The document summarizes the human ventilation system and respiratory process. It describes: 1) The ventilation system which allows air to flow from the external environment into the lungs through a network of passageways in the upper and lower respiratory tract. 2) The breathing process of inspiration and expiration which is controlled by muscles like the diaphragm and intercostals. 3) Gas exchange that occurs in alveoli through diffusion between air in lungs and blood in capillaries, allowing for oxygenation and removal of carbon dioxide.

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Human Respiratory:
Ventilation

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Human Respiration
 Involves the process of:
a) cellular respiration:
Glucose + O2  H2O + CO2 + 36 ATP’s
b) gas exchange:
exchange of gases between the internal
and external environment with the use of
lungs
c. ventilation – bringing fresh air in; removing
stale air

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Ventilation System
why do we need it!?
 adequate lung ventilation is essential to
gas exchange
 ventilation provides a continual supply of
fresh air to the lungs needed to
maintain a large concentration gradient
for gas exchange >> surface of the
alveoli
 O2 must be delivered regularly
 CO2 must be quickly eliminated

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(I) Human Ventilation System
Composed of a network of
passageways which permits
air to flow from the external
environment and into the
lungs

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The Upper Respiratory Tract

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Nasal Cavity
 The nose
 Lined with a ciliated
mucus membrane
 The cilia and mucus:
1. Filters air
2. Warms air
3. Moistens air

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Pharynx
Known as the
throat region
It is an area
in which both
air and food
pass through

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Epiglottis
 A cartilaginous
flap
 It “covers” the
trachea when
swallowing food

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Larynx
 Humans
 use the larynx as a
voice box
 contains vocal cords
that vibrate and
produce sound as air
passes through

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Trachea
 Known as the windpipe
 Kept open by rings of
cartilage
 Lined with a ciliated
mucus membrane

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Lung

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Bronchi
 Bronchus = singular
 Trachea divides into two major
divisions known as bronchi
 The bronchi contain cartilage
rings as well
 The bronchi subdivide many times
forming smaller tubules known as
bronchioles

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Bronchioles
Lack cartilage
rings
Tiny bronchioles
subdivide and
terminate (end)
with structures
known as alveoli

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Alveoli

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Alveoli
Adapted for efficient gas exchange:
Are thin: single layer of cells – easy
diffusion
Moist: helps gases to dissolve before
passing thru membranes
Spherical Alveoli increase surface area
for gas exchange
Associated Capillary bed near to allow
for fast diffusion of gases

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(II) Breathing Process
 Inhaling – Inspiration
 Exhaling – Expiration
 Lungs are highly elastic (stretchable)
 Thoracic Cavity is sealed
 Atmospheric Pressure Constant
 Atmospheric Pressure forces air into the lungs:
 Volume Inc. / Pressure Dec. = Inhale
 Volume Dec. / Pressure Inc = Exhale
4 sets of MUSCLES that control breathing include:

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Diaphragm and Abdominal
Muscles
 Diaphragm contracts –
flattens dome – Inhale
 Abdominal muscles relax
 Diaphragm relaxes –
abdominal muscles
contract - Exhale

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Intercostal Muscles
 External Intercostals –
 Attached to rib cage
 Contracts to move rib cage up and out
 Inhale
 Internal Intercostal
 Attached to rib cage
 Contracts to move rib cage down and in
 Exhale

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II – Breathing Process

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III – Gas Exchange

23. Monitoring Ventilation
 Ventilation Rate – number of inhalations or
exhalations per minute.
 Tidal Volume – volume of air taken in and out with
each inhalation or exhalation.
 Instrument: Spirometer
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24. Lung Disease
Cancer:
Causes:
 Smoking
 Passive smoke
 Air Pollution
 Radon gas
 Asbestos…
Consequences:
 Breathing…
Emphysema:
Causes:
 Smoking
 Air pollution
Consequences:
 Loss of alveoli lead
to decreased ability
to breathe
 Low O2 , High CO2
 Chronic
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Epidemiology – study of the incidences and causes of disease

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THE END