The document discusses respiration and the transport of gases in the human body. It explains: 1) How gases are exchanged between the alveoli and blood in the lungs, and between the blood and body cells, via diffusion. 2) How oxygen is transported from the lungs to body cells by binding to hemoglobin in red blood cells and being carried to tissues. 3) How carbon dioxide is transported from tissues to the lungs, carried in three forms: as carbonic acid, carbaminohaemoglobin, and bicarbonate ions.

1. BIOLOGY FORM 4
CHAPTER 7
RESPIRATION PART 2

2. 7.3 Understanding the concept
of gaseous exchange across
the respiratory surfaces and
transport of gases in human

3. The gases exchange
occurs at two parts:
a. Between the
surface of
alveolus – blood
capillaries
b. Between the
blood capillaries –
body cells

4. IN THE LUNGS

5. Gases exchange (alveoli-blood capillary)
1. High Partial
Pressure of O2
2. Low Partial
Pressure of O2
3. O2 diffuses from the alveoli into the blood capillaries

6. Gases exchange (alveoli-blood capillary)
2. Low Partial
Pressure of CO2
1. High Partial
Pressure of
CO2
3. CO2 diffuses from the blood capillaries into the alveoli

7. BLOOD LEAVES THE LUNGS
TO BODY CELLS

8. The Transport of Respiratory Gases in Humans
a) Transport of O2 from lungs to body cell
1. O2 is transported from alveoli to the
body cells for cellular respiration
2. O2 combines with a pigment called
haemoglobin in the red blood cells
3. O2 is carried in the form of
oxyhaemoglobin to all parts of the body:
Haemoglobin + O2 → Oxyhaemoglobin

9. Oxygen transport
in lungs
Hb + 4O2 HbO8
in tissues
haemoglobin + oxygen oxyhaemoglobin

10. BLOOD REACHES
THE CELL

11. Gases exchange (blood capillary-body cells)
Oxygen
Blood
capillary
Body cells
1. High
Partial
Pressure
of O2
2. Low
Partial
Pressure
of O2
3. Oxyhaemoglobin in blood breaks down and releases O2 which
then diffuses through the capillaries walls into the body cells

12. Gases exchange (blood capillary-body cells)
Carbon Dioxide
Blood
capillary
Body cells
2. Low Partial
Pressure of
CO2
1. High
Partial
Pressure of
CO2
3. CO2 in cells produced from cellular respiration diffuses
from the body cells into the blood capillaries

13. The Transport of Respiratory Gases in Humans
b) Transport of CO2 from body cells to lungs
CO2 released by body cells can be
transported in 3 ways:
• Carbonic acid (H2CO3) (7%) - CO2 dissolve in
water in the blood plasma
• Carbaminohaemoglobin (23%) - CO2
combines with haemoglobin
• Bicarbonate ions (HCO3-) (70%) – Forms
from the breakdown of carbonic acid

14. carbon dioxide + haemoglobin
carbaminohaemoglobin

15. CO2 + H2O
H2CO3 (Carbonic acid)
The reaction is catalysed by
carbonic anhydrase enzyme
in the red blood cell
H+ + HCO3
-
(Bicarbonate ions)
Bicarbonate ions transported in the blood plasma to the body cells

16. CO2 + Hb
Carbaminohaemoglobin
CO2 + H2O
H2CO3 (carbonic acid)
-
HCO3
H+
(Bicarbonate ion)
-
Blood plasma
RED
BLOOD
CELL
CO2
HCO3

17. BLOOD LEAVES THE CELL
 HEART  LUNGS

18. BLOOD REACHES
THE LUNGS

19. CO2 + Hb
Carbaminohaemoglobin
CO2 + H2O
H2CO3 (carbonic acid)
-
HCO3
H+
(Bicarbonate ion)
-
Blood plasma
RED
BLOOD
CELL
HCO3

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

21. Gaseous Exchange in the Alveolus
Oxygen
dissolved in
mucous
layer
diffuses
through
alveolar and
capillary
walls
alveolus
capillary
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

22. The composition of inhaled
and exhaled air

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

24. Compare the Oxygen
Content of Inhaled &
Exhaled Air

26. deflagrating
spoon
burning
candle
gas jar
gas jar
water trough
rubber tubing
In which jar does the candle burn longer ?
Ans: The candle burns longer in the jar of inhaled air.

27. deflagrating
spoon
burning
candle
gas jar
gas jar
water trough
rubber tubing
Which gas must be present for the candle to burn
longer ?
Ans: Oxygen.

28. burning
candle
What do the results tell you about the amount of
this gas in inhaled and exhaled air ?
This shows that inhaled air contains more
oxygen than exhaled air.
Ans:
deflagrating
spoon
gas jar
water trough
rubber tubing
gas jar

29. burning
candle
Does the flame go out immediately when the
burning candle is put into the gas jar of exhaled air ?
What does this show ?
No. This shows that exhaled air also contains
oxygen.
Ans:
deflagrating
spoon
gas jar
water trough
rubber tubing
gas jar

30. Compare the Carbon Dioxide
Content of Inhaled & Exhaled
Air

31. A B
In which tube did bubbles appear when you
breathed in ?
Ans: Tube B.

32. A B
What happens to the lime water in tube A ?
Ans:The lime water in tube A remains clear.

33. A B
What happens to the lime water in tube B ?
Ans: The lime water in tube B turns cloudy.

34. What do the results tell you about the amount of
carbon dioxide in inhaled air and exhaled air ?
The carbon dioxide content in exhaled air
is higher than the inhaled air.
Ans:
A B

35. What solution can you use instead of lime water ?
If :
this is used what changes would you expect in tubes
A and B ?
Ans: Hydrogen carbonate indicator solution can be used.
It changes from red to yellow when more carbon dioxide
dissolves in tube B.
A B

36. J TUBE EXPERIMENT

37. 7.4
Understanding the regulatory
mechanism in respiration

38. Control of breathing

39. Breathing
is an involuntary function of the CNS
a respiratory / breathing center in the
medulla oblongata [part of brain stem] :
 establishes basic breathing pattern
Brain stem Spinal cord

40. Within limits the:
 rate and
 depth of breathing
are also under voluntary
control e.g. holding the
breath

41. During voluntary control:
impulses originating in the
cerebral hemispheres
breathing centre:
carries out the appropriate action

42. Basic breathing rhythm is generated in the medulla
& is modified by neurones in or above the pons
If the brainstem is cut
below the pons, but above
the medulla, breathing
continues but is irregular.
If the spinal cord in the
neck is severed, breathing
ceases.

43. Two centres:
1. inspiratory centre
 increases the rate and depth of inspiration
2. expiratory centre
 inhibits inspiration and stimulate expiration
The breathing centres
intercostal muscles
by way of the
intercostal nerves diaphragm by the
phrenic nerves
communicate with the:

44. The bronchi and bronchioles are connected to
the brain by the:
Vagus nerve
Constricts
bronchi

45. Rhythm of breathing
 INSPIRATION inflates the
lungs
 stretch receptors in the
bronchioles are
stimulated to send more
and more nerve impulses
via the vagus nerve to the
expiratory centre

46. Rhythm of breathing
 this temporarily
inhibits the inspiratory
centre and inspiration
 the external intercostal
muscles relax, elastic
recoil of the lung
tissues occurs:
EXPIRATION takes
place
Intercostal
nerve to
internal
intercostal
muscle to
stimulate
expiration

47. Rhythm of breathing
 the bronchioles is no
longer stretched and
the stretch receptors no
longer stimulated
 thus the expiratory
centre becomes inactive
 INSPIRATION can begin
again
Phrenic nerve to diaphragm
to stimulate inspiration
Intercostal
nerve to
external
intercostal
muscle to
stimulate
inspiration

48. Rhythm of breathing
Inspiratory
centre
active
Inspiratory
centre
inhibited

49. A rise in CO2 = low pH: detected by
chemoreceptors in:
Medulla oblongata
Carotid body
Aortic body

50. Central chemoreceptors in medulla:
 are sensitive to H+
in cerebrospinal
fluid resulting from
CO2 in blood

51. Peripheral chemoreceptors in
carotid & aortic bodies are:
 sensitive to:
 carbon dioxide
 pH
 oxygen levels

52. Respiratory Control Centre
( Medulla oblongata )
impulses
Also helps to
monitor CO2
level &
regulating the
amount of CO2
released during
exhalation
Control the
respiration
rate
Intercostal muscles & diaphragm

53. REGULATION OF CO2 LEVELS

54.  An average human breathing rate:
 12-20 times per minute
 Newborns:
 30-40 breaths per minute
Why does the breathing rate
increase during exercise?

56. During exercise, the CO2 level in the
blood rises, lowering the blood pH
Brain
Cerebrospinal fluid
BREATHING CONTROL
CENTERS—stimulated by:
CO2 increase / pH decrease
in blood
Nerve signal
indicating low
O2 level
O2 sensor
in artery
Pons
Medulla
Nerve signals
trigger
contraction
of muscles
Diaphragm
Rib muscles
 CO2 dissolve in
water forming
carbonic acid
 pH blood drop
 Detected by central
chemoreceptor in
medulla oblongata
 Nerve impulse send
to respiratory centre
 Respiratory centre
send impulse to
intercostal muscle
and diaphragm
 Ventilation increase

57. Regulatory mechanism
After vigorous exercise
• the rate of respiration increase
• and heartbeat increase
– To supply more oxygen to the muscle
– To eliminate more carbon dioxide from the muscle

58. Resting stage
• Breathing rate = 16 – 18 breaths/minute
• Heartbeat rate = 60 – 80 beats/minute
After activities
• Breathing rate = 30 – 40 breaths/minute
• Heartbeat rate = 120 – 150 beats/minute

59. CO2
Water
Carbonic acid pH
Central chemoreceptor
[medulla oblongata]
Impulse
Respiratory centre
Detected by
Impulse
Intercostals muscle diaphragm
Ventilation faster CO2 eliminate faster

60. CO2 affects breathing rate
A large drop in
arterial O2 has little
effect on breathing
rates.
A small amount of CO2 in
the blood stimulates a large
increase in breathing rate.

61. Hyperventilation:
Excessive breathing
-Blood has
abnormally low PCO2
Hypoventilation:
Insufficient breathing
-Blood has
abnormally high PCO2

62. Q: Correlate the rate of respiration with
the rate of heart beat
• During vigorous exercise, the muscle require
more O2 and glucose to release more energy
during cellular respiration. Therefore, the rate of
respiration increases
• In order to supply more O2, the rate and depth of
breathing increases
• This means the breathing rate increases (no. of
breath per minute)
• At the same time, the heartbeat rate increases to
pump more blood into circulation

63. Q: Correlate the rate of respiration with
the rate of heart beat
• This enable more O2 and glucose to be
supplied for cellular respiration and for more
CO2 to be removed from the cells
• The ventilation rate also increases
• Rate of ventilation is the rate of gases
exchange between the alveoli and blood
capillaries

64. In fear
• Breathing & heartbeat rates increase
increase rate of cellular respiration
generate more energy
can cope better in distress or in
fear
• Adrenal glands secretes hormone
adrenaline, increases heartbeat and
breathing rates (more glucose and
oxygen supplied to muscles)
• Prepares the person to respond to
dangerous situation

65. REGULATION OF O2 LEVELS

66. If level of oxygen is severely low (high altitudes)
Sensors on the walls of aorta and carotid arteries
(neck)(peripheral chemoreceptor)
Send nerve impulses to the medulla oblongata
The rate of breathing and ventilation increases
( to obtain more O2) , concentration of O2 back to
normal
The respiratory centre usually does not
respond directly to O2 level

67. Detected by
chemoreceptors in aorta,
carotid artery, and medulla
oblongata in brain
Increase in oxygen
Optimum concentration
of oxygen in blood
Decrease in
ventilation rate (and
in heart rate)
Decrease in
oxygen
Optimum concentration
of oxygen in blood
Decrease in oxygen
Detected by chemoreceptors
in aorta, carotid artery, and
medulla oblongata in brain
Increase in
oxygen
Increase in ventilation
rate (and in heart rate)

68. At high altitudes
• Atmospheric pressure is low, difficult to breathe.
• Partial pressure of oxygen decreases  drop in
blood oxygen level
• Will experience headaches, nausea, dizziness
• After few days, the body will become acclimatised
to the condition as
haemoglobin’s affinity for
oxygen is reduced and more
oxygen is released to body
tissues.

69. Explain this statement:
Persons who are born and live at sea level
will have a smaller lung capacity than those
who spend their life at a high altitude.

70. Answer:
This is because there is less oxygen in
the air at high altitude, so the lungs
gradually expand to process more air.

71. 6.5
Realising the importance of
maintaining
a healthy respiratory system

73. To show the presence
of Tar in Cigarette
Smoke

74. to suction
pump
white cotton wool
U-tube
cigarette
What is the function of the cotton wool ?
The c Ans: otton wool in the U-tube serves to collect tar.

75. to suction
pump
white cotton wool
U-tube
cigarette
What has happened to the colour of the cotton wool
at the end of the experiment ?
Ans: It changes from white to brown.

76. to suction
pump
white cotton wool
U-tube
cigarette
Which substance in cigarette smoke causes the colour
change ?
Ans: Tar.

77. How does smoking effect the gas exchange
system and circulatory system?

78. • Smoking contributes to the following lung
conditions:
– Lung Cancer
– Chronic Bronchitis
– Emphysema
• Smoking also contributes to:
– coronary heart disease
– Ulcers of the stomach and duodenum

79. Harmful Substances in Cigarette
Smoke

80. • In healthy lungs the cells lining the bronchi and
bronchioles have tiny little hairs on them called cilia.
• There are also cells called goblet cells which secrete
mucus.
Ciliated epithelial cell
Cilia Goblet cell Mucus

81. • The mucus traps bacteria and dust to stop it entering
the lungs.
• The cilia waft the mucus up to the throat where it
can be swallowed and destroyed in the stomach acid.

82. • In a smoker the cilia get destroyed.
reduced numbers of cilia  mucus not swept away
 mucus clogs the airways.
• Smoke also irritates the linings of the airways  stimulates
more mucus to be secreted.
• Trapped mucus  more bacteria in the lungs  infections.
• A smokers cough develops to try and cough up the infected
mucus  more irritation and infections.
• This is called chronic bronchitis.

83. • Due to prolonged breathing of irritants

84. • Kills about 20,000 people in Britain a year.
• Smoke damages the alveoli walls  they burst
and fuse together.
• Greatly reduces the surface area for gaseous
exchange.
• Sufferer unable to carry out basic tasks
like walking due to lack of oxygen.
• No cure.

85. • 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

86. • Due to persistent and violent coughing

87. A section from a lung with emphysema showing large
black cavities where many alveoli have burst. These
are also full of tar.

88. http://www.flickr.com/photos/pulmonary_pathology
/
Another image showing the large cavities in
lung tissue created by emphysema.

90. This is a diseased lung showing a large tumour and a
few smaller tumours. It is also black from the tar in
cigarettes.
Large tumour

94. • Smoking increases
blood pressure and
damages blood vessels.
• Increased chances of
developing
cardiovascular disease.
• Arteries become
narrower due to a build
up of cholesterol in the
artery walls.

95. • More likely to get
blood clots.
• Lead to a heart
attack / stroke.

97. What is Passive Smoking?

98. Why do we need to
maintain a healthy
respiratory system ??

101. DON’T SMOKE !!!!!

102. 7.6
Understanding
respiration in plants

103. ENERGY REQUIREMENT IN PLANT
Plants need energy
to carry out living processes
1. Meristems cells - cell
division
2. Root hair cells – active
transport
3. Growth
4. Reproduction

104. Energy requirement in plants
• The energy requirement
for living processes of
plants is lower compared
to animals. Why?
Because plants are less
active than animals. Plants
do not move about like
animal do.

105. The Intake Of Oxygen
By Plants For Respiration
• Plants do not have
specialised breathing
mechanisms for gaseous
exchange.
• Gaseous exchange
between plants cells and
the environment occurs
by diffusion through
stomata and lenticels.

106. stomata

107. lenticels

108. Stomata open during daytime & close at night
stomata may close in bright sunlight in hot dry conditions

109. STOMATA

110. Upper
epidermis
Lower
epidermis
Cuticle
Palisade
mesophyll
Vascular
bundle
Xylem
Phloem
Spongy
mesophyll
Air
space
stoma
O2
CO2

111. Gaseous Exchange in Plants
–depends on the rates of photosynthesis
& respiration
- at daytime with light, stomata open
photosynthetic rate > respiration rate
CO2 absorbed

112. Gaseous exchange in the light
• Stomata open
• O2 from atmosphere
enters leaf through
stomata  air
spaces.
• When the leaf is
photosynthesising, O2
released as waste
product
RESPIRATION
+
PHOTOSYNTHESIS

113. Gaseous exchange in the light
 O2 concentration ↑
in the air spaces than
in the surrounding
cells  O2 diffuses
into the cell
• Difference in
concentration gradient
of O2 cause O2 to
diffuse continuously
into the cell.
RESPIRATION
+
PHOTOSYNTHESIS

114. Gaseous Exchange in Plants
- at night with stomata closed,
∵ no photosynthesis carried out,
only respiration occurred
O2 absorbed

115. Gaseous exchange in the dark
• Stomata are
normally closed at
night.
• < O2 in the air
spaces than
atmosphere.
 O2 diffuses
inward though
lenticels.
 CO2 will diffuse
outwards.
RESPIRATION ONLY
NO PHOTOSYNTHESIS
O2 CO2

116. AEROBIC AND ANAEROBIC RESPIRATION IN PLANTS
2 Types of respiration in plants :
a) aerobic
b) anaerobic

117. Aerobic respiration in plants
• Carried out day &
night by plants
• Need O2
• Waste products =
CO2 & H2O
• O2 concentration in
cells lower than in air
spaces  O2 diffuses
continuously into cells
C6H12O6 + 6O2
 6CO2 + 6H2O + 2880 kJ Energy

118. Aerobic respiration in plants
• O2 combines with
glucose to produce
energy
• CO2 produced during
aerobic respiration is
used in
photosynthesis during
the day because
photosynthesis is
faster than respiration

119. Anaerobic respiration in plants
• Yeast respires anaerobically to produce alcohol
(alcoholic fermentation).

120. Anaerobic respiration in plants
• For short periods.
• During flooding, plants
can survive for several
days completely
submerged in water.
• Young rice plants
respire anaerobically
using its roots in
waterlogged field which
have little or no O2.

121. Anaerobic respiration in plants
• During initial stages of
germination when
embryo is completely
enclosed within an
airtight seed coat.

122. Aerobic & Anaerobic Respiration
in Plants.
C6H12O6 + 6O2
 6CO2 + 6H2O + 2880 kJ Energy
C6H12O6
Aerobic @ Anaerobic ?
 2C2H5OH + 2CO2 + 210 kJ Energy

123. Respiration & Photosynthesis
• Respiration is the reverse of photosynthesis.

124. Compare & Contrast
Respiration & Photosynthesis
Respiration Photosynthesis
Similarities
• Both take place in living cells.
• Both are metabolic process.
• Both needed to maintain levels
of O2 & CO2 in atmosphere

125. Differences
Respiration Photosynthesis
A process of
catabolism (breaking
down of organic
materials)
A process of
anabolism
(synthesis of organic
materials)
Occurs in all living
cells
Occurs in cells
containing
chlorophyll.
Take place in the
presence / absence
of light
Takes place only in
the presence of light

126. Respiration Photosynthesis
Uses glucose and
oxygen
Uses carbon dioxide
and water
Produces carbon
dioxide and water
Produces glucose
and oxygen

127. Respiration Photosynthesis
Chemical energy is
converted into heat
and energy ATP.
Solar energy is
converted into
chemical energy
Cell loses weight Cell gains weight

128. The differences of photosynthesis and respiration

130. CO2 concentrations in air around plants throughout the day

131. Day
CO2 O2

132. night
O2 CO2

133. Compensation point
Light intensity
O2 CO2
All the CO2 produced during respiration is
reused during photosynthesis

134. The Compensation Point
The light intensity
at which
the rate of CO2 production
during respiration is equal
to that of CO2 consumption
during photosynthesis.

135. Graph shows CO2 uptake in plants related to light intensity

137. Daytime
• As light intensity increases,
rate of photosynthesis also
increases.
 quantity of CO2 released
into the atmosphere decrease.
• Because CO2 released during
respiration is used for
photosynthesis.
At night,
• no photosynthesis.
• Only respiration
• CO2 is released into the
atmosphere.
• So CO2 uptake - negative

138. COMPENSATION POINT.
a certain point of light
intensity whereby
the rate of photosynthesis
is equal to the rate of
respiration.
At this point, all the CO2
released from respiration
is equal to the CO2 used
up for photosynthesis.

140. If the rate of photosynthesis and the rate of
respiration remained at compensation point:
• The plant would not be able to store
food.
• There would be no growth and
development in green plants.
• No oxygen released into the
atmosphere to sustain living things.

141. THE END

142. To study the Effect of Light
Intensity on Carbon Dioxide
Exchange in Plants

143. water trough ( to maintain a
constant temperature)
dark dim light control
A B C D
hydrogencarbonate indicator solution
(orange-red at the beginning)
What has happened to the colour of the hydrogen
carbonate indicator solutions in the four boiling tubes ?
Ans: For tube A: red to yellow.
For tube B: red to orange-red or yellow or
purple. . .
aluminum
foil
muslin

144. Ans: For tube C: red to purple.
For tube D: no colour change.
water trough ( to maintain a
constant temperature)
dark dim light control
A B C D
hydrogencarbonate indicator solution
(orange-red at the beginning)
aluminum
foil
muslin
What has happened to the colour of the hydrogen
carbonate indicator solutions in the four boiling tubes ?

145. water trough ( to maintain a
constant temperature)
dark dim light control
A B C D
hydrogencarbonate indicator solution
(orange-red at the beginning)
aluminum
foil
muslin
Explain the differences in the colour of the hydrogen
carbonate indicator solution in the tubes.

146. For tube A:
There is more CO2 than
atmospheric air. No photosynthesis
occurs. Only respiration takes place.
CO2 is given off.

147. For tube B: There is the same amount of
CO2 as in atmospheric air. CO2
given off in respiration = CO2
absorbed in photosynthesis
because the rates of respiration
and photosynthesis are about
the same.

148. For tube C: There is less CO2 than
atmospheric air. All the CO2
given off in respiration is
absorbed for use in
photosynthesis because
photosynthesis rate >
respiratory rate.

149. For tube D: This is the control.
Photosynthesis and
respiration do not occur
because there is no leaf.

150. water trough ( to maintain a
constant temperature)
dark dim light control
A B C D
hydrogencarbonate indicator solution
(orange-red at the beginning)
aluminum
foil
What is the purpose of setting up tube D ?
Ans : For tube D: This is the control. It ensures the
change in CO2 concentration is due to the leaves.
muslin

151. water trough ( to maintain a
constant temperature)
dark dim light control
A B C D
hydrogencarbonate indicator solution
(orange-red at the beginning)
aluminum
foil
What is the purpose of keeping all tubes in a water trough ?
Ans : All four boiling tubes are kept in a water trough as it can
provide constant temperature. It is used to ensure that
light is the only possible factor affecting carbon dioxide
exchange in plants.
muslin

152. water trough ( to maintain a
constant temperature)
dark dim light control
A B C D
hydrogencarbonate indicator solution
(orange-red at the beginning)
aluminum
foil
muslin
What can be concluded about the relationship between
light intensity and amount of carbon dioxide produced
and taken in by the green leaves?

153. Light Intensity
CO2
absorb
CO2
release
Compensation point
photosynthesis rate = respiration rate
Respiration only
Rate: Photosynthesis
> Respiration
Conclusion: