This is a comprehensive and detailed note on Unit 3 objectives - cardiovascular system- heart, vessels, and circulation for Bio 173.
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UNIT 3 OBJECTIVES
Chapter 19 Cardiovascular System: Heart
Introduction to the Cardiovascular System
1. General function of the cardiovascular system
a. Transport blood throughout the body to allow the exchange of substances, like
respiratory gases, nutrients, and waste products, between the blood of capillaries and
the body’s cells
b. Perfusion- blood flow through a tissue, measured in mL per minute per gram (mL/min/g)
2. Three primary types of blood vessels
a. Arteries- carry blood away from the heart
b. Veins- carry blood back to the heart
c. Capillaries- serve as sites of exchange, either between the blood and the air sacs of lungs
or the blood and systemic cells
3. General structure and function of the heart
a. Three anatomic structures that are significant in the normal function of the heart- the 2
sides of the heart, great vessels attached to the heart, and the 2 sets of valves that are
located within the heart
b. Atrium- superior chamber for receiving blood
c. Ventricles-inferior chamber for pumping blood away from the heart
d. Great vessels- transport blood directly to and from the chambers of the heart,
continuous with hearts chambers
e. Arteries
i. Pulmonary trunk (splits into pulmonary arteries)- transports blood from the
right ventricle
ii. Aorta- transports blood from the left ventricle
f. Veins
i. Superior/inferior vena cava- drain blood into the right atrium
ii. Pulmonary veins- drain blood into the left atrium
g. Atrioventricular (AV) valves
i. Right AV valve (tricuspid)- between right atrium and ventricle
ii. Left AV valve (bicuspid or mitral)- between left atrium and ventricle
h. Semilunar valves- mark the boundary between a ventricle and its associated arterial
trunk
i. Pulmonary semilunar valve- between right ventricle and pulmonary trunk
ii. Aortic semilunar valve- between left ventricle and aorta
i. Function of all valves- open to allow blood flow through the heart and then close to
prevent backflow; ensures one way flor of blood through heart
, 4. Circulation routes
a. Pulmonary circulation
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 circulation
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
The Heart within the Thoracic Cavity
1. Location/position of heart in thoracic cavity
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. Structural components of the 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. Function of pericardium
a. Anchors the heart within the thoracic cavity and prevents the heart chambers from
overfilling with blood
4. Purpose of serous fluid within pericardial cavity
a. Two layers of serous pericardium produce/release serous fluid into pericardial cavity,
which lubricates the serous membranes to decrease friction with heart beats.
Heart Anatomy
1. Three layers of 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
2. Four chambers 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
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