Thorax 08: Heart Innervation and Function Flashcards
Where do cardiac visceral sympathetic efferents go to?
Smooth muscle in coronary arteries, cardiac myocytes, and pacemaker cells
Where do cardiac visceral parasympathetic efferents go to?
Cardiac atrial myocytes and pacemaker cells. Does not go to coronary arteries and very sparsely goes to ventricular myocytes
What branches of the vagus go to the heart?
Cervical and thoracic parasympathetic cardiac nerves
What branches of the sympathetic trunk go to the heart?
Cervical and thoracic sympathetic cardiac nerves
Cardiac plexus
A neural plexus located below and deep to the aortic arc, anterior to the bifurcation of the trachea
Nerves that stem from the cardiac plexus go where in the heart?
Coronary arteries, myocytes, and pacemakers
Sinoatrial node
A node at the junction of the vena cava and right atrium walls that originates all cardiac muscle electric potential
Atrioventricular node
A node inside the atrioventricular septum that conducts SA potential into the ventricles
How do electric potentials reach the AV node from the SA node?
They travel through the atria walls by conducting through atrial myocytes
“lupp” sound
At the beginning of systole; the sound of the closing of the mitral and bicupsid valves
“dubb” sound
At the end of systole; the sound of the closing of the two semilunar valves
P wave
Atrial depolarization
QRS complex
Ventricular depolarization
T wave
Ventricular repolatization
The ECG waves is the sum of what action potentials?
SA node, AV node, atrial myocytes, Bundle of His, Purkinje fibers, and vnetricular myocytes
Preganglionic cardiac sympathetic cell bodies leave the CNS where?
T1-T4
Do cardiac sympathetic cell bodies synapse at the cardiac plexus?
No
Do cardiac sympathetic cell bodies use the dorsal or ventral ramus? Do they use white or gray ramus communicons?
Ventral ramus; white ramus communicons
What are the actions of sympathetics on the heart?
On pacemaker cells: increase calcium conductance and increase heart rate
On cardiac myocytes: increase calcium conductance and increase rate and force of contractions
On coronary arteries: dilate arteries and relax smooth muscles
Which nerve do cardiac parasympathetics primarily use?
Cranial nerve 10
Do cardiac parasympathetic cell bodies synapse at the cardiac plexus?
No
What is the role of the parasympathetics on the SA node?
Control it to prevent it from beating at its intrinsic rhythm of 100-110 bpm (instead 50-80 bpm)
What do parasympathetics do to the pacemaker cells?
increase outward flow of K+ to hyperpolarize membrane and decrease rate
What do parasympathetics do to cardiac myocytes
Decrease production of cAMP mostly on atrial myocytes
Which nerve is used for nonsensory afferents from the heart?
Cranial nerve 10
Which nerves are used for sensory afferents from the heart?
T1-T4. They use the same pathway as sympathetic efferents (Except use dorsal roots)
Atrial systole
Part of the systole where the atrium contracts; atrial pressure increases slightly
Isoventricular contraction
Part of the systole where the ventricle contracts without changing volume; ventricular pressure increases significantly
Rapid ejection
Part of the systole where the ventricle squeezes out its blood rapidly; atria begin to fill up again
Reduced ejection
Part of the systole where ventricle lets out blood more slowly’ semilunar valves start closing; atria volume increases
Isovolumetric relaxation
Part of the diastole where the ventricle relaxes without filling up with more blood. Aortic pressure dips up and atria are at max volume
Rapid ventricular filling
Part of the diastole where blood flows through the atriaventrical valves and into the ventricles; atrial pressure decreases and ventricular pressure remains low
Diastesis
Part of the diastole where blood flows into ventricles more slowly. All pressures stabilize
What is the blood supply of cardiac myocytes?
Coronary arteries
Coronary arteries
The blood supply of cardiac myocytes; they are epicardial and rise from the aortic arch just distal of the aortic semilunar valve; they fill during diastole
Right coronary artery
A branch off of the right aortic sinus containing the atrial branch
Left coronary artery
A branch off of the left aortic sinus containing LAD and circumflex
Anterior Interventricular artery
LAD; comes off of the left coronary artery; most common and dangerous site of heart attacks
Right dominant
If the posterior interventricular artery is a branch of the right coronary artery
Left dominant
If the posterior interventricular artery is a branch of the circumflex artery
What regions of the heart are supplied by the right coronary artery?
Right atrium, right ventricle free wall, posterobasal wall of left ventricle. If right-dominant, posterior third of intraventricular septum
What regions of the heart are supplied by the left coronary artery?
Circumflex artery: left atrium, side and back of left ventricle. If left-dominant, posterion third of intraventricular septum
LAD: apex of heart, anterior wall of left ventricle, anterior two-thirds of intraventricular septum, bundle branches of conducting system
In order, what are the five common coronary artery occlusion sites?
1) Junction LAD and circumflex
2) LAD
3) Right coronary artery
4) Circumflex branch of left artery
5) Posterior intraventricular artery
1 and 2 are mostly fatal
What area of the heart is affected by occlusion of the left anterior descending branch?
Anterior side
What area of the heart is affected by occlusion of the left circumflex branch?
Left pulmonary side
What area of the heart is affected by occlusion of the right coronary artery?
Posterior side
Where does the left coronary artery originate from?
Left aortic valve sinus
Where does the right coronary artery originate from?
Right aortic valve sinus
Venae cordis minimae
Small veins tha draw blood from cardiac myocytes and dump it directly into the heart chambers
What kind of metabolism do cardiac myocytesuse to produce ATP energy?
Oxidative phosphorylation
What are the three branches of the right coronary artery?
Atrial branch, right marginal branch, posterior descending artery in right-dominant hearts
What are the three branches of the left coronary artery?
Left anterior descending artery, left circumflex branch, left marginal branch. In left dominant hearts, the posterioe descending artery also branches off of the left coronary artery
What are the three major cardiac veins?
Great cardiac vein, middle cardiac vein, smaller cardiac vein
Great cardiac vein
A vein that drains the area perfused by the LAD
Middle cardiac vein
A vein that drains the area perfused by the posterior descending artery
Smaller cardiac vein
A vein that drains the area perfused by the marginal branch of the right coronary artery
What are the components (in order) of the heart conducting system?
SA node, atrial myocytes, AV node, Bundle of His, bundle branches, Perkinje fibers, ventricular myocytes
What is the main nerve responsible for controlling the heart?
Vagus nerve
