Respiration involves both internal and external respiration. Internal respiration is the process of aerobic respiration that occurs in cells to release energy from glucose, producing carbon dioxide and water. External respiration refers to the process of gas exchange where oxygen is transported from the lungs to cells and carbon dioxide is transported from cells to the lungs. Breathing is the muscular process of inhaling and exhaling air from the lungs and is part of the process of external respiration and gas exchange.

1. Qn: Does respiration equate to breathing?
respiration = breathing???
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2. Aerobic respiration
Internal respiration
(tissue respiration)
External respiration
(gaseous exchange)
- oxidation of organic food
molecules with the liberation
of energy; occurs in
cells/tissues of living
organisms
- process of O2 transfer from
surrounding air/water to cells and
the transfer of products of
respiration (CO2+H2O) from cells to
surrounding medium (air/water)
Tissue respiration, Gas exchange
and Breathing
- Breathing part of gaseous
exchange; muscular contractions
and movement of ribs resulting in
the movement of air in and out of
lungs
involves
both

3. Internal respiration
Glucose + oxygen
in living cells
carbon dioxide + water + energy
energy
water
glucose
nucleus
living cell
oxygen
carbon
dioxide

4. Respiration and breathing
Respiration Breathing
Takes place in every living
cell
Takes place in the lungs
A process that involves the
release of energy from food
A process of gaseous
exchange – taking air in and
out of the body
Uses the oxygen absorbed
during breathing
Removes the carbon dioxide
produced during respiration

5. Gaseous exchange in animals
unicellular aquatic organisms
large surface area: volume ratio
efficient diffusion
Do not require special gas
exchange/O2 transport
mechanisms
large animals
small surface: volume ratio
thickened external surface
protection
prevent H2O
loss
possess special organs;
gills/lungs + breathing movements
gas exchange surface
enlarged; thin covering
efficient diffusion

6. Gas exchange system in Man
[pg.202 textbk]nasal passages
(antagonistic)
(air sacs)
(thin layer of
lubricating fluid)
(dome-shaped sheet of
muscle + elastic tissue)

7. Identify the following components:
3.
1.
4.
11.
5.
6.
7.
9.
10.
8.
2.
12.

8. Structure of trachea [pg.203
textbook] Epithelium lining of trachea
and bronchi
(traps dust particles and bacteria)
(helps to sweep particles up the bronchi
+ trachea → pharynx → oesophagus)
(ensures that
nasal passages
are always open)

9. Activity:
Place your hand on your chest.
Breathe in and out.
What do you observe?

10. Breathing (rib cage movement)
(breathing in) (breathing out)

11. What happens during breathing?
(external
intercostal
muscles
contract;
internal
intercostal
muscles
relax)
(flattens
downwards) (arches upwards)
(external intercostal
muscles relax;
internal intercostal
muscles contracts)
(thoracic
cavity
increases)
(thoracic
cavity
decreases)
Boyle’s law: p V = constant
When volume increases, pressure decreases
When volume decreases, pressure increases

12. Gas exchange system in Man
[pg.202 textbk]nasal passages
(antagonistic)
(air sacs)
(thin layer of
lubricating fluid)
(dome-shaped sheet of
muscle + elastic tissue)

13. Gaseous exchange in lungs
High [O2]
low [O2]
Establish diffusion gradient

14. Gas Exchange Between
Alveoli and Capillaries

15. What are the adaptations of the
alveoli to its function?
thin film of
moisture
RBC
alveolar wall (one celled thick)
alveolar cavity
air movement
blood capillary
High [O2]
low [O2]
Establish diffusion gradient

16. Formation of oxyhaemoglobin

17. Oxyhaemoglobin
High [O2] (lungs)
Low [O2] (O2-poor tissues)
reversible
How do we know the direction of association/dissociation?

18. Transport of CO2 [refer to pg.209
textbook]
• CO2 is carried in blood in 3 different ways
1. Most of it (about 80%–90%) transported in
the plasma as hydrogencarbonate ions
(HCO3
-
)
2. 5%–10% is dissolved in the plasma
3. 5%–10% is bound to haemoglobin as
carbamino compounds

19. Transport of CO2

20. Transport of CO2
carbonic
anhydrase
hydrogencarbonate
ion + hydrogen ion
carbonic acidcarbon dioxide + water
↔H2CO3 HCO3
-
+ H+CO2 + H2O ↔

21. Summary

22. Composition of inspired and
expired air
glucose + oxygen  carbon dioxide + water + energy
in living cells
Aerobic respiration

23. 10.6 To compare the amount of
CO2 in inspired and expired air
[pg.210 textbk]
Inspired air Expired air
(slightly white ppt.) (white ppt.)

24. 10.7 To compare the amount of O2
in inspired air and expired air
downward displacement of water
downward displacement of water
oxidation of yellow phosphorus
upward displacement of water
Collection of expired air
reflects volume of O2 present

25. 10.7 To compare the amount of O2
in inspired air and expired air
Calculations:
Volume of expired air at
beginning of experiment = a cm3
Volume of expired air at end of
experiment = b cm3
Volume of oxygen absorbed
= (a – b) cm3
Percentage of O2 in expired air
= (a – b)/a x 100%
Note: Repeat experiment using
inspired air (atmospheric air)

26. Activity for lung capacity

27. Lung capacities
(same volume of air that
enter or exits in a normal
breathing cycle; varies for
diff. individuals)
(extra volume of air that
is taken in when taking
a deep breath)
(extra volume of air that
can be forced out by
expiration)
(residual volume of air
after expiration)
(max. volume of air
that can be taken
in/ breathed out)

28. **Stimulus for breathing
 Is the high conc. of CO2 in the blood/alveolar air
 And not a lack of O2
 No breathing movements occur when low CO2 in
lungs
Irritant particles
 Filtered by nose hair/trapped in mucus
 If enter respiratory passages → automatic violent
coughing (expulsion)/ sneezing to expel them
 Occupational hazard (wear protective masks, if not
can give rise to lung damage)