Respiratory System Functions and Anatomy

Respiratory
System
Chapter 15
Copyright © 2020 by Elsevier Inc. All
rights reserved.

1. Discuss the major functions of the respiratory system.
2. List the major organs of the respiratory system and
describe the functions of each.
3. Compare, contrast, and explain the mechanism
responsible for the exchange of gases that occurs
during external and internal respiration.
5. List and discuss the volumes of air exchanged during
pulmonary ventilation.
6. Identify and discuss the mechanisms that regulate
respiration.
Learning Objectives
Copyright © 2020 by Elsevier Inc. All rights reserved. 2

Respiration - distribution and gas exchange
Respiration maintains a constant environment that enables the body
cells to function effectively and is a vital homeostatic mechanism
 Constant supply of adequate oxygen (O2)
 Removal of carbon dioxide as it forms (CO2)
Air purification
filters, warms, and humidifies the air we breathe
pH-balancing function
gas exchange helps the removal of excess acid from the body.
Other functions
Respiratory organs help to produce speech (vocal cords) and
the sense of smell (sinuses, and specialized epithelium)
Role of Respiratory System
3
Copyright © 2020 by Elsevier Inc. All rights reserved.

The respiratory system is the organs and other parts of
your body involved in breathing
 Respiratory organs (airways and lungs)
 Pulmonary vessels and breathing muscles
Respiratory system can be divided:
 Functionally: into conducting zone and respiratory zone
 Anatomically: into the upper and lower respiratory tracts
What Respiratory System Is
4

Conducting
zone
The structures form
a continuous
passageway for air
to move in and out
of the lungs.
Functionally Divisions
5

Respiratory zone
Thin-walled structures
found deep inside the
lungs
Allow inhaled oxygen
(O2) to diffuse into the
lung capillaries in
exchange for carbon
dioxide (CO2).
6
Functionally Divisions

The same structures are divided into the upper and lower
respiratory tracts.
Anatomical Divisions

 Structure
 Specialized membrane that lines the air
distribution tubes in the respiratory organs
 More than 125 mL of mucus (slime)
produced each day forms a “mucous
blanket” over much of the respiratory
mucosa
 Mucus serves as an air purification
mechanism by trapping inspired irritants
such as dust and pollen
 Function
 Cilia on mucosal cells beat in only one
direction, moving mucus upward to
pharynx for removal
Respiratory mucosa

Air enters the respiratory tract through the nostrils (External nares) and then flows into the
right and left nasal cavities
 Structure
 Nasal septum separates interior of nose into two cavities
 Shelflike structures, called conchae, protrude into the nasal cavity on each side
 Mucous membrane lines nose
 Frontal, maxillary, sphenoidal, and ethmoidal sinuses drain into nose
 Function
 Warms and moistens inhaled air
 Contains sense organs of smell
Nose

Function
Air and food pass through the pharynx on their way to the lungs and the stomach, respectively.
 Air enters the pharynx from the two nasal cavities or the oral cavity and leaves it by way of
the larynx.
 Chewed food enters the pharynx from the mouth and leaves it by way of the esophagus.
Pharynx
Structure
 About 12.5 cm (5 inches) long
 Divided into nasopharynx, oropharynx, and
laryngopharynx
 Two nasal cavities, mouth, esophagus, larynx,
and auditory tubes all have openings into
pharynx
 Tonsils found in oropharynx.
 Pharyngeal tonsils and openings of auditory
tubes open into nasopharynx;
 Mucous membrane lines pharynx

Structure
 Several pieces of cartilage form
framework
 Thyroid cartilage (Adam’s apple) is largest
 Epiglottis partially covers opening into larynx
 Mucous lining
 Vocal cords stretch across interior of
larynx
Function
 Air distribution; passageway for air
to move to and from lungs
 Voice production
Larynx
Epiglottis closes off the larynx during swallowing preventing food and
liquid from entering the trachea

Structure
 Tube about 11 cm (4.5 inches) long
that extends from larynx into the
thoracic cavity
 Mucous lining
 C-shaped rings of cartilage hold
trachea open
Function
 Passageway for air to move to
and from lungs (known as the
windpipe)
 Blockage of trachea occludes
the airway, and if blockage is
complete, causes death in
minutes
Trachea

Structure
 Trachea branches into right and left bronchi
 Each bronchus branches into smaller and
smaller tubes eventually leading to
bronchioles
 Bronchioles end in clusters of microscopic
alveolar sacs, the walls of which are made
up of alveoli
Function
 Air distribution
 Passageway for air to move to and from
alveoli
Bronchial Tree

Alveoli
Structure
 Thin and tiny balloon shaped structures
 There are millions of alveoli which together
create an enormous surface for gas
exchange
 The total surface area is approximately 84
square meters (915 square feet)
Function: the endpoint of the respiratory system
 Oxygen molecules diffuse through a single
cell in an alveolus and then a single cell in
a capillary to enter the bloodstream.
 At the same time, carbon dioxide molecules,
(a byproduct of cellular respiration) are
diffused back into alveolus where they are
expelled out of the body through the nose or
mouth.
Alveolus and Respiratory Membrane

Structure
 Sections: three lobes in the right
lung and two in the left lung.
 Apex: Narrow upper part of each
lung, under collarbone
 Base: Broad lower part of each
lung; rests on diaphragm
 Each lung is made up of a
combination of several kinds of
structures that form a unit for
respiration.
 the bronchial tree, alveoli, and
pulmonary blood vessels—along
with connective tissues,
lymphatic vessels, and nerves.
Lungs
15
Pleura: Thin sacs that surround each lung lobe and separate lungs from the
chest wall.
• Parietal pleura: Adheres to the wall of the thoracic cavity
• Visceral pleura: Adheres directly to each lung
Function: Breathing (pulmonary ventilation)

Study Activity 1
Watch Video
 Overview of the Respiratory System
Group or Individual Activity
 Use the lesson worksheet to complete
• The chart of the respiratory system anatomy
• Fill-in-blank questions
Class Activity
 Students will present answers to the class
 The instructor will check for understanding and provide feedback

Respiration means exchange of gases
between a living organism and its
environment
Respiration involves several
processes and mechanisms
1. External respiration—pulmonary
ventilation (breathing) and
pulmonary gas exchange
2. Transport of gases by blood and
regulation of set point levels of
blood gases
3. Internal respiration—systemic gas
exchange and cellular respiration
Respiration

Changes to the volume and air pressure in
the lungs trigger pulmonary ventilation
(breathing)
 The lungs are enclosed within the thoracic
cavity.
 Respiratory muscles are responsible for the
changes in the shape of the thoracic cavity
that change the internal air pressures within
that cavity and in the lungs
 The difference in air pressure is the driving
force of movement of air into and out of the
lungs
Mechanics of breathing
18

Pulmonary ventilation or breathing has two phases: Inspiration and expiration
 Air is inhaled through the nasal and oral cavities (the nose and mouth).
 It moves through the pharynx, larynx, and trachea into the lungs.
 Then air is exhaled, flowing back through the same pathway.
Inspiration (inhalation)
 Active process—movement of air into lungs
 Inspiratory muscles include diaphragm and external intercostals
Expiration (exhalation)
 Passive process - movement of air out of lungs
 During expiration, thorax returns to its resting size and shape
 Expiratory muscles used in forceful expiration are internal intercostals and abdominal muscles
Pulmonary ventilation
19

 Cerebral cortex control of
respiration
• Voluntary (but limited) control
of respiratory activity
 Respiratory reflexes
• Chemoreceptors respond to
changes in carbon dioxide,
oxygen, and blood acid levels:
Located in carotid and aortic
bodies
• Pulmonary stretch reflexes:
Respond to the stretch in
lungs
Regulation of ventilation

Mechanism of Breathing

Process of exchanging carbon dioxide waste
inside the lungs through hundreds of millions
of alveoli
 Oxygen from inhaled air diffuses from the
alveoli into pulmonary capillaries
surrounding them. It binds to hemoglobin
molecules in red blood cells, and is
pumped through the bloodstream.
 Meanwhile, carbon dioxide from
deoxygenated blood diffuses from the
capillaries into the alveoli, and is expelled
through exhalation.
External Respiration
22

Process of Exchanges Gases Between the
Bloodstream and Body Tissues
 Red blood cells carry oxygen absorbed from
the lungs around the body, through the
vasculature. When oxygenated blood
reaches the narrow capillaries, the red blood
cells release the oxygen. It diffuses through
the capillary walls into body tissues.
 Meanwhile, carbon dioxide diffuses from the
tissues into red blood cells and plasma. The
deoxygenated blood carries the carbon
dioxide back to the lungs for release.
Internal Respiration
23

Blood transports the respiratory gases (oxygen and carbon dioxide)
primary by combining with other chemicals:
1) Immediately on entering the blood both oxygen and carbon
dioxide dissolve in the plasma, but fluids can hold only small
amounts of gas in solution
2) Most of the oxygen and carbon dioxide rapidly form a chemical
union with hemoglobin or water (oxyhemoglobin,
carbaminohemoglobin, carbonic acid)
3) Once gas molecules are bound to another molecule, more gas
can diffuse into the plasma.
This process allows comparatively large volumes of the gases to be
transported by blood.
Transport of Gases in the Blood
24

Gas Exchange

Lungs and the respiratory system help homeostasis by balancing out
the gases in the body.
 Maintain oxygen levels
 the lungs adapt to bring in more oxygen on demand (e.g., breath quicker and
more heavily when exercising)
 Maintain carbon dioxide levels
 the deoxygenated blood, which is full of carbon dioxide, comes to be filtered by
the lungs and removed when exhaled.
 Maintain sufficient water content
 when we exhale, not only do we remove carbon dioxide, but we also remove lots
of water vapor,.
 Maintain Acidity
 By removing the carbon dioxide, the lungs also help to keep a healthy pH
balance because when carbon dioxide dissolves in water it forms acid.
Roles of the respiratory system in homeostasis
26

 Tidal volume
 We take 500 mL of air into our lungs with each normal inspiration and
expel it with expiration
 Tidal volume and vital capacity are frequently measured in patients with lung
disease conditions that often lead to abnormally low volumes of air being
moved in and out of the lungs (emphysema or heart problems)
 Vital capacity
 The largest amount of air that we can inhale deeply and exhale fully
Pulmonary volumes
Spirometer measures
amount of air exchanged in
breathing

Various breathing patterns
 Eupnea
• Normal breathing
 Hyperventilation
• Rapid and deep respirations
 Hypoventilation
• Slow and shallow respirations
 Dyspnea
• Labored or difficult respirations
 Apnea
• Stopped respiration
 Respiratory arrest
• Failure to resume breathing after a period of apnea
Breathing Patterns

Breathing Patterns
29

Allergies Inhaling proteins, such as dust, mold, and pollen, can cause
respiratory allergies in some people. These proteins can cause inflammation
in your airways. Example: Allergic Rhinitis (Hay Fever)
Asthma A chronic (long-term) disorder, asthma causes inflammation in the airways
that can make breathing difficult.
Infection Infections can lead to pneumonia (inflammation of the lungs)
or bronchitis (inflammation of the bronchial tubes). Common respiratory
infections include the flu (influenza) or a cold.
Diseases Respiratory disorders include lung cancer and chronic obstructive pulmonary
disease (COPD). These illnesses can harm the respiratory system’s ability to
deliver oxygen throughout the body and filter out waste gases.
Other Lung/ Throat cancer
Lung capacity decreases as you get older.
Damage to the respiratory system can cause breathing problems.
Common Diseases and Disorders of
The Respiratory system?
30

Study Activity 2
Watch Video
 The lungs and respiratory diseases
Group or Individual Activity
 Use the lesson worksheet to complete
• Fill-in-blank questions
• Review questions
Class Activity
 Students will present answers to the class
 The instructor will check for understanding and provide feedback

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