Chapter 5
The
Cardiovascular
System
Functions of the Cardiovascular System
▪ Consists of the heart, blood vessels
and blood
▪ Pumps blood to all body tissues
▪ Blood…
▪ Fluid tissue that transports oxygen and
nutrients to body tissues
▪ Returns some waste products from these
tissues to the kidneys and carries carbon
dioxide back to the lungs
▪ Blood cells are also important to the
immune system
THE HEART
▪ Hollow muscular organ
▪ In the thoracic cavity
between lungs
▪ Pumps blood through
the entire body
▪ The lower tip is called
the apex
The Pericardium
▪Double-walled
membranous sac
that encloses the
heart
▪Peri- surrounding,
cardi heart, -um
singular noun ending
Walls of the Heart
▪ Epicardium – external layer of the
heart, and inner layer of the
pericardium
▪ Myocardium – Middle (thickest)
layer of the heart
▪ Made of Cardiac muscle
▪ Receives oxygen-rich blood from the
coronary arteries
▪ Endocardium – Inner lining of the
heart
▪ Surface that comes into contact with
the blood
Heart Chambers
▪ Atria:
▪ 2 upper chambers
▪ All blood entering the
heart comes through an
atria
▪ Ventricles
▪ 2 lower chambers
▪ Thicker walls
▪ Pump blood out of the
heart
Valves of the Heart
▪ Tricuspid: R atrium and
R ventricle
▪ Pulmonary semilunar
valve: R ventricle and
pulmonary artery
▪ Mitral valve: L atrium
and L ventricle (AKA
bicuspid)
▪ Aortic semilunar valve:
L ventricle and aorta
Systemic and Pulmonary Circulation
▪ Systemic circulation:
flow of blood to all
parts of the body
except the lungs
▪ Pulmonary
circulation: flow of
blood only between
heart and lungs
Blood Flow Through
The Heart
▪ Oxygen poor blood enters heart at the RA
via the superior and inferior vena cava
▪ Out of the RA thru the tricuspid to the RV
▪ Pumped through the pulmonary
semilunar valve and into the pulmonary
artery to the lungs
▪ Oxygen rich blood returns to heart via the
pulmonary veins and flows into the LA
▪ Thru the mitral valve to the LV
▪ Thru the aortic semilunar valve and into
the aorta.
▪ Goes to body, oxygen used up
▪ Starts over again!
The Heartbeat
▪ Rate and regularity of the heartbeat is determined by
electrical impulses
▪ Sinoatrial Node (SA node)
▪
▪
▪
▪
Back of RA
Establishes rate/rhythm
Called the natural pacemaker of the heart
This impulse travels over both atria so they contract together
▪ Atrioventricular Node (AV node)
▪ Located on floor of RA
▪ Receives impulse from SA node
▪ Sends impulse to the Bundle of His
▪ Bundle of His
▪ Group of fibers located between the ventricles
▪ Sends impulse to RV and LV and Perkenje fibers
▪ Perkenje Fibers
▪ Located in walls of ventricles
▪ Send impulses thru ventricles so they contract together
Electrocardiogram
▪ P wave – contraction
of the atria
▪ QRS complex –
Contraction of the
ventricles (the atria
are relaxing)
▪ T wave – relaxation
and recovery of the
ventricles
Arrhythmia: loss of the
normal rhythm of the heart
asystole
Arteries
▪ Large blood vessels that carry blood
away from the heart
▪ Arterial blood is bright red b/c it is
oxygen rich
▪ Aorta is the largest blood vessel in the
body
▪ Carotid arteries carry blood to head
▪ Arterioles are smaller branches of the
arteries that give blood to the
capillaries
Capillaries
▪ Smallest blood vessels, only 1 cell thick!
▪ Exchange of oxygen, nutrients and waste
materials occurs here
▪ Connect to venules to begin the trip back to the
heart
Veins
▪ Return oxygen-poor blood to the
heart
▪ Have valves that keep the blood
flowing only toward the heart
▪ Two largest veins are the
superior vena cava (blood from
upper part of the body) and the
inferior vena cava (blood from
lower part of the body)
Pulse and Blood Pressure
▪ Pulse: rhythmic pressure against
the walls of an artery caused by the
contraction of the heart
▪ Blood pressure: measurement of
the amount of pressure exerted
against the walls of the arteries
▪ Systolic pressure – occurs when
ventricles contract – it is the highest
pressure against the walls of an
artery
▪ Diastolic pressure – occurs when
ventricles are relaxed
Blood the “Fluid Tissue”
▪ Plasma
▪ Straw-colored fluid (91% water); contains
nutrients, hormones and waste products
▪ Erythrocytes
▪ Mature red blood cells, made in red bone
marrow, transports oxygen using the
protein hemoglobin
▪ Leukocytes
▪ White blood cells, defend the body
▪ Most common is the neutrophil
▪ Thrombocytes
▪ AKA platelets, small, important in clotting
Blood Types
▪Classified according to the presence or absence
of certain antigens (something the body sees as
foreign)
▪A, AB, B, O
The universal red cell donor
has Type O negative blood
type.
The universal plasma donor
has Type AB positive blood
type.
Terms related to blood
▪ Hematologist: physician who
specializes in diagnosing and
treating abnormalities, diseases
and disorders of the blood and
blood forming tissues
▪ Hemostasis: To stop or control
bleeding
▪ Forming a blood clot
▪ External pressure to block blood flow