THE CARDIOVASCULAR
SYSTEM
Honors Anatomy Chapter 18
Heart a Pump
Left Side


receives O2-rich
blood from lungs
-- > pumps it to
tissues
Right Side

receives O2-poor
blood from tissues
 pumps it to lungs
Heart Anatomy



~ fist size
250 – 350 g mass (<1 lb)
in mediastinum:
Heart Anatomy - 2

Heart
 rests
on superior surface of diaphragm
 anterior to vertebral column
 posterior to sternum
 just left of midsternal line
Base & Apex of Heart
Coverings of the Heart


1.
Pericardium: dbl-walled sac that heart is in
2 layers:
Fibrous Pericaridum: dense CT



2.
protection
anchors heart to surrounding structures
prevents overfilling of heart with blood
Serous Pericardium:2 layers


Parietal layer: lines internal surface of fibrous
pericardium
Visceral layer = epicardium
Coverings of the Heart - 2
2.

Serous Pericardium:
2 layers
forms closed sac around heart =
pericardial cavity



contains serous fluid: lubricates, decreasing
friction of moving pumping heart
Parietal layer: lines internal surface of
fibrous pericardium
Visceral layer = epicardium covers heart
Layers of Heart Wall

1.
2.
3.
3 layers:
Epicardium = visceral layer of serous
pericardium
Myocardium: cardiac muscle
Endocardium : squamous epithelium lining
chambers of the heart
Chambers of the Heart

2 superior atria
 separated

by interatrial septum
2 larger ventricles
 separated
by interventricular septum
2 grooves seen on exterior view of heart:
1.
Coronary sulcus between upper & lower
chambers
2. Anterior/Posterior Interventricular Sulcus
between ventricles
Atria
right & left both have wrinkled, protruding
appendages = auricles “little ear”
Right Atrium: 2 internal features:
1.
posterior wall is smooth
2. anterior wall has ridges of muscle =
pectinate muscles
Left Atrium: pectinate muscles only in its
auricle
Fossa Ovalis


depression in interatrial septum
marks opening of foramen ovale =“oval
window” an opening in fetal heart that
shunted blood from right  left atrium
(blood does not go to lung for oxygenation
until birth)
Functions of Atria


receiving chambers of the heart
Right:
 forms
anterior surface of heart
 deoxygenated blood from all parts of body
through inferior & superior vena cavas and
from the coronary sinus = venous blood from
myocardium

Left:
 oxygenated
blood from lungs through
pulmonary veins
Ventricle Features

Trabeculae Carnae:
 irregular

ridges of muscle on internal walls
Papillary Muscles:
 conelike
muscle bundles attached to heart
valves via cordae tendinae
Functions of the Ventricles



receive blood from atria
Right Ventricle: pumps deoxygenated blood
to lungs through pulmonary trunk 
pulmonary arteries
Left Ventricle: pumps oxygenated blood to
entire body through aorta
Heart Valves



blood flows through the heart in one
direction: atria  ventricle
valves connected to papillary muscles by
chordae tendinae
1 way direction due to 4 heart valves
 open/close
in response to differences in BP on
their 2 sides
 https://www.youtube.com/watch?v=y5maHDAk
zUs
Atrioventricular Valves
Tricuspid Valve



right AV valve
3 flexible cusps
both AV valves close
when ventricles
contract/open when
ventricles relax
Mitral Valve


left AV valve
Bicuspid valve: 2
cusps
Semilunar (SL) Valves
Pulmonary Valve



right side SL valve
between right
ventricle &
pulmonary trunk
SL valves open
when ventricles
contract
Aortic Valve



left side valve
between left
ventricle & aorta
SL valves close
when ventricles
relaxed
Valves




https://www.youtube.com/watch?v=2jPTt23
lRB8
https://www.youtube.com/watch?v=AO_aIs
WpSkI
https://www.youtube.com/watch?v=1hrhPww
5jKY
https://www.youtube.com/watch?v=AHBzu5
zhFuA
Coronary Circulation

Base of
Aorta
Left
Right
Coronary
A
Coronary
A
Anterior
InterventricularA
Circumflex
Artery
Rt
Marginal
Posterior
Interventricular
A
Coronary Circulation
Angina Pectoris


chest pain caused by fleeting deficiency in
blood delivery to myocardium
cardiac muscle fibers weakened by
temporary lack of O2 but do not die
Myocardial Infarction MI



prolonged coronary blockage  cardiac fibers
do die
dead tissue  scar tissue
http://www.dnatube.com/video/1708/Myocardi
al-infarction-pathology
Energy Requirements of Cardiac
Muscle



cardiac muscle fibers have more
mitochondria than other muscle fibers
depend almost exclusively on aerobic
respiration so cannot tolerate hypoxia for
long
cardiac fibers can use glucose or fatty acids
as a fuel source
Heart Physiology

cardiac muscle has intrinsic ability to
depolarize & contract (does not require
nervous system)
 Autonomic
fibers do alter basic rhythm
Coronary Conduction System

1.
2.
independent, coordinated activity of the
heart is function of:
gap junctions
intrinsic conduction system

noncontractile cardiac cells specialized to
initiate & distribute impulses throughout the
heart
Arrhythmias



irregular heart rhythms due to abnormal
electrical activity
https://health.sjm.com/arrhythmiaanswers/videos-and-animations.aspx
http://www.nhlbi.nih.gov/health/healthtopics/topics/arr/types
Extrinsic Innervation
of the Heart

1.

1.

Medulla Oblongata:
cardioacceleratory center
sympathetic fibers  SA & AV nodes
Cardioinhibitory center
parasympathetic fibers  SA & AV nodes
ECG


Electrocardiography: a graphic record of
heart activity tracing the composite of all
action potentials generated in nodal &
contractile cells at a given time
http://www.getbodysmart.com/ap/circulato
rysystem/heart/electricalevents/ecg/tutori
al.html
Heart Sounds




Auscultating thorax with stethoscope
reveals 2 sounds during each heartbeat
lub-dub, pause, lub-dub
pause = heart is relaxed
“lub” = AV valves closing
 louder

& longer than the dub
“dub” = SL valves snap shut @ beginning of
ventricular relaxation
Heart Sounds -2



left side valves (mitral & aortic) close
slightly quicker =S1
right side valves (tricuspid & pulmonary)
close ~1/4 s slower = S2
so can listen to individual valve sounds by
auscultating 4 specific regions of thorax
Heart Sounds




affected by valves closing + flow of blood
http://www.dnatube.com/video/9217/Reviewof-heart-sounds
http://familymedicine.osu.edu/products/physi
calexam/exam/flash/heart/heart2.cfm
http://www.blaufuss.org/tutorial/index1.html
Heart Murmurs



abnormal heart sounds
occur when blood flow strikes obstructions 
flow becomes turbulent
can be normal in young children & elderly
 heart
flow

wall thinner & vibrate with rushing blood
often indicate valve problems
 insufficiency
or incompetence: valves not closing
all the way blood regurgitates
 stenotic: valve not opening all the way restricts
blood flow
Heart Murmurs

https://www.youtube.com/watch?v=6YY3O
OPmUDA
Valve Problems
Insufficieny
Stenosis
Cardiac Output (CO)


amount of blood pumped out by each
ventricle in 1 min.
Stroke Volume (SV) = vol of blood pumped
out by 1 ventricle with each beat
 correleates
contraction

with force of ventricular
CO = HR x SV
 HR
= Heart Rate (pulse)
 average adult: SV = 70 mL, HR = 75
 * CO = ~ 5.25 L/min
Cardiac Reserve



difference between resting & maximal CO
nonathletic adult = 4-5x resting CO
athletic adult = 7x resting CO
Tachycardia

>100 beats/min
 may

1.
2.
3.
4.
promote fibrillation
Causes:
Fever
Stress
Drugs
Heart disease
Bradycardia


1.
2.
3.
4.
<60 beats/min
Causes:
Hypothermia
Drugs
Parasympathetic activation
well-trained athlete:

endurance training  hypertrophy of cardiac
muscle  increases SV  allows lower resting
HR w/out changing CO
CHF



1.
2.
3.
4.
Congestive Heart Failure
Heart inefficient pump so circulation
inadequate
Causes:
Coronary Atherosclerosis
high BP over long period of time
MIs
DCM: dilated cardiomyopathy
Heart Failure

1 or both sides of heart may fail
 left
side failure  pulmonary congestion
 right side failure  peripheral congestion


1.
2.
3.
4.
if 1 side fails  greater strain on other side
 whole heart fails
Treatment:
removing excess fluid: diuretics
reducing BP
increasing contractility with digitalis
Heart transplant
Cardiac Tamponade

fluid build-up in pericardial cavity  can
lead to inability of ventricles to fill fully
heart cannot pump normally  death if not
tx’d
 Causes:
1.
2.
3.
4.
infection (bacterial or viral) causing
pericarditis
MI
dissecting aortic aneurysm
heart surgery/ trauma
Development of the Heart

https://www.youtube.com/watch?v=5DIUk9
IXUaI