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PowerPoint® Lecture Slide Presentation by Robert J. Sullivan, Marist College
Human Biology
CHAPTER 10
RESPIRATORY SYSTEM:
EXCHANGE OF GASES
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings.
The Need for Oxygen:
•O2 is vital to life! Humans can survive for only a
few minutes without oxygen (3-4 minutes is
enough to cause some brain damage). Needed in
most chemical reactions in our body (cellular
respiration)
•Air is 78% nitrogen, 21% oxygen, and 1% other
gases including carbon dioxide
•We take between 17000 and 29000 breaths
everyday. It happens subconsciously and we can
stop breathing momentarily, but it resumes
automatically regardless of how hard you try
Function:
The two main functions of the respiratory system
is to provide O2 from the ambient (outside) air to
the blood and to pick up waste gas, CO2 from the
blood and transport it out of the body
O2
CO2
Other Functions:
Other functions of respiratory system
include protecting body from microorganisms:
-cells of trachea secrete mucous that can trap foreign objects that were not
stopped in nasal cavity
-microscopic cilia then work to “sweep” out trapped substances back to the
pharynx
-once in pharynx these substances can be swallowed or expelled
Respiratory system also provides sound by vocal cords (in
larynx) – these cords vibrate as air is forced past them,
producing sound
Aerobic Cellular Respiration
•Aerobic cellular respiration: the series of chemical
reactions that occur in the cell that provide energy and
consume oxygen
•C6H12O6 + 6O2  6CO2 + 6H2O + energy
Glucose + oxygen  carbon dioxide + water + energy
• About 64% of our energy is released as thermal
energy created during respiration, the rest is stored as
ATP (adenosine triphosphate). 36 ATP are made for
every glucose molecule
Making ATP
•ATP is formed when energy from the breakdown of
glucose is used to attach a phosphate group (Pi) to
adenosine diphoshate ADP
•Called phosphorylation
•Cells use ATP to power most all energy requiring
reactions like active transport and building new
molecules
•When ATP is converted back to ADP energy is released
and is able to do work
•C6H12O6 + 6O2 + 36 ADP + 36 Pi  6CO2 + 6H2O +
36 ATP + thermal energy
Gas Exchange:
•The process by which oxygen diffuses into the body
cells and carbon dioxide diffuses out of the cells
•External respiration (lungs and environment)
•Oxygen diffuses from the air into the blood stream
•Internal respiration (blood and cells)
•Oxygen diffuses from the blood stream into the cells
through interstitial fluid (fluid surrounding all cells)
•Carbon dioxide follows the reverse
•Ventilation (breathing): the process of moving oxygenrich air into the lungs and carbon dioxide rich air out of
the lungs
Human Respiratory System
Alveoli
R lung
L lung
Components of the Upper
Respiratory Tract
Figure 10.2
Requirements for Function:
•1. A thin permeable membrane through which diffusion
can occur
•Alveoli have a membrane that is 1 cell thick
2. A large surface area for gas exchange
• There are 150 million alveoli per lung
3. A breathing system for bringing in oxygen-rich air to
the respiratory membrane
• Lungs assisted by diaphragm and intercostal muscles
4. Large blood supply
• capillaries surround alveoli
Structure:
•Passage:
•Nasal cavity or mouth, to the pharynx, to the trachea and
moves down the trachea into lungs. Within the lungs the air
moves into the bronchi, which branch into bronchioles and
into alveoli.
•Air is warmed and moistened in the nose and mouth before
entering the lungs so as to prevent damage to the thin
delicate tissue. Cilia and mucus in nose filter dust, bacteria
and other air borne particles
Structure:
Trachea: a semi-rigid tube of soft tissue, wrapped
around c-shaped bands of cartilage that leads from the
mouth towards the lungs. Lined with cells that have
cilia and produce mucus.
Cilia: tiny hair-like structures that are found on some
cells ( ex. Trachea, lungs and nose)
•wavelike motions of the cilia sweep the trapped
material upward through the trachea where it is
swallowed or expelled through coughing or
sneezing
Lungs:
•Enclosed in the thoracic (chest) cavity
and are protected by the ribs
•Provide respiratory membranes, large
surface area and have a good supply of
blood
Components of the Lower
Respiratory Tract
Figure 10.3
Structure:
Bronchi: the trachea branches into two bronchi
(singular: bronchus)
Bronchioles: the bronchi repeatedly branch into smaller
and smaller tubes called bronchioles
Alveoli: airway end in clusters of tiny sacs called alveoli
that form the respiratory membrane. Each cluster is
surrounded by a network of capillaries. Each alveolus is
tiny measuring (0.1 to 0.2 micrometers in diameter).
There are approximately 150million in each lung
•If the entire surface area of our lungs was flattened
out it would cover a tennis court
Gas Exchange Between the Blood
and Alveoli
•Air is at 37C.
•Moist air is critical as
diffusion cannot occur until
gas is dissolved in a liquid
Respiratory
membrane
is 1 cell thick
Figure 10.8A
Mechanism of ventilation:
breathing…..
•Based on the principle of NEGATIVE PRESSURE
•When lungs have a lower pressure than atmospheric
pressure, air is forced in
•When air pressure is higher in the lungs air is forced
out
•Diaphragm: large dome shaped sheet of muscle beneath
the lungs that facilitates breathing.
•INHALATION: diaphragm contracts (negative pressure)
•EXHALATION: diaphragm relaxes (positive pressure)
External Intercostal muscles: during inhalation these
muscles between each rib, pull the ribs outward and
upward. This INCREASES volume and DECREASES
pressure
Internal intercostal muscles: are a second set of muscles
that start to contract and relax during strenuous exercise
Ventilation:
Pleural membranes: a thin layer of connective tissue that
covers the outer surface of the lungs and lines the
thoracic cavity. Prevents friction between lungs and
thoracic cavity
Pleural cavity: the space between the pleural membranes.
Filled with fluid to prevent the membranes from
separating, but still slide past one another (like 2 wet
slides).
Pneumothorax: a collapsed lung caused by the
introduction of air between the pleural membranes
Respiratory Cycle
Figure 10.9
Lung Capacity:
with a spirometer
Total lung capacity: the maximum volume of air that can
be inhaled during a single breath
Tidal volume: the volume of air inhaled or exhaled
during a normal, involuntary breath
Inspiratory reserve volume: the volume of air that can
be forcibly inhaled after normal inhalation
Expiratory reserve volume: the volume of air that can be
forcibly exhaled after normal exhalation
Residual volume: the volume of air remaining in the
lungs after forced exhalation
Vital capacity: the maximum amount of air that can be
inhaled or exhaled
Factors Affecting Lung Capacity
Larger volumes
Smaller volumes
males
females
taller people
shorter people
non-smokers
heavy smokers
professional athletes
non-athletes
people living at high altitudes
people living at low altitudes
Figure 10.10A
Oxygen usage:
• physical activity depends on the energy released during
aerobic cellular respiration and this depends on the
supply of oxygen
•A high maximum rate of oxygen usage(the rate at which
oxygen can be used in cellular respiration) indicates an
efficient respiratory system
•VO2 : an estimated or measured value representing the
rate at which oxygen is used in the body. (ml/kg/min)
•VO2max: the maximum rate at which oxygen can be
used in an individual (ml/kg/min); during exercise
Spirometer:measuring oxygen usage efficiency
and lung capacity
Oxygen usage
efficiency depends
on gender, age
and fitness