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ANATOMY AND PHYSIOLOGY II
Lecture #2: Heart Anatomy
Name
I. Heart
A. Background
1. Location - in the mediastinum between the lungs, 2/3 to the left of the midline, 1/3 to the right, in the
region of the 2nd - 6th ribs.
Mediastinum - the area in the center of the thorax between the two pleural cavities.
2. Shape and position – the heart is roughly cone shaped
Apex – the pointed portion directed down, forward, and to left.
Base – the broad upper portion that points posteriorly and to the right.
Great vessels – (aorta, SVC, pulmonary trunk) enter and exit through the base of the heart.
B. Structure of the Heart
1. Coverings of the heart (pericardial sac) – membranes that surround and protect the heart.
a. Fibrous pericardium – the outer layer. Attached to the diaphragm, sternum, and the great vessels.
Composed of dense regular C.T.
b. Serous pericardium - one continuous membrane that folds to form two layers:
1. Parietal pericardium - attached to inside of fibrous layer.
Secretes serous fluid (pericardial fluid) into pericardial cavity.
2. Visceral pericardium (epicardium) – the serous membrane covering the surface of heart.
c. Pericardial cavity (space) – the potential space between the parietal pericardium and the visceral
pericardium (epicardium).
- Contains pericardial fluid which lubricates the surface of the heart.
- Significance: allows the heart to beat without friction.
Pericarditis - inflammation of the parietal pericardium.
In mild cases this can hinder production of serous fluid, causing friction and adhesions. In
severe cases inflammatory fluid may build up in this cavity. This fluid pushes against the
heart wall and interferes with its functioning. This produces a sound called “cardiac
tamponade”.
To Do: Answer the following questions.
The area between the two pleural cavities is the: a) pericardial cavity b) mediastinum
The broad upper part of the heart is the:
The fibrous pericardium is composed of:
a) apex
b) base
a) dense regular c.t.
c) cap
b) a serous
membrane
The layer of pericardium on the surface of the heart is the:
The pericardial cavity is between the
a) fibrous b) parietal
layers. a) fibrous and parietal
c) visceral
b) parietal and
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visceral
Pericarditis is inflammation of the
pericardium.
a) fibrous b) parietal
c) visceral
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2. Layers of the heart wall
a. Epicardium – the outermost layer of the heart wall. This is also called the visceral pericardium.
Composition – a thin layer of serous membrane that binds blood vessels, lymph capillaries, and
nerve fibers to the surface of the heart. This is often infiltrated with fat.
b. Myocardium – the middle layer of the heart wall.
Composed of cardiac muscle; this is the thickest layer and the one that does the actual work of
pumping blood.
Arrangement - cardiac muscle fibers are arranged in spiral and circular bundles that link all parts
of the heart together.
Fibrous skeleton of the heart – this is connective tissue within the myocardium that reinforces and
anchors the cardiac muscle. It is extra thick around valves and openings for the great vessels to
provide strength.
It is nonconductive, so it directs the path of the action potentials that cause the cardiac muscle to
contract.
c. Endocardium – the innermost layer of the heart wall.
Composed of simple squamous epithelium; this layer is continuous with the endothelium lining
blood vessels. It helps form the valve flaps of the heart and completely covers them.
Endocarditis - inflammation of the endocardium.
To Do: Complete the following:
Another name for the visceral layer is the:
a) epicardium
b) myocardium
c) endocardium
The fibrous skeleton is part of the
a) epicardium
b) myocardium
c) endocardium
layer.
Which layer is composed of simple squamous epi.? a) epicardium b) myocardium c) endocardium
On the diagram below, label the following:
A. fibrous pericardium
B. pericardial cavity
C. parietal layer of serous pericardium
D. visceral layer of serous pericardium
E. epicardium
F. myocardium
G. endocardium
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3. Heart chambers
The heart has four chambers:
Two atria – these are the upper chambers, which receive blood from veins.
They have only a thin myocardial layer.
Two ventricles - these are the lower chambers, which do the majority of the pumping.
They have a thick myocardial layer.
- The right chambers are involved in pulmonary circulation (to the lungs)
- The left chambers are involved in systemic circulation (to the rest of the body)
a. Atria
1) Right atrium
Location - this is the most right-sided chamber of heart and makes up all of right border.
Function - receives deoxygenated blood returning from body tissues and pumps this into the
right ventricle.
Vessels entering - SVC, IVC and coronary sinus
2) Left atrium
Location - the most posterior chamber of the heart.
Function - receives oxygenated blood from the four pulmonary veins and pumps this into the left
ventricle.
3) Other structures of the atria:
Auricle - (little ear) the portion of the atria visible on the anterior surface of the heart where the
atria fold over the top of the ventricles.
Pectinate muscles – ("comb-like") muscular ridges in the auricle.
Interatrial septum – the wall separating the right and left atria.
Foramen ovale – found in the fetal heart; this is an opening in the interatrial septum that lets
blood pass from the right atrium to the left atrium and by-pass the pulmonary circulation.
Fossa ovalis – found in the heart after birth, this is a thin region in the interatrial septum where
the foramen ovale has closed up.
To Do: Answer the following questions:
The receiving chambers of the heart are the:
a) atria
b) ventricles
The chambers with the thickest walls are the:
a) atria
b) ventricles
The chamber on the posterior side of the heart is the
a) right atrium
The chamber that receives deoxygenated blood is the: a) right atrium
b) left atrium
b) left atrium
c) both
atria
The right atrium and right ventricle are involved in
systemic
circulation.
a) pulmonary
b)
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Muscular ridges in the atria are called: a) auricles
The
b) septa
c) pectinate muscles
allows fetal blood to pass from the right to left sides. a) fossa ovalis
b) foramen
ovale
b. Ventricles
1) Right ventricle
Location – This is the most anterior chamber of the heart.
Receives blood from the right atrium (this is deoxygenated blood)
Function – contracts to force the blood into the pulmonary trunk and from there into the right
and left pulmonary arteries which carry it to the lungs.
2) Left ventricle
Location – forms the apex of the heart and most of the inferior, left margin.
Receives blood from the left atrium (this is oxygenated blood).
Function – pumps blood out through the aorta and into the systemic circulation.
Structure – The left ventricle has thicker walls than the other chambers since more force is
required to send blood throughout the entire body.
3) Features of both ventricles
Thick myocardium for strong pumping of blood.
Interventricular septum – the wall that separates the left and right ventricles.
Trabeculae carneae – muscular ridges in the walls of the ventricles.
Papillary muscles – enlarged projections of myocardium that extend into the inner cavity of the
chamber. These connect to:
Chordae tendineae – tendonous cords extending from the papillary muscles to the valves
between the atrial and ventricular chambers (AV valves).
To Do: Indicate whether each of the following refers to the atria (A) or ventricles (V):
Has pectinate muscles
Has thin walls
Has trabeculae carneae
Pumping chambers
Has thick walls
Receiving chambers
4. Great vessels
a. Superior vena cava – enters the right atrium from above. Carries deoxygenated blood from the head,
arms and upper trunk.
b. Inferior vena cava – enters the right atrium from below. Carries deoxygenated blood from the lower
trunk and legs.
c. Pulmonary trunk – exits from the right ventricle upwards. Carries deoxygenated blood to the
pulmonary circulation. Color: blue.
d. Pulmonary veins – enter the left atrium from either side. These are four vessels that carry oxygenated
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blood back from the lungs. Color: red.
e. Ascending aorta – exits from the left ventricle upwards. Carries oxygenated blood to the systemic
circulation.
5. Valves
Function - to keep blood flowing in only one direction.
a. Atrioventricular valves (AV valves)
Location – between the atrium and ventricle on the same side of the heart.
Composition - flaps or cusps of endocardium covering connective tissue and held in position by
the chordae tendineae, which prevent the flaps from
flopping backwards.
The AV valves open when atrial pressure is greater than ventricular pressure.
The AV valves close when atrial pressure is less than ventricular pressure.
1) Tricuspid valve
Location - On the right side of the heart between the right atrium and right ventricle.
(Think tRicuspid on the Right)
Structure - three cusps (hence the name).
2) Bicuspid valve (mitral valve)
Location – on the left side of the heart between the left atrium and left ventricle.
(Think mitraL on the Left)
Structure – two cusps. Said to look like a bishop's mitre (hence mitral).
b. Semilunar valves
Location - Located between the ventricles and the great vessels that flow out of them.
Composition - three half- moon -shaped pieces of endocardium. Each is shaped like a pouch.
The semilunar valves open when ventricular pressure is greater than exit vessel pressure.
The semilunar valves close when ventricular pressure is less than exit vessel pressure.
- Returning blood fills the half-moons which blocks the vessel.
1) Pulmonary semilunar valve - located between the right ventricle and the pulmonary trunk.
2) Aortic semilunar valve - located between the left ventricle and the ascending aorta.
To Do: Answer the following questions:
Which of these would be red on a model? a) SVC
b) pulmonary artery
c) pulmonary vein
Which vessel carries blood away from the right ventricle? a) pulmonary trunk b) aorta
Chordae tendineae attach to:
a) semilunar valves
b) atrioventricular valves
The valve between the left atrium and left ventricle is the:
Valves with three pouch-like cusps are:
c) SVC
a) tricuspid
a) semilunar valves
b) bicuspid
b) atrioventricular valves
Which valves close when atrial pressure is less than ventricular pressure? a) semilunar b) AV
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Semilunar valves are named for:
Valves function to:
a) the vessel they are in.
a) help pump blood
b) the number of cusps they have.
b) prevent backwards flow of blood
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6. Blood supply to the heart wall (coronary circulation)
a. Arteries - the myocardium of the heart is supplied with blood by the coronary arteries.
Source: Ascending aorta. The coronary arteries are the first vessels to branch off the aorta. They
exit just above the aortic semilunar valve.
1) Right coronary artery – a long vessel that travels along the right atrioventricular sulcus (the
depression on the surface of the heart between the right atrium and right ventricle) and curves
around to the back of the heart.
Supplies the right atrium and part of the right ventricle.
2) Left coronary artery - very short, only 1 to 2 cm. This travels behind the pulmonary trunk then
branches to form the:
a) Anterior interventricular artery - descends along the anterior interventricular sulcus (the
depression between the two ventricles in front).
Supplies the medial portion of the right and left ventricles.
b) Circumflex artery - travels along the left atrioventricular sulcus to the left posterior surface of
the heart. This anastomoses (connects) with branches of the right coronary artery.
b. Venous return - blood is returned through the cardiac veins.
1) Cardiac veins - drain deoxygenated blood from the myocardium and carries it to the:
2) Coronary sinus - located in the posterior atrioventricular sulcus. Receives deoxygenated blood
from the cardiac veins.
Returns blood to the right atrium. The coronary sinus enters the atrium through the medial wall
just in front of and a little below the fossa ovalis.
7. Blood flow through the heart
The SVC and IVC carry deoxygenated blood from the rest of the body to the right atrium. This
blood travels through the tricuspid valve into the right ventricle. As the right ventricle contracts it
pushes blood up through the pulmonary semilunar valve and into the pulmonary trunk. The blood
then passes through the right and left pulmonary arteries to the right and left lungs where it becomes
oxygenated. The blood returns to the heart through the right and left pulmonary veins to enter the
left atrium. Next it passes through the bicuspid valve into the left ventricle. This chamber pushes it
up through the aortic semilunar valve into the ascending aorta. Branches of the aorta carry it
throughout the systemic circulation.
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To Do: Answer the following questions:
The first vessels to branch off the aorta are the:
a) SVC & IVC
b) coronary arteries
What artery supplies the medial portion of the right and left ventricles?
a) right coronary b) circumflex c) anterior interventricular
What artery supplies the right atrium?
a) right coronary
b) circumflex c) anterior interventricular
The
returns deoxygenated blood to the right atrium.
a) right coronary artery
b) coronary sinus
c) circumflex artery
Which of these does blood pass through first after passing through the right atrium?
a) pulmonary arteries
b) pulmonary veins
c) pulmonary trunk
To Do: Use p. 744 in your book to help with the following:
1. On the diagram below label the following structures:
a.
b.
c.
d.
aorta (aortic arch)
left atrium
left pulmonary artery
left pulmonary veins
e.
f.
g.
h.
left ventricle
pulmonary capillary (#5)
pulmonary trunk
right atrium
i.
j.
k.
right pulmonary artery
right pulmonary veins
right ventricle
2. Number the labels on the diagram to show the order in which blood passes through each structure.
Begin with #1 for the right atrium and finish with #9 for the aortic arch. Give structures that are the
same on the right and left the same number. Specifically, the left and right pulmonary veins would
have the same number, as would the left and right pulmonary arteries.
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Learning Objectives for Lecture #2: Heart Anatomy
After studying this material you should be able to:
1.
Describe the location, shape and position of the heart.
2.
Describe the composition and location of the membranes and spaces surrounding the heart.
3.
Describe the three layers of the heart wall.
4.
Identify the four chambers of the heart and describe the function, location and structural features
of each.
5.
Explain the location and function of the interventricular septum, the interatrial septum, the
foramen ovale and the fossa ovalis.
6.
Identify the vessels that empty into or receive blood from each of the four heart chambers and
know if the blood carried is oxygenated or deoxygenated.
7.
Explain the location, function, and structure of each of the four heart valves.
8.
Explain how atrioventricular and semilunar valves differ.
9.
Describe the arterial supply to the heart and the pathway of venous return from the heart.
10.
List in order the vessels, chambers, and valves through which blood passes as it travels through
the heart, to the lungs and back to the heart, and out to the aorta.
11.
Identify on diagrams all structures labeled in this handout.
Lecture #2: Heart Anatomy - Answer Key
Page 1 - Answer the following questions.
B
The area between the two pleural cavities is the: a) pericardial cavity b) mediastinum
B
The broad upper part of the heart is the:
A
The fibrous pericardium is composed of:
a) apex
b) base
c) cap
a) dense regular c.t.
b) a serous
membrane
C
The layer of pericardium on the surface of the heart is the:
B
The pericardial cavity is between the
a) fibrous b) parietal
layers. a) fibrous and parietal
c) visceral
b) parietal and
visceral
B
Pericarditis is inflammation of the
pericardium.
a) fibrous b) parietal
c) visceral
Page 2 - Complete the following:
A
Another name for the visceral layer is the:
a) epicardium
b) myocardium
c) endocardium
B
The fibrous skeleton is part of the
a) epicardium
b) myocardium
c) endocardium
C
Which layer is composed of simple squamous epi.? a) epicardium b) myocardium c) endocardium
layer.
On the diagram below, label the following:
A. fibrous pericardium
B. pericardial cavity
C. parietal layer of serous pericardium
D. visceral layer of serous pericardium
E. epicardium
F. myocardium
G. endocardium
A
C
B
D and E
F
G
Page 3 - Answer the following questions:
A
The receiving chambers of the heart are the:
a) atria
b) ventricles
B
The chambers with the thickest walls are the:
a) atria
b) ventricles
B
The chamber on the posterior side of the heart is the
A
The chamber that receives deoxygenated blood is the: a) right atrium
a) right atrium
b) left atrium
b) left atrium
c) both
atria
A
systemic
The right atrium and right ventricle are involved in
circulation.
a) pulmonary
b)
2
C
Muscular ridges in the atria are called: a) auricles
B
The
b) septa
c) pectinate muscles
allows fetal blood to pass from the right to left sides. a) fossa ovalis
b) foramen
ovale
Page 4 - Indicate whether each of the following refers to the atria (A) or ventricles (V):
A
Has pectinate muscles
A
Has thin walls
V
Has trabeculae carneae
V
Pumping chambers
V
Has thick walls
A
Receiving chambers
Page 5 - Answer the following questions:
C
Which of these would be red on a model? a) SVC
b) pulmonary artery
A
Which vessel carries blood away from the right ventricle? a) pulmonary trunk b) aorta
B
Chordae tendineae attach to:
B
The valve between the left atrium and left ventricle is the:
A
Valves with three pouch-like cusps are:
B
Which valves close when atrial pressure is less than ventricular pressure? a) semilunar b) AV
A
Semilunar valves are named for:
B
Valves function to:
a) semilunar valves
c) SVC
b) atrioventricular valves
a) tricuspid
a) semilunar valves
a) the vessel they are in.
a) help pump blood
c) pulmonary vein
b) bicuspid
b) atrioventricular valves
b) the number of cusps they have.
b) prevent backwards flow of blood
Page 7 - Answer the following questions:
B
The first vessels to branch off the aorta are the:
a) SVC & IVC
C
What artery supplies the medial portion of the right and left ventricles?
a) right coronary b) circumflex c) anterior interventricular
A
What artery supplies the right atrium?
B
The
returns deoxygenated blood to the right atrium.
a) right coronary artery
b) coronary sinus
c) circumflex artery
C
Which of these does blood pass through first after passing through the right atrium?
a) pulmonary arteries
b) pulmonary veins
c) pulmonary trunk
a) right coronary
b) coronary arteries
b) circumflex c) anterior interventricular
Page 7 - Use p. 744 in your book to help with the following:
4.C.
9. A.
3. G.
4. I.
F. 5.
3
6. J.
1. H.
D. 6.
2. K.
B. 7.
8. E.