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Biology 212
Anatomy & Physiology I
Dr. Thompson
Heart
Heart:
Mass:
Located in center of
thorax (mediastinum)
Anterior to
Posterior to
Superior to
Surrounded by
All vessels, nerves, etc. enter or leave superior end ("base")
Layers of Heart:
(Outer Surface)
(Inner Surface)
Thin, connective tissue
Thick, cardiac muscle
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:
Cardiac myocytes spontaneously depolarize:
Na+ constantly leaks into the cells,
Thereafter: contraction similar to what we discussed for
skeletal muscle:
Cardiac myocytes spontaneously depolarize:
Na+ constantly leaks into the cells, decreasing the
voltage until threshold voltage is reached
Thereafter: contraction similar to what we discussed for
skeletal muscle:
Action potential moves
along sarcolemma and
into the cell through
transverse tubules
Sarcoplasmic reticulum
Actin binding sites uncovered,
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:
Heart rate:
Stroke volume:
Cardiac Output:
Cardiac Index:
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