Unit 4 - A & P Assignment - Cardiovascular System Flashcards
Diagram to identify structure and function of the cardiovascular system
Pathway of Blood Through the Heart
The heart is actually (one, two, or three) pumps?
Two pumps, the right side of the heart pumps to/from the lungs (pulmonary circuit) and the left side of the heart pumps to/from the rest of the body (the systemic circuit)
Pathway of Blood Through the Heart
Which chamber receives blood from the superior and inferior venae cavae?
Right atrium, the right atrium receives oxygen-poor blood from the systemic circuit
Pathway of Blood Through the Heart
Which heart chamber receives blood from the pulmonary veins?
Left atrium, receives oxygenated blood from the pulmonary veins
Pathway of Blood Through the Heart
Which heart chamber pumps oxygen-poor blood out the pulmonary trunk?
Right ventricle, pumps oxygen-poor blood out the pulmonary trunk to the lungs
Pathway of Blood Through the Heart
Which chamber pumps oxygenated blood out the aorta to the systemic circuit?
Left ventricle, pumps oxygenated blood out the aorta to the entire body (systemic circuit)
Action Potentials in Autorhythmic Cells
Action potentials generated by the autorhythmic cells spread to the contractile cells through what structures in the membrane?
Gap junctions
Action potentials generated by the autorhythmic cells spread waves of depolarization to contractile cells through gap junctions. If the depolarization causes the contractile cells to reach threshold, they will in turn generate an action potential.
Action Potentials in Autorhythmic Cells
One of the changes that occurs in the pacemaker potential (unstable resting membrane potential) in the SA node (an autorhythmic cell) is a decreased efflux of what ion?
Potassium
If there is a decreased efflux of potassium while there is a normal influx of sodium, the inside of the cell would become less negative. Thus, threshold would be reached. The ability of these autorhythmic cells to spontaneously depolarize is what results in the pacemaker potential.
Action Potentials in Autorhythmic Cells
When threshold is reached at the SA node (an autorhythmic cell), what channels open causing further depolarization of the membrane?
Fast calcium
Unlike nerve cells or cardiac muscle cells, fast calcium channels are responsible for the depolarization phase of the autorhythmic cell action potential. When the fast calcium channels open, calcium rushes into the cell making it less negative (or more positive).
Action Potentials in Autorhythmic Cells
Repolarization of an autorhythmic cell is due to the opening of which channels?
Voltage-gated potassium channels
Opening of voltage-gated potassium channels causes positive potassium ions to move out of the cell. This efflux of potassium causes the cell to become more negative inside thus, repolarizing the cell.
Action Potentials in Autorhythmic Cells
In order to cause cardiac muscle contraction, the contractile cells must also depolarize. What causes the depolarization of the contractile cells?
The flow of positive ions from adjacent cells
The flow of positive ions from the autorhythmic cells (or adjacent cells) brings the membrane to threshold initiating depolarization of the contractile cell.
Intrinsic Conduction System of the Heart
Which part of the conduction system initiates the depolarizing impulse, which spreads throughout the heart?
SA node
SA Node spontaneously depolarizes, causing the wave of depolarization that spreads through the rest of the conduction system and heart
Intrinsic Conduction System of the Heart
What does the ECG wave tracing represent?
Electrical activity in the heart
The ECG waves show the depolarization and repolarization in various areas of the heart.
Intrinsic Conduction System of the Heart
What does the QRS complex represent in the ECG wave tracing?
Ventricular depolarization
The QRS complex represents depolarization in the ventricles, which have greater mass than the atria
Intrinsic Conduction System of the Heart
Contraction of the atria results from which wave of depolarization on the ECG tracing?
P wave, represents atrial depolarization, which leads to atrial contraction.
Intrinsic Conduction System of the Heart
Which part of the intrinsic conduction system delays the impulse briefly before it moves on to the ventricles?
AV node, slows down the impulse giving the atria time to contract before the ventricles contract.
Sympathetic and parasympathetic influences on cardiac output
Wiggers diagram to identify specific events during the cardiac cycle
Diagram to identify factors that affect mean arterial pressure
Arterial Baroreceptor Reflex
If blood pressure is increased at the arterial baroreceptors, what would happen with the activity level of the parasympathetic nervous system (PNS) and sympathetic nervous system (SNS)?
Increased PNS activity and decreased SNS activity
The PNS activity would increase and the SNS activity would decrease in an attempt to lower blood pressure.
Arterial Baroreceptor Reflex
What would cause vasodilation of arterioles?
Decreased activity of the sympathetic nervous system
Results in decreased activity of vasomotor fibers, resulting in vasodilation.
Arterial Baroreceptor Reflex
Where are the sensors for the arterial baroreceptor reflex located?
Carotid sinus and aortic arch
The sensors are the arterial baroreceptors themselves, located at the carotid sinus and aortic arch. They detect changes in blood pressure by the degree of stretch on the blood vessel.
Arterial Baroreceptor Reflex
Stimulation of the adrenal medulla would result in which of the following?
An increase in heart rate and contractility
Epinephrine and norepinephrine are released from the adrenal medulla and act as part of the sympathetic nervous system, increasing heart rate and contractility. Epinephrine and norepinephrine have other effects that would also increase blood pressure.
Arterial Baroreceptor Reflex
A decrease in blood pressure at the arterial baroreceptors would result in which of the following?
An increase in heart contractility
Sympathetic nervous system activity would be increased because of the low blood pressure. Sympathetic fibers go to the ventricles of the heart and increase their contractility. An increase in contractility would increase stroke volume which would lead to an increase in cardiac output and blood pressure.
