RESPIRATORY SYSTEM
Introduction


So far we have studied respiration on a cellular level
What do we remember?
Purpose?
 Reactants?
 Products?


What is respiration on an internal and external level?
external respiration = process of exchanging respiratory
gases with the external environment.
 Internal respiration = the exchange of oxygen and carbon
dioxide between blood and the cells of the surrounding
tissue

Respiratory System

What structures make up the human respiratory
system?
 Trace
a molecule of O2 from the outside air through
your body, and back out again as CO2
Respiratory System

most organisms on earth are aerobic
 require


oxygen to survive.
For both unicellular organisms, like the amoeba, or
multicellular organisms (us), every cell in the body
needs O2
Why do all of our cells need O2?
 Cellular
respiration: the process that releases the energy
needed to drive all cell functions
Respiratory System


We also need respiration to remove CO2.
Therefore, the basic function of the respiratory
system is gas exchange
= to make sure that O2 can enter each cell in the
organism, and that CO2 can leave each cell.
Gas Exchange


Different organisms have different kinds of
respiratory systems to accomplish the task of gas
exchange.
Every respiratory system shares two requirements:
1.
2.
Respiratory surface area must be high enough for gas
exchange to occur at a rate that will meet the
organism’s energy needs
Second, respiration must take place in a moist
environment, so that the oxygen and carbon dioxide
are dissolved.
Gas Exchange
Simple Respiratory Systems:
 Most single-celled aerobic organisms do NOT have a
distinct respiratory system.



Algae, fungi, and some bacteria, etc
Rely on simple diffusion to meet their gas exchange
requirements.
These organisms need moist environments,
aquatic environments
 Other moist places such as within the body of a host
organism

Gas Exchange


O2 that is dissolved in the water around the cell
diffuses through the outer cell membrane at the
same time, carbon dioxide diffuses out.
The cell membrane itself provides a moist surface
area big enough to accommodate gas exchange.
Diffusion
Volvox: These simple organisms can also depend on diffusion
alone to meet their gas exchange requirements.
Gas Exchange
The Specialized Respiratory System:
 The larger and more complex an organism is
 the
more oxygen it requires to supply its cells
 the greater the distance over which that oxygen must
travel in order to reach all of the cells
 The more specialized it’s body become, reducing the
surface for gas exchange

Therefore, these complex organisms can not rely on
diffusion alone to provide O2 to the cells of the
body
Gas Exchange


Adaptations within complex animals have produced
several different respiratory systems.
All of the higher animals have evolved a
specialized respiratory system that includes:
A
respiratory surface
 Passageways to connect this surface to the external
environment
 Muscular structures that help bring air into contact with
the respiratory surface
Respiratory Systems
Skin Respiration



e.g. Worms
can survive only in
water or in damp
earth
Gas is exchanged
through the moist
skin into tiny
capillaries
Respiratory Systems
Gills
 e.g. fish
 a mechanism has evolved that enables the animal to
move the oxygen-containing water over the respiratory
surface (Ventilation)
 This allows the respiratory surface to be constantly
exposed to a fresh supply of oxygen, which makes up
for the reduced surface area
 Gills are feathery tissue structures with numerous delicate
branches
Respiratory Systems



As creatures begin to colonize land environments,
adaptations were needed to provide a constantly
moist surface
Therefore, all terrestrial animals have evolved some
way to carry a moist respiratory environment
wherever they go.
Terrestrial animals also utilize ventilation.
= passing an oxygen-rich medium over the respiratory
surface
Breathing


Breathing = the act of ventilating a respiratory
surface with air
Breathing relies on a basic law of physics:
 air
will move from a region of higher pressure to a
region of lower pressure until equilibrium is reached.

Different terrestrial animals have evolved different
ways to make use of this principle in their
respiratory systems.
Breathing
LUNG
EXTERNAL
ENVIRONMENT
Breathing
LUNG
EXTERNAL
ENVIRONMENT
Breathing
LUNG
EXTERNAL
ENVIRONMENT
Respiratory Systems
Tracheal Respiration
 Insects use spiracles to solve the dilemma of
maintaining a moist respiratory surface
controlled by valves
 lead to an internal network of tubes called tracheae


the abdomen of a grasshopper actually contracts and
relaxes rhythmically.
= breathing

the animal’s breathing causes an orderly movement of
air through the tracheae
Respiratory Systems

In insects, the respiratory and circulatory systems
are separate from one another
 The

circulatory system is not needed to transport O2
Instead, there are many branches of the tracheal
tubes
 ensures
that the respiratory surface is in close enough
contact with all of the living cells
 allow gas exchange to occur by diffusion across the
moist tracheal walls
Respiratory Systems
The Lung
 an internal respiratory surface connected to the
external environment by means of internal
passageways
 Although they vary from species to species, all lung
systems consist of three basic elements:
1.
2.
3.
One or two lungs that have a moist respiratory surface
Forcibly bring air into contact with the lung surface
A circulatory system to carry gases between the lungs
and the other cells of the body.
Lungless
Lunged
Gills
Class Activity

Design a living creature that makes use of several
different respiratory systems.
 Skin
Respiration
 Gills
 Tracheal
Tubes
 Lungs

Make sure you address the two main requirements
for all respiratory systems