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Figure 8.6a The heart.

Blood Pathway Through the Heart & Lungs

Figure 17.5

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Figure 8.7 A view of the heart showing major blood vessels, chambers, and valves.

Superior vena cava

Pulmonarysemilunar valveRight atrium

Right AV valveRight ventricle

Inferior vena cava

Pulmonary trunk

Left pulmonary veins

Left atrium

Left AV valve

Aortic semilunar valve

Chordae tendineae

Papillary muscles

Left ventricle

Septum

Right pulmonary artery

Left pulmonary artery

Aorta

External Heart: Posterior View

Figure 17.4d

•The auricle is a part of each atrium. A small, cone-shaped, muscular pouch that projects from each atrium, located at the receiving end of the atria. Visually, they look like wrinkled pouch-like structures.

•Auricles help their respective atria hold more blood. •They are called auricles because they were thought to resemble dog's ears.

•In older references, “auricle” was used to describe the entire atrium.

Alternate names for AV valves

Right

Tricuspid

Left

Bicuspid

Mitral

Heart Valves

Figure 17.8a, b

Semilunar Valve Function

Figure 17.10

Atrioventricular Valve Function

Figure 17.9

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Figure 8.12 Heart valves.

Heart Valves

Figure 17.8c, d

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Figure 8.10 Blood vessels of the heart.

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Figure 8.18 A coronary angiogram.

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Figure 8.19 Coronary artery bypass grafts.

Sequence of Excitation

Figure 17.14a

Heart Physiology: Sequence of Excitation

• Sinoatrial (SA) node in right atrium generates impulses about 75 times/minute; dominant autorythmic cells; nervous system may regulate

• Atrioventricular (AV) node delays the impulse approximately 0.1 second

• Impulse passes from atria to ventricles via the atrioventricular bundle (AV bundle)

• AV bundle splits into two bundle branches in the interventricular septum

• Bundle branches carry the impulse toward the apex of the heart

• Purkinje fibers carry the impulse from the heart apex to the ventricular walls

Cardiac Cycle

• Cardiac cycle refers to all events associated with blood flow through the heart; electrical events, valve activity, heart sounds, chamber contractions and changes in blood pressure– Systole – contraction of heart muscle– Diastole – relaxation of heart muscle

Heart Sounds

• Heart sounds (lub-dup) are associated with closing of heart valves– First sound occurs as AV valves close and

signifies beginning of systole– Second sound occurs when SL valves close

at the beginning of ventricular diastole

• Heart murmurs-obstruction in the flow of blood, valve irregularity

Cardiac Conditioning

• Exercise will increase cardiac muscle mass

• Increased cardiac muscle mass increases the strength of contraction

• Heart beats less and rests more