Cardiovascular System

Heart

Heart

• Location – Mediastinum

• Pericardial Sac

• Pericardial Cavity

• Pericardial Fluid

• Parietal Pericardium

Heart Wall

• Epicardium = Visceral Pericardium

• Myocardium– Trabeculae carneae

• Endocardium

Heart Chambers

• Atria (Atrium)

• Auricles

• Interatrial septum

Heart Chambers

• Ventricles

• Interventricular septum

• Coronary sulcus

Valves

• Atrioventricular (Tricuspid & Bicuspid)– Chordae tendineae– Papillary muscles

• Semilunar– Pulmonary– Aortic

Vessels

• Superior Vena Cava

• Inferior Vena Cava

• Pulmonary Trunk (Arteries)

• Pulmonary Veins

• Aorta

Coronary Circulation

• Aorta

• Coronary arteries

• Myocardium

• Cardiac veins

• Coronary sinus

• Right atrium

Cardiac Muscle physiology

• Myocardium

• Automated excitement

• No graded responses

• No tetany

• No anaerobic metabolism

Cardiac Muscle

• Striated, Involuntary

• Intercalated discs

• Refractory period prevents tetany

• Energy– ATP – aerobic metabolism– Coronary circulation providing O2

Excitation of cardiac muscle

• Depolarization to threshold is spontaneous due to decreased outflow of K+

• Sinoatrial node (SA)– Depolarizes every .8 sec. At rest– Depolarizes due to change in permeability– Pacemaker

Conduction

• Spread to both atria

• AV node (.1 sec. Delay)

• AV Bundle (Bundle of His)

• Purkinje = Conduction fibers

• Myocardial cells of ventricle

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Cardiac Cycle

• Systole

• RV = 30 mm Hg

• LV = 120 mm Hg

Cardiac Cycle

• Diastole

Time for cardiac cycle

• Entire cycle is .8 sec.

• Atrial systole .1 sec

• Atrial diastole .7 sec

• Ventricular systole .3 sec

• Ventricular diastole .5 sec

Pressure Curves

• Atrium

• Ventricle

• Aortic

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Heart Sounds

• S1 = AV valves closing

• S2 = Semilunar valves closing

CARDIAC OUTPUT

• CO = HR x SV

• 5-6 liters/minute

• 70 beats/minute x 80 mls/beat

Cardiac Reserve

• Difference between maximum CO and resting CO

• Can increase 700%!!

Heart Rate Control

• Sympathetic Stimulation

• Parasympathetic Stimulation

Stroke Volume Control

• SV = End-diastolic volume – End-systolic volume

• End-diastolic volume– Length of diastole– Venous Return

Stroke Volume Control

• End-systolic volume– Frank-Starling Law– Sympathetic Nervous System– Parasympathetic Nervous System

Factors influencing Cardiac Function

• Cardiac Center in Brainstem

• Exercise,Temperature

• Ions (K, Ca, Na)

• Sex

• Age

Electrocardiogram

• EKG, ECG

• Leads

• P wave – atrial depolarization

• QRS complex – ventricular depolarization

• T wave - ventricular repolarization