Biology 212Anatomy & Physiology I

Dr. Thompson

Heart

Heart:Mass:

Located in center of thorax (mediastinum)Anterior to Posterior to

Superior toSurrounded by

All vessels, nerves, etc. enter or leave superior end ("base")

Layers of Heart:(Outer Surface) Thin, connective tissue

Thick, cardiac muscle

(Inner Surface) Thin, connective tissue Simple squamous epithelium lines inner surface, next to blood

Myocardium: Cardiac Muscle

Heart surrounded by double-layered pericardium

Heart surrounded by double-layered pericardium

Heart

Heart

Anterior View

Posterior View

Valves of the Heart:

Contraction of the heart (or any one of its chambers) is

Relaxation of the heart (or any one of its chambers) is

One systole followed by one diastole is one

Flow of blood through the heart is controlled entirely by changes in pressure.

Blood always flows along its pressure gradient, from the area of higher pressure to an area of lower pressure.

Flow of blood through the heart is controlled

Blood always flows along its pressure gradient,.

Assume the chambers of the heart and vessels have the following pressures: Left ventricle = 115 mm Hg Right ventricle = 5 mm Hg Pulmonary trunk = 22 mm Hg Superior vena cava = 2 mm Hg Inferior vena cava = 2 mm Hg Left atrium = 20 mm Hg Right atrium = 10 mm Hg Aorta = 125 mm Hg

Which valves of the heart will be open?Which valves of the heart will be closed?

Terms to know:

Stroke volume:

Cardiac Output:

Cardiac Index:

Heart rate:

Given the following information: a) Dr. Thompson's total blood volume is 5.8 liters b) His heart ejects 75 ml of blood per contraction c) His kidneys produce 320 ml of urine per hour d) All of his wisdom teeth have been removed e) His heart contracts 70 times per minute f) His systolic blood pressure is 130 mmHg g) His diastolic blood pressure is 80 mmHg h) The pressure in his left ventricle changes between 1 mmHg and 133 mmHg during each cardiac cycle

Calculate his Heart Rate Stroke Volume Cardiac Output

Therefore: You can regulate your cardiac output, and therefore your cardiac index, by:

a) Increasing or decreasing your heart rate b) Increasing or decreasing your stroke volume

Therefore: You can regulate your cardiac output, and therefore your cardiac index, by:

a) b)

In fact: Your ventricles modify both heart rate and stroke volume on a beat-by-beat basis.

This depends on how much the cardiac muscle cells are stretched during the preceding diastole, which itself depends on the volume of blood in the chamber

= Frank-Starling Law of Cardiac Contraction