to exercise - s
j) Cardiac Output (CO) [ ml blood/min ] -
k) Oxygen content of arterial blood (CO2a) [ml O2/ml blood] = sameas when resting
l) Oxygen content of venous blood (CO2v) [ml O2/ml blood] -

Now answer these questions:

1. By what multiplication factor (e.g. 2 times, 3 times, etc.)did oxygen consumption
increase over resting when the person exercised?
2. a. Did minute volume increase by the same factor that oxygenconsumption
increased? If not, what made up the difference?
b. Did cardiac output increase by the same factor that oxygenconsumption
increased? If not, what made up the difference?
3. What was most responsible for the change in minute volume? i.e.compare the
factorial change in breathing rate with that of tidal volume.
4. What was most responsible for the change in cardiac output? i.e.compare the
factorial change in heart rate with that of stroke volume.
5. Calculate total peripheral resistance during rest and exercise(see pg 21). What
physiological changes led to the change in peripheral resistance?In what part of the
body did they occur, and why is this adaptive?

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BIOL 4510 Lecture Notes - Atrioventricular Node, Paravertebral Ganglia, Purkinje Fibers

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