Download Chapter 12 The Cardiovascular System: The Heart Pages 388

CHAPTER 12
THE CARDIOVASCULAR SYSTEM:
THE HEART
PAGES 388 - 411
LOCATION & GENERAL
FEATURES OF THE HEART
TWO CIRCUIT CIRCULATORY
SYSTEM
DIVISIONS OF THE HEART
FOUR CHAMBERS

Right Atrium

Receives blood from
the systemic circuit

Left Atrium

Receives blood from
the pulmonary circuit
FOUR CHAMBERS

Right Ventricle

Ejects blood into the
pulmonary circuit

Left Ventricle

Ejects blood into the
systemic circuit
FOUR VALVES – ATRIOVENTRICULAR
VALVES

Right Atrioventricular
Valve (AV)

Tricuspid Valve

Left Atrioventricular
Valve (AV)

Bicuspid Valve and
Mitral Valve
FOUR VALVES – SEMILUNAR
VALVES

Pulmonary valve

Guards entrance to
the pulmonary trunk

Aortic Valve

Guards entrance to
the aorta
FLOW OF BLOOD
MAJOR VEINS AND ARTERIES AROUND THE
HEART
• Arteries carry
blood AWAY
from the heart
• Veins allow
blood to VISIT
the heart
MAJOR VEINS AND ARTERIES ON THE
HEART
Coronary Circulation – Supplies blood to the muscle tissue of the heart
ARTERIES

Elastic artery: Large, resilient vessels.


Muscular artery: Medium-sized arteries. They
distribute blood to skeletal muscles and internal
organs.


pulmonary trunk and aorta
external carotid artery of the neck
Arteriole: Smallest of arteries.

Lead into capillaries
VEINS

Large veins: Largest of the veins.


Medium-sized veins: Medium sized veins.


Superior and Inferior Vena Cava
Pulmonary veins
Venules: the smallest type of vein.

Lead into cappilaries
CAPILLARIES

Exchange of molecules between blood and
interstitial fluid.
FLOW OF BLOOD THROUGH HEART
TISSUES OF THE HEART
THE HEART WALL

Pericardium
Outermost layer
 Serous membrane


Myocardium
Middle layer
 Thick muscle layer


Endocardium
Inner lining of pumping
chambers
 Continuous with endothelium

CARDIAC MUSCLE

Depend on oxygen to obtain energy


Abundant in mitochondria
In contact with several other cardiac muscles

Intercalated disks – interlocking membranes of adjacent
cells
Desmosomes
 Gap junctions

CONNECTIVE TISSUE




Wrap around each cardiac muscle cell and tie
together adjacent cells.
Provide support for
cardiac muscle fibers
Add strength and prevent
overexpansion of the heart
Help the heart return to normal
shape after contractions
CHORDAE TENDINEAE


Cord-like tendons that connect the papillary
muscles to the tricuspid valve and mitral valve
Connected to Papillary Muscle.
Cone shaped projections on the inner surface of the
ventricle
 Contraction of papillary
muscles tenses the chordae
tendineae and prevents the backflow
of blood into the right and left atrium.

WHY DO YOU THINK THE LEFT VENTRICLE
HAS THE LARGEST AMOUNT OF MUSCLE??
ELECTRICAL ACTIVITY OF THE
HEART
THE HEARTBEAT


The entire heart – atria and ventricles – contracts in
a coordinated manner so that blood flows in the
correct direction at the proper time.
Two Types of Cardiac Muscle Cells Involved
Contractile cells – contractions that propel blood
 Specialized noncontractile muscle cells – control and
coordinate the activities of the contractile cells in the
heart


Part of the conducting system
THE CONDUCTING SYSTEM

A network of specialized
cardiac muscle cells that
initiates and distributes
electrical impulses.

Nodal Cells
Located at the sinoatrial and
atrioventricular nodes
 Responsible for establishing the
rate of cardiac contraction.
 Coupled to one another causing a
coordinated contraction when an
action potential is initiated.


Conducting Cells
Include the Atrioventricular
Bundle, bundle branches, and
purkinje fibers
 Responsible for distributing the
contraction

THE CONDUCTING SYSTEM CONT.

Pacemaker Cells – Depolarize rapidly, generating
70 – 80 action potentials per minute (bpm)



Located in the sinoatrial node
Atriventricular (AV) Bundle – (the bundle of His)
extend along the interventricular septum before
dividing into left and right ventricles
Purkinje Fibers – Convey the impulses to the
contractile cells of the ventricle muscles.
THE ELECTROCARDIOGRAM


A machine that records the electrical events
occurring in the heart.
Each time the heart beats a wave of
depolarization radiates through the atria,
reaches the AV node, travels down the
interventricular septum to the apex, turns, and
spreads though the ventricular muscles towards
the base of the heart.
THE CARDIAC CYCLE
THE CARDIAC CYCLE


The peiod between the start of one heartbeat and
the start of the next is a single cardiac cycle.
Includes a period of contraction - systole


The chambers contract squeezing blood into an
adjacent chamber or arterial trunk
Includes a period of relaxation – diastole

When the chambers fill with blood and prepares for
the start of the next cardiac cycle.
HEART DYNAMICS

Refers to movements and forces generated during
cardiac contractions.


Stroke volume - is the amount ejected by a ventricle
during a single beat


Each time the heart beats, two ventricles eject equal
amounts of blood
Stroke volume varies beat to beat so physicians are often
more interested in cardiac output
Cardiac output - is the amount of blood pumped by
each ventricle in 1 minute

Provides indication of blood flow through peripheral
tissues; without adequate blood flow, homeostasis cannot
be maintained
FACTORS CONTROLLING CARDIAC OUTPUT


The major factors that regulate cardiac output
often affect both heart rate and stroke volume
Primary factors include:
Blood volume reflexes
 Autonomic innervation
 hormones
