Chapter 10 respiration

1. RESPIRATION

2. What Is Respiration?
We know that living cells need food in
order to sustain life.
Food provides energy for the cell.
The process of breaking down food
molecules to RELEASE energy in
living cells is called respiration.

3. The main food substance
used to provide energy is glucose
Anaerobic respiration does not require oxygen.
From these equations, we can see why living things
take in oxygen and give out carbon dioxide.
Aerobic respiration requires oxygen.

4. Oxygen is taken in from the surroundings,
and carbon dioxide is given out.
This is called gaseous exchange.
In simple organisms like the Amoeba,
which consists of only one cell, the process
is very simple.
Gaseous Exchange

5. Why Do We Need To Breathe?
Humans are large organisms made up of millions of
cells.
It is not practical for oxygen and carbon dioxide to
diffuse freely between the environment and all our cells.
We have evolved a special system of organs to bring
these gases in and out of our bodies.
The mechanism of this exchange of gases is also
known as external respiration to distinguish it from what
happens in the cells, which is called cellular respiration.
This exchange of gases by the body is known as
breathing.
The need for a respiratory system

6. The Human Respiratory System
Trachea (‘windpipe’)
Lungs
Diaphragm
- separates chest
from abdomen
Nasal cavity
Larynx (‘voice box’)
Pharynx

7. Structures of Chest in Context
The expanded lungs fit neatly into the thoracic cavity, against the ribcage
with its intercostal muscles, and the diaphragm below.
The pulmonary arteries bring deoxygenated blood from the right heart,
and oxygenated blood returns to the left heart via the pulmonary veins
larynx
right pulmonary vein
branches of right
pulmonary artery
right lung cut open
to show structures
inside
trachea
ribs
intercostal
muscles
diaphragm
right bronchus
left lung
location of heart
(removed)

8. A Look at Mr Q’s beautiful rib cage! WoW!

9. The Human Respiratory System
Trachea (‘windpipe’) which is
supported by C-shaped rings of
cartilage
Inside the lungs the bronchi divide
further into a network of
progressively smaller ‘tubes’
called bronchioles
Each bronchiole ends in a cluster
of grape-like structures called
alveoli
Branches into 2
Right main bronchus leading to
right lung
Left main bronchus leading to left
lung
Passage of inspired air

10. The Human Respiratory System
Lung tissue is like a ‘sponge’, made up of
thousands of tiny air sacs called alveoli.
The alveolus is where gaseous exchange
actually takes place.
The bronchioles leads to clusters
of alveoli which look like grapes.
The whole structure of the lungs is designed to provide
a very large surface area for gaseous exchange.

11. The wall of each
alveolus is only one cell
thick.
The inner surface is
coated with a thin film
of moisture.
It is supplied by a
capillary whose
wall is also only
one cell thick.
This is the
site where
exchange
of gases
takes
The Human Respiratory System

12. 3D Look at Alveolus!

13. A model of the breathing mechanism
The jar is sealed tight to
create a vacuum, like
the chest cavity.
When the rubber
diaphragm is pulled
down, the balloons
expand, sucking in air
from the outside due to
negative pressure.
glass tube
(trachea)
glass tube
(bronchus)
balloon
(lung)
rubber sheet
(diaphragm)
bell jar
(thoracic wall)

14. A model of the breathing mechanism
To take this example further, imagine each alveolus like a tiny balloon
so the lung is a collection of many, many balloons all connected to the
same network of tubes
Full expiration
very little air left in lungs.
Alveoli collapse, lung is
shrunken, diaphragm
pulled upwards
Equilibrium
Some air in
lungs
Full inspiration
-lungs (alveoli) fully
inflated, diaphragm
pushed down

15. vertebral
column
stemum
Internal
intercostal
muscles
rib
external
intercostal
muscles
A model of the breathing
mechanism
This model is not perfect because the rib cage is
not represented
Unlike the rigid gas jar, the rib cage can move to a
certain extent, expanding and contracting the
thoracic cavity with each breath
These diagrams illustrate how the
ribs are able to move
position when
breathing in
position when
breathing out
stemum
external
intercostal
muscles

16. Mechanism of Breathing
rib
sternum
vertebral
column
Front view Side view
When you breathe in or inspire, the following events take place:
Movement of rib cage during inspiration
rib cage

17. Mechanism of Breathing
rib
sternum
vertebral
column
Front view Side view
• Your diaphragm contracts and flattens.
Movement of rib cage during inspiration
diaphragm
contracts and
flattens
rib cage

18. Mechanism of Breathing
rib
sternum
vertebral
column
Front view Side view
• Your external intercostal muscles contract while your internal intercostal
muscles relax.
Movement of rib cage during inspiration
rib cage
diaphragm
contracts and
flattens

19. Mechanism of Breathing
ribs and
sternum
raised
rib
sternum
vertebral
column
Front view Side view
Ribs swing up
• Your ribs move upwards and outwards. Your sternum also moves up and
forward.
Movement of rib cage during inspiration
rib cage
diaphragm
contracts and
flattens
ribs and
sternum
raised

20. Mechanism of Breathing
ribs and
sternum
raised
rib
sternum
vertebral
column
Front view Side view
Ribs swing up and
increase volume of thorax
• The volume of your thoracic cavity increases.
Movement of rib cage during inspiration
rib cage
diaphragm
contracts and
flattens
ribs and
sternum
raised
volume of
thorax
increases

21. Mechanism of Breathing
ribs and
sternum
raised
rib
sternum
vertebral
column
Front view
Ribs swing up and
increase volume of thorax
• Air pressure in your lungs causes them to expand to fill up the enlarged
space in your thorax.
Movement of rib cage during inspiration
Side view
rib cage
diaphragm
contracts and
flattens
ribs and
sternum
raised
volume of
thorax
increases
and lungs
expand

22. Mechanism of Breathing
ribs and
sternum
raised
rib
sternum
vertebral
column
Front view Side view
Ribs swing up and
increase volume of thorax
• Expansion of your lungs causes the air pressure inside them to decrease.
Movement of rib cage during inspiration
Side view
rib cage
diaphragm
contracts and
flattens
ribs and
sternum
raised
lungs
expand,
causing air
pressure
inside lungs
to decrease

23. Mechanism of Breathing
ribs and
sternum
raised
rib
sternum
vertebral
column
Front view
Ribs swing up and
increase volume of thorax
• Atmospheric pressure is now higher than the pressure within your lungs.
This causes air to rush into your lungs.
Movement of rib cage during inspiration
rib cage
diaphragm
contracts and
flattens
ribs and
sternum
raised
lungs
expand,
causing air
pressure
inside lungs
to decrease
air enters lungs
Side viewSide view

24. Mechanism of Breathing
When you breathe out or expire, the following events take place:
rib
sternum
vertebral
column
Side viewFront view
Movement of rib cage during expiration
rib cage

25. Mechanism of Breathing
• Your diaphragm relaxes and arches upwards.
rib
sternum
vertebral
column
Side viewFront view
Movement of rib cage during expiration
rib cage diaphragm
relaxes and
arches
upwards

26. Mechanism of Breathing
• Your internal intercostal muscles contract while your external intercostal
muscles relax.
rib
sternum
vertebral
column
Side viewFront view
Movement of rib cage during expiration
rib cage diaphragm
relaxes and
arches
upwards

27. Mechanism of Breathing
ribs and
sternum
lowered
rib
sternum
vertebral
column
Ribs swing down
• Your ribs move downwards and inwards. Your sternum also moves
down to its original position.
Front view
Movement of rib cage during expiration
Side view
rib cage diaphragm
relaxes and
arches
upwards
ribs and
sternum
returned to
original
position

28. Mechanism of Breathing
ribs and
sternum
lowered
rib
sternum
vertebral
column
Ribs swing down and
decrease volume of thorax
• The volume of your thoracic cavity decreases.
volume of
thorax
decreases
Front view
Movement of rib cage during expiration
Side view
rib cage diaphragm
relaxes and
arches
upwards
ribs and
sternum
returned to
original
position

29. Mechanism of Breathing
ribs and
sternum
lowered
rib
sternum
vertebral
column
Ribs swing down and
decrease volume of thorax
• Your lungs are compressed and air pressure inside them increases as the
volume decreases.
Front view
Movement of rib cage during expiration
lungs are
compressed,
causing air
pressure
inside lungs
to increase
Side view
rib cage diaphragm
relaxes and
arches
upwards
ribs and
sternum
returned to
original
position

30. Mechanism of Breathing
ribs and
sternum
lowered
rib
sternum
vertebral
column
Front view
Ribs swing down and
decrease volume of thorax
Movement of rib cage during expiration
• Air pressure within the lungs is now higher than atmospheric pressure.
The air is forced out of your lungs to the exterior.
lungs are
compressed,
causing air
pressure
inside lungs
to increase
Side view
rib cage diaphragm
relaxes and
arches
upwards
air expelled
from lungs

31. Mechanism of Breathing
What happens to your intercostal muscles when you are breathing?

32. Mechanism of Breathing
When you inhale, you…
Relax your
Internal intercostal muscles and
Contract your
External intercostal muscles
R
I
C
E
What happens to your intercostal muscles when you are breathing?

33. Mechanism of Breathing
When you inhale, you…
Relax your
Internal intercostal muscles and
Contract your
External intercostal muscles
R
I
C
E
&
E
R
I
C
What happens to your intercostal muscles when you are breathing?
When you exhale, your…
External intercostal muscles
Relax and your
Internal intercostal
muscles
Contract

34. The Mechanics of Breathing
Side view of movements in the thorax during inspiration and expiration
air in
rib cage is
raised
volume of
thorax
increases, so
air is drawn into
the lungs
diaphragm
contracts and
flattens down
spinal
column
Inspiration Expiration
rib cage drops dow
volume of
thorax
decreases,
forcing air out
of the lungs
diaphragm
relaxes and
arches up
air out
spinal
column

35. Inspired and Expired air
Inspired Air Expired Air
Oxygen 21% 16.4%
Carbon
dioxide
0.03% 4.0%
Nitrogen 78.0% 78.0%
Water
vapour
Variable Saturated
Temperature Variable Body
temperature
Dust Variable Little, if any

36. Gaseous Exchange in the Alveolus
Deoxygenated blood
carrying carbon
dioxide
Oxygen-rich blood
Oxygen
Carbon
dioxide
(which will go
back to the
heart and enter
the systemic
circulation)
Inhaled oxygen
Carbon dioxide to be
exhaled
capillary
alveolus

37. Oxygen
dissolved in
mucous
layer
diffuses
through
alveolar and
capillary
walls
capillary
alveolus
Carbon
dioxide
gas to be
exhaled
Binds to haemoglobin
in red blood cells to
form oxyhaemoglobin
HCO3
-
ions in
plasma of blood
converted back to
CO2 which
diffuses across
barrier
Gaseous Exchange in the Alveolus

38. Gaseous Exchange in the Alveolus

39. Transport of O2 and CO2 in the blood
Oxygen is transported by haemoglobin in red blood cells.
Haemoglobin is a protein which contains iron. Each Hb
molecule can bind up to 4 oxygen molecules in a reversible
reaction.
Carbon dioxide is transported in the plasma. The enzyme
carbonic anhydrase converts the dissolved CO2 to form
hydrogen carbonate ions, also in a reversible reaction.

40. Oxygen Concentration and Haemoglobin
The binding of oxygen to haemoglobin molecules is
dependent on the concentration of oxygen in the
surroundings. In oxygen-rich areas (such as in the
lungs), oxygen binds to Hb to form oxyhaemoglobin. In
surroundings where the oxygen concentration is low
(other organs eg muscles), the process is reversed
and oxygen molecules are released.
This allows efficient transporting and distribution
of oxygen
Low O2 concentration
High O2 concentration

41. More about aerobic
and anaerobic respiration
What is the difference between the 2
equations?
 Why does anaerobic respiration produce
a smaller amount of energy per glucose
molecule?

42. More about aerobic
and anaerobic respiration (Explanation)
The energy released in respiration comes from
the oxidation of glucose.
In aerobic respiration, the glucose molecule is
completely used up. All 6 carbon atoms are
oxidised to carbon dioxide.
In anaerobic respiration, the glucose is
partially oxidised to ethanol. Not all the energy
is released, as ethanol can actually be oxidised
further.
Why use anaerobic respiration if it is
less efficient?

43. The Uses of Anaerobic Respiration
Organisms such as yeast and bacteria may
predominantly respire anaerobically. This may come
about because their habitat contains little oxygen
Anaerobic respiration of yeast cells is used in the baking
of bread. Mixed in the dough, the yeast cells respire,
using up the sugar present, and replicate at high speed.
The carbon dioxide gas given off forms ‘pockets’ of gas
in the bread, causing it to ‘rise’ and be light and spongy
in texture
Yeast are also used in alcoholic fermentation to make
beer, wine and other alcoholic drinks
Lactobaccillus bacteria is added to milk to make yoghurt.
The lactic acid produced ‘separates’ the milk solids and
gives the characteristic sour taste

44. Anaerobic Respiration in Humans
Why do our muscles ache after
vigorous exercise?
What makes the pain go away after
some time?
When exercised vigourously, muscles need
a lot of energy. Even though we breathe
faster and deeper than usual, they may not
be able to receive enough oxygen fast
enough to meet the demand for aerobic
respiration
What happens then is that the muscle cells

45. Anaerobic Respiration in Humans
Anaerobic respiration in human cells produces
lactic acid. Lactic acid builds up in the muscle
cells and causes muscle pain (called fatigue)
when it reaches a certain concentration. This
way of obtaining energy cannot be sustained for
long.
The lactic acid must be removed by oxidation.
This requires oxygen, thus the body is said to
have incurred an oxygen debt.
During a period of rest, the body cells continue
working ‘overtime’ to oxidise all the lactic acid
thus ‘repaying’ the ‘debt’ and relieving the pain.

46. Energy is released Energy is stored in
carbohydrate molecule
Oxygen is used, carbon
dioxide and water are
given off.
Carbon dioxide and water
is used, oxygen is given
off.
Occurs at all times in all
cells, independent of
chlorophyll and sunlight.
Occurs only in cells
containing chlorophyll and
in the presence of sunlight.
Results in a loss in dry
masses.
Results in a gain of dry
masses.
Differences between
Respiration and Photosynthesis

48. Function of Cilia
• Form a lining on the thin epithelium lining
• Cilia helps to sweep dust particles and
bacteria up the bronchi and trachea into
the pharynx  to get swallowed into the
oesophagus

49. Harmful Substances in Cigarette
Smoke

51. Chronic bronchitis
Due to prolonged breathing of irritants

52. Chronic bronchitis
Inflammation of trachea, bronchi,
bronchioles (airways)
Cilia along the epithelium lining being paralysed
Irritants are trapped in the mucus lining the
airways
Leads to inflammation
Airways become blocked, making breathing
difficult
Persistent coughing, in order to clear airways
There is an increased risk of getting lung
infections

53. Emphysema
Due to persistent and violent coughing

54. Emphysema
Violent coughing breaks the partition walls
between the alveoli
Surface area for gaseous exchange will
decrease
Lungs also lose their elasticity
Air is trapped in the lungs
Breathing becomes difficult
Person will wheeze and suffer from severe
breathlessness

55. What happens when a person
suffers BOTH chronic bronchitis
and emphysema?
This person is suffering from COPD!
Chronic Obstructive Pulmonary Disease lah!