22 Cardiac output

22 Cardiac output - Biology141 (Physiology) 4/6/08 1:05 AM...

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4/6/08 1:05 AM Biology141 (Physiology) Page 1 of 4 https://courses.bio.psu.edu/spring2008/biol141/Lecture%2022(2008).htm Biology141 (Physiology) Lecture 22 M. Whim CARDIAC OUTPUT [1]. BACKGROUND. amount of blood ejected by each ventricle in 1 minute is the cardiac output (CO). CO = HR x SV assuming HR (heart rate) is ~ 70 bpm, and SV (stroke volume) is ~ 75 ml (see lecture #20). then CO ~ 5.5 litres per minute . what is total volume of blood in the human body? so how often does the heart pump the total blood volume round the body? cardiac output is not constant (e.g. exercise). How does the CO vary?: since CO = HR x SV a change in heart rate or stroke volume are the only ways to change cardiac output. [2]. CHANGING HEART RATE. resting heart rate is set by the frequency of actions potentials generated by the SA node (see previous lecture). however the heart rate is modified by the autonomic nervous system. the activity of the SA node is controlled by a balance of inputs from the sympathetic and parasympathetic nervous systems. but what, in turn, controls the autonomic nervous system?
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This note was uploaded on 04/05/2008 for the course BIOL 141 taught by Professor Viti,janehartwel during the Spring '08 term at Penn State.

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22 Cardiac output - Biology141 (Physiology) 4/6/08 1:05 AM...

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