Lecture Medical assisting: Administrative and clinical procedures with anatomy and physiology (4/e) – Chapter 24

CHAPTER

24
The Respiratory
System

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24­2

Learning Outcomes
24.1 Explain the functions of the respiratory
system.
24.2 Explain the difference between internal
respiration and external respiration.
24.3 Describe how the larynx produces voice
sounds.
24.4 List the structures contained within the lungs.
24.5 Describe the coverings of the lungs and
chest cavity.
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24­3

Learning Outcomes (cont.)
24.6 Describe the events that lead to the
inspiration and expiration of air.
24.7 Explain how the brain controls breathing and
how normal breathing patterns can be

disrupted.
24.8 Describe how oxygen is transported from the
lungs to body cells.

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24­4

Learning Outcomes (cont.)
24.9 Describe how carbon dioxide is transported
from body cells to the lungs.
24.10List and explain various respiratory volumes
and tell how they are used to diagnose
respiratory problems.
24.11Describe the causes, signs and symptoms,
and treatments of various diseases and
disorders of the respiratory system.

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24­5

Introduction
• Function
– Move air in and out of lungs (ventilation)
– Delivers oxygen (O2)
– Removes carbon dioxide (CO2)
CO2

• External respiration
O2

– Occurs in the lungs

• Internal respiration
– Occurs in the hemoglobin

O2

Lungs

CO2
CO2

O2

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24­6

Organs of the Respiratory System


Nose



Pharynx



Larynx



Trachea



Bronchial tree



Lungs
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24­7

Nasal Cavity
• Nasal septum divides the cavity into right and
left portions
– Nares – openings of the nose

• Nasal conchae extend from walls of nasal
cavity
• Mucous membrane warms and moistens the air

• Cilia help eliminate particles

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24­8

Paranasal Sinuses
• Air-filled spaces within
the skull bones
– Open into the nasal
cavity

• Reduce the weight of
the skull
• Equalize pressure

• Give the voice its
certain tone
• Skull bones with
sinuses include:
–
–
–
–

Frontal
Sphenoid
Ethmoid
Maxillae bones

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24­9

Pharynx and Larynx
•

Pharynx
– Serves both the respiratory and digestive systems

• Larynx
– Also called the “voice box”
– Moves air in and out of the trachea and

produces voice
– Composed of three cartilages:
• Thyroid cartilage
• Epiglottic cartilage
• Cricoid cartilage
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24­10

Vocal Cords
• Stretched between the
thyroid cartilage and
the cricoid cartilage

• Upper – false cords
• Lower – true vocal
cords
• Glottis – the opening
between the vocal
cords
• Stretch = pitch of
voice

Posterior
Portion of
Tongue
False
Vocal
Cords

Glottis

True
Vocal
Cords

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24­11

Trachea
• Referred to as the windpipe
• Tubular organ made of rings of

cartilage and smooth muscle
• Extends from the larynx to the
bronchi
• Lined with cells possessing
cilia (microscopic hair-like projections)

Trachea

Cilia move mucus up to the throat, where 
it is swallowed. Smoking destroys cilia. 

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24­12

Bronchial Tree
• Bronchi
– Primary: First
branches off
trachea
– Secondary
– Tertiary

Bronchi

• Bronchioles
– Branch off tertiary
bronchi

Bronchioles

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24­13

Bronchial Tree (cont.)
• Alveoli
– Thin sacs of cells
surrounded by
capillaries
– Secrete surfactant
• Fatty substance
• Helps maintains the
inflation of the
alveoli between
inspirations

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24­14

Lungs
• Cone-shaped organs
• Right lung – three lobes
• Left lung – two lobes
• Pleura – membranes surrounding the
lungs

The lungs contain connective tissue, the bronchial
tree, nerves, lymphatic vessels, and blood vessels.

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24­15

Apply Your Knowledge
Which of the following sites would be the most
lethal if obstructed by a foreign body?
ANSWER:
a. Right bronchus
b. Left bronchus
c. Trachea

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24­16

The Mechanisms of Breathing
Expiration

Inspiration





Air rich in O2 enters the lungs
from the atmosphere



Air rich in C02 exits the lungs

The diaphragm contracts or
flattens



The diaphragm relaxes



The intercostal muscles lower
the ribs

The intercostal muscles raise
the ribs

Breathing, or pulmonary ventilation, consists of inspiration
(inhalation) and expiration (exhalation).

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24­17

The Mechanisms of Breathing (cont.)
• Respiratory center
of the brain

• Other factors
– CO2 levels in the blood

– Medulla oblongata –
controls rhythm and
depth of breathing

– pH of the blood

– Pons – controls the
rate of breathing

– Inflation reflex

– Fear and pain

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24­18

The Mechanisms of Breathing (cont.)
• Causes of altered breathing patterns
– Coughing
– Sneezing
– Laughing

– Crying
– Hiccups
– Yawning
– Speaking
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24­19

Apply Your Knowledge
Indicated whether each statement refers to (I) inhalation or
(E) exhalation:
ANSWER:
E The intercostal muscles lower the ribs
__
I The diaphragm contracts or flattens
__
I The intercostal muscles raise the ribs
__
E The diaphragm relaxes
__
I Air rich in O2 enters the lungs from the atmosphere
__
E Air rich in C0 exits the lungs
__
2

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The Transport of Oxygen and Carbon Dioxide
in the Blood
•

24­20

Most of the oxygen
binds to hemoglobin
– Oxyhemoglobin
– Bright red in color

•

Some oxygen remains
dissolved in plasma

• If CO2 combines with hemoglobin at O2
sites, it forms carboxyhemoglobin
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The Transport of Oxygen and Carbon Dioxide
in the Blood (cont.)
•

24­21

Carbon dioxide gets into the bloodstream
– Reacts with water in plasma and forms
carbonic acid

– Carbonic acid ionizes and releases hydrogen
and bicarbonate ions
– Bicarbonate ions attach to hemoglobin
•

Exhaled as waste product in the lungs

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24­22

Apply Your Knowledge
Describe what happens to carbon dioxide in the
blood.
ANSWER: Carbon dioxide can combine with hemoglobin
and form carboxyhemoglobin. Most reacts with water in
plasma to form carbonic acid. The carbonic acid ionizes
and releases hydrogen and bicarbonate ions. The
bicarbonate ions then attach to hemoglobin and are
exhaled as a waste product from the lungs.

Super!
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24­23

Respiratory Volumes
• Different volumes of

air move in and out of
lungs with different
intensities of
breathing
• Measured to assess
health of respiratory
system

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24­24

Respiratory Volumes (cont.)
Tidal
TidalVolume
Volume

Amount of air that moves in or out of the
lungs during a normal breath

Inspiratory
Inspiratory
Reserve
Reserve
Volume
Volume

Amount of air that can be forcefully
inhaled following a normal inhalation

Expiratory
Expiratory
Reserve
Reserve
Volume
Volume

Amount of air that can be forcefully
exhaled following a normal exhalation

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24­25

Respiratory Volumes (cont.)
Residual
Residual
Volume
Volume

Volume of air that always remains in
the lungs even after a forceful
exhalation

Vital
Vital
Capacity
Capacity

Amount of air that can be forcefully
exhaled after the deepest inhalation
possible

Total
TotalLung
Lung
Capacity
Capacity

The total amount of air the lungs can
hold

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