The Heart
Cardiovascular System - 3
for student copy
Position of the Heart
• human heart is about the size of a fist
• lies in the thoracic cavity w/in the
mediastinum (area from sternum to
vertebrae, between the lungs)
• tilted @ angle so its inferior surface
lies against the diaphragm
Parts of the Heart
• Base of the heart is
its superior border
• Apex of the heart is
lowest point
Major Heart Structures:
the Pericardium
• Outer Layer: Fibrous Pericardium
– tough, attaches to diaphragm
• Inner Layer: Serous Pericardium
– dbl membrane:
• outer parietal: attaches to fibrous pericardium
• inner visceral layer: covers cardiac muscle
– between the 2: pericardial cavity filled
with serous fluid
Wall of the Heart
• 3 layers
1. outer epicardium
– same as visceral pericardium
2. middle myocardium
– cardiac muscle
3. inner endocardium
– thin layer of endothelium that lines
inside chambers of the heart & valves
Surface Features of the Heart
• 4 chambers of heart:
– 2 atria form the base
• Auricles (ear-like) pouch-like extensions
– tip of left ventricle forms the apex
– Sulci: grooves where coronary blood
vessels & adipose tissue that externally
mark the boundaries between the 4 heart
chambers
• coronary sulcus: separates atria from
ventricles
• anterior & posterior interventricular sulcus:
separate 2 ventricles
Right Atrium
• Receives
deoxygenated blood
from SVC & IVC
Right Atrium
• inside surface has honeycombed
appearance & ridges called pectinate
muscles
• wall separating rt & lt atrium=
interatrial septum: in fetus hole called
foramen ovale (blood shunts from rt
atrium  lt atrium avoiding
pulmonary circulation); when scarred
over called fossa ovalis
Right Ventricle
• receives blood from
right atrium
• sends blood to
pulmonary trunk 
lungs to be
oxygenated
Right Ventricle
• inside has ridges of
muscles called
trabeculae carnae:
largest ones called
papillary muscles:
have string-like
cords called cordae
tendinae
Right Ventricle
• separated from left ventricle by:
interventricular septum
Left Atrium
• receives oxygenated
blood thru 4
pulmonary veins
• delivers blood to left
ventricle
• seen on posterior
surface of heart
Left Atrium
• thin-walled
• identifiable characteristic: 4
pulmonary veins entering it
Left Ventricle
• receives oxygenated blood from left
atrium
• sends blood to systemic circulation
thru Aorta
• has thickest muscle (pumps blood the
farthest)
4 Heart Valves
• control 1-way flow of blood
• 2 AV valves
– between atria & ventricles
– Tricuspid : rt AV valve
– Mitral : lt AV valve, aka bicuspid
• 2 semilunar valves
– blood exits rt ventricle thru
Pulmonary (semilunar) valve
– blood exits lt ventricle thru Aortic
(semilunar) valve
AV Valves
• Tricuspid valve
• Mitral Valve
Semilunar Valves
• Pulmonary Valve
• Aortic Valve
Blood Flow thru the Heart
• thinner walled atria receive blood
returning to heart from veins
• pressure of blood in filled atria opens
the AV valves & most of the blood
flows into ventricles
• both atria contract simultaneously to
pump remaining blood into ventricles
Blood Flow thru the Heart
• when atria have stopped contracting
AV valves close
• Ventricles contract together forcing
semilunar valves open
• walls of left ventricle thicker providing
more force to pump blood thru
systemic circulation
Blood Flow thru the Heart
• Ventricular Systole:
– when both ventricles are contracting
– AV valves close
– Semilunar valves open
• Ventricular Diastole:
– when both ventricles relaxed
– Semilunar valves close
– AV valves open
Cardiac Cycle
Systemic & Pulmonary
Circulation
Heart Sounds
• Auscultation: listening to body sounds
• 1 heartbeat produces 2 heart sounds:
lub-dub
• heart murmurs: abnl heart sounds
usually due to valve abnl
• http://www.blaufuss.org/tutorial/ind
ex1.html
Pulse
• when ventricles contract a blood
pressure wave is produced that travels
in the arteries and can be felt as your
pulse
• radial pulse: check over radial artery
• carotid artery pulse: check over
carotid artery
Calculate Pulse
• Count the # of beats in 15 s and
multiply x 4
• If the math is too difficult count for 30
s and multiple x 2
Blood Pressure
• pressure exerted by blood against
blood vessel walls
• highest in the aorta & large elastic
arteries & decreases as arteries get
smaller & further from heart
Systolic Blood Pressure
• top # on a BP
• pressure generated by ventricular
systole
• normal adult: ~120
Diastolic BP
• bottom # on BP
• pressure exerted during ventricular
diastole
• normal adult: 60- 80
Arterial Blood Pressure
• normal adult ~ 120/80
• normal venous BP: ~16 mm Hg
BP
• pump used to inflate cuff to a
pressure > the systolic pressure:
– puts pressure on the artery, flattens it, &
stops blood flow in the artery
– pressure slowly released from cuff as
stethoscope used to auscultate over
brachial artery
BP
• reported in mm Hg
• as pressure in cuff becomes <
pressure in artery…examiner will
hear a sound can be heard, caused
by the turbulent flow of blood as
artery goes from flattened  normal