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

CHAPTER

23
The Cardiovascular
System

© 2011 T he McGraw -Hill Com panie s, Inc. A ll rights reserv ed.


23-2

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.

© 2011 T he McGraw -Hill Com panie s, Inc. A ll rights reserv ed.


23-3

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.

© 2011 T he McGraw -Hill Com panie s, Inc. A ll rights reserv ed.


23-4

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.
© 2011 T he McGraw -Hill Com panie s, Inc. A ll rights reserv ed.


23-5

Learning Outcomes (cont.)
23.14 Explain the difference between Rhpositive 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 T he McGraw -Hill Com panie s, Inc. A ll rights reserv ed.


23-6

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

© 2011 T he McGraw -Hill Com panie s, Inc. A ll rights reserv ed.

23-7

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

© 2011 T he McGraw -Hill Com panie s, Inc. A ll rights reserv ed.


23-8

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

© 2011 T he McGraw -Hill Com panie s, Inc. A ll rights reserv ed.


23-9

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
© 2011 T he McGraw -Hill Com panie s, Inc. A ll rights reserv ed.

23-11

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

© 2011 T he McGraw -Hill Com panie s, Inc. A ll rights reserv ed.


23-12

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

© 2011 T he McGraw -Hill Com panie s, Inc. A ll rights reserv ed.


23-14

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

© 2011 T he McGraw -Hill Com panie s, Inc. A ll rights reserv ed.

23-15

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

© 2011 T he McGraw -Hill Com panie s, Inc. A ll rights reserv ed.


23-16

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

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

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

– Bicuspid valve closes
– Aortic semilunar valve
opens
– Blood pushed into aorta

© 2011 T he McGraw -Hill Com panie s, Inc. A ll rights reserv ed.


23-17

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

© 2011 T he McGraw -Hill Com panie s, Inc. A ll rights reserv ed.

23-18

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

© 2011 T he McGraw -Hill Com panie s, Inc. A ll rights reserv ed.


23-19

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

© 2011 T he McGraw -Hill Com panie s, Inc. A ll rights reserv ed.


23-20

Cardiac
Conduction
System

Back

© 2011 T he McGraw -Hill Com panie s, Inc. A ll rights reserv ed.


23-21

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

© 2011 T he McGraw -Hill Com panie s, Inc. A ll rights reserv ed.


23-22

Blood Vessels
• Closed pathway that
carries blood from
the heart to cells
and back to the
heart

• Types
– Arteries
– Arterioles
– Veins

– Venules
– Capillaries

© 2011 T he McGraw -Hill Com panie s, Inc. A ll rights reserv ed.


23-23

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
© 2011 T he McGraw -Hill Com panie s, Inc. A ll rights reserv ed.


23-24

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
© 2011 T he McGraw -Hill Com panie s, Inc. A ll rights reserv ed.


23-25

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
© 2011 T he McGraw -Hill Com panie s, Inc. A ll rights reserv ed.


23-26

Apply Your Knowledge
How do arteries control blood pressure?
ANSWER: The muscular walls of arteries can
constrict to increase blood pressure or dilate to
decrease blood pressure.

© 2011 T he McGraw -Hill Com panie s, Inc. A ll rights reserv ed.


23-27

Blood Pressure
•

Force blood exerts on the inner walls of blood vessels
– Highest in arteries
– Lowest in veins

•

Systolic pressure
– Ventricles contract
– Blood pressure in arteries is at its greatest

•

Diastolic pressure
– Ventricles relax
– Blood pressure in arteries is at its lowest

•

Reported as the systolic number over the diastolic
number

© 2011 T he McGraw -Hill Com panie s, Inc. A ll rights reserv ed.