Podcast
Questions and Answers
What is the approximate resting potential of a cardiac muscle cell?
What is the approximate resting potential of a cardiac muscle cell?
Which ion plays a crucial role in creating the resting potential of a cardiac muscle cell?
Which ion plays a crucial role in creating the resting potential of a cardiac muscle cell?
In a theoretical cell with an initial equal number of positive and negative charges, what creates the charge imbalance for the resting potential?
In a theoretical cell with an initial equal number of positive and negative charges, what creates the charge imbalance for the resting potential?
What is the primary form of negative charge inside cardiac cells contributing to the resting potential?
What is the primary form of negative charge inside cardiac cells contributing to the resting potential?
Signup and view all the answers
Which pump is responsible for maintaining the ionic concentration gradients in cardiac muscle cells for resting potential?
Which pump is responsible for maintaining the ionic concentration gradients in cardiac muscle cells for resting potential?
Signup and view all the answers
What happens to the sodium gates when the membrane potential reaches between +20 and +30 mV?
What happens to the sodium gates when the membrane potential reaches between +20 and +30 mV?
Signup and view all the answers
During which phase of the action potential does the K+ permeability begin to increase significantly?
During which phase of the action potential does the K+ permeability begin to increase significantly?
Signup and view all the answers
What role do L-type voltage gated calcium channels play in the action potential?
What role do L-type voltage gated calcium channels play in the action potential?
Signup and view all the answers
Why does the membrane potential not immediately fall to the equilibrium potential for potassium despite increased K+ permeability?
Why does the membrane potential not immediately fall to the equilibrium potential for potassium despite increased K+ permeability?
Signup and view all the answers
When does the myocyte contraction occur in relation to the action potential phases?
When does the myocyte contraction occur in relation to the action potential phases?
Signup and view all the answers
Which phase of the cardiac action potential is characterized by the opening of sodium gates and a hundred-fold increase in sodium permeability?
Which phase of the cardiac action potential is characterized by the opening of sodium gates and a hundred-fold increase in sodium permeability?
Signup and view all the answers
What ion has its concentration gradient reversed in the Goldman equation used to calculate the true resting potential?
What ion has its concentration gradient reversed in the Goldman equation used to calculate the true resting potential?
Signup and view all the answers
During which phase of the cardiac action potential does the membrane potential depolarize to reach the threshold potential (-60 to -65mV)?
During which phase of the cardiac action potential does the membrane potential depolarize to reach the threshold potential (-60 to -65mV)?
Signup and view all the answers
What is the primary characteristic of the plateau phase of the cardiac action potential?
What is the primary characteristic of the plateau phase of the cardiac action potential?
Signup and view all the answers
Which type of muscle tissue is primarily responsible for generating the wave of excitation that triggers the opening of sodium gates in cardiac muscle membranes?
Which type of muscle tissue is primarily responsible for generating the wave of excitation that triggers the opening of sodium gates in cardiac muscle membranes?
Signup and view all the answers
What is the main reason for the initial resting potential in the SAN being less negative compared to the rest of the heart?
What is the main reason for the initial resting potential in the SAN being less negative compared to the rest of the heart?
Signup and view all the answers
What causes the pacemaker potential or 'prepotential' to drift upwards towards depolarization?
What causes the pacemaker potential or 'prepotential' to drift upwards towards depolarization?
Signup and view all the answers
Which ion channel type is responsible for the diastolic depolarization phase in pacemaker cells?
Which ion channel type is responsible for the diastolic depolarization phase in pacemaker cells?
Signup and view all the answers
During which phase is there an inward calcium current that accelerates depolarization towards the threshold potential?
During which phase is there an inward calcium current that accelerates depolarization towards the threshold potential?
Signup and view all the answers
What distinguishes the maximum depolarization level in the pacemaker cells from contractile myocardial cells?
What distinguishes the maximum depolarization level in the pacemaker cells from contractile myocardial cells?
Signup and view all the answers
What triggers the opening of sodium ion channel gates in cardiac muscle, leading to rapid ion permeability rise and the generation of another action potential?
What triggers the opening of sodium ion channel gates in cardiac muscle, leading to rapid ion permeability rise and the generation of another action potential?
Signup and view all the answers
Which parts of the heart exhibit automaticity, generating action potentials spontaneously?
Which parts of the heart exhibit automaticity, generating action potentials spontaneously?
Signup and view all the answers
What is the term used to describe the ability of the sinoatrial node (SAN) to have the fastest intrinsic rhythm in the human heart?
What is the term used to describe the ability of the sinoatrial node (SAN) to have the fastest intrinsic rhythm in the human heart?
Signup and view all the answers
Which type of muscle cells in the heart typically do not display automaticity?
Which type of muscle cells in the heart typically do not display automaticity?
Signup and view all the answers
What determines the rate of contraction in cardiac muscle?
What determines the rate of contraction in cardiac muscle?
Signup and view all the answers
During which phase of the cardiac action potential do Na+ channels remain closed, leading to the 'absolute refractory' period of the myocytes?
During which phase of the cardiac action potential do Na+ channels remain closed, leading to the 'absolute refractory' period of the myocytes?
Signup and view all the answers
What is the primary consequence of the 'absolute refractory' period in cardiac myocytes?
What is the primary consequence of the 'absolute refractory' period in cardiac myocytes?
Signup and view all the answers
Where do some areas of the heart have particularly unstable 'resting potential'?
Where do some areas of the heart have particularly unstable 'resting potential'?
Signup and view all the answers
What happens to many Na+ channels during the repolarization phase of the cardiac action potential?
What happens to many Na+ channels during the repolarization phase of the cardiac action potential?
Signup and view all the answers
Why is it harder to generate a subsequent action potential during the 'relative refractory period' of the cardiac action potential?
Why is it harder to generate a subsequent action potential during the 'relative refractory period' of the cardiac action potential?
Signup and view all the answers
What concept is the Nernst equation based on?
What concept is the Nernst equation based on?
Signup and view all the answers
Why is the equilibrium potential for potassium in cardiac muscle cells slightly more negative than the resting membrane potential?
Why is the equilibrium potential for potassium in cardiac muscle cells slightly more negative than the resting membrane potential?
Signup and view all the answers
What is the primary ion influencing the magnitude of the resting potential in cardiac muscle cells?
What is the primary ion influencing the magnitude of the resting potential in cardiac muscle cells?
Signup and view all the answers
Why is the membrane potential far from the Na+ equilibrium potential of +60 mV at rest?
Why is the membrane potential far from the Na+ equilibrium potential of +60 mV at rest?
Signup and view all the answers
What is responsible for maintaining the ionic concentration gradients in cardiac muscle cells?
What is responsible for maintaining the ionic concentration gradients in cardiac muscle cells?
Signup and view all the answers
What contributes to the resting membrane potential being slightly more negative than the potassium equilibrium potential in cardiac muscle cells?
What contributes to the resting membrane potential being slightly more negative than the potassium equilibrium potential in cardiac muscle cells?
Signup and view all the answers
What is the role of the Na+/K+-ATPase pump in relation to ion gradients and membrane potential?
What is the role of the Na+/K+-ATPase pump in relation to ion gradients and membrane potential?
Signup and view all the answers
Why is sodium far from electrochemical equilibrium at rest in cardiac muscle cells?
Why is sodium far from electrochemical equilibrium at rest in cardiac muscle cells?
Signup and view all the answers
Why does potassium have a substantial influence on the resting membrane potential?
Why does potassium have a substantial influence on the resting membrane potential?
Signup and view all the answers
What determines the slightly more negative equilibrium potential for potassium in cardiac muscle cells compared to the RMP?
What determines the slightly more negative equilibrium potential for potassium in cardiac muscle cells compared to the RMP?
Signup and view all the answers
