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Biology
Unit 6
Control of heart rate
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Cards (26)
What does myogenic mean in relation to cardiac muscle?
It can
contract
and
relax
on its own
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How is the rate of cardiac muscle contraction controlled?
By the
nervous system
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What triggers atrial systole?
Wave of
depolarization
from
SAN
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What is the function of the atrioventricular node (AVN)?
Releases a wave of
depolarization
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Why is there a layer of non-conductive tissue between the atria and ventricles?
To prevent direct
depolarization
to ventricles
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What is the role of the bundle of His?
Conducts
depolarization
to
ventricles
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What are Purkinje fibers also known as?
Perkin
fibers
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How does the contraction sequence in the ventricles occur?
Apex
contracts first, then outer walls
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Why is the contraction sequence in the heart compared to squeezing toothpaste?
To
maximize
blood ejection from the heart
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What is the advantage of the slight delay caused by non-conductive tissue?
Allows
atria
to fully contract and fill
ventricles
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What part of the nervous system controls heart rate?
Autonomic nervous system
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What is the role of the medulla oblongata in heart rate control?
Coordinates heart rate through
nervous impulses
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How does the sympathetic nervous system affect heart rate?
Increases
heart rate
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What effect does the parasympathetic nervous system have on heart rate?
Decreases
heart rate
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What are the two key stimuli that affect heart rate?
Changes in
pH
and blood pressure
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Where are the chemoreceptors located?
Aorta and
carotid
artery
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What happens when blood pressure is too high?
Triggers action potential in
pressure receptors
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What is the response when blood pressure is too low?
Increases heart rate via
sympathetic nervous system
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What happens when pH decreases in the blood?
Increases heart rate to remove
acids
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What is the role of baroreceptors?
Detect changes in
blood pressure
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What is the effect of increased carbon dioxide on heart rate?
Increases heart rate to remove
CO2
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What is the flow of information in the heart rate control process?
Stimulus detected by receptors
Coordinator:
Medulla oblongata
Impulses sent via
sympathetic or parasympathetic nervous system
Effector:
SAN
in
cardiac muscle
Response: Adjusted heart rate
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What are the differences in responses to high and low blood pressure?
High Blood Pressure:
Detected by
baroreceptors
More impulses to
medulla oblongata
Increased
parasympathetic
activity
Decreased heart rate
Low Blood Pressure:
Detected by baroreceptors
More impulses to medulla oblongata
Increased sympathetic activity
Increased heart rate
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How does the body respond to decreased pH in the blood?
Detected by
chemoreceptors
More impulses sent to
medulla oblongata
Increased
sympathetic nervous system
activity
Increased heart rate to remove acids
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What are the key components involved in the cardiac cycle control?
Sinoatrial Node (SAN)
Atrioventricular Node (AVN)
Bundle of His
Purkinje Fibers
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What is the significance of the delay caused by non-conductive tissue in the heart?
Allows
atria
to fully contract
Ensures
ventricles
are filled with blood
Prevents simultaneous contraction of
chambers
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