Lecture Anatomy/Physiology Heart and its associates

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Lecture
Anatomy/Physiology
Heart and its associates
THE HEART
I.
Heart General Information
a. Center of the cardiovascular system
b. Pumps 30x its weight per minute
c. Equates to 7,000 L/day = 1.3 million gal/year
d. Blood vessels (60,000 miles of vessels)
i. circle the earth 2 times (24,859 miles = circ. of earth)
II.
Where?
a. Located within the thoracic cavity between the lungs; region known as the
mediastinum
b. 2/3 of the hears is left of the mid-line
c. apex (cone-shaped end) points down towards diaphragm
d. enclosed by parietal pericardium- loose-fitting sac of dense connective
tissue
e. parietal pericardium forms the pericardial cavity; holds the heart in place
i. pericardial fluid: water, lubricant cushioning/protecting heart;
minimizes friction between the pericardial layers.
ii. outer layer of pericardium is called fibrous pericardium- dense
connective tissue
iii. inner layer is called the serous pericardium- thinner, more
delicate tissues
III.
Composition of the Heart Wall: 3 layers
a. Epicardium (visceral pericardium)- thin outer layer
b. Myocardium: composed of cardiac muscle tissue that contracts in a
manner that “squeezes” the blood out of each chamber
c. Endocardium: similar in composition to endothelium of blood vessels;
forms part of the valves of heart
IV.
Chambers of the Heart:
a. Left and Right Atria (upper)- separated by interatrial septum
b. Left and Right Ventricles (lower)- separated by interventricular septum
c. Coronary sulcus: external groove between atria and ventricles
V.
Primary (1) Vessels of the Heart (Veins and Arteries):
a. Rt. Atrium- receives blood from superior/inferior vena cava
b. Lt. Atrium- receives oxygenated blood from the pulmonary veins (lungs)
c. Rt. Ventricle- blood through tricuspid valve (an atrioventricular valveAV) from rt. atrium; blood exits through pulmonary trunk into lungs via
pulmonary arteries
d. Lt. Ventricle- oxygenated blood received through bicuspid valve (mitral
valve); blood exits through ascending portion of the aorta
VI.
The Valves
a. Chordae tendineae: strong tendinous cords holding cusps of the valves in
place
b. Secured to wall by papillary muscles
c. The valves stopping backflow into the ventricles are called semilunar
valves (pulmonary semilunar- entrance to pulmonary trunk; aortic
semilunar- entrance to ascending aorta)
VII.
Routes of the Blood
a. 2 routes: pulmonary and systemic circulation
b. Pulmonary route: consists of blood vessels that transport blood from the
rt. ventricle to lungs for gas exchange and then into left atrium of heart
c. Systemic route: composed of all the remaining vessels of the body that
are not part of the pulmonary route
“I DON’T UNDERSTAND WHAT THE DOCTOR MEANS”
I.
The Cardiac Components: the repeating pattern of the contraction and
relaxation of the heart (ventricles)
a. Systole- contraction phase
b. Diastole- relaxation phase
c. Contraction ejects approx. 2/3 of blood in ventricles- this amount is called
the stroke volume; blood remaining is the end-systolic volume.
**(stroke volume) x (beats/minute) = Cardiac Output (minute)
(70 mls/beat) x (63 beats/minute) = 4410 ml/min or 4.4 L/min
d. The Cycle:
i. Atrial Systole: contractions forces blood into ventricles; opens AV
valve
ii. Ventricular Diastole: allow blood in
iii. Ventricular Systole: pressure closes AV valve and opens semilunar
valves; blood goes out
iv. Atrial Diastole: Relax; blood flows in
II.
The Sounds
a. “lub”- (first sound) produced by the closing of the AV valves during
contraction of ventricles
b. “dub”- (second sound) produced by the closing of the semilunar valves
when the pressure in the ventricles falls below pressure of arteries
c. murmurs- abnormal sounds caused by valvular leakage or structural
abnormalities that produce turbulence as blood passes through the heart
III.
Blood Pressure- pressure exerted on the wall of one’s arteries
a. Average is 100 mm Hg when in aorta (leaving) and about 0 when entering
the rt. atrium
b. Stronger during contraction; stronger in arteries than in veins
c. Reported in two (2) numbers: 120/80 What does that mean?
d. Systolic pressure (contraction)/diastolic pressure (relaxation)
e. Blood pressure tells your doctor how hard your heart is working; if higher
than normal, you have high blood pressure = means your heart is
working extra hard to push blood through your arteries.
IV.
The Electrocardiogram (ECG/EKG): reading of electric changes
a. Each portion of heartbeat produces a different action potential
i. P-wave: small upward wave; atrial depolarization
ii. QRS- wave: (sections of the peak) ventriclular depolarization
(masks the atrial repolarization)
iii. T-wave: second, small upward wave; ventricular depolarization
http://www.bmb.psu.edu/courses/bisci004a/cardio/ekg.jpg
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