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The Circulatory System
Anatomy & Physiology
The Heart
• Muscular pump
• Pumps 5 liters of
blood every minute
• Size of closed fist
• Less than a pound
• Central location
between lungs
• Apex pointed end
• Base is opposite apex
2
Coverings & layers of the Heart
Pericardium: sac that
encloses/covers the heart.
• Layers
1. Epicardium-inner
part of pericardium
but outermost layer
2. Myocardium-thick,
middle layer
(Muscular).
3. Endocardiumsmooth, inner lining
Elsevier items and derived items © 2009 by Saunders, an
imprint of Elsevier Inc.
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Fatty
Connective
Tissue
Coronary
Vessels
Outside
of the
Heart
Pericardium
Pericardial Space
Epicardium
Myocardium
Endocardium
Inside
of the
Heart
4
The Septum
• Partition between
two sides
• Thick muscular wall
• Completely
separates right side
of heart from left
side of heart
5
4 Heart Chambers
Upper heart chambers
• Right atrium
• Left atrium
• The receiving
chambers
6
4 Heart Chambers
Lower Heart Chambers
• Left ventricle
• Right ventricle
• The pumping
chambers
7
The Right Side
Right Atrium
• Thin walled cavity
• Receives deoxygenated
blood from the Superior
& Inferior Vena Cava
– Superior – returns blood
from the head and upper
body
– Inferior – returns blood
from the lower body
Right Ventricle
• Receives deoxygenated
blood from Right
Atrium
• Pumps blood to the
lungs through the
pulmonary artery
8
The Left Side
Left Atrium
Left Ventricle
• Thin walled cavity
• Receives oxygenated
blood from L atrium
• Primary function to
pump blood into
general circulation
• Blood leaves L
Ventricle thru aorta
(largest artery in body)
• Has thicker muscle
than R Ventricle
• Receives oxygenated
blood from lungs
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Structure of the Heart
10
• Keep the blood flowing
in a forward direction.
• Prevent backflow of
blood
• Heart sounds are
produced by closure of
the heart valves.
Creates a lubb dubb
sound
• Located at the
entrance and exit of
the ventricles.
• https://www.youtube.c
om/watch?v=dDg7GDp
R1RE
The Heart Valves
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Heart Valves
• There are 4 heart
valves
• 2 valves located at
the entry of the
ventricles are called
atrioventricular
valves (AV)
• 2 valves located at
the exit of the
ventricles are called
semilunar valves
(SL)
• Atrioventricular
• Tricuspid
• Bicuspid (Mitral)
• Semilunar
• Aortic
• Pulmonary
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Tricuspid & Bicuspid Valve
•
Atrioventricular
(AV) valves
• Tricuspid valve:
between right
atrium and
right ventricle.
Has three
cusps
• Bicuspid
(mitral) valve:
between left
atrium and left
ventricle. Has
two cusps
13
Valves of the Heart
• Semilunar (SL)
valves
• Pulmonary SL
valve: located
at the exit of
the right
ventricle
• Aortic SL valve:
located at the
exit of the left
ventricle
Elsevier items and derived items © 2009 by Saunders, an
imprint of Elsevier Inc.
14
Structure of the Heart
https://www.youtube.com/watch?v=oHMmtqKgs50
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Pathway of Blood through the Heart
• Both atria contract at the same time
• Both ventricles contract at the same time
• Heart functions as two pumps:
– Pulmonary circulation: pump on the right
side
• Pumps blood to lungs
– Systemic circulation: pump on the left side
• Pumps blood to rest of body
Elsevier items and derived items © 2009 by Saunders, an
imprint of Elsevier Inc.
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Pathway of Blood
through the Heart
• Blood enters right atrium through
superior vena cava and inferior
vena cava
• Flows through tricuspid valve
into right ventricle
• Passes through pulmonary SL
valve
• Flows into pulmonary trunk
and into pulmonary arteries
• Blood carried to lungs
• Carbon dioxide is released and
oxygen is picked up
• Pulmonary veins carry blood
to left atrium
• Blood flows through bicuspid
valve into left ventricle
• Flows through aortic SL valve
into aorta
• Distributed to all parts of the
body through the systemic
circulation
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imprint of Elsevier Inc.
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Functions of the Heart
•
•
•
Pump blood to the
lungs through the
pulmonary circulation
Pump blood to the rest
of the body through
the systemic circulation
Accomplished by
contraction and
relaxation of the
cardiac muscle in the
myocardium
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imprint of Elsevier Inc.
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19
http://www.biologycorner.com/anatom
y/circulatory/heart/heart_dissection.ht
ml
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Trace the blood through the heart
https://www.youtube.com/watch
?v=KSbbDnbSEyM
Heart dissection video:
https://www.youtube.co
m/watch?v=LWfA1lV92
E0
What makes the heart beat?
The heart has an electrical conduction system
Starts at the SA
(sinoatrial) Node
LOCATED: RIGHT ATRIUM
FREQUENTLY CALLED THE
“PACEMAKER”
Fires an electrical signal 60100 times per minute
This electrical signal causes
the atria to contract
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Conduction System of the Heart
“AV”/
ATRIOVENTRICULAR
NODE
BUNDLE OF
HIS/PURKINJE FIBERS
HOLDS” the electrical
signal FOR 1/10 of a
second
• The electrical signal
travels rapidly down
the BUNDLE OF HIS
and out to the
PURKINJE FIBERS.
The slower conduction
allows the ventricles time
to fill-up
• This electrical signal
causes the ventricles
to contract
Elsevier items and derived items © 2009 by Saunders, an
imprint of Elsevier Inc.
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https://www.youtube.com/watch
?v=fZT9vlbL2uA
http://www.nhlbi.nih.go
v/health/healthtopics/topics/hhw/elect
rical.html
http://highered.mheducatio
n.com/sites/0072495855/st
udent_view0/chapter22/ani
mation__the_cardiac_cycle
__quiz_2_.html
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Conduction System of the Heart
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imprint of Elsevier Inc.
25
The Cardiac Cycle
1. Consists of one complete heartbeat
a. Two atria contract at same time
b. Then relax while two ventricles contract
c. If the heart beats 75 times per minute it takes about 0.8
seconds to complete one cardiac cycle.
• Systole-the contraction phase of the chambers
• Diastole-the relaxation phase of the chambers
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imprint of Elsevier Inc.
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The Cardiac Cycle-Atrial Systole
–
Both atria contract at the
same time
– AV valves are open
– Ventricles are in diastole
(relaxed)
– Blood is forced into
ventricles
– Takes about 0.1 second
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The Cardiac Cycle-Ventricular Systole
•
•
•
•
Both ventricles are
contracting
Blood is forced from
ventricles into pulmonary &
aortic (SL) valves and then to
lungs/aorta
Atria are in diastole and are
filling with blood returned
through vena cava
Lasts 0.3 second
29
The Cardiac Cycle-Diastole
All chambers are in
simultaneous diastole
–
–
70% of ventricular
filling occurs during
this period
Lasts 0.4 second
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Heart Sounds
1. First heart sound: lubb
a. Caused by closure of AV valves
2. Second heart sound: dupp
a. Caused by closure of SL valves
3. Pause between dupp of the first beat
and lubb of second beat
a. Entire heart is resting
4. Abnormal heart sounds: murmurs
a. Caused by faulty valves
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imprint of Elsevier Inc.
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Arteries
1. Carry blood away from heart
2. Pulmonary arteries: transport
blood from right ventricle to lungs
3. Systemic arteries: transport
oxygenated blood from left
ventricle to body tissues
4. The aorta is the largest artery
5. All other arteries branch from the
aorta
6. It forms an arch as emerges from
upper part of heart
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imprint of Elsevier Inc.
32
Blood Supply to the Myocardium
• Myocardium: needs a
continuous supply of
oxygen and nutrients
• The first branch from
the aorta
a. Right coronary artery
b. Left coronary arteries
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Locate your carotid, radial, brachial, femoral,
posterior tibial and dorsalis pedis pulses.
Capillaries
•
•
•
•
Smallest and most
numerous of the
blood vessels
Connection
between artery and
vein
Thin wall where
exchange takes
place
So small
erythrocytes must
pass through in
single file
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imprint of Elsevier Inc.
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Veins
Carry deoxygenated blood
back to the heart
Carry blood high in CO2
Valves are needed to
help transport blood
back to the heart –
remember, blood is
going up – -- - valves
prevent back flow!
Smallest veins are called
venules
Walls are thinner than
arteries
Venous blood is a dark
burgundy color
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imprint of Elsevier Inc.
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All veins empty into the
Superior or Inferior Vena Cava
Superior Vena
Cava
Inferior Vena
Cava
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You will not feel a pulsation
when feeling veins.
Circulatory Pathways
• The blood vessels of
the body are
functionally divided
into two distinct
circuits:
– Pulmonary circuit
– Systemic circuit
Elsevier items and derived items © 2009 by Saunders, an
imprint of Elsevier Inc.
39
Circulatory Pathways, cont.
Pulmonary Circuit
• Transports blood from right side of the
heart to lungs
– Then returns it to left side of heart
• Contains oxygen-poor blood (increased
levels of carbon dioxide)
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imprint of Elsevier Inc.
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Circulatory Pathways, cont.
Systemic Circuit
•
•
•
•
•
Provides blood supply to all body tissues
Carries oxygen and nutrients to cells
Picks up carbon dioxide and waste products
Carries oxygenated blood from left ventricle
through the arteries to the capillaries in the
tissues
From tissue capillaries: deoxygenated blood
returns through a system of veins to right
atrium
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imprint of Elsevier Inc.
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Circulatory Pathways, cont.
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imprint of Elsevier Inc.
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CORONARY ARTERIES
NARROWING OF A
CORONARY ARTERY
Diseases of the Heart
 Coronary Heart Disease –
narrowing of the arteries
that supply blood to the
heart
 Caused by:
Atherosclerosis (buildup
of plaque)
 Or Arteriosclerosis
(loss of elasticity and
thickening of the wall)
Angina
• Nitroglycerin–
dilates the coronary
arteries
• May take up to 3 (5
minutes apart) then
call 911
• NTG may cause
severe headache
and hypotension
Myocardial Infarction
•
•
•
•
•
•
•
•
Heart attack or MI
Lack of blood supply to myocardium
Crushing chest pain
Pain in left arm, jaw, shoulder
Nausea
Perspiration
SOA
Pale or gray color
Heart Failure
 Ventricles fail to pump
adequately
 Right side Failure – edema or
ascites
 Left side Failure – SOA, cough,
congestion
 Congestive Heart failure –
edema in lower extremiteis,
SOA,
 Abnormal lung sounds
Rheumatic Heart Disease
Having frequent strep
infections as a child
Lead to Rheumatic fever
Antibodies that help
protect next time will
then also attack lining of
the heart
Important to take full
course of antibiotics
EKG
Holter Monitor
Stress Test
Echocardiogram
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Cardiac Catheterization
ANGIOPLASTY
• OFTEN
REFERRED TO
AS BALLOON
SURGERY.
Pacemaker
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Implanted Defibrillator
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Ventricular Assist Device
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Coronary Artery Bypass Graft-CABG
Heart Transplant
• Heart Transplant – last resort, high risk of
rejection.