Respiration & Human Respiratory System
Objectives
Explain the process of respiration
Explain the role of breathing in the respiratory
system
Identify the structures of the respiratory
system and explain their functions.
Describe the process of gas exchange
Explain how smoking affects the respiratory
system
Respiration
Body cells need oxygen in order to release
energy from nutrients.
Respiration is the process by which the body
uses oxygen to release energy from nutrients.
C6H12O6 + O2  H2O + CO2 + Energy
The respiratory system is the system that
provides the body with the oxygen it needs for
respiration.
Upper Respiratory System:
Structures and Functions
The Upper
Respiratory
System contains:
nose
mouth
pharynx
larynx
epiglottis
trachea
Upper respiratory system structures
and functions
Structure
Nose
Function
Filters and warms inhaled air
Pharynx
Larynx
Connects nose and mouth
Opening of trachea, contains vocal
chords
Epiglottis
Flap of cartilage; covers entrance of
trachea when swallowing
Trachea
Windpipe that branches into two;
leads inhaled air into lungs
Lower Respiratory System
The Lower
Respiratory
System
contains:
Trachea
Bronchi
Bronchioles
Lungs
Diaphragm
Alveoli
Lower Respiratory System Structures & Functions
Structure
Bronchi
Function
Bronchioles
Two branches of the trachea; lead into each
lung
Smaller branches of the bronchi; continue to
branch and get smaller until they end in the
alveoli (air sacs)
Lungs
Gas exchange organs inflate with inhaled air.
Diaphragm
Large flat breathing muscle, expands and
contracts during breathing
Alveoli
Tiny clusters of air sacs covered with
capillaries; site of gas exchange
Other Essential Structures

Cilia- Small
hair-like
projections of
the cells lining
the trachea.
They beat
rhythmically
moving mucus
and foreign
particles
toward the
pharynx.
Scanning Electron Micrograph of tracheal
cilia.
Other Essential Structures
Mucous membrane –
Cells lining the nasal
passages, trachea, and
bronchi also secrete
mucus which traps
foreign particles so
they can be swept up
to the pharynx and out
of the respiratory tract
by the cilia
Breathing
Breathing: The movement of air into and out of
the lungs
A. Inhalation: Diaphragm contracts, volume of
chest cavity increases, air goes in to lungs.
(This is an active process)
B. Exhalation: Diaphragm relaxes, volume of
chest cavity decreases, air is forced out of
lungs. (This is a passive process)
Control of Breathing
You can control when you breathe, but it is not
a completely voluntary action.
After a while of holding your breath, your
body takes over and forces you to breathe.
Breathing is so important that your nervous
system will not let you have complete control
over it.
The medula oblongata in the brain controls
breathing. It forces you to breathe even if you
are willing yourself not to.
Gas Exchange – Lungs and RBC’s


After an inhalation, the amount of oxygen in
the alveoli is greater than the amount of
oxygen in the blood.
Oxygen diffuses from the area of higher O2
concentration (in the alveoli) to the area of
lower O2 concentration (the blood).
CO2
CO2 poor
Alveoli
O2 rich
Diffusion
O2
Diffusion
CO2 rich
RBC
O2 poor
Gas Exchange – RBC’s & Body Cells
In the capillaries, O2 diffuses from the blood (O2
rich) to the cells of the body (O2 poor).
Also CO2 diffuses from the cells (CO2 rich) to the
blood (CO2 poor).
Each gas is diffusing from an area of high
concentration to an area of low concentration
Gas Exchange – RBC’s & Body Cells
In the capillaries, O2 diffuses from the blood (O2
rich) to the cells of the body (O2 poor).
Also CO2 diffuses from the cells (CO2 rich) to the
blood (CO2 poor).
Each gas is diffusing from an area of high
concentration to an area of low concentration
CO2
O2 rich
RBC
CO2 poor
Diffusion
O2
Diffusion
O2 poor
BODY CELL
O2 rich
Oxygen Transport
Most oxygen is carried from the
lungs to the body tissue by the
red blood cells.
Hemoglobin (abbreviated Hb)
is a red, iron containing protein
in RBC’s that combines easily
with oxygen.
The amount of oxygen in the
surrounding tissues will
determine whether hemoglobin
will bind to or release oxygen.
Respiratory Diseases
Asthma
Bronchitis
Emphysema
Respiratory Diseases
Pneumonia
Lung Cancer
Questions
1.
List and describe the four stages of gas exchange.
2.
Oxygen and carbon dioxide are exchanged by the
blood and alveoli by which process?
3.
Why is inhalation considered and active process?
Questions
4. Describe the structure and function of cilia in the
cells lining the nasal passages, trachea, and bronchi.
5. What is the difference between internal respiration
and external respiration?
Questions
6. List the structures of the upper respiratory system
and briefly describe their function.
7. Explain the structure and function of the alveoli in
the lungs.
Questions
8. List and describe 4 diseases that affect the
respiratory system.