10. Diffusion in the Alveoli
O2
CO2
Air In
& Out
Alveolus
Oxygenated
Blood
Deoxygenated Blood
Blood
Capillary
11. Structure and Function of
Alveoli
The Alveoli are where gaseous
exchange takes place. For this they
have:
an enormous surface area
a moist lining
very thin walls
an excellent blood supply.
Oxygen passes into the blood.
Carbon dioxide passes out of the
blood.
12. AIR PASSESTHROUGH OUR
NOSTRILSINTO THE NASAL CAVITY AND
AIR REACHES TO THE LUNGS THROUGH
WIND PIPE.
LUNGS PRESESNT INE THE CHEST
CAVITY.
A LARGE MUSCULAR SHEET CALLED
DIAPHRAGM FORMS THE FLOOR OF THE
CHEST CAVITY
13. Lungs and Breathing
Trachea
Bronchus
Bronchiole
Alveoli
Ribs
Intercostal muscles
Diaphragm
Plural fluid
– carries air from the mouth
– one goes to each lung
– small branching tubes split
bronchi
– air sack where gasses are
exchanged
– protect the heart and lungs
– pull ribs and sternum up and
out
– moves up and down during
breathing
17. Breathing In and Out
Diaphragm
contracts
Rib cage raised
Thorax volume
increases
Air pressure
lowered
Air drawn in
Diaphragm relaxes
Rib cage lowers
Thorax volumes
decreases
Air pressure raised
Air forced out
Inspiration Expiration
18. Breathing In and Out
Diaphragm
_______
Rib cage
_________
Thorax volume
__________
Air pressure
______
Air drawn in
Diaphragm
________
Rib cage
_________
Thorax volumes
__________
Air pressure
_______
Air forced out
Inspiration Expiration
19. Composition of Inhaled and
Exhaled Air
Gas Air in Air out
Nitrogen 79% 79%
Oxygen 21% 16%
CO2 0.04% 4%
Water
vapour
Varies Saturated
21. Tracheal Breathing
Insects, and some other invertebrates,
exchange oxygen and carbon dioxide
between their tissues and the air by a
system of air-filled tubes called
tracheae.
Tracheae open to the outside through
small holes called spiracles. In the
grasshopper, the first and third
segments of the thorax have a spiracle
on each side. Another 8 pairs of
spiracles are arranged in a line on either
side of the abdomen.
The spiracles are guarded by
valves controlled by muscles that
enables the grasshopper to open and
close them;
hairs that filter out dust as the air enters
the spiracles.
22. Spiracles open into large tracheal tubes. These, in turn, lead to ever-finer
branches. The branches penetrate to every part of the body. At their extreme
ends, called tracheoles, they may be less than 1 µm in diameter, and are
probably filled with liquid. Every cell in the insect's body is adjacent, or very
close to, the end of a tracheole.