The Heart
General Information


The heart is the Pump
of the Cardiovascular
system
Located behind the
sternum, between the
lungs

Slightly shifted to the
left side of the chest



Apex: Points
downward
Base: (Top) Where all
major vessels leave
the heart.
Size: About the size of
your fist
BASE
APEX
Pericardium

Membrane surrounding the heart

Two Parts:

Fibrous Pericardium: Connects directly to heart
 Dense connective tissue for protection
 Serous
Pericardium: Lines the inner
surface of the pericardial sac
 Pericardial Cavity: Lies between the two
pericardial layers

Filled with pericardial fluid: Reduces friction
between membranes during heart beats
Heart Anatomy

Two Atria:


Two Ventricles:


Right and left atrium are receiving chambers
Right and left ventricles are pumping
chambers
Coronary Sulcus:

Deep groove that separates atria from
ventricles
Major Vessels


Superior Vena Cava:
Returns blood from
above the heart to
the rt. Atrium
Inferior Vena Cava:
Returns blood from
below the heart to the
rt. Atrium.
Major Vessels



Pulmonary Artery: Delivers Oxygen
deficient blood to the lungs, from the rt.
Ventricle
Pulmonary Veins: Delivers oxygen rich
blood to the left atrium from the lungs
Ascending Aorta: All oxygen rich blood
being pumped from the left ventricle to
the systemic circulation

Branches into many other major arteries
Heart Valves

Atrioventricular Valves (cuspid valves):




Between atria and ventricles
Rt. AV valve: Tricuspid valve (3 flaps)
Lt. AV valve: Bicuspid valve (2 flaps)
Cordae Tendinae: tendon like cords attached
to valves that control blood passage
Valves open an close based on pressure
differences
 When pressure within the ventricles increase,
valves close

Heart Valves

Semilunar Valves:



Prevent the backflow of ejected blood
Pulmonary Semilunar Valve: Between rt.
Ventricle and pulmonary artery
Aortic Semilunar Valve: Between left ventricle
and ascending aorta
Heart Wall

3 Layers


Epicardium: Very thin outer surface of the
heart
Myocardium: Muscular wall of the heart


Cardiac muscle: Involuntary
Endocardium: Inner surface of the heart

In direct contact with blood
Cardiac Blood Supply

Coronary Circulation (Huge blood demand)



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Lt. And rt. Coronary arteries: arise from
ascending aorta
All coronary venous return empties into the
coronary sinus and empties directly into the
rt. Atrium
Angina Pectoris: Chest pain due to ischemia
(lack of oxygen supply)
Myocardial Infarction (MI)/Heart Attack: death
of tissue
The Heartbeat

Conducting System:


Heart is self activating
The heart has specialized cells that initiate
and transmit impulses throughout the heart’s
muscular tissue (myocardium)

Sinoatrial Valve (SA): in the wall of the right atrium

Sets the rhythm/pace of the heart
Atrioventricular Node (AV): between atria and
ventricles
 AV bundles, Bundle Branches, and purkinje fibers
transmit these impulses throughout the heart

The Heartbeat
Conducting Pathway:
1.
2.
3.
4.
5.
SV Node
AV Node
AV bundles
Bundle Branches
Purkinje Fibers
Heartbeat Cycle

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Systole: Contraction
Diastole: Relaxation
Pathway of Blood Propulsion
1.
2.
Atrial systole (blood pumped to ventricles)
and ventricular diastole (receive atrial blood)
occur at the same time
Ventricular systole (pumps blood out of
heart) and atrial diastole (receives blood
from body and lungs) occur at the same
time
Heart Murmur

Valves do not close properly and blood
gets pushed back through valves


Can occur at any valve
Usually occurs due to faulty cordae tendinae
or papillary muscles
Heartbeat Dynamics


Heart rate (beats/minute) ~ 75 times/min.
Blood Pressure: Pressure exerted on
vessel walls


Read by a sphygnomometer as sounds
Measures left ventricle diastole and systole
Read systole/diastole
 Avg. adult male ~ 120/80
 Avg. adult female ~ 110/70
 What happens if part of the vessels are blocked???
(i.e. atherosclerosis)

Electrocardiogram

(ECG)/(EKG): Measures electrical events
within the heart


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P wave: Atrial depolarization
QRS wave: Ventricle depolarization (masks
atrial repolarization)
T wave: Ventricle repolarization
Heart Sounds

Recorded using a stethoscope

1st sound: Lubb


2nd sound: Dubb


Caused by the closing of the Atrioventricular valves
as the ventricles contract
Caused by the closing of the Semilunar Valve as
the ventricles relax
Murmur: Caused by the swirling and gurgling
of blood as it is forced back through valves
Cardiac Output

Cardiac Output = (Stroke volume) X (Heart rate)



CO = 75 bpm X 80 ml/beat
CO = 6000 ml/min or 6.0 Liters/minute
Cardiac output is altered by either heart rate or
stroke volume


Elite athletes actually have slower heart rates but
increased stroke volumes
Both are altered by autonomic nervous system and
chemicals within the body