Physiology of the Heart

Physiology of the Heart

Study of how the heart functions and pumps blood throughout the body.

Heartbeat

Consists of two phases: diastole and systole.

Diastole

Relaxation phase of the heartbeat when the ventricles fill with blood.

What Happens During Diastole

Ventricle walls relax and blood flows into the heart from the venae cavae and pulmonary veins.

Valves Open During Diastole

Tricuspid and mitral valves.

Valves Closed During Diastole

Pulmonary and aortic valves.

Systole

Contraction phase of the heartbeat when the ventricles pump blood out of the heart.

What Happens During Systole

Ventricle walls contract and pump blood into the pulmonary artery and aorta.

Valves Closed During Systole

Tricuspid and mitral valves.

Purpose of Tricuspid and Mitral Valve Closure

Prevents blood from flowing back into the atria.

Blood Vessels Receiving Blood During Systole

Pulmonary artery and aorta.

Cardiac Cycle

One complete sequence of diastole and systole.

Normal Heart Rate

The cardiac cycle occurs about 70 to 80 times per minute.

Heartbeats Per Day

The heart beats approximately 100,000 times each day.

Blood Pumped Per Contraction

About 3 ounces of blood.

Blood Pumped Per Minute

About 5 quarts of blood.

Blood Pumped Per Hour

About 75 gallons of blood.

Blood Pumped Per Day

About 2,000 gallons of blood.

Heart Sounds

Sounds produced by the closing of heart valves.

Lubb-Dubb Sound

Normal heart sounds heard through a stethoscope.

First Heart Sound (S1)

The "lubb" sound caused by closure of the tricuspid and mitral valves at the beginning of systole.

Second Heart Sound (S2)

The "dubb" sound caused by closure of the aortic and pulmonary valves at the end of systole.

Stethoscope

Instrument used to listen to heart sounds.

Heart Murmur

An abnormal swishing sound caused by blood flowing through heart valves.

Cause of a Murmur

Abnormal blood flow through heart valves.

Order of Heart Sounds

S1 (lubb) followed by S2 (dubb).