Respiratory System

Home H. Bio Anatomy

Notes on this page Outside links
Functions_of_the_Respiratory_System Textbook website
Upper Respiratory Structures Web anatomy
Lower Respiratory Structures Fundamentals of Respirology
Pulmonary ventilation_ Bonus question:  Z-Z-Z-Z-Z
Respiratory Gas Transport  
Control_of Respiration  
Disorders and Diseases  

Functions of the Respiratory System

1.        Supply O2 to tissues
O2 needed to break down (burn) glucose to make ATP (energy!)

Remove CO2
Waste product of cellular respiration
(Carbon comes from C6H12O6)


O2 ààCO2

4 Stages of Respiration

1.  Pulmonary ventilation
Air moves into and out of lungs
Gases are continuously refreshed

2.  External respiration
Gas exchange between pulmonary blood and air sacs in lungs
O2 loaded into RBC, CO2 unloaded

3.  Respiratory gas transport
O2 transported from lungs
à tissues
CO2 transported from tissues
Uses circulatory system (blood)

4.  Internal respiration
Gas exchange between RBC & tissue cells
Diffusion through capillary walls

Structures of Respiratory System

Conducting zone
”Upper” respiratory tract
     Conducts air to lungs
     Purifies incoming air (removes particles)
     Humidifies to allow diffusion

Warms air

Respiratory zone structures
Part of ”Lower” respiratory tract
     Structures are within the lungs
     Respiratory bronchioles, alveolar ducts, alveolar sacs,

Alveoli –only site of gas exchange
O2 in and CO2 out

F Structure & Function correlated in biological systems

Think:  How do the structures of the respiratory system allow it
to function efficiently?

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Upper Respiratory Structures:  Conducting Zone


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Lower Respiratory Structures (Conducting & Respiratory Zones)



FClick through this Review of Structures and Video (See this!)


Respiratory Zone Structures


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Simple squamous epithelial cells Thin, delicate (also called Type I cells)
Surfactant secreting cells Secrete oily mixture of phospholipids & proteins to reduce surface tension in the watery coating of the alveolar surface.  Without surfactant, the alveoli would collapse. (also called Septal cells, Type II cells)
Macrophages "Dust cells"  gobble up any particles that have managed to elude other respiratory defense mechanisms; protect delicate alveolus
Red blood cells Transport oxygen from alveoli to body tissues



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Pulmonary ventilation


Mechanics of breathing


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External respiration



Respiratory gas transport
  • Gas exchange - use these websites to learn about the role of hemoglobin in oxygen transport


Internal respiration




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Control of respiration

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Developmental Aspects


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Respiratory System Disorders


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