Term
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Definition
- Cylindrical shaped cells.
- Intercalated disks join cells end-to-end.
- Filaments- as in skeletal muscle.
- Thin filaments activation by Ca++ binding to troponin.
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Term
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Definition
- Strong connections between cells.
- Desmosomes for strength.
- Gap junctions for electrical activation spread.
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Term
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Definition
- Systemic: LV to aorta to body to vena cava to RA.
- Pulmonary: RV to pulmonaryartery to lungs to pulmonary vein to LA.
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Term
| Cardiac Activation Structures |
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Definition
- Activation pathway has autorhythmic cells.
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Term
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Definition
- Site of normal heartbeat initation.
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Term
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Definition
- In right atrium.
- Depolarizes to threshold starts AP.
- Fastest depolarizer- no stable vaseline membrane potential.
- The internodal pathway connects the SA node to the AV node.
- Premature beats occur if the heartbeat starts elsewhere--not usually harmful.
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Term
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Definition
- Right atrium activated by SA node- spreads toward the LA using the interatrial pathway.
- Spread through gap junction.
- Not autorhythmic-contraction spreads downward.
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Term
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Definition
- Electrical connection from atria to ventricles.
- Delays AP spread, allows ventricular filling to be completed.
- AV block produces seperate atrial and ventricular activation.
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Term
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Definition
- AP enters septum first, spreadsto apex, then up to ventricular muscle.
- V muscle contraction spreads upward.
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Term
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Definition
- Off the AV node and down to septum.
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Term
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Definition
- Apex cells activated first by Purkanje Fibers, then muscle cell-to-cell through gap junctions.
- Contraction spreads upward, forcing blood into aorta and pulmonary artery.
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Term
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Definition
- Autorhythmic, no stable baseline potential.
- SA and AV nodes, some cells of Bundle of His and Perkenje Fibers.
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Term
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Definition
- Closing of K+ channels, opening of Ca++ channels.
- Little Na+ influence.
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Term
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Definition
- Sympathetic neurons- NE opens Ca++ channels.
- Parasympathetic Neurons- ACH.
- Decreases K+ closing rate.
- ACH decreases Ca++ channel opening.
- Decreases heart rate.
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Term
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Definition
- Sequence of contraction and relaxation
- 4-valves, ZA-V, aortic/pulmonary, keep blood flowing one way.
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Term
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Definition
- Relaxed heart.
- Time for filling.
- End diastolic volume- 130 mL.
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Term
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Definition
- Contracts first.
- Completes filling of ventricles.
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Term
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Definition
- Follows atrial contraction.
- Contraction spreads upward.
- Pressure must begreater than aorta to open aortic valve.
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Term
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Definition
- Load left ventricle works against.
- High BP puts greater load on heart.
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Term
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Definition
- 70-90 mL of blood ejected/beat.
- 65% of end diastolic volume.
- Lower HR means higher ejected volume.
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Term
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Definition
- The max heart rate is (220-age).
- Rates above 180 decrease filling time.
- Must be motivated to exceed 180.
- This can decrease cardiac output.
- Potentially life threatening.
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Term
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Definition
- Arterial walls expand to hold blood.
- Rebounds during diastole-creates pulse.
- Little drop in BP throughout arteries.
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Term
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Definition
- Closing of the valves-turbulent blood flow creates sounds.
- Low pressure AV (mitral and tricuspid) first, thenhigh pressure aortic and pulmonary valves.
- Different sound intersitles.
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Term
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Definition
- Non-laminer (non smooth) flow -> sound when valves should be closed.
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Term
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Definition
- Stiff valve-small opening.
- Turbulent flow as blood squirts through.
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Term
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Definition
- Valve leaves dont properly mesh.
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Term
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Definition
- 70 mL- at 70 beats/min= ~5L/min.
- Body has about 5L of blood.
- Circulation time: 1 minute.
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Term
| Stroke Volume x Heart Rate |
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Definition
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