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Heart Dynamics
By Alyssa, Seth and Jasmyn
Vocab
• Heart Dynamic- the movements and forces
generated during cardiac contractions.
o Also known as cardio dynamics
• Atrial reflex- involves adjustments in heart
rate in response to an increase in venous
return.
• Venous return- The flow of blood into the
heart
• Frank- Starling principle- “more in = more
out”
Heart dynamics
• Stroke volume- volume of blood ejected by a
ventricle in one beat.
• Cardiac output- volume of blood ejected from a
ventricle in one minute
Autonomic Innervation
Autonomic Effects on the Heart rate:
• Acetylcholine released by parasympathetic motor
neurons results in lowering of the heart rate.
• Norepinephrine released by sympathetic neurons
increases the heart rate.
Autonomic Effects on the Stroke Volume:
• NE and E- the sympathetic release increases the
force and degree of ventricle contractions.
o Increase in stroke volume
• Ach- the parasympathetic release decrease in the
force of cardiac contractions.
o Cut vagus nerves increase heart rate and blocking agents slow heart rate.
Autonomic Innervation
• Cardio acceleratory center-controls the sympathetic
motor neurons that increase heart rate.
• Cardio inhibitory center- controls the parasympathetic
motor neurons that slow heart rate.
• Cardiac centers respond to changes in blood pressure.
o They are monitored by baroreceptors and chemoreceptors innervated by the
glossopharyngeal and vagus nerves.
• Decline in blood pressure or oxygen concentrations or
an increase in carbon dioxide levels indicates the
oxygen demands of peripheral tissues have increased.
Hormones
• Epinephrine and Norepinephrine secreted by the
adrenal medullae increases heart rate and force of
contraction.
• Thyroid hormones and glucagon increase force of
contraction.
o Glucagon was used to stimulate heart function.
Checkpoint
• 11) volume of blood ejected from a ventricle in one
minute
• 12) would increase the heart rate
• 13) would slow the heart rate
• 14) increase the stroke volume
• 15) does not have sufficient time to fill completely
between beats