Chapter 19.1 – 19.3
Heart
Biology 41: Anatomy and Physiology II
Instructor: Eva Sheridan
Laboratory lecture 2
Outline
Part 1 (19.1 – 19.3)
• Introduction to the cardiovascular system
• The heart within the thoracic cavity
• Heart anatomy
Part 2 (19.4)
• Coronary vessels: blood supply to and from the
heart wall
Cardiovascular System
• Circulation of the blood is accomplished by the
cardiovascular system, which is composed of both the
heart and the blood vessels
• The general function of the cardiovascular system is to
transport blood throughout the body to allow the
exchange of substances (e.g., respiratory gases,
nutrients, and waste products) between the blood
capillaries and the body’s cells
• The goal of the cardiovascular system is to provide
adequate perfusion of all the body tissues
– Perfusion is the delivery of blood per unit time per gram of
tissue (mL/min/g)
Heart
Components of the
Cardiovascular
System
The blood vessels – see
lecture 1, slide 4
– Remember: the
defining factor is
whether blood is
moving away from the
heart or toward the
heart
Blood vessels
Capillaries
(exchange with
air sacs)
Vein
Artery
Capillaries
(exchange with
cells)
Components of the Cardiovascular
System
2.The heart is a hollow, four chambered organ,
serving to pump blood throughout the body
– It is a relatively small, conical, muscular organ
approximately the size of a person’s clenched fist
– Three anatomical features are significant in the
normal function of the heart: (1) the two sides of
the heart, (2) the great vessels attached to the heart,
and (3) the two sets of valves that are located
within the heart
• The heart is composed of
two sides: the right side
and the left side
• Each side of the heart
has two chambers
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to body
to lungs
to
lungs
– A superior chamber for
receiving blood called the
atrium
– An inferior chamber for
pumping blood away
from the heart called a
ventricle
Left
atrium
Right
atrium
Left
ventricle
Right
ventricle
Right side
Left side
Two pumps
Each pump has a receiving chamber
(atrium) and a pumping chamber (ventricle).
Thus, four chambers in the heart are identified:
right atrium and right ventricle on the right
side of the heart, and the left atrium and left
ventricle on the left side of the heart
• Right side: pumps deoxygenated
blood
to the lungs
• Left side: pumps oxygenated blood
to
the body
Note: the two sides of the heart allow separation
of circulating deoxygenated blood and
oxygenated blood
(a)
RightAtrium
Right Ventricle
Heart
LeftAtrium
Left Ventricle
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• Blood is transported directly
to and from the chambers of
the heart by the great vessels
that are continuous with
specific chambers of the
heart
• There are two large arteries
attached to the superior
border of the ventricles that
transport blood from a
ventricle away from the heart
Veins
Arteries
Superior
vena cava
(SVC)
Aorta
Pulmonary
trunk
Pulmonary
veins
Inferior
vena cava
(IVC)
– Pulmonary trunk
– Aorta
Aorta
Great
vessels
Arteries (arterial trunks) transport blood
away from the heart.
• Large veins deliver blood to
the heart into an atrium
• Pulmonary trunk transports
from
right side
• Aorta transports from
left side
Veins transport blood toward the heart
• Vena cavae (SVC and IVC)
– Vena Cavae (SVC and IVC)
– Pulmonary veins
drain into
•Pulmonary vreiginhstsdirdaeininto left
side
(b)
Heart External Anatomy
Great Vessels
Pulmonary
Trunk
Ascending
Aorta
Superior Vena
Cava
Inferior Vena
Cava
Lt. Pulmonary Veins
Rt. Pulmonary Veins
Lt. Atrium
Superior Vena Cava
Inferior Vena Cava
Rt.Atrium
Pulmonary Trunk
AscendingAorta
Lt.Auricle
• Two sets of valves are
located within the heart
– The atrioventricular (AV)
valves are between the
atrium and ventricle on each
side of the heart
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Pulmonary
semilunar
valve
Aortic
semilunar
valve
Right AV
valve
Left AV
valve
• Right AV valve (tricuspid)
• Left AV valve (bicuspid)
– The semilunar valves mark
the boundary between a
ventricle and its associated
arterial trunk
Valves
Heart valves prevent backflow to ensure
one-way blood flow.
• Pulmonary semilunar valve
• Aortic semilunar valve
• Atrioventricular (AV) valves (i.e.,
right
AV valve and left AV valve)
are between
atrium and ventricle
•
Note: the valves ensure one-way, or
unidirectional, flow of blood through the heart
by preventing backflow
Semilunar valves (i.e.,
pulmonary semilunar
valve and aortic
semilunar
valve) are between ventricle
and
arterial trunk
(c)
The Heart Valves
Pulmonary
Tricuspid
Aortic
Bicuspid
Atrioventricular Valves
Tricuspid
Bicuspid (Mitral)
Tricuspid Valve
Chordae tendineae
Papillary muscles
Bicuspid Valve (Mitral)
Chordae tendineae Papillary muscles
Semilunar Valves
Pulmonary
Aortic
Pulmonary Valve &
Pulmonary Trunk
Aortic Valve
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The cardiovascular
system is composed
of two circulation
routes (two sides of
the heart)
• Pulmonary
circulation
• Systemic
circulation
Systemic
circulation
Systemic cells
4
Lung
Pulmonary
circulation
Lung
2
2
Right
side
1
Pulmonary
circulation
3
Oxygenated blood
Deoxygenated blood
Gas exchange
Left
side
Basic pattern of blood flow
1 Right side of heart
Heart
2 Lungs
3 Left side of heart
4 Systemic cells
4
Systemic cells
Systemic
circulation
Circulation Routes
• The pulmonary circulation includes the movement of
deoxygenated blood through the (1) right side of the
heart, (2) blood vessels to the lungs for pickup of O2
and release of CO2, (3) and blood vessels that return
blood to the left side of the heart
• The systemic circulation includes the movement of
oxygenated blood through the (1) left side of the heart,
(2) blood vessels to the systemic cells (e.g., liver, skin,
muscle) for the exchange of nutrients, respiratory
gases, and wastes, and (3) blood vessels that return
blood to the right side of the heart
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Pulmonary
Circulation
(a) Pulmonary Circulation
Transports blood from the right side of the heart to the alveoli of
the
lungs for gas exchange and back to the left side of theheart
Blood flow through pulmonary circulation
Pulmonary
capillaries
of rightlung
Pulmonary
capillaries
of left lung
Right
pulmonary
artery
Left
pulmonary
artery
6
6
Superior
vena cava
(SVC)
7
Pulmonary trunk
5
7
Left atrium
9
8
4
8
1
Right pulmonary
veins
Left pulmonary veins
Right atrium
Blood flow through pulmonary circulation
2
Right AVvalve
3
1 Deoxygenated blood enters the right atrium
from the vena cavae (SVC and IVC) and
coronary sinus (not shown).
Right ventricle
Inferior
vena cava
(IVC)
Pulmonary
semilunar valve
2 Blood passes through the right AV valve
(tricuspid valve).
3 Blood enters the right ventricle.
4 Blood passes through the pulmonary
semilunar valve.
5
Blood enters the pulmonary trunk.
6
Blood continues through the right and left
pulmonary arteries to both lungs.
7 Blood enters pulmonary capillaries of both
lungs for gas exchange.
8
Oxygenated blood exits the pulmonary
capillaries of the lungs and returns to the
heart by right and left pulmonary veins.
9
Blood enters the left atrium of the heart.
1 Deoxygenated blood enters the right atrium
. from the vena cavae (SVC and IVC) and
coronary sinus (not shown).
2 Blood passes through the right AV valve
. (tricuspidvalve).
3 Blood enters the right ventricle.
4. Blood passes through the pulmonary
. semilunar valve.
5 Blood enters the pulmonarytrunk.
. Blood continues through the right andleft
6
. pulmonary arteries to bothlungs.
7 Blood enters pulmonary capillaries of both
. lungs for gasexchange.
8 Oxygenated blood exits the pulmonary
. capillaries of the lungs and returns to the
heart by right and left pulmonary veins.
9 Blood enters the left atrium of the heart.
.
Systemic
Circulation
(b) Systemic Circulation
Transports blood from the left side of the heart to the systemic cells of
the
body for nutrient and gas exchange, and back to the right side of the
heart
Systemic capillaries
of head, neck, and upper limbs
Blood flow through systemic circulation
7
1 Oxygenated blood enters the left atrium.
2 Blood passes through the left AV valve
(bicuspid or mitral valve).
3 Blood enters the left ventricle.
4 Blood passes through aortic semilunar
valve.
5 Blood enters the aorta.
6 Blood is distributed by the systemic
arteries.
7 Blood enters systemic capillaries for
nutrient and gas exchange.
8 Deoxygenated blood exits systemic
capillaries and returns to the heart by
systemic veins that ultimately drain into the
SVC, IVC, and coronary sinus (not shown).
9 Blood enters right atrium.
Systemic
veins
6
8
Systemic
arteries
Aorta
Superior
vena cava
(SVC)
5
Left atrium
Left AVvalve
1
Right atrium
2
9
4
3
Blood flow through systemic circulation
Left ventricle
1 Oxygenated blood enters the left atrium.
2 Blood passes through the left AV valve
(bicuspid or mitral valve).
6
Inferior
vena cava
(IVC)
Aortic semilunar valve
3 Blood enters the left ventricle.
4 Blood passes through aortic semilunar
valve.
5 Blood enters the aorta.
6 Blood is distributed by the systemic
arteries.
7 Blood enters systemic capillaries for
nutrient and gas exchange.
8 Deoxygenated blood exits systemic
capillaries and returns to the heart by
systemic veins that ultimately drain into the
SVC, IVC, and coronary sinus (not shown).
9 Blood enters right atrium.
8
Systemic
arteries
Systemic
veins
Systemic capillaries of
trunk and lower limbs
7
The Heart Within the Thoracic Cavity
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Mediastinum
Right lung
Left lung
Sternum
2nd rib
Left atrium
Right atrium
Left ventricle
Right
ventricle
Apex of
heart
Diaphragm
(a) Position of the heart in the thoracic cavity
Location and Position of the Heart
• The heart is located posterior to the sternum left of the
body midline between the lungs within mediastinum
• The position of the heart is slightly rotated such that its
right side or border is located more anteriorly, whereas
its left side is located more posteriorly (this is reflected
in the images on slide 31 and 33)
• The postero-superior surface of the heart is called the
base, and the inferior, conical end is called the apex
– The apex projects slightly anterionferiorly toward the left
side of body with the right ventricle lying on the diaphragm
Pericardium
•
•
Parietal layer of
serous pericardium
Fibrous pericardium
Visceral layer of
serous pericardium
(epicardium)
–
Pericardial cavity
(contains serous fluid)
Tough, dense, irregular
connective tissue that encloses
the heart, but does not attach
to it
Attached inferiorly to the
diaphragm and superiorly to
the base of the great arterial
trunks
Parietal layer of the
serous pericardium
–
–
•
Fibrous pericardium
The heart is enclosed by
three layers, collectively
called the pericardium
–
•
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Fibrous
pericardium
Simple squamous epithelium
and an underlying delicate
layer of areolar tissue
Adheres to inner surface of
fibrous pericardium
Parietal layer
of serous
pericardium
Visceral layer
of serous
pericardium
(epicardium)
Visceral layer of serous
pericardium
–
–
Simple squamous epithelium
and an underlying delicate
layer of areolar tissue
Adheres directly to the heart
Diaphragm
Pericardial
sac
Pericardium
• The tough fibrous pericardium serves to both
anchor the heart within the thoracic cavity and
prevent the heart chambers from overfilling with
blood
• The parietal and visceral layers of the serous
pericardium produce and release serous fluid into
the pericardial cavity, which separates the two
serous layers
– This fluid has the consistency of an oily mixture, and it
lubricates the serous membranes to decrease friction
with every heartbeat
Heart Anatomy – Superficial Features
• The atria are separated from the ventricles by a
relatively deep groove called the coronary sulcus (or
the atrioventriuclar sulcus)
• An interventricular sulcus is a groove between the
ventricles that extends inferiorly from the coronary
sulcus
– It delineates the superficial boundary between the right and
left ventricles
– The anterior interventricular sulcus is located on the
anterior side of the heard
– The posterior interventricular sulcus is located on the
posterior side of the heart
Note: coronary vessels (described later) are located within the sulci
Heart External Anatomy
Sulci
Anterior Interventricular
Sulcus
Atrioventricular
(Coronary)
Sulcus
Heart External Anatomy
Sulci
Posterior Interventricular
Sulcus
Posterior
Atrioventricular
(Coronary) Sulcus
Heart Anatomy – AnteriorView
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Ascending aorta
Aortic arch
Superior vena cava
Ligamentum arteriosum
Left pulmonary artery
Pulmonary trunk
Branches of right
pulmonary artery
Left pulmonary veins
Right pulmonary veins
Left auricle
Left coronary artery
(in coronary sulcus)
Right auricle
Right atrium
Circumflex artery
(in coronary sulcus)
Right coronary artery
(in coronary sulcus)
Anterior interventricular artery
(in anterior interventricular sulcus)
Right ventricle
Left ventricle
Right marginal artery
Inferior vena cava
Apex of heart
Descending aorta
Heart Anatomy – Posterior View
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Aortic arch
Descending aorta
Superior vena cava
Left pulmonary artery
Left pulmonary veins
Right pulmonary artery
Right pulmonary veins
Left atrium
Coronary sinus
(in coronary sulcus)
Left ventricle
Right atrium
Inferior vena cava
Right coronary artery
(in coronary sulcus)
Posterior interventricular artery
(in posterior interventricular sulcus)
Right ventricle
Apex of heart
Anterior vs. Posterior View
• The right atrium and right ventricle are
prominent when observing the heart from an
anterior view
– Also visible are the right auricle, a small portion of
the left auricle, the anterior interventricular sulcus,
and part of the coronary sulcus
• The left atrium and left ventricle are prominent
when observing the heart from a posterior view
– Also visible are the SVC, IVC, pulmonary arteries,
pulmonary veins, posterior interventricular sulcus,
and part of the coronary sulcus
Heart External Anatomy
Ant. Chambers
Rt.
Atrium
Lt.
Atrium
Rt. Ventricle
Lt. Ventricle
Heart External Anatomy
Post. Chambers
Rt.
Atrium
Lt.
Atrium
Rt. Ventricle
Lt. Ventricle
Layers of the Heart Wall
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Notice: thickness
of the walls
Ascending aorta
Aortic arch
Ligamentum arteriosum
Superior vena cava
Left pulmonary artery
Right pulmonary artery
Right auricle
Pulmonary trunk
Right pulmonary veins
Left pulmonary veins
Interatrial septum
Left atrium
Aortic semilunar valve
Fossa ovalis
Left AV valve
Pectinate muscle
Opening for coronary sinus
Chordae tendineae
Right atrium
Trabeculae carneae
Pulmonary semilunar valve
Left ventricle
Right AV valve
Interventricular septum
Chordae tendineae
Pericardial sac
Papillary muscles
Right ventricle
Pericardial cavity
Inferior vena cava
Descending aorta
Right ventricular
wall
(a)
Left ventricular
wall
Three Layers of Heart Wall
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Simple squamous
epithelium
(endothelium)
Simple squamous
epithelium
Areolar connective
tissue and adipose
connective tissue
Areolar connective
tissue
Endocardium
(b)
Myocardium
(cardiac muscle)
Epicardium
(visceral layer of
serous pericardium)
Three Layers of Heart Wall
• The epicardium is the outermost layer of the heart layer and
is also called the visceral layer of the serous membrane
– Simple squamous epithelium and an underlying layer of areolar
tissue
• The myocardium is the middle layer of the heart wall
– Cardiac muscle tissue
– Thickest layer
– Contraction of the cardiac muscle composing the myocardium
generates the force necessary to pump the blood
• The endocardium covers the internal surface of the heart
and the external surfaces of the heart valves
– Simple squamous epithelium and an underlying layer of areolar
tissue
– Continuous with the endothelium of the blood vessels
Heart Chambers – Defining
Characteristics
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Ascending aorta
Aortic arch
Ligamentum arteriosum
Superior vena cava
Left pulmonary artery
Right pulmonary artery
Right auricle
Pulmonary trunk
Right pulmonary veins
Left pulmonary veins
Interatrial septum
Left atrium
Fossa ovalis
Aortic semilunar valve
Pectinate muscle
Opening for coronary sinus
Left AV valve
Chordae tendineae
Right atrium
Trabeculae carneae
Pulmonary semilunar valve
Left ventricle
Right AV valve
Interventricular septum
Chordae tendineae
Pericardial sac
Papillary muscles
Right ventricle
Pericardial cavity
Inferior vena cava
Descending aorta
(a)
Some terms to supplement the previous
slide
• The fossa ovalis is an oval depression on the interatrial
septum that occupies the former location of the
foramen ovale
• Pectinate muscles are muscular ridges found on the
inner walls of the atria
• Trabeculae carnae are large, smooth, irregular
muscular ridges found on the inner walls of the
ventricles
• Papillary muscles are cone-shaped, muscular
projections that anchor thin strands of collagen fibers
called chordae tendineae, which are attached to the
atrioventricular valves
Interatrial
Septum
Interventricular
Septum
Interatrial
septum
Interventricular
septum
Pectinate
muscles
Papillary
muscles
Chordae
tendineae
Trabeculae
carnae
Right Atrium
Opening
of
coronary
sinus
Fossa
ovalis
Opening
of
superior
vena
cava
Opening
of inferior
vena cava
Right
Ventricle
Rt.AV
valve
Trabeculae
carnae
Papillary
muscle
Pulmonary
trunk
Chordae
tendineae
Pulmonary
Semilunar
valve
Left Atrium
LeftAtrium
Openings of
pulmonary veins
Auricle
Left Ventricle
Lt.AV
valve
Aortic
semilunar
valve
Papillary
muscles
Chordae
tendineae
Heart Valves
• Effective blood flow requires valves to control
blood flow and ensure it is “one-way”
• Each valve consists of endothelium-lined
fibrous connective tissue flaps called cusps
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Atrioventricular
valves –
Anatomy
• The right AV valve
covers the right
atrioventricular opening,
and has three cusps
(tricuspid valve)
• The left AV valve covers
the left atrioventricular
opening, and has two
cusps (bicuspid or mitral
valve)
Pulmonary semilunar
valve
Aortic semilunar
valve
Left
atrioventricular
valve
Right atrioventricular
valve
Coronal section
Right
atrioventricular
valve
Left
atrioventricular
valve
Aortic semilunar
valve
LAB RAT
Pulmonary semilunar valve
Transverse section
(a) Heart valves
Atrioventriuclar Valves – Physiology
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Atrioventricular
valve open
Blood
flow
Atrioventricular
valve closed
Atrium
Cusp
Chordae
tendineae
Papillary
muscle
Blood in
ventricle
Ventricle
(b) Atrioventricular (AV) valves
Atrioventriuclar Valves – Physiology
The AV valves prevent blood flow back into the atrium
The AV valves open as the ventricles relax
–
The cusps of the valve extend into the ventricles. Blood
flows from the atria to ventricles.
The AV valves close as the ventricles contract
–
Ventricular contraction pushes blood against the AV
valves, forcing them closed.
The AV valves do not invert into the atria because
they are secured by the papillary muscles and chordae
tendineae.
–
The chordae tendineae attach to the lower surface of each
cusp.
Semilunar
Valves –
Anatomy
• The pulmonary
semilunar valve is located
between the right ventricle
and the pulmonary trunk
• The aortic semilunar
valve is located between
the left ventricle and the
aorta
• Each valve is composed of
three half-mooned-shaped,
pocket-like cusps
• No papillary muscles, and
no chordae tendineae
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Pulmonary semilunar
valve
Aortic semilunar
valve
Left
atrioventricular
valve
Right atrioventricular
valve
Coronal section
Right
atrioventricular
valve
Left
atrioventricular
valve
Aortic semilunar
valve
Pulmonary semilunar valve
Transverse section
(a) Heart valves
Semilunar Valves – Physiology
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Semilunar valve closed
Semilunar valve open
Blood flow
Arterial
trunk
(aorta or
pulmonary
trunk)
Cusps of
semilunar
valve
Ventricle
(c) Semilunar valves
Blood flow
Semilunar Valves – Physiology
The function of the semilunar valves is to prevent backflow
into the ventricles
The semilunar valves open as the ventricles contract.
– Ventricular contraction pushes blood against the semilunar valves
forcing them open. Then blood enters the arterial trunks.
The semilunar valves close as the ventricles relax.
– Ventricular relaxation decreases the pressure in the ventricles. The
semilunar valves close when the pressure in the ventricles
becomes less than the pressure in the arterial trunks.
After the semilunar valves close, the arterial trunks
contract.
– The blood in the arterial trunks moves downward, but is caught in
the cusps of the semilunar valves.
Atrioventricular Valves
Tricuspid
Bicuspid (Mitral)
Semilunar Valves
Pulmona
ry
Aortic
Cardiac Muscle Anatomy
Openings of
transverse (T) tubules
Endomysium
Intercalated disc
Sarcolemma
(a) Cross section of cardiac muscle cells
Nucleus
Mitochondrion
Myofilament arrangement
• The myofilaments are arranged in sarcomeres
• A difference between skeletal and cardiac muscles is
when maximum overlap of myofilaments occurs
• Note: maximum overlap of thin and thick filaments
does not occur when cardiac muscle is at rest (unlike
skeletal muscle)…
• …Instead, the maximum overlap of thin and thick
filaments occurs when cardiac muscle is stretched as
blood is added to the heart
– This (1) provides a means of forming additional
crossbridges (remember biology 41) between thin and thick
filaments, and (2) cardiac muscle contracting with
increasingly greater degrees of force as additional blood
enters the chamber (explain this further next semester)
Gap Junctions
• These are protein pores
between sarcolemma
that provide a
low-resistance pathway
for the flow of ions
between cardiac
muscles
• In this way, a chamber
functions as a single
unit, or functional
syncytium
Folded
sarcolemma
Desmosomes
Gap junctions
Intercalated discs
(b) Intercellular junctions
Metabolism of Cardiac Muscle
• Cardiac muscle has great demand for energy, as it pumps
continuously from birth to death
• Therefore, it requires:
– Extensive blood supply
– Numerous mitochondria
– Myoglobin and creatine kinase
• Cardiac muscle cells are able to use different types of fuel
molecules
– Fatty acids, glucose, lactic acid, amino acids, and ketone bodies
• Cardiac muscle cells rely mostly on aerobic metabolism
– This makes muscle susceptible to failure in low-oxygen
Note: the structure to function relationship
The heart is
supported
internally by a
fibrous skeleton
composed of
dense, irregular
connective tissue
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Functions
1.Structural
support between Right
atria and ventricle atrioventricular
valve
2.Fibrous rings
to anchor the
Aortic semilunar
heart valves
valve
3.Rigid
framework for
cardiac muscle
Pulmonary semilunar valve
tissue
4.Electrical
(a)
insulator
Posterior
Left
atrioventricular
valve
Fibrous
skeleton
Anterior
Supply vs. Drain
• Please understand the terms (1) supply, and (2)
drain…let’s define each…
• Arteries carry blood away from the heart, and
supply different areas (i.e., cells, tissues,
organs) of the body with either oxygenated
(systemic) or deoxygenated (pulmonary) blood
• Veins drain either oxygenated (pulmonary) or
deoxygenated (systemic) blood from different
areas (i.e., cells, tissues, organs), and take that
blood back towards the heart
Example
Artery: right marginal artery
Tissue it supplies: lateral wall of the right
ventricle
Vein: small cardiac vein
Tissue it drains: lateral wall of the right ventricle
Coronary Circulation – Why is it
needed?
• Initially, you would think that blood in the four
chambers of the heart would diffuse through the three
layers of the heart wall to supply each layer with
oxygen and nutrients, while collecting its waste.
• However, diffusion does not happen at a fast enough
rate through the THICK layers of the heart wall.
Basically, if the body relied on diffusion through the
heart wall, you would die before the blood successfully
diffused into and back out of the three layers.
• Therefore, the heart is supplied and drained by its own
set of arteries and veins called coronary vessels
– Coronary arteries transport oxygenated blood to the walls
of the heart
– Coronary veins transport deoxygenated blood away from
the heart walls
Coronary Arteries
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Ascending aorta
Left atrium
Left coronary artery
Right atrium
Circumflex artery
Anterior
interventricular
artery
Right coronary artery
Branches of right
coronary artery
Posterior
interventricular artery
Right marginal artery
Right ventricle
Left ventricle
(a) Coronary arteries
Branches of left
coronary artery
Coronary Arteries
• The right and left coronary arteries are positioned within
the coronary sulcus of the heart
– They are the first branches of the ascending aorta and originate
immediately superior to the aortic semilunar valve
• The right coronary artery branches into the
– Right marginal artery
• Supplies the lateral wall of the right ventricle with blood
– Posterior interventricular artery
• Supplies the posterior wall of both the left and right ventricles with
blood
• The left coronary artery branches into the
– Circumflex artery
• Supplies the lateral wall of the left ventricle with blood
– Anterior interventricular artery
• Supplies both the anterior wall of the left ventricle and most of the
interventricular septum with blood
Coronary Arteries – Pathways
Right
coronary
artery
Ascending
aorta
Left
coronary
artery
Aortic semilunar
valve
Right
marginal
artery
Posterior
interventricular
artery
Left
Ventricle
Anterior
interventricular
artery
Circumflex
artery
Coronary Veins
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Coronary sinus
Middle cardiac vein
Great cardiac vein
Small cardiac vein
(b) Coronary veins
Coronary Veins
Coronary Veins – Pathways
Right
atrium
Coronary
Sinus
Great
cardiac
vein
Middle
cardiac
vein
Small
cardiac
vein
Coronary Blood Flow
• Coronary blood flow is intermittent
• This is because…
– Coronary vessels are patent (open) when the heart
is relaxed and blood flow is possible
– However, coronary vessels are compressed when
the ventricles contracts, temporarily interrupting
blood flow