Transcript Anatomy and Physiology of the Heart

Anatomy & Physiology/Cardiovascular System
 About the size of a an adult fist
 Hollow and cone shaped
 Weighs less than a pound
 Sits atop the diaphragm and is
centered between the left and right
lung.
 The pointed apex is directed towards
the left hip, while the base is directed
towards the right shoulder.
 The heart is composed of four chambers:
 The right and left atria, which make up the top portion
of the heart, are receiving chambers.
 The right and left ventricles, which make up the bottom
portion of the heart, are the discharging and pumping
chambers.
 The lengthwise membrane that divides the heart is
referred to as the interatrial septum OR
interventricular septum, depending on which
chambers it is dividing.
 The heart functions as a
double pump.
 Pump #1 controls
pulmonary circulation,
which brings blood to and
from the lungs.
 Pump #2 controls
systemic circulation,
which carries blood
throughout the body and
back to the heart.
 Superior and Inferior
Vena Cava = located above
and below the right
atrium, carry deoxygenated
blood from the body into
the right atrium of the
heart.
 Pulmonary Arteries =
Exit from the right
ventricle and carry
deoxygenated blood from
the heart to the lungs.
 Pulmonary Veins = Exit
the lungs and carry
oxygenated blood to the
left atrium of the heart.
 Aorta (Artery) = Exits
the left ventricle of the
heart and carries
oxygenated blood to the
body tissues.
 Coronary Arteries =
branch out from the
aorta and deliver
oxygenated blood to
the heart tissues.
 Cardiac Veins = carry
deoxygenated blood
from the heart tissues
to the right atrium.
 The heart has four valves, which allow blood to flow in
only one direction through the heart:
 Atrioventricular (AV) Valves = located between the atrial
and ventricular chambers on each side. These valves
prevent backflow into the atria when the ventricles
contract.
 The left atrioventricular valve is also called the
bicuspid valve because it is made of two flaps.
 The right atrioventricular valve is also called the
tricuspid valve because it is made of three flaps.
 The heart has four valves, which allow blood to flow in
only one direction through the heart:
 Semilunar Valves = located between the ventricles and
the large arteries that exit them. These valves prevent
backflow into the ventricles when the ventricles relax.
 Pulmonary semilunar valves = located between right
ventricle and pulmonary arteries.
 Aortic semilunar valves = located between left
ventricle and aorta.
 Systole = heart contraction
 Diastole = heart relaxation
 These terms refer to the contraction and relaxation of
the ventricles, unless otherwise noted.
 Blood Pressure readings are recorded as systolic
pressure over diastolic pressure, which refer to the
pressure in the arteries during contraction and
relaxation, respectively.
 A typical blood pressure reading is around 120/80
mmHg
 Unlike skeletal muscle, cardiac muscle can contract
independently, even if it is severed from all nerve
connections.
 Two systems act to regulate heart activity:
 The nerves of the nervous system act to decrease and
increase heart rate in response to environmental
changes.
 The intrinsic conduction system (nodal system) built
into the cardiac muscle tissue.
 There are four major parts that make up the intrinsic
conduction system:
 Sinoatrial (SA) Node = tissue located on the right atrium
which starts each heartbeat and sets the pace for the
whole heart. Also known as the pacemaker.
 Atrioventricular (AV) Node = tissue located at the
junction of the atria and ventricles.
 Atrioventricular (AV) Bundle = groups of fibers located
on the interventricular spetum.
 Purkinje Fibers = spread throughout the muscle of the
ventricle walls.
 The electrochemical impulse that travels through the
heart and generates each heart beat follows this path:
 The impulse is generated in the SA Node
 The impulse travels through the right and left atrium,
triggering contraction of the atria.
 The impulse reaches the AV Node where it is delayed
long enough for the atria to complete contraction.
 The impulse then travels along the Bundle of His to the
Purkinje fibers and begins contraction of the ventricles
at the apex of the heart.
 The impulses generated by the heart can be detected
on the surface of the body.
 A typical EKG includes three waves:
 P Wave = the first wave, which signals the
depolarization of the atria
 QRS Complex = signals the depolarization of the
ventricles
 T Wave = the second wave, signals the repolarization of
the ventricles.