Lecture Medical assisting: Administrative and clinical procedures with anatomy and physiology (4/e) – Chapter 23

CHAPTER

23
The Cardiovascular
System

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23­2

Learning Outcomes
23.1 Describe the structure of the heart and the
function of each part.
23.2 Trace the flow of blood through the heart.
23.3 List the most common heart sounds and
what events produce them.
23.4 Explain how heart rate is controlled by the
electrical conduction system of the heart.

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23­3

Learning Outcomes (cont.)
23.5 List the different types of blood vessels and
describe the functions of each.
23.6 Define blood pressure and tell how it is
controlled.
23.7 Trace the flow of blood through the

pulmonary and systemic circulation.
23.8 List the major arteries and veins of the body
and describe their locations.

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23­4

Learning Outcomes (cont.)
23.9 List and describe the components of blood.
23.10 Give the functions of red blood cells, the
different types of white blood cells, and
platelets.
23.11 List the substances normally found in
plasma.
23.12 Explain how bleeding is controlled.
23.13 Explain the differences among blood types
A, B, AB, and O.
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23­5

Learning Outcomes (cont.)
23.14 Explain the difference between Rh-positive
blood and Rh-negative blood.
23.15 Explain the importance of blood typing and
tell which blood types are compatible.
23.16 Describe the causes, signs and symptoms,

and treatments of various diseases and
disorders of the cardiovascular system.

© 2011 The McGraw-Hill Companies, Inc. All rights reserved.


23­6

Introduction
•

The cardiovascular system consists of heart
and blood vessels

•

Sends blood to
– Lungs for oxygen
– Digestive system for nutrients

•

Also circulates waste products to certain
organ systems for removal from the blood

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23­7

Structures of the Heart
•

•
•

•

Cone-shaped organ
about the size of a
loose fist
In the mediastinum
Extends from the
level of the second rib
to about the level of
the sixth rib
Slightly left of the
midline

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23­8

Structures of the Heart (cont.)


 Heart is bordered:







Laterally by the lungs
Posteriorly by the vertebral 
column
Anteriorly by the sternum

Rests on the diaphragm 
inferiorly

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23­9

Structures of the Heart (cont.)
•

Heart coverings
– Pericardium
•

•

Covers the heart and
large blood vessels
attached to the heart

Visceral pericardium
– Innermost layer
– Directly on the heart

•

Parietal pericardium
– Layer on top of the
visceral pericardium

Click for Larger View

• Heart walls:
– Epicardium
• Outermost layer
• Fat to cushion heart

– Myocardium
• Middle layer
• Primarily cardiac muscle

– Endocardium
• Innermost layer
• Thin and smooth
• Stretches as the heart
pumps
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23­10

Back

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23­11

Structures of the Heart (cont.)
•

Four chambers
– Two atria
•
•
•

Upper chambers
Left and right
Separated by
interatrial septum

– Two ventricles
•
•
•

Lower chambers
Left and right
Separated by

interventricular
septum

   Atrioventricular septum separates the atria 

     from the ventricles

Click for 
View of 
Heart

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23­12

Structures of the Heart (cont.)
•

•

•
•

Tricuspid valve – prevents blood from flowing
back into the right atrium when the right ventricle
contracts
Bicuspid (mitral) valve – prevents blood from
flowing back into the left atrium when the left
ventricle contracts

Pulmonary semilunar valve – prevents blood
from flowing back into the right ventricle
Aortic semilunar valve – prevents blood from
flowing back into the left ventricle
Click for 
View of 
Heart

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23­13

The Heart Labeled

Back

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23­14

Blood Flow Through the Heart
Deoxygenated
blood in from
body

Oxygenated
blood out to
body

Oxygenated blood
in lungs

Deoxygenated
blood out
to lungs
Atria Contract

Ventricles Contract

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23­15

Blood Flow Through the Heart (cont.)

Right
Atrium

Tricuspid
Valve

Right
Ventricle

Pulmonary
Valve

Body

Lungs

Aortic
Semilunar
Valve

Left
Ventricle

Bicuspid
Valve

Left
Atrium

Pulmonary
Semilunar
Valve

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23­16

Cardiac Cycle


One heartbeat = one cardiac cycle




Atria contract and relax
Ventricles contract and relax

• Right atrium contracts
– Tricuspid valve opens
– Blood fills right ventricle

• Right ventricle contracts
– Tricuspid valve closes
– Pulmonary semilunar valve
opens
– Blood flows into pulmonary
artery

• Left atrium contracts
– Bicuspid valve opens
– Blood fills left ventricle

• Left ventricle contracts
– Bicuspid valve closes
– Aortic semilunar valve
opens
– Blood pushed into aorta

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23­17

Cardiac Cycle (cont.)
• Influenced by
– Exercise
– Parasympathetic nerves
– Sympathetic nerves
– Cardiac control center
– Body temperature
– Potassium ions
– Calcium ions

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23­18

Heart Sounds
•

One cardiac cycle – two heart sounds
(lubb and dubb) when valves in the heart
snap shut
– Lubb – first sound
•

When the ventricles contract, the tricuspid and
bicuspid valves snap shut

– Dubb – second sound

•

When the atria contract and the pulmonary and
aortic valves snap shut

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23­19

Cardiac Conduction System
• Group of structures that send electrical impulses through
the heart
• Sinoatrial node (SA node)
–
–
–
–

Wall of right atrium
Generates impulse
Natural pacemaker
Sends impulse to AV node

• Atrioventricular node (AV
node)

•

Bundle of His

– Between ventricles
– Two branches
– Sends impulse to Purkinje
fibers

•

– Between atria just above ventricles
– Atria contract
– Sends impulse to the bundle of His

Purkinje fibers
– Lateral walls of ventricles
– Ventricles contract
Click the i below for a 
Diagram

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23­20

Cardiac 
Conduction 
System

Back

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23­21

Apply Your Knowledge
Match the following:

ANSWER:

C Tricuspid valve
__

A. Two branches; sends impulse to Purkinje
fibers

F Bicuspid valve
__

B. Covering of the heart and aorta

B Pericardium
__

C. Between the right atrium and the right
ventricle

E SA node
__

D. In the lateral walls of ventricles

A Bundle of His
__

E. Natural pacemaker

D Purkinje fibers
__

F. Between the left atrium and the left ventricle

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23­22

Blood Vessels
• Closed pathway that
carries blood from the
heart to cells and
back to the heart
• Types
– Arteries
– Arterioles
– Veins

– Venules
– Capillaries

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23­23

Arteries and Arterioles
•
•
•

Strongest of the
blood vessels
Carry blood away
from the heart
Under high pressure
– Vasoconstriction
– Vasodilation

•

Arterioles
– Small branches of
arteries

• Aorta
– Takes blood from the
heart to the body

• Coronary arteries
– Supply blood to heart
muscle
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23­24

Veins and Venules
•

Blood under no pressure
in veins
– Does not move very easily
– Skeletal muscle
contractions help move
blood
– Sympathetic nervous
system also influences
pressure

•

Valves prevent backflow

• Venules
– Small vessels formed when
capillaries merge

• Superior and inferior vena
cava
– Largest veins
– Carry blood into right
atrium

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23­25

Capillaries
•

Branches of arterioles

•

Smallest type of blood vessel

•

Connect arterioles to venules

•

Only about one cell layer thick

•

Oxygen and nutrients can pass out of a capillary into
a body cell

•

Carbon dioxide and other waste products pass out of

a body cell into a capillary

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