The Heart is resposible for delivering the most important chemical throughout the body oxygen.

The location of the heart is beneath the ribs under the left breast. The heart has 4 chambers left/ right atria and left/right ventricles.  The left venticles is the most important chamber it’s Job is to send blood through the entire body except the lungs.

The body largest artery is the aorta the left ventricle pumps oxygen rich blood through the aorta.  Blood moves through a circuit  the more red blood cells and hemoglobin equal more  oxygen the blood can carry throughout the body.

Hemoglobin– red protien that transport oxygen in the blood of vertbrates.

Myoglobin– is a protein that carries oxygen inside the muscles. These two protiens work together like passing the baton in track.

Heart Rate- The HR can climb up 200 beats per min when running. High heart rate means more blood/oxygen travel to walking musles. Older runners has lower maximum heart rate.

Stroke Volume- When the heart is contracts specific voulme of blood is pumped out of the left ventricle ( not the lungs).

How does the blood get to the muscles? Travels through the arteries back to the heart through the veins.  Venous is the amount of blood that travels back to the heart.

The heart produce more force and pumps more blood when it contracts strongly. This is called contractility.

Next we have Preload– blood enters the left ventricle from left atrium pushes aganist the left ventricles wall. Afterload– pressure head at the front end of the aorta that creating resistance to blood flow. Greater stroke Volume when the afterload is smaller.

Size of the heart matters- Harder workouts the heart has to increase it’s pumping strength by enlarging it’s most important chamber left ventricle.  The larger the heart the more blood it can hold and pump. Runners  heart are enlarged from running.

Cardiac Output – Volume of blood the hearts left ventricle pumps per min.  More blood heart pumps each min the more oxygen the muscles get. Faster pace one can run!  Resting  Cardiac Output everyone is the same.

Unfit people have a much higher heart rate and low stroke volume then fit people. Fit people have a low heart rate and high stroke volume.

Max cardiac output– Heart working as hard as it can. Why do we breathe more when we run fast? Carbon dioxide is produced in our muscles from metabolism need to be expelled.

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