Anatomy of the Cardiovascular
System
Anatomy & Physiology
Heart song
 http://www.youtube.com/watch?v=q0s-1MC1hcE
Location of the heart
 In mediastinum behind the
sternum between 2nd & 6th
ribs. Shifted to left.
 Posteriorly between 5th to
8th thoracic vertebrae
 Apex (lowest point) lies on
diaphragm
Pericardium
 Sac covering the heart
 Fibrous pericardium –
tough, inelastic
 Serous pericardium- 2 layers
 Parietal layer- lines fibrous
pericardium
 Visceral layer (epicardium)adheres to outside of heart;
space between parietal &
visceral layer contain small
amount of fluid
Function of pericardium
 Provides protection against friction
Layers of the heart
 Epicardium (also the serous pericardium)
 Myocardium-thick contractile layer of muscle cells
 Endocardium-cover trabeculae (muscular projections);
specialized folds of endocardium make up the major valves
of heart
Chambers of heart
 Atria: upper
chambers
 Ventricles: lower
chambers
 Chambers are
separated by an
extension of heart
wall, septum
Atria
 Receive blood from
veins
 Send blood to
ventricles
 Thin myocardial wall
 Auricle: earlike flap
protruding from each
atrium
Ventricles
 Receive blood from the
atria
 Pump blood out of
heart into arteries
 Thicker myocardium
 Myocardium of left
ventricle thicker than
right ventricle
Heart valves
 Permit flow of
blood in one
direction
 Atrioventricular
valves
 Semilunar valves
Atrioventricular valves
 Made of flaps of
endocardium
 Flaps anchored to
papillary muscle by
chordae tendineae
 Rt AV valve: tricuspid
valve
 Lt AV valve: mitral
(bicuspid) valve
Semilunar valves
 Consists of half moon
shaped flaps
 Pulmonary semilunar
valve: at the entrance
to the pulmonary
artery
 Aortic semilunar valve:
at the entrance to aorta
Flow of blood through the heart
Heart video
 http://www.youtube.com/watch?v=DAXa4eR1s0M
Blood supply to heart
 Blood supplied thru the right & left
coronary arteries
 Coronary arteries are first branches off
aorta
 After blood has passed thru capillary beds,
enters cardiac veins then thru common
channel, coronary sinus, then into rt atrium
Conduction system of heart
 Sinoatrial node (pacemaker): in rt atrium near
opening of superior vena cava
 Atrioventricular node: in rt atrium along lower
part of interatrial septum
 Atrioventricular bundle: originate in AV node &
extend by 2 branches thru the 2 sides of the
interventricular septum
 Purkinje fibers: extension of AV bundle out to the
lateral walls of the ventricles & papillary muscles
Conduction System
Blood vessels
 Arteries: carry blood away from heart
Arterioles: small arteries
 Veins: Carry blood toward heart
Venules: small veins
 Capillaries: microscopic blood vessels
that carry blood from arterioles to
venules
3 layers of blood vessels
 Tunica adventitia: outer
layer, fibrous
connective tissue
 Tunica media: layer of
smooth muscle &
elastic connective
tissue
 Tunica intima: made of
smooth endothelium
Blood Vessel Structure
Type of
vessel
Tunica
intima
Tunica
media
Tunica
adventitia
artery
Smooth
lining
Thicker
than in
veins
Thinner
than tunica
media
vein
Smooth
lining with
valves
Thinner
than in
arteries
Thicker
than tunica
media
capillary
Makes up
absent
entire wall:
very thin
absent
Functions of capillaries
 Transport materials
to and from cells
 Capillaries so
numerous & so small
that blood flows at
its slowest rate in
capillaries
Functions of arteries
 Function as
“distributors”
 Arterioles also function
as resistance vessels
 Smooth muscle cells on
arterioles act as
precapillary sphincters
where a capillary
originates
Functions of veins
 Return blood to heart
 Act as reservoir vessels
 Ability to stretch by veins called
capacitance thus veins are capacitance
vessels
Circulatory routes
 Systemic circulation:
blood flow from
heart to all parts of
body (except lungs)
 Pulmonary
circulation: blood
flow from heart to
lungs
Arteries
 End-arteries: most of the arteries, they
diverge into capillaries
 A few arteries open into branches of
other arteries; this communication is an
arterial anastomosis
 Incidence of arterial anastomosis
increases as distance from the heart
increases
Aorta
 Major artery that serves as
trunk of the entire
systemic arterial system
 First few cm conducts
blood up away from lt
ventricle-ascending aorta
 Then turns 180 degreesaortic arch
 Then downward from
arch-descending aorta
Veins
 Large veins that
return blood to
heart in systemic
circulation are
superior & inferior
vena cava