Session 11 Flashcards
(35 cards)
What are the four types of specialized ion channels in cardiac myocytes?
Sodium, Potassium, Calcium, Chloride
These channels are responsible for the electrical currents that activate cardiac myocytes.
What is depolarization in the context of cardiac action potential?
Changes in membrane potential leading to muscle contraction
Depolarization occurs when positive ions enter the cell.
What is repolarization in cardiac action potential?
Resets the membrane potential, causing muscle relaxation
This process restores the resting state of the cardiac myocyte.
What is the resting state of a cardiac myocyte?
Negatively charged
-90 mV
The interior of the cell is negatively charged compared to the exterior.
What is the function of ion channels in cardiac myocytes?
Allow passage of specific ions and are voltage-gated
They open and close in response to changes in membrane potential.
What are the two types of sodium channels in cardiac myocytes?
Fast channels, Slow channels
Fast channels are involved in depolarization, while slow channels are important for pacemaker cells.
What are the states of sodium channels?
Deactivated (closed), Activated (open), Inactivated (closed)
These states reflect the channel’s ability to conduct ions.
What are the two types of potassium channels?
Inward-rectifier, Outward-rectifier
Inward-rectifier allows potassium into the cell, while outward-rectifier allows potassium out.
What is the function of L-type calcium channels?
Sustain action potential by allowing calcium into cells
These channels are critical during the plateau phase of the action potential.
What is the sodium-potassium pump’s transport ratio?
3 sodium ions out for every 2 potassium ions in (3:2 ratio)
This active transport mechanism helps maintain resting membrane potential.
What occurs during Phase 4 of the cardiac myocyte action potential?
Resting potential of ~-90mV
The membrane is more permeable to K+, balancing K+ efflux and influx.
What happens during Phase 0 of cardiac myocyte action potential?
Rapid depolarization due to Na+ influx
Sodium channels open, allowing Na+ to enter the cell.
What characterizes Phase 1 of cardiac action potential?
Initial repolarization due to outward K+ and Cl- flow
This phase follows rapid depolarization.
What occurs during Phase 2 of the cardiac myocyte action potential?
Plateau phase with inward Ca++ movement and outward K+ flow
Excitation-contraction coupling occurs during this phase.
What is the primary event during Phase 3 of cardiac action potential?
Rapid repolarization as L-type Ca++ channels close
Continued K+ movement extracellularly contributes to this phase.
True or False: The sodium-potassium pump is fueled by ATP.
True
ATP is necessary for the active transport of sodium and potassium.
Fill in the blank: The sodium-calcium exchanger moves ______ out in exchange for sodium ions.
Calcium
This mechanism involves secondary active transport.
What are the four types of specialized ion channels in cardiac myocytes?
Sodium, Potassium, Calcium, Chloride
These channels are responsible for the electrical currents that activate cardiac myocytes.
What is depolarization in the context of cardiac action potential?
Changes in membrane potential leading to muscle contraction
Depolarization occurs when positive ions enter the cell.
What is repolarization in cardiac action potential?
Resets the membrane potential, causing muscle relaxation
This process restores the resting state of the cardiac myocyte.
What is the resting state charge of a cardiac myocyte?
Negatively charged
The interior of the cell is negatively charged compared to the exterior.
What is the function of ion channels in cardiac myocytes?
Allow passage of specific ions and are voltage-gated
They open and close in response to changes in membrane potential.
What are the two types of sodium channels in cardiac myocytes?
Fast channels, Slow channels
Fast channels are involved in depolarization, while slow channels are important for pacemaker cells.
What are the states of sodium channels?
Deactivated (closed), Activated (open), Inactivated (closed)
These states reflect the channel’s ability to conduct ions.
