Respiratory System
Chapter 21 – Day 1
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Respiratory System Overview
Respiratory System Functions
Expulsion of CO2
External vs. Internal Respiration
Organization – Upper & Lower
Pathway of O2
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Respiratory System
O2 delivery to cells is critical & the respiratory
system makes it possible for O2 from the atmosphere
to enter the blood
Function
♦ O2 transport to the blood
♦ CO2 transport from the blood
♦ Some role in speech (in terms of air movement)
Do we really breath out CO2?
How does the body take in O2 & expel CO2?
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Respiratory System
Special organs
♦ Nose
♦ Pharynx
♦ Larynx
♦ Trachea
♦ Bronchi
♦ Lungs -
Direct air
into/out of
lungs
exchange of gases takes place here
Additional help comes from skeletal muscles
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Process of Respiration
Physical movement of air
♦ = External Respiration
Use of O2 in cells for metabolism
♦ = Internal/Cellular respiration
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Pathway of Air/ O2
Nose – external nares → nasal cavity → internal nares

Pharynx – nasopharynx → oropharynx → laryngopharynx

Larynx – epiglottis → larynx

Trachea – trachea

Bronchi – primary bronchi → secondary bronchi → tertiary bronchi → bronchioles

Lungs – alveoli → blood stream
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Pathway of Air/ O2
Each component is composed of special tissues which
aid in their function
Passageways & accessory structures in the nose and
pharynx = upper respiratory system
Nose: external & internal nose
♦ Outside: cartilage & skin structure with 2 openings = external
nares
♦ Directs air into nasal passageways
♦ External = object of “vanity’
• “nose job” = Rhinoplasty – surgery to repair or alter nose
structure – involves addition or removal of tissue
• Involves inconspicuous incisions & local anesthesia
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Pathway of Air/ O2 - Skull
Nostrils lead into 2 chambers separated by the nasal
septum
Right and left chambers of the nasal cavity
Walls of the nasal septum = ethmoid & vomer bones
Protrusions of the bone = nasal conchae (superior,
middle, inferior)
♦ Allows air to swirl in the nasal cavity – airborne particles get
trapped in mucus
♦ Cavity is lined with mucous membrane
♦ Mucus is secreted by the paranasal sinuses (=air cavity with
epithelium in the skull)
Floor of the nasal cavity = hard palate (roof of the
mouth)
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Function of the Nose
Directs air into the nasal passageway
Warms air via blood circulation
Location for olfaction sensation
Traps particles & microbes = non-specific defense
♦ These then get swallowed with mucous
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Pathway of Air/ O2 – Pharynx and on
From the nasal cavity, air enters internal nares then
the pharynx (throat)
Pharynx
♦ Shared by digestive and respiratory systems
♦ It is a muscular tube lined with mucous epithelium
Just behind the nasal cavity = nasopharynx
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Pathway of Air/ O2
Nose – external nares → nasal cavity → internal nares

Pharynx – nasopharynx → oropharynx → laryngopharynx

Larynx – epiglottis → larynx

Trachea – trachea

Bronchi – primary bronchi → secondary bronchi → tertiary bronchi → bronchioles

Lungs – alveoli → blood stream
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Mechanics of Respiration
You will cover the details of aspects of the respiratory
system in lab and lecture on Wednesday
For lab today you also need to be familiar with
Pulmonary Ventilation (the fancy way to say
“breathing”)
Air is pulled in & pushed out by a mechanical process
♦ = ventilation
♦ This process involves the diaphragm and skeletal muscles
(intercostal muscles)
Breathing consists of 2 phases:
♦ Inspiration
• air is taken into the lungs
♦ Expiration
• Air passes out of the lungs
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Mechanics of Respiration
Air is moving in and out of the lungs due to pressure
gradients
We will cover the mechanism in more detail in lecture,
but be sure you read the introduction to each lab and
to each section/activity…you will be responsible for
the information presented there in lab and lecture!
Happy breathing
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