This is a comprehensive and detailed summary on; Lab exam 2 objectives - heart, veins, arteries, capillaries, route of blood flow, lymphatic system for Biol 173.
*Essential Study Material!!
OBJECTIVES FOR LAB EXAM 2
UNIT 3
1. Location of the heart
a. Posterior to the sternum, left of the body midline between the lungs within the
mediastinum
b. Slightly rotated, right side is located more anteriorly
c. Base- postero-superior surface
d. Apex- inferior, conical end of heart (think of heart like upside down pyramid with apex
below the base)
2. Pericardium
a. Heart is enclosed in three layers, collectively called the pericardium
b. Fibrous pericardium
i. Outermost, composed of tough, dense irregular CT
ii. Encloses heart but doesn’t attach to it. Attached inferiorly to the diaphragm and
superiorly to the base of the pulmonary trunk and aorta
c. Parietal layer of the serous pericardium
i. Composed of simple squamous epithelium and an underlying delicate layer of
areolar CT
ii. Adheres to the inner surface of the fibrous pericardium
d. Visceral layer of the pericardium (aka epicardium)
i. Composed of simple squamous epithelium and an underlying delicate layer of
areolar CT
ii. Adheres directly to heart
e. The two serosal layers are continuous with one another and separated by space called
pericardial cavity
3. Layers of the heart wall
a. Epicardium (outermost)- aka visceral layer of the pericardium, composed of simple
squamous epithelium and an underlying layer of areolar CT
b. Myocardium- composed of cardiac muscle tissue, thickest
i. Contraction of cardiac muscle composing the myocardium generates the force
necessary to pump blood
c. Endocardium- covers internal surface of heart and external surfaces of heart valves,
composed of simple squamous epithelium and an underlying layer of areolar CT
i. Continuous with endothelium, which lines blood vessels
4. Anatomic structures of the heart
a. Right atrium
i. Internal wall is smooth but exhibits muscular ridges call pectinate muscles on
anterior wall and within auricle
ii. Fossa ovalis- oval depression that occupies the former location of the foramen
ovale, which shunted blood from the right atrium to left atrium
iii. Coronary sinus- opening, drains deoxygenated blood from the heart wall
iv. Openings for the superior/inferior vena cavae
, b. Right ventricle
i. Trabeculae carneae- large, smooth, irregular muscular ridges on internal wall of
right ventricle
ii. Papillary muscles- three cone shaped projections, anchor chordae tendineae
iii. Chordae tendineae- attached to right AV valve
iv. Pulmonary trunk and pulmonary semilunar valve
c. Left atrium
i. Pectinate muscles, openings of pulmonary veins, left AV valve
d. Left ventricle
i. Trabeculae carneae, 2 papillary muscles, entrance to aorta, aortic semilunar
valve
e. Interatrial septum- thin wall that separates right and left atria
f. Interventricular septum- thick wall that separates right and left ventricles
5. AV and semilunar valves
a. Atrioventricular valves- right has 3 cusps (tricuspid) and left has 2 (bicuspid or mitral),
prevent blood flow back into atrium
i. When open, cusps extend into ventricles
ii. When the ventricles contract, blood is forced superiorly as ventricular pressures
rises. This causes valves to close
b. Semilunar valves
i. Pulmonary semilunar valve- located between right ventricle and pulmonary
trunk
ii. Aortic semilunar valve- located between left ventricle and ascending aorta
iii. They open when the ventricles contact and the force of the blood pushes the
semilunar valves open and blood enters atrial trunks
iv. Valves closer when the ventricles relax and pressure of ventricle becomes less
than pressure in an arterial trunk
v. Prevent blood flow back into ventricles
6. Coronary arteries (red)
a. Transport oxygenated blood to the wall of the heart
b. Right and left coronary arteries are positioned within the coronary sulcus of heart to
supply the heart wall, only branches of ascending aorta
i. Right- branches into right marginal artery to supply the lateral wall of right
ventricle and the posterior interventricular artery to supply the posterior wall of
both ventricles
ii. Left- branches into the circumflex artery to supply the lateral wall of left
ventricle and anterior interventricular artery to supply both anterior wall of left
ventricle and most of interventricular septum
c. Blood flow through coronary arteries
i. Intermittent (not a steady stream) because coronary vessels are patent when
heart is relaxed and blood flow is possible. Coronary vessels are compressed
when heart contracts, temporarily stopping blood flow. Blood flow is impeded
and then flows, as the heart rhythmically contracts and relaxes
, 7. Coronary veins (blue)
a. Transport deoxygenated blood away from the heart wall
b. Great cardiac veins- in anterior interventricular sulcus, alongside anterior
interventricular artery
c. Middle cardiac vein- within posterior interventricular sulcus, alongside posterior
interventricular artery
d. Small cardiac vein- positioned alongside right marginal artery
e. Coronary sinus- where these cardiac veins drain, large vein that lies within the posterior
aspect of the coronary sulcus, returns deoxygenated blood directly into right atrium
8. Pathway of blood through the heart- pulmonary and systemic circuits
a. Pulmonary
i. Deoxygenated blood enters right atrium from venae cavae and coronary sinus
ii. Passes through right AV valve (tricuspid)
iii. Right ventricle
iv. Passes through pulmonary semilunar valve
v. Pulmonary trunk
vi. Continues through right and left pulmonary arteries to both lungs
vii. Pulmonary capillaries of both lungs for gas exchange (now oxygenated)
viii. Right and left pulmonary veins
ix. Returned to left atrium of heart
b. Systemic
i. Oxygenated blood enters left atrium
ii. Passes through left AV valve (bicuspid or mitral)
iii. Left ventricle
iv. Passes through aortic semilunar valve
v. Aorta
vi. Distributed by systemic arteries
vii. Systemic capillaries for nutrient and gas exchange (now deoxygenated)
viii. Drains into venae cavae and coronary sinus
ix. Enters right atrium of heart
9. Heart’s conduction system
a. Specialized cardiac cells found within the heart inside internally to the endocardium,
don’t contract but initiate and conduct electrical signals
b. Sinoatrial (SA) node- located in posterior wall of right atrium, next to opening of SVC
i. Cells initiate the heartbeat, pacemaker of the heart
c. Atrioventricular (AV) node- located on floor of right atrium between right AV valve and
opening for coronary sinus
d. Atrioventricular (AV) bundle- extends from AV node into and through the
interventricular septum, divides into left and right bundles
e. Purkinje fibers- extend from left and right bundles beginning at the apex of heart and
then continue through walls of ventricles
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