PCOL 825 Exam 1 Questions And Answers
Latest 2025
What does a heart beat (cardiac excitation) rely on? -
correct answer ✅Sequential/organized action potential
generation
Organized propagation of the action
potentials
What is automaticity? -
correct answer ✅Heart contracts without outside signal
What is The primary pacemaker of the heart? -
correct answer ✅the SA node
What are the autorhythmic/ pacemaker tissue of the hears? -
correct answer ✅SA node
AV node
His purkinje sysrem
What kind of tissue is in the heart? What is included in both? -
correct answer ✅autorhythmic: SA node, AV node, His purkinje
,PCOL 825 Exam 1 Questions And Answers
Latest 2025
contractile tissue: atrial and ventricular myocytes
What are ion concentrations inside and outside the cell at resting
membrane potential? -
correct answer ✅inside: inc. K+
outside: inc. Na+ and Ca++
What are the voltage gated channels for K+, Na+ and Ca++? -
correct answer ✅K+: Ikr (rapid), Iks (slow), IK1 (inward rectifier)
Na+: INa (rapid), IF (slow)
Ca++: ICa,L (Long)
What happens to the ion channels at resting membrane potential? -
correct answer ✅Open:
K+ channels (IK1) - potassium goes out
Closed:
Na+ channels
Ca++ channels
,PCOL 825 Exam 1 Questions And Answers
Latest 2025
What is depolarization? -
correct answer ✅Depolarization: Membrane potential becoming
more positive ! Leads to contraction
What is repolarization? -
correct answer ✅Repolarization: Membrane potential returning to
resting potential
Leads to relaxation
What is hyperpolarization? -
correct answer ✅Hyperpolarization: Membrane potential
becoming more negative than resting potential
How do Autorhythmic/ Pacemaker Cells; SA & AV Nodes
depolarize? -
correct answer ✅with calcium
How does phase 0 in his-purkinje and the SA node/AV node differe?
-
correct answer ✅his purkinje/ contractile cells phase 0: Rapid
influx of Na+
, PCOL 825 Exam 1 Questions And Answers
Latest 2025
SA/AV noce phase 0: influx of Ca++
What is the difference between phase 2 of pacemaker/nodal cells
and contractile/non-pacemaker cells? -
correct answer ✅pacemaker/nodal cells: no phase 2
contractile/non-pacemaker: influx of Ca++ and some efflux of K+
How is phase 4 different in autorhythmic/pacemaker cells? -
correct answer ✅Phase 4 depolarization (pacemaker potential)
Continuous and slow depolarization towards threshold - small influx
of Na+
in contractile cells: K+ leaks out
What is the difference between action potentials of contractile cells
and nodal cells? -
correct answer ✅contractile: fast depolarization, long refractory
period
nodal: slow depolarization, short refractory period
Latest 2025
What does a heart beat (cardiac excitation) rely on? -
correct answer ✅Sequential/organized action potential
generation
Organized propagation of the action
potentials
What is automaticity? -
correct answer ✅Heart contracts without outside signal
What is The primary pacemaker of the heart? -
correct answer ✅the SA node
What are the autorhythmic/ pacemaker tissue of the hears? -
correct answer ✅SA node
AV node
His purkinje sysrem
What kind of tissue is in the heart? What is included in both? -
correct answer ✅autorhythmic: SA node, AV node, His purkinje
,PCOL 825 Exam 1 Questions And Answers
Latest 2025
contractile tissue: atrial and ventricular myocytes
What are ion concentrations inside and outside the cell at resting
membrane potential? -
correct answer ✅inside: inc. K+
outside: inc. Na+ and Ca++
What are the voltage gated channels for K+, Na+ and Ca++? -
correct answer ✅K+: Ikr (rapid), Iks (slow), IK1 (inward rectifier)
Na+: INa (rapid), IF (slow)
Ca++: ICa,L (Long)
What happens to the ion channels at resting membrane potential? -
correct answer ✅Open:
K+ channels (IK1) - potassium goes out
Closed:
Na+ channels
Ca++ channels
,PCOL 825 Exam 1 Questions And Answers
Latest 2025
What is depolarization? -
correct answer ✅Depolarization: Membrane potential becoming
more positive ! Leads to contraction
What is repolarization? -
correct answer ✅Repolarization: Membrane potential returning to
resting potential
Leads to relaxation
What is hyperpolarization? -
correct answer ✅Hyperpolarization: Membrane potential
becoming more negative than resting potential
How do Autorhythmic/ Pacemaker Cells; SA & AV Nodes
depolarize? -
correct answer ✅with calcium
How does phase 0 in his-purkinje and the SA node/AV node differe?
-
correct answer ✅his purkinje/ contractile cells phase 0: Rapid
influx of Na+
, PCOL 825 Exam 1 Questions And Answers
Latest 2025
SA/AV noce phase 0: influx of Ca++
What is the difference between phase 2 of pacemaker/nodal cells
and contractile/non-pacemaker cells? -
correct answer ✅pacemaker/nodal cells: no phase 2
contractile/non-pacemaker: influx of Ca++ and some efflux of K+
How is phase 4 different in autorhythmic/pacemaker cells? -
correct answer ✅Phase 4 depolarization (pacemaker potential)
Continuous and slow depolarization towards threshold - small influx
of Na+
in contractile cells: K+ leaks out
What is the difference between action potentials of contractile cells
and nodal cells? -
correct answer ✅contractile: fast depolarization, long refractory
period
nodal: slow depolarization, short refractory period
