BIOL 1412 - CARDIOVASCULAR
PHYSIOLOGY EXAM QUESTIONS WITH
100% CORRECT ANSWERS LATEST
VERSION 2025/2026.
Parts of the cardiac system - ANS - Heart
- Conduction System
Heart - ANS - Dual pump with valves
- Muscle cells connected by gap junctions
Conduction System - ANS - Non-contractile cardiac muscle cells that are modified to initiate &
distribute impulses throughout the heart
- Produce APs spontaneously (no stimulus required) BUT at different rates
- Multiple parts
Parts of the conduction system - ANS - Sinoatrial (SA) node - in right atrium
- Atrioventricular (AV) node - in right atrium
- Bundle of His (AV bundle)
- Purkinje fibres
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,Sinoatrial (SA) node - ANS - In right atrium
- Rate = 100 APs/min (modified by PSNS to be 75 APs/min
at rest)
- Produces APs faster than other areas, therefore is the pacemaker
Atrioventricular (AV) node - ANS - In right atrium
- Rate 50 APs/min
Bundle of His (AV bundle) - ANS - Originates at AV node
- ONLY route for electrical activity to go from atria to ventricles
- Bundle Branches (right and left) produce 30 APs/ min
Purkinje fibres - ANS - Terminal fibres
- Stimulate contraction of the ventricular
myocardium
- 30 APs/min
If a part in the conduction system is damaged, which part becomes the pacemaker? -
ANS The next fastest part
Artificial pacemaker - ANS Stimulates SA or AV node if they are damaged
APs of SA & AV nodes - ANS - Cells are non-contractile autorhythmic cardiac muscle cells
(self-excitable)
- Threshold = -40 mV
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, Phases of Pacemaker Activity - ANS - 1) Pacemaker Potential
- 2) AP Depolarization
- 3) AP Repolarization
- 4) Na+ channels open at -50 mV
Pacemaker phase 1: Pacemaker Potential - ANS - Low K+ permeability (K+ voltage gates
closed)
- Slow inward leak of Na+ (Na+ voltage gates open)
- Causes slow depolarization toward threshold (-40mV)
Pacemaker phase 2: AP Depolarization - ANS - At threshold → AP
- Ca++ voltage gates open and Ca++ moves in → depolarization (Na+ voltage- gates close at
threshold, therefore not involved in AP)
- Ca++ voltage-gates close at peak
Pacemaker phase 3: AP Repolarization - ANS - K+ voltage gates open at peak, K+ out →
repolarization
- K+ gates close below threshold
Pacemaker phase 4: Na+ channels open at -50 mV - ANS - Starts pacemaker potential (1)
again,
once K+ gates close (continuous cycle)
Does the pacemaker have resting membrane potential? - ANS No
APs in Ventricular Myocardium - ANS - Cells are contractile
3 @COPYRIGHT 2025/2026 ALLRIGHTS RESERVED.
PHYSIOLOGY EXAM QUESTIONS WITH
100% CORRECT ANSWERS LATEST
VERSION 2025/2026.
Parts of the cardiac system - ANS - Heart
- Conduction System
Heart - ANS - Dual pump with valves
- Muscle cells connected by gap junctions
Conduction System - ANS - Non-contractile cardiac muscle cells that are modified to initiate &
distribute impulses throughout the heart
- Produce APs spontaneously (no stimulus required) BUT at different rates
- Multiple parts
Parts of the conduction system - ANS - Sinoatrial (SA) node - in right atrium
- Atrioventricular (AV) node - in right atrium
- Bundle of His (AV bundle)
- Purkinje fibres
1 @COPYRIGHT 2025/2026 ALLRIGHTS RESERVED.
,Sinoatrial (SA) node - ANS - In right atrium
- Rate = 100 APs/min (modified by PSNS to be 75 APs/min
at rest)
- Produces APs faster than other areas, therefore is the pacemaker
Atrioventricular (AV) node - ANS - In right atrium
- Rate 50 APs/min
Bundle of His (AV bundle) - ANS - Originates at AV node
- ONLY route for electrical activity to go from atria to ventricles
- Bundle Branches (right and left) produce 30 APs/ min
Purkinje fibres - ANS - Terminal fibres
- Stimulate contraction of the ventricular
myocardium
- 30 APs/min
If a part in the conduction system is damaged, which part becomes the pacemaker? -
ANS The next fastest part
Artificial pacemaker - ANS Stimulates SA or AV node if they are damaged
APs of SA & AV nodes - ANS - Cells are non-contractile autorhythmic cardiac muscle cells
(self-excitable)
- Threshold = -40 mV
2 @COPYRIGHT 2025/2026 ALLRIGHTS RESERVED.
, Phases of Pacemaker Activity - ANS - 1) Pacemaker Potential
- 2) AP Depolarization
- 3) AP Repolarization
- 4) Na+ channels open at -50 mV
Pacemaker phase 1: Pacemaker Potential - ANS - Low K+ permeability (K+ voltage gates
closed)
- Slow inward leak of Na+ (Na+ voltage gates open)
- Causes slow depolarization toward threshold (-40mV)
Pacemaker phase 2: AP Depolarization - ANS - At threshold → AP
- Ca++ voltage gates open and Ca++ moves in → depolarization (Na+ voltage- gates close at
threshold, therefore not involved in AP)
- Ca++ voltage-gates close at peak
Pacemaker phase 3: AP Repolarization - ANS - K+ voltage gates open at peak, K+ out →
repolarization
- K+ gates close below threshold
Pacemaker phase 4: Na+ channels open at -50 mV - ANS - Starts pacemaker potential (1)
again,
once K+ gates close (continuous cycle)
Does the pacemaker have resting membrane potential? - ANS No
APs in Ventricular Myocardium - ANS - Cells are contractile
3 @COPYRIGHT 2025/2026 ALLRIGHTS RESERVED.
