Transcript Gas Exchange in Vertebrates

Gas Exchange in Vertebrates
• Gas exchange refers to the physical methods that
organisms have for obtaining oxygen from their
surroundings and removing excess carbon
dioxide.
Gas Exchange
•
Why must organisms carryout gas
exchange?
•
Organisms that carry out the process of aerobic
respiration require oxygen to break down and
obtain energy from nutrients like glucose.
C6H12O6 +O2 (g)  CO2 (g) + H2O(l) + Energy
Respiratory Surfaces
• In order for oxygen to enter an organism it must
first pass through a respiratory surface.
Respiratory surfaces have several characteristics:
1.
2.
The surface must be very thin
The surface must be moist. This is due to the fact
both oxygen and carbon dioxide must be dissolved
in water.
Respiratory Surfaces
3. It must be in contact with a source of oxygen in the
environment
4. In large multicellular organisms such as humans, the
surface, must be in contact with a transport system
that will be able to carry these gases to and from the
cells.
5. Land living, air breathing organisms such as humans,
have their respiratory surfaces inside the body. This
internal surface is important for protection and the
reduction of evaporation of the moist surface.
Respiratory Surfaces
• How do gases cross the respiratory surfaces?
– The external side of the respiratory surface has a high
concentration of oxygen compared to the internal side.
Therefore Oxygen will diffuse across the surface and
into the transport system. The opposite is true of
carbon dioxide.
– The larger the surface area of the respiratory surface,
the faster the rate of diffusion of gases across it.
The Human Respiratory System
• The human respiratory system consists of
the lungs and the systems of air tubes that
carry air to and from the lungs.
Air Pathway
Nose  Pharynx  Larynx  Trachea  Bronchi
 Bronchiole Tubes  Bronchioles  Alveoli
Nose
• Air normally enters the respiratory tract
through the nostrils, it then enters spaces
called the nasal passages.
The Nose
The nose has three main functions:
1. Filters the air
-
hair at the opening of the nasal passages
traps foreign particles.
nasal passages are lined with mucus
producing cells and cilia that work to trap
foreign particles.
Nose
2. Moistens the air
-
Mucous works to moisten the air (moist air will
diffuse faster into the blood stream than colder
air
3. Warms the Air
-
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Just below the mucous membranes of the nasal
passages are many tiny capillaries. The blood
flow through the capillaries works to warm the
air.
Warm air diffuses across the surface of the lungs
at a faster rate than cold air
Pharynx and the Larynx
Pharynx and the Larynx
• From the nasal passages the air enters the pharynx which
is also called the throat.
• air leaving the pharynx enters the larynx (also called the
voice box). The larynx contains the vocal cords. The
vocal cords are membranes stretched over the pharynx
that vibrate as air passes over them.
• The epiglottis prevents food from entering the larynx
when we swallow
Trachea
Trachea
• Also called the windpipe
• 12 cm long, 2.5 cm in diameter
• composed of rings of cartilage that ensure that
the windpipe always remains open.
• Lined with ciliated mucous membrane. The
sweeping action of the cilia move debris upwards
into the pharynx, here they are either swallowed
or coughed out.
Bronchi
Bronchi
• Two bronchi branch from the trachea
• Composed or cartilage rings and are lined
with ciliated mucous membranes
• Branch in a tree-like fashion into numerous
bronchiole tubes located with in the lungs
Bronchioles
• Bronchi tubes branch into increasingly
smaller and thinner tubes called
bronchioles
Alveoli
Alveoli
• Each bronchiole ends in tiny air sacs called
alveoli
• There are thought to be 300 million alveoli in the
lungs
• Alveoli are one cell thick and surrounded by
many capillaries
• The alveoli are the structures through which
gases are exchanged between the lungs and the
blood
• Tremendous surface area = tennis court
Lungs
• The gas exchange organs in humans and
other vertebrate animals.
Lungs
• Fill a large part of the chest cavity and are
separated from the chest cavity by a large
muscle called the diaphragm.
• Surrounded by a two layer membrane
called the pleura.