What are pacemaker potentials?
Electrical changes in the heart that initiate action potentials.
What are cardiac myocytes?
Contractile muscle cells in the heart.
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Electrical Impulses and Ion Flow
How do cardiac myocytes respond to electrical impulses?
They depolarize and contract in response to electrical signals.
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Cardiac Conduction Pathway
What is the heart's 'in-house' conduction system responsible for?
Conducting electrical information.
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Myogenic Pacemaker Cells
What is the role of the SA node in the cardiac conduction pathway?
It acts as the primary pacemaker of the heart.
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Cardiac Conduction Pathway
What initiates the conduction pathway in the heart?
Impulses generated via pacemaker cells.
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Electrical Impulses and Ion Flow
Why do action potentials in the ventricles differ from those in the atria?
Due to different physiological events and ion movements.
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Excitation Sequence of the Heart
What is the primary function of the conduction pathway in the heart?
To ensure coordinated contraction of cardiac myocytes.
What do pacemaker potentials initiate?
Action potentials that spread throughout the heart.
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Refractory Period in Cardiac Muscle
What is the refractory period?
The time following an action potential when a new action potential cannot be initiated.
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Myogenic Pacemaker Cells
What is the role of pacemaker cells in the heart?
They generate impulses that initiate the heart's contraction.
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Geographical Features
What are some common characteristics of plateaus?
They often have steep sides and can be formed by volcanic activity or erosion.
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Cardiac Conduction Pathway
What is the role of Purkinje fibers?
They distribute the electrical impulse throughout the ventricles, causing them to contract.
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Refractory Period in Cardiac Muscle
What causes the refractory period?
It is caused by the inactivation of sodium channels and the prolonged opening of potassium channels.
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Geographical Features
What is a plateau?
A flat elevated landform that rises sharply above the surrounding area.
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Geographical Features
Can plateaus be found in different climates?
Yes, plateaus can exist in various climates, including deserts and tropical regions.
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Modifying Heart Rhythm
What is the function of the parasympathetic nervous system in heart rate regulation?
It acts as 'brakes' to decrease heart rate.
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Excitation Sequence of the Heart
What is the role of action potentials in the heart?
To trigger contractions of the heart.
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Physiological Mechanisms of Heart Rate Changes
How do norepinephrine and acetylcholine affect heart rate?
They influence heart rate through physiological mechanisms.
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Refractory Period in Cardiac Muscle
What ions are responsible for the refractory period in the heart?
Sodium and potassium ions.
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Geographical Features
How is a plateau different from a mountain?
A plateau is flat on top, while a mountain has a peak.
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Myogenic Pacemaker Cells
What is the function of the AV node?
It serves as a relay station, slowing down the electrical impulse before it moves to the ventricles.
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Cardiac Conduction Pathway
What is the conductive pathway of the heart?
The sequence in which action potentials move along the heart's conduction system.
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Electrical Impulses and Ion Flow
What is the significance of potentials in the conduction pathway?
They facilitate the electrical signals that trigger heart contractions.
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Geographical Features
What is an example of a well-known plateau?
The Colorado Plateau in the United States.
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Modifying Heart Rhythm
What do heart rate fluctuations indicate?
Variations in the balance between sympathetic and parasympathetic activity.
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Cardiac Conduction Pathway
What are cardiac muscle cells modified to conduct electrical information called?
Myogenic pacemaker cells.
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Cardiac Conduction Pathway
What do the bundle branches do?
They carry the electrical impulses from the AV bundle to the Purkinje fibers.
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Electrical Impulses and Ion Flow
What is the significance of gap junctions in cardiac muscle?
They allow for the rapid spread of electrical impulses between cells.
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Refractory Period in Cardiac Muscle
Why is a long refractory period important in cardiac muscle?
It prevents tetanus and allows the heart to fill with blood.
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Refractory Period in Cardiac Muscle
Why is the refractory period important?
It prevents the heart from undergoing tetany and ensures proper timing of contractions.
What role do cardiac myocytes play in the heart?
They are responsible for the contraction of the heart muscle.
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Myogenic Pacemaker Cells
What type of cells are autorhythmical?
Myogenic pacemaker cells.
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Modifying Heart Rhythm
What is the role of the sympathetic nervous system in heart rate?
It acts as an 'accelerator' to increase heart rate.
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Modifying Heart Rhythm
What are cardiac nerves responsible for?
They transmit signals from the sympathetic nervous system to the heart.
What causes electrical impulses in a cell?
The change in ion flow across the cell membrane.
What are the two types of cardiac muscle cells?
<p>Myogenic pacemaker cells and cardiac myocytes</p>
