Unit 2-Heart Physiology Flashcards
Why doesn’t cardiac muscle require nervous stimulus?
Because the heart uses an intrinsic method of conduction
What kind of cells are autorhytmeic cells? Where can these cells be found
- Noncontractile, leaky cells
- In the heart muscle
What does leaky cells mean?
Cells have an unstable resting membrane potential where there is reduced permeability to potassium ( This means sodium is able to leak in but potassium isn’t moving out)
Describe the movement and type of ion that leads to an action potential.
The influx of calcium will cause an action potential
How are the autorhytmic cells connected?
Intercalated disk
In regards to the heart muscle, what will an action potential lead to?
Muscle contraction
What allows for the inflow of calcium ions during an intrinsic conduction?
Threshold being reached and at that threshold ion channels open up which allow for calcium to flow in
Depolarization in the intrinsic conduction is called _____ potential
Pacemaker potential
Describe the process that gives rise to the pacemaker potential
- Sodium flows into noncontractile leaky cells
- Potassium can’t flow out so positive accumulates
- Once threshold is reached, ion channels open which allow for Calcium to flow in
- The influx of calcium triggers muscle contraction
Where is the sinoatrial node? What action comes from sinoatrial node?
-top right atrium beneath coronary sinus
-Main pacemaker of the heart; generates action potential and depolarization occurs here
(Depolarization starts here)
Where is the AV node? What actions are involved in the AV node?
- top of ventricles
- Directional pathway down the apex: signal shoots down the bundle of his
Where is the bundle his? What actions are associated with the bundle his?
- Middle of the heart and down the interventricular septum
- Branches into the left and right bundles branches
Where is the bundle branches? What action is associated with the bundle branches?
- where the bundle of his has split into right and left
- Sends signal up walls of purkinje fibers
Where are the purkinje fibers? What are the actions associated with Purkinje fibers?
- Ventricle walls at apex
- Deliver impulse to papillary muscle
Describe the type of innervation and effect on heart in the cardioacceleratory center
- Sympathetic innervation
- Increases heart rate
Describe the type of innervation and effect on the heart at the cardioinhibitory center.
- Parasympathetic innervation
- Decreases heart rate: asleep/ at rest
What kind of recording does the ECG reflect?
ECG is a graphical recording of electrical events of the heart.
List the types of deflection waves that can occur in a ECG.
- P wave
- T wave
- QRS complex
In an ECG, what does the P wave show?
-depolarization of the atria
In an ECG, what does the QRS complex show?
Depolarization of ventricles
Repolarization of atria
In an ECG, what does the T wave show?
Repolarization of the ventricles
What information can be drawn from an ECG?
- Diagnosis of disruptions/pathologies in conduction of system heart
- Heart rate determined by picking any particular portion of ECG and then determining time from that point to the next point.
What causes normal heart sounds?(Give broad answer)
Closing of valves
What cause the LUB sound heard in a normal heart sound?
LUB sound comes from the AV (atrioventricular) valve closing
