Lecture Anatomy/Physiology Heart and its associates

Heart and its associates
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)
a. Located within the thoracic cavity between the lungs; region known as the
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
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
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
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
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
The Valves
a. Chordae tendineae: strong tendinous cords holding cusps of the valves in
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)
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
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
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
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
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.
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