Cardiac pt.2

Contrast the structure and function of cardiac muscle tissue with skeletal muscle tissue.

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Describe the normal heart sounds and the events in the heart they correspond to.

Auscultation: act of listening to sounds within the body . Lub DUB!

Define and describe autorhythmicity.

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Describe the possible consequences of failure of the cardiac conduction system.

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Explain what an EKG measures and the information that it provides.

Electrocardiograph (ECG/EKG) is used to detect changes in electrical currents in the heart Each part of the tracing corresponds to an event in the heart

Name the heart valves and describe their location, function, and mechanism of operation.

Heart valves open and close in response to pressure changes as the chambers contract and relax. Two types of valves: atrioventricular valves (tricuspid, bicuspid) semilunar valves (pulmonary, aortic) Atrioventricular valves are forced OPEN as pressure increases in the atria. Blood returning to atria forces heart places pressure on atrioventricular valves! As atria fills, A flaps hang loose into ventricles. Atria contract, forcing blood flow into ventricles. AV valves are then forced closed by ventrical pressure. Semilunar Valves: (Pulmonary and aortic) Forced open as pressure grows in ventricles! Blood is pressing against them... so they open. Pressure from blood in the arteries makes it close.

Trace the pathway of conduction in the heart.

Sinoatrial (SA) node (pacemaker): generates impulses. Atrioventricular (AV) node: impulse pauses here Atrioventricular (AV) bundle: Connects atria to ventricles Right/left bundle branches: conducts impulses through interventricular septum Purkinje fibers (in walls of ventricles): Depolarize!

Name the components of the cardiac conduction system.

Specialized cardiac muscle fibers called autorhythmic fibers make your heart beat!! Autorhythmic fibers act as: Pacemaker: initiates the signal Conduction system: propagates the signal throughout the heart

Describe the structural and functional characteristics of cardiac muscle tissue.

Study Slide

Describe the events that occur during cardiac muscle contraction.

Three major phases during contraction: Depolarization: Rapid depolarization due to Na+ inflow when voltage gated fast Na channels open. Plateau : Maintained depolarization due to Ca2 inflow when voltage gated slow Ca2+ channels open and K+ outflow when some K+ channels emerge. Repolarization: Dulse to close of Ca+ channels and K+ outflow when additional voltage gated K+ channels open.