Cardiac - Pt 1 Flashcards
The apex of the heart points to what area of the body?
Left hip
What is the “double” walled sac enclosing the heart?
Pericardium
What is the outermost layer of the pericardium?
What is this layer involved in?
The fibrous pericardium
Protection and stabilization of the heart, also prevents from “overfilling” with blood.
What layer of the pericardium lies underneath the fibrous pericardium?
Serous Pericardium, but specifically the Parietal Serous Pericardium
What is the base layer of the pericardium?
T/F - this layer is continuous with the epicardium of the heart?
- Visceral Serous Pericardium
- True
What layer lies between the Visceral and Parietal Pericardium?
What Fluid inhabits this area?
- The pericardial Cavity
- The pericardial Fluid
The atria are seperated by an [] []…
The ventricles are seperated by an [] []….
Intratrial septum
Intraventricular septum
- The right ventricle is the pump for the [] circuit.
- The left ventricle is the upmp for the [] circuit.
- Pulmonary
- Systemic
How many pulmonary arteries and veins exist?
Arteries - 2
Pulmonary Veins - 4
What is the “pump” of the pulmonary circuit?
What is the pulmonary circuit?
- The right ventricle
- Right Vent -> Pulm Trunk –> Pulm Arteries -> Pulmonary Capillaries –> Pulmonary veins –> Left Atrium
What is the “pump” of the systemic circuit?
The Left Ventricle
Why are the atria lacking surrounding muscle tissue when compared to the ventricle?
- Because the ventricles are pumping blood out throuhgout the body.
- The atria are pumping blood to the ventricles.
The right atrium receives [] blood from the [] circuit
What 3 veins feed the right atrium?
- deoxygenated blood; systemic
- Superior Vena Cava, Inferior Vena Cava, Coronary Sinus
Which valve seperates the right atrium from the right ventricle?
Tricuspid Valve
Which valve seperates the Right ventricle from the pulmonary truink?
Semilunar Valve
The left atrium receives [] blood from the [] veins
What are the names of the veins?
- oxygenated; pulmonary veins
- Right/Left Superior Pulmonary Veins; Right and Left Inferios Pulmonary Veins
What valve seperates the left atrium from the left ventricle?
Bicuspid Valve
OR Mitral Valve
What is another name for the bicuspid valve?
Mitral Valve
What is the name of the valve between the left ventricle and the aorta?
The aortic semilunar valve
Which circuit is higher or lower in pressure: the systemic or pulmonary?
- The pulmonary circuit is lower in pressure
Which circuit pumps more blood per beat, the systemic or the pulmonary circuit?
NEITHER!
They both pump the same amount of blood per beat.
[] is the molecular link between electrical and mechanical processes?
Ca2+
If you were to have hormones, neurotransmitters, or drugs taht alter the inward Ca2+ current during the cardiac action potential plateau - what would be the expected change in muscle tension produced by myocardial cells?
- It would depend on the effect on Ca2+ levels
- If you increased Ca2+ amounts - you’d have even more muscle tension
- If you decreased Ca2+ amounts - you’d expect less muscle tension
- BECAUSE - muscle tension is directly related to the sarcoplasmic levels of Ca2+
What “cells” are responsible for the initiation and fast conduction of the depolarization wave that travels throughout conduction system of the heart.
Nodal Cells
What are the 2 types of cells in the heart? What structure connects these cells?
- Cardiac Muscle Cells, Cardiac Nodal Cells
- Intercalated Discs
What is one mechanism that allows for the fast travel of electrical signals through the heart?
Gap Junctions!
What is the path of electrical current through the heart? (1-6)
- SA node
- Internodal Pathway
- AV Node
- Bundle of His
- Bundle Branches
- Perkinje Fibers
What is the AV delay?
Why does it exist?
- The AV delay is the slow down of the current sent forth initially from teh SA node.
- It happens to create a delay in the pumping of the atria and ventricles. The atria are much weaker than the ventricles, and if the atria and ventricles were to pump at the same time, no blood would ever go from Atria –> Ventricle!
T/F
The SA node stimulates the Left and Right Atrium to beat at approximately the same time?
True
What conduction pathway does links the following:
SA Node - AV Node
SA Node - Left Atrium
SA Node - Right Atrium
- Internodal pathway
- Bachman’s Bundle
- Internodal Pathway
T/F
Cardiac muscle cells are innervated by motor neurons?
False
Stimulated by pacemaker cells.
What are the spontaneous depolarization rates of the following: (beats/min)
SA Node
AV Node
Purkinje Fibers
Muscle FIbers
- SA Node: 60 - 80 bpm
- AV Node: 50 - 60 bpm
- Purkinje: 30 - 50 bpm
- Muscle Fiber: < 30 bpm
What layer of tissue resides between the epicardium and endocardium?
Myocardium
What are the 4 main currents in the heart?
Na+ current
Ca2+ Current
K+ Current
Pacemaker Current
What are the currents of a cardimyocyte?
Na+
Ca2+
K+
NO funny current
What are the currents in a nodal cardiac cell?
Ca2+
K+
Pacemaker current
How does the current in a normal cardiomyocyte differ from a nodal cardiac cell?
The nodal cardiac cell does not have any fast-voltage gated Na+ channels, so there is no Na+ current in the nodal cells.
What are the 5 phases of a ventricular action potential?
Phase 0
Phase 1
Phase 2
Phase 3
Phase 4
Which phase of the ventricular action potential is considered to be at the resting membrane potential?
Phase 4
Phase 0 of the cardiac action potential is characterized by 2 main “events?”
What are these and how does it effect the cell?
- Fast-Voltage gated Na+ channels and Voltage-gated L-type Ca2+ channels OPEN and Na+ and Ca2+ rush IN and DOWN their electrochemical gradient.
- This causes the upstroke in the action potential curve to about +20mV.
At what point in the ventricular action potential do Fast Na+ channels close?
- 1st - these channels inactivate!!
- At the very tip of the upstroke during Phase 0
- At ~ 20mV these channels inactive.
What is the name of Phase 1 of the ventricular action potential?
How does it effect the action potential curve?
What are the causes of Phase 1?
- Initial Repolarization
- Fast Na+ channels inactivate at the tip of the upstroke
- Voltage gated K+ channels open
- This causes an initial dip in the curve, towards repolarization
- K+ effluxes down its steep electrochemical gradient
What causes Phase 2 of the ventricular action potential?
- Phase 2 is the plateau. This is caused by the balancing of K+ efflux and Ca2+ influx.
- The Ca2+ influx is the same L-type channels that opened during the initial rapid depolarization. These channels are slow to close
- So, Ca2+ is coming, and its channels are slowly closing…while K+ is moving out of the cell.
What are the characteristics of Phase 2 of the ventricular action potential?
- The plateau phase is due to the outward K+ current being balanced by the inward Ca2+ current
What is another term used to describe the balance of eflux and influx during the plateau phase of a ventricular action potential? (Phase 2)
isoelectric
What is the name of Phase 3 in the ventricular action potential?
What are the characteristics of this phase?
- Repolarization
- K+ efflux ramps up and peaks, decreasing membrane potential, thus repolarizing the cell
- Calcium conductance continues to decrease
At the end of phase 3, the outward [] current is reduced because repolarization brings the membrane potential closer to the [] equilibrium potential, thus decreasing the drive force on []
K+
T/F
Repolarization is produced when inward currents are greater than outward currents?
FALSE
K+ is flowing out of the cell to repolarize it!
Therefore the outward currents must be greater than the inward currents.
What effect does the plateau phase have on cardiac muscle contraction?
- Slow closing Ca2+ channels influx causes teh plateau phase
- This Ca2+ influxing through DHRP (L-type) channels causes the CICR effect - releasing more Ca2+ from intracellular stores for an excitation-contraction coupling
What are the 3 layers of the heart wall?
Epicardium (or the Visceral Serous Layer)
Myocardium
Endocardium
