This slides will help learners to be much easeir for them to understand the chapter in summary.

1. UNIT 9:
RESPIRATORY SYSTEM AND
GASEOUS EXCHANGE

2. BREATHING
• Sequence of events that results in gas exchange.
• In terrestrial vertebrates it includes 3 steps:
1. Ventilation: Inspiration and
expiration.
2. External respiration: Gas exchange
between air (in lungs) and blood.
Blood then transport Oxygen to the
body tissue cells.
3. Internal respiration: Gas exchange
between blood and tissue fluid.
Blood then transports carbon
dioxide to the lungs.

3. Gas exhange surface
must be: Alveoli filled with air (gas) External
•Moist respiration
Carbon dioxide oxygen
•Thin
•Large in relation of size
of body
Blood – part of
circulatory system
contain red pigment –
Process: Diffusion of hemoglobin, to
gasses (oxygen and transport gasses
carbon dioxide
Internal
respination
oxygen Carbon dioxide
Body cells surrounded by tissue fluid

4. Cellular respiration
• Is the process whereby an organism uses
oxygen and food to produce energy (ATP) and
2 by products e.g. water and carbon dioxide
• Glucose + O2 ATP + H2O + CO2
Therefore gaseous exchange is necessary to get
oxygen for cellular respiration.

5. HUMAN RESPIRATORY SYSTEM
• Consists of:
1. Nose
2. Air passages:
 Pharynx
 Trachea
 Bronchus
 Bronchioles
3. Lungs – Alveoli

6. • Nose has a nasal cavity that
leads to the pharynx.
• Nasal cavity is lined with cilia
NOSE
and hairs and goblet cells that
make mucus (anti-septic and
moisten air)– filter the air –
dust, pollen and other foreign
material sticks to it.
• 3 x turbinate bones divide the
nasal cavity into 4 passages –
This enlarges the surface of the
nasal cavity – For warming,
cleaning and moisten of air.
• Several surface blood vessels
help to warm air.

7. AIRPASSAGES
• Pharynx – pass air form
nose to trachea via larynx.
• Trachea: long, straight
tube kept open by C-
shaped cartilage rings.
• Trachea – lined with cilia
and goblet cells (mucus
production) – traps
foreign particles

8. Lining of airpassages
CILIA (SEM) TRACHEAL LINING

9. AIRPASSAGES: BRONCHI AND
BRONCHIOLES
• Trachea divides in a right
and left bronchus –
consist of C-shaped
cartilage rings and lined Right bronchus-short
with goblet cells (mucus) Branch in 3 Left bronchus – long,
• Bronchi branch in lung to branch in 2
form bronchioles –
branch further and
cartilage rings disappears
– lead air to air sacs of
lung. Bronchiole

10. LUNGS
• Right lung (3 lobes - shorter)
and left lung (2 lobes – longer,
narrow)
• Spongy, elastic pink organ.
• Consists of several air sacs
called alveoli.
• Alveoli are grouped together
and form the endings of the
bronchioles.

11. ALVEOLI
• Lined with single layer
squamous epithelial cells –
Thin easy diffusion of gas.
• Alveoli is surrounded by a
network of blood capillaries –
gasses diffuse into and out of
blood.
• Alveoli is lined with moist
layer – oxygen dissolves in
moisture and diffuses through
alveoli wall into blood
capillary.

12. Pulmonary vein
Pulmonary artery
(Oxygenated
(Deoxygenated
blood)
blood)
Turbinate bones
Pharynx
Alveoli
Trachea
Bronchus
Bronchiole
Diaphragm
SEM TEM

13. BREATHING - The process whereby air (gasses)
move in and out of the body.
EXPIRATION
INSPIRATION
• INSPIRATION Air inhaled
• EXPIRATION Air exhaled
Rib cage
expands as Rib cage gets
rib muscles smaller as rib
contract muscles relax
When pressure in
lungs increase – air is
When pressure in pushed out
Diaphragm Diaphragm
lungs decrease – air
contracts (moves relaxes (moves
rush in
down) up)

14. TIDAL VENTILATION MECHANISM
• Air moves in and out of the body via the same
route.
• All terrestrial vertebrates do this except for birds.
• The lungs are not completely emptied during
each breathing cycle.
• The air entering mixes with used air remaining in
the lungs.
• This help to conserve water, but decreases gas-
exchange efficiency

15. Determining lung capacity
• A spyrometer can be used to determine how much air
enters the lungs.
• Your lungs has a volume of +/- 5 liters.
• During a normal breath, only 0.5 liters of air is
exchanged – This air is known as tidal volume.
• During forced breathing, as much as 3.5 liters of air can
be exchanged, this is known as vital capacity. (The fitter
you are, the higher your vital capacity.)
• +/- 1.5 liters of air always remains in the lungs – this air
is known as residual air/volume.

17. RESPIRATORY CENTER
• Normal breathing rate for adults: 12 – 20
ventilations per minute.
• Respiratory Center in the Medulla Oblongata
of the brain controls breathing.
• The respiratory center send impulses through
the phrenic nerve to the diaphragm and
through the intercostal nerve to the
intercostal muscles to either contract or relax.
(Contract during inspiration and relax during
expiration)

18. Nervous control of breathing
Brain
Respiratory center automatically
regulates breathing
Intercostal nerves
stimulate the
intercostal muscles
Intercostal muscles
Pheric nerve stimulates the
diaphragm
Diaphragm

19. GAS EXCHANGE
• Gas exchange between air in
lungs and blood
EXTERNAL RESPIRATION INTERNAL RESPIRATION
• Movement driven by diffusion • Gas exchange between
gradient. ( [] to []) blood and tissue fluid
• Gasses exerts pressure, the • Movement driven by
amount of pressure each gas diffusion gradient. ( [] to
exerts is called – partial [])
pressure (PO2 and PCO2) • Gasses exerts pressure, the
amount of pressure each
gas exerts is called – partial
pressure (PO2 and PCO2)

20. EXTERNAL RESPIRATSION
• If PO2 differs across a membrane – oxygen will
diffuse from a high to a low pressure.
• If PCO2 differs across a membrane – carbon
dioxide will diffuse from a high to a low
pressure.
• During inspiration the alveoli fills with air –
higher PO2 and lower PCO2 than blood.
• Oxygen diffuse from alveoli into blood and
carbon dioxide diffuse from blood into alveoli.

21. INTERNAL RESPIRATION
• When blood reaches the tissue, cellular
respiration in cells causes the tissue fluid to
have a lower PO2 and a higher PCO2 than the
blood.
• Thus oxygen diffuse from a high pressure in
the blood to a low pressure in the tissue fluid
and eventually in the tissue cells.
• Carbon dioxide diffuse from a high pressure in
the tissue fluid to a low pressure in the blood.

23. TRANSPORT OF OXYGEN
• Most oxygen is transported by hemoglobin
(red pigment protein in erythrocytes).
• Oxygen combines with hemoglobin to form
oxyhemoglobin.
Hb + O2 = HbO2
Hemoglobin Oxygen Oxyhemoglobin
• A small amount of oxygen is transported in
solution in the blood plasma.