Cardiovascular Disorders Flashcards
What does the bicuspid valve do?
It is the valve between the left atrium and left ventricle. Also called the mitral valve.
What does the tricuspid valve do?
It separates the right atrium and ventricle.
What does the aortic valve do?
It separates the left ventricle and aorta.
What does the pulmonary valve do?
It separates the right ventricle and the pulmonary artery.
Where does the electrical activity of the heart start?
It starts in the sinoatrial node.
Which arrhythmia has an electrical short?
Re-entry
Which arrhythmia has an extended depolarization?
EAD
What is the pathway of calcium in a myocite?
- The current travels through a gap junction from one myocite into another
- The action potential travels through the plasma membranes and through the T tubules
- Ca channels open in the membrane and SR
- Ca induces more Ca release from SR
- Ca binds to troponin, exposing myosin binding sites
- muscle fiber contracts
- Ca releases from troponin and is transported into the SR and ECF
- tropomyosin blocks myosin binding sites, and muscle fiber relaxes.
What are the phases of cardiac myocite action potential? (Also called atrial and ventricular action potential?)
Phase 0: Depolarization Phase 1: Initial Depolarization Phase 2: Plateau Phase 3: Re-polarization Phase 4: Resting potential
Action potentials: what happens in phase 0?
Depolarization. The fast Na channels open at -85mV, and close at 20mV
Action potentials: what happens in phase 1?
Initial repolarization. Na channels close, K leaves.
Action potentials: what happens in phase 2?
The plateau. Fast K channels close, and voltage-gated Ca channels open to let Ca into the cell
Action potentials: what happens in phase 3?
Re-polarization. Ca channels close, slow K channels open.
Action potentials: what happens in phase 4?
Resting potential. Na leaves, K reenters the cell via the Na-K-ATPase pump.
What does the Wigger’s diagram tell us?
It shows what happens in the systole and diastole. The atrium and ventricles oppose each other.
What is the obstruction of blood flow in myocardium by partial or complete blockage of a coronary artery?
Myocardial ischemia
What is reentry?
When a premature beat fails to activate an area near the sinoatrial node because it is still refractory. The premature stimulus travels via an alternative route back the area to stimulate, and is restimulated in return.
Mild or severe ischemia? Which has a short action potential and a shorter resting potential?
mild
Mild or severe ischemia? Which has a delayed recovery of sodium channels from inactivation after depolarization?
severe
Does the force of contraction change in ischemia?
Yes, the force of contraction decreases.
Does the force of contraction change in ischemia?
Yes, the force of contraction decreases.
How do the outflow valves move?
They open and close due to blood pressure gradients.
How do the outflow valves move?
They open and close due to blood pressure gradients.
Explain nodal action potential:
No fast Na channels
- Phase 4: spontaneous depolarization (pacemaker potential). Slow Na, T-type Ca at -50mV and L-type Ca at -40 mV
- Phase 0: depolarization phase (increase Ca conductance)
- Phase 3: Repolarization. K channels open to hyper polarize. L-type Ca channels close.
How does a voltage-gated channel (such as a sodium channel) work?
- At rest, the channel is closed but not inactivated (intercellular gate closed but intracellular gate open)
- At depolarization, the intercellular gate opens and allows the ion (Na) to pass through
- At inactivation, the intracellular gate closes and prevents the ion (Na) from entering the cell until depolarization occurs again. Intercellular gate is open still.
How does a voltage-gated channel (such as a sodium channel) work?
- At rest, the channel is closed but not inactivated (intercellular gate closed but intracellular gate open)
- At depolarization, the intercellular gate opens and allows the ion (Na) to pass through
- At inactivation, the intracellular gate closes and prevents the ion (Na) from entering the cell until depolarization occurs again. Intercellular gate is open still.
How does a voltage-gated channel (such as a sodium channel) work?
- At rest, the channel is closed but not inactivated (intercellular gate closed but intracellular gate open)
- At depolarization, the intercellular gate opens and allows the ion (Na) to pass through
- At inactivation, the intracellular gate closes and prevents the ion (Na) from entering the cell until depolarization occurs again. Intercellular gate is open still.
Myocardium or nodal? Stable at -90mV.
Myocardium
Myocardium or nodal? Rising phase of AP is caused by calcium entry.
Nodal
Myocardium or nodal? In the repolarization phase, the plateau is caused by calcium entry and the rapid phase is caused by K efflux.
myocardium
Myocardium or nodal? There is no hyper polarization phase.
Both in the myocardium and the nodal cells
Myocardium or nodal? The depolarization phase is caused by Na entry into the cell.
Myocardium
Myocardium or nodal? The unstable pacemaker potential is caused at -60mV.
Nodal cells
Myocardium or nodal? Depolarization is caused through gap junctions.
Myocardium
Myocardium or nodal? Repolarization phase is caused by K efflux.
Nodal cells
Myocardium or nodal? Events leading to threshold potential include Na entry through If channels, reinforced by Ca entry.
Nodal cells
