chapter 7 : respiration
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CHAPTER 7RESPIRATIO
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Sub topics7.1 - Understanding the respiratory processes in energy production7.2 - Analysing the respiratory structure and breathing mechanism in human and animal7.3 - Understanding the concept of gaseous exchange across the respiratory surfaces and transport of gaseous in human7.4 - Understanding the regulatory mechanism in respiration7.5 - Realising the importance of maintaining a healthy respiratory system7.6 - Understanding respiration in plants
7.1 Understanding the respiratory processes in energy production
What is respiration??
Refer to the process of obtaining oxygen and delivering it to the cells for cellular respiration and removing carbon dioxide produced by cells
Respiration
External Respiration(Breathing)
Internal Respiration(Cellular respiration)
Aerobic Respiration
Anaerobic Respiration
2 stages
2 types
External respiration (Breathing)
• The exchange of respiratory gases (oxygen and carbon dioxide) between the body and the environment
Internal respiration ( cellular respiration)
• A metabolic process which occurs in cells, involves oxidation of organic molecules to produce energy (in the form of ATP)
• Controlled by enzymes• Two types :1. Aerobic respiration2. Anaerobic respiration
The main substrate to produce energy is
GLUCOSE
Aerobic respiration• Require oxygen• Glucose is completely oxidised to produces
36 to 38 molecules of ATP// 2898 kJ energy (high energy)
• Takes place in the cytoplasm and mitochondria of cells
C6H12O6 + 6O2
6CO2 + 6H2O + Energy (2898 kJ)
Anaerobic respiration• Without oxygen• Glucose is not completely broken down
to energy• Microorganisms live in animal intestine,
in soil or sediment underlying lakes, an active contracting muscle
• Releases only 2 ATP (low energy)• Takes place in the cytoplasm
Muscle cells (anaerobic respiration)
• Prolonged physical activity- O2 supplied not enough- O2 needed > O2 supplied- muscle cells undergo anaerobic respiration
• Muscles in state of O2 deficiency, O2 debt occurred
• Oxygen debt : muscle cells produce ATP without oxygen
• Glucose molecules break down partially into intermediate substance – LACTIC ACID
• Energy low because much of energy still trapped within molecules of lactic acid.
• High concentration of lactic acid may cause muscular cramp and fatigue, tiredness
C6H12O6 2C3H6O3 + Energy (150kJ) lactic acid
• After the activity the person need to breathe deeply and rapidly to inhale more O2- Oxygen is used to oxidise accumulated lactic
acid to form carbon dioxide and water (occur mainly in liver)
Lactic acid + Oxygen CO2 + water + energy
Remaining lactic acid converted into glycogen and stored in muscle cells
• Oxygen debt is paid off when all of lactic acid is removed (increasing breathing rate after vigorous activity)
Oxygen debt – Amount of oxygen needed to remove lactic acid from muscle cells
C6H12O6 + O2
CO2 H2O+ + energy
In yeast• Anaerobic respiration in yeast also
known as fermentation C6H12O6
2CO2 + 2C2H5OH + Energy(210kJ)
ethanol
Zymase
• Ethanol can be used in wine & beer production• CO2 released causes the dough to rise (to make bread)
Why aerobic respiration
produced more energy than anaerobic
respiration???
Comparison between Aerobic Respiration & Anaerobic Respiration
Similarities
• To form cellular respiration• Involve the breakdown of glucose
• Produces energy• Are catalyzed by enzymes
• Occurs in animal and plants
Comparison between Aerobic Respiration & Anaerobic Respiration
Aerobic Respiration Items Anaerobic Respiration
Almost every living cells
Work by Certain plant, yeast, bacteria and muscle
Required Oxygen requirement Not required
Complete oxidation Oxidation of glucose Incomplete oxidation
CO2, Water and Energy
Product YeastCO2, Ethanol and Energy MuscleLactic acid and Energy
Comparison between Aerobic Respiration & Anaerobic Respiration
Aerobic Respiration Items Anaerobic Respiration
Large amount Energy released Small amount
Mitochondria and cytoplasm
Site Cytoplasm
C6H12O6 + 6O2 Glucose ↓
6CO2 + H20 + 2898 kJ Energy
Chemical Equation In Yeast:C6H12O6
Glucose
↓2CO2 + 2C2H5OH + 210 kJ Ethanol Energy
In Muscle cells:C6H12O6
Glucose
↓2C3H6O3 + 150kJ
Lactic acid Energy
38 molecules Number of ATP molecules produced
2 molecules
7.2 Analysing the respiratory structure and
breathing mechanism in human and animal
Adaptations of respiratory structures(General characteristics)
• Respiratory surface is moist – easy for gases to dissolve before diffuse
• Cells lining the respiratory surface are thin – allow rapid diffusion of gases
• Respiratory structure has large surface area – efficient gaseous exchange
addition• Ventilation mechanism
- move gases from respiratory medium respiratory structures- increase the rate of gaseous exchange,
maintain high level of oxygen and low level of c.dioxide at respiratory surfaces
• Respiratory structures covered by a network of blood capillaries – efficient exchange and transport of respiratory gases
The larger the size of organism, the smaller the TSA/V ratio
Protozoa – Unicellular Organism
Oxygen
nutrientsCarbon dioxide
Waste products
The respiratory surface of an unicellular organism is through plasma membrane
• Unicellular has no special structure to absorb oxygen or to expel carbon dioxide
• The gaseous exchange occurs through the entire plasma membrane by simple diffusion
• Concentration of O2 is higher in surrounding water compared in the cell, so O2 diffuse into the cell through plasma membrane by simple diffusion
• Concentration of CO2 is higher in the cell compared to surrounding water, so CO2 diffuse out of the cell through plasma membrane by simple diffusion
Adaptations• Size is small, so has a large surface area to
volume ratio _ so rate of diffusion increases
• The surrounding is wet , plasma membrane constantly moist, so gases easily dissolve and diffuse across respiratory surface.
• Thin plasma membrane, rapid diffusion of gases
Multicellular organism
• Small, flattened, thin body- has high TSA/V ratio, gaseous exchange occur efficiently- do not require specialised gaseous exchange system,
diffuse through the body
• Complex multicellular organism- needs specialised respiratory
stuctures for efficient gaseous exchange- must have large TSA/V ratio
The respiratory structure and
breathing mechanism of fish
The gill of fish
Operculum
The gill of fish
• Four pairs of gills (protected by operculum)• Each gill consists of bony gill arch supporting
two rows of thin gill filament• Each gill filament is composed of numerous
thin-walled lamellae• Lamellae - arranged parallel to each other
- rich with blood capillaries• Lamellae and filament provide a large
surface area for gaseous exchange
• Absorb dissolved oxygen from the surrounding water
• The membrane of the gill filaments is thin – allows the absorption of respiratory gases into the blood capillaries rapidly
• The filaments are supplied with blood capillaries – for efficient exchange and transport of respiratory gases
The structural Adaptation of the gills:a. Thin membrane of filament to allow rapid
diffusion of respiratory gases into the blood capillaries
b. Rich of blood capillaries for efficient exchange and transport of respiratory gases
c. Surrounded by water which enable respiratory gases to be dissolved
d. Large surface area of filaments and lamellae for efficient gases exchange
The Mechanism of Countercurrent Exchange (gaseous exchange efficiently)
a. The water flows over the gills in one directionb. The blood flows in the opposite direction through
blood capillaries in the lamellaec. As deoxygenated blood enters the blood
capillaries, it encounters water with a higher oxygen content
d. Along the blood capillaries, the concentration gradient allow the transfer of O2 into the blood
e. However, the concentration of CO2 is higher than in water, makes the CO2 diffused from blood into water
• The efficiency of fish gills is further increased by ventilation ( by swimming, opening and closing the operculum,)increase in flow of water over respiratory surface
Draws freshwater into mouth, then passes over gills.
• Absorb dissolved oxygen from the surrounding water
• The membrane of the gill filaments is thin – allows the absorption of respiratory gases into the blood capillaries
• The filaments are supplied with blood capillaries – for efficient exchange and transport of respiratory gases
INHALATION EXHALATION
INHALATION
• The floor of the buccal cavity is lowered
• At the same time, the opercular cavity is enlarge and the operculum closes
• This lowers the pressure in the buccal cavity
• Water with dissolved oxygen is drawn into the mouth
EXHALATION
• When the mouth closes, the floor of the buccal cavity is raised
• Water flows through the lamellae and gases exchange between the blood capillaries and water occurs
• The pressure in buccal cavity is higher than the pressure outside
• The higher water pressure forces the operculum to open and water to flow out through the operculum
The respiratory structure and breathing mechanism of
insects
• The respiratory system of insects is the tracheal system (it consists of air tubes called tracheae)
• Air enter the trachea through spiracles which are located at the thorax and abdomen
• Spiracles have valve which allow air go in and out of the body
• Tracheae reinforced with rings of chitin – prevent from collapsing
• The branching of trachea and tracheoles increase the surface area for gases exchange
• Certain insects have air sacs in tracheal system
• Contain air that speeds up movement of gases to and from tissues during vigorous body movement.
The tracheal system of an insectBody wall
spiracle
tracheole
Body cellTrachea
(Reinforced with rings of chitin which prevent from collapsing)
AIR
ADAPTATIONS OF TRACHEOLES• Large number- provide large surface area for
gases exchange• Tip of tracheoles have thin permeable wall –
allow rapid diffusion of respiratory gases• Tips of tracheoles have fluid-allow
respiratory gases to dissolve• Direct contact with tissues and organs,o2
directly diffuse into the cells, and co2 directly diffuse out of the cells (no need blood to transport)
• Larger insects like grasshopper have air sacs in their tracheal system which speed up the movement of gases
BREATHING MECHANISM• Rhythmic contraction and relaxation of
abdominal muscles• The movement of abdominal muscle will
compress and expand the trachea to speed up the diffusion of gases into the cell
• Inhales – abdominal muscles relax, spiracles open
- air pressure inside tracheae lowered, air drawn in
• Exhales – abdominal muscles contract
- air pressure increased, air forced out through
spiracles
Circulatory system not involved in transporting O2 and CO2
The respiratory structure and
breathing mechanism of amphibians
The respiratory structure in an amphibian
Skin
Lung
Adaptation of the skin for gases exchange
1. The skin is thin and highly permeable
- To allow rapid diffusion of respiratory gases into the blood capillaries
2. Beneath the skin is a
network of blood
capillaries
- To transport respiratory gases to and from body cells
3. The skin is kept moist by the secretion of mucus by
glands found on the outer
surface of the body
- Facilitate rapid and efficient exchange of
gases between the skin and the
environment
Adaptation of the Lung for gases exchange
1. The surface area for gases exchange is increased by
numerous inner partition
- To increase the surface area for gases exchange
2. Covered with a rich network
of blood capillary
- To transport respiratory
gases to and from body
cells
3. The membrane of the lungs thin
and moist
- Facilitate the efficient
diffusion of respiratory
gases in and out rapidly
The Breathing Mechanism of FrogINHALATION
1. During inhalation, the air is drawn into the bucco-pharyngeal cavity through a nostril
2. The glottis is closed and the stale air remains in the lungs
3. When the glottis open, the nostrils are closed4. The increased air pressure forces air into the lungs5. The lungs expand when air is pushed into them from
bucco-pharyngeal cavity 6. The rapid movements of bucco-pharyngeal floor, this
will accumulate fresh air for ventilation
The Breathing Mechanism of Frog
EXHALATION
When the lungs muscles contract, air is expelled from the lungs (with the help of abdominal pressure and elasticity of the lungs)
Some air escapes through the nostrils while the rest of the air mixes with that in the bucco-pharyngeal cavity
Respiratory Structure of Humans
1. Gases exchange in humans take place in the lungs.
2. Air enters the lungs the lungs through:Trachea →Bronchi → Bronchioles → Alveoli
3. Trachea is supported by cartilage which keep it from collapse during inhalation
The human lung
Rib cage (protect the lungs)
Alveoli
Features of Alveoli and the Function In Gases Exchange
Walls are made of a single of cells
Large number of alveoli in the lungs
Walls secrete a thin lining of moisture
Surrounded by a network of blood capillaries
Increased surface area for gases exchange
Gases can diffuse rapidly across the thin walls
Gases can dissolve in moisture and diffuse easily across walls
Can transport oxygen and CO2 efficiently
Breathing Mechanism in Humans
INHALATION
1. External intercostal muscles contract2. Internal intercostal muscle relax3. The rib cage move upwards and outwards4. The diaphragm muscle contracts and flattens5. Volume of the thoracic cavity increase resulting in
reduced air pressure in alveoli6. Higher atmospheric pressure outside causes the air to
rush in
Breathing Mechanism in Humans
EXHALATION
1.External intercostal muscles relax2.Internal intercostal muscle contract3.The rib cage mobe downwards and inwards4.The diaphragm relaxes and returns to
dome-shaped5.Volume of thoracic cavity decrease
resulting in higher air pressure in alveoli6.Air is forced out of lungs
Breathing Mechanism in Humans
INHALATION/INSPIRATION EXHALATION/EXSPIRATION
Diaphragm
Breathing Mechanism in Humans
INHALATION/INSPIRATIONEXHALATION/EXSPIRATION
Structures Inhalation Exhalation
External intercostal muscles
Internal intercostal muscles
Rib cage
Diaphragm
Volume
Pressure
Air flow
Compare and contrast the human respiratory system with that of other organisms
AdaptationOrganisms
Large surface
area
Respiratory structure
Moisture Network of blood
capillaries
Protozoa Small size Plasma membrane
Dissolved gases
None
Insects Numerous tracheoles
Tracheoles Tip of tracheoles
None
Fish Numerous filaments and lamellae
filaments and lamellae
Dissolved gases
Available
Amphibians Lungsskin
Lungs and skin
Wet skin Available
Humans Numerous alveolus
alveoli Moist surface
Available
The gases exchange occurs at two parts:
a. Between the surface of alveolus – blood capillaries
b. Between the blood capillaries – body cells
Gases exchange (alveoli-blood capillary)
High Partial Pressure of O2
Low Partial Pressure of O2
Gas Partial pressure EffectsAir in the
alveoliBlood
capillariesO2 High Low O2 diffuses
from the alveoli into the blood
capillariesCO2 Low High CO2 diffuses
from the blood capillaries into
the alveoli
The differences between the partial pressure of O2 and CO2 in the air of the alveoli and in the blood capillaries
Oxygen
Body cells
Gases exchange (blood capillary-body cells)
High Partial Pressure of
O2
Low Partial Pressure of
O2
Gas Partial pressure EffectsAir in the
blood capillaries
Body cells
O2 High Low Oxyhaemoglobin breaks down and releases O2
which then diffuses through the capillaries
walls into the body cellsCO2 Low High CO2 produces from
cellular respiration diffuses from the body
cells into the blood capillaries
The differences between the partial pressure of O2 and CO2 in the air in the blood capillaries and body cells
Oxygen ( blood capillary- body cells)
The partial pressure of oxygen in the blood capillary is higher than in the tissue fluid
Oxyhaemoglobin breaks up into oxygen and haemoglobin
Oxygen diffuses out of the blood capillary into the tissue fluid and then to the tissues
a) Transport of O2 from lungs to body cell1. O2 in the blood that leaves the alveoli is transported to body cells for cellular respiration2. O2 is combines with a pigment called haemoglobin which is contained in the red blood cells3. A haemoglobin molecule consists of 4 units, each with a heme group that has a ferum atom at its centre4. O2 is carried in the form of oxyhaemoglobin to all parts of the body:
The Transport of Respiratory Gases in Humans
Haemoglobin + O2 → Oxyhaemoglobin
b) Transport of CO2 from body cells to lungsCO2 released by body cells can be transported in 3 ways:
• Carbonic acid (7%) - CO2 dissolve in water in the blood plasma
• Carbaminohaemoglobin (23%) - CO2
combines with haemoglobin • Bicarbonate ions (HCO3-) (70%) –Form from
the breakdown of carbonic acid
The Transport of Respiratory Gases in Humans
Carbon dioxide ( body cells-blood capillary)
The partial pressure of CO2 in the body cells/tissue fluid is higher than in the blood capillary
CO2 diffuses into the blood capillary
• Small amount is taken up by haemoglobin in the form of carbaminohaemoglobin
carbon dioxide + haemoglobin
carbaminohaemoglobin
• Most of CO2 combines with water to form carbonic acid
• Carbonic acid will break down into bicarbonate ions
• The reaction is catalysed by carbonic anhydrase enzyme in the red blood cell
CO2 + Hb
Carbaminohaemoglobin
CO2 + H2O
H2CO3 (carbonic acid)
HCO3-
(Bicarbonate ion)
H+
Blood plasma
Carbon dioxide ( blood capillary-alveoli)The partial pressure of CO2 in the alveolus is lower than
in the blood capillary
Bicarbonate ions diffuses from the blood plasma into the red blood cell to form carbonic acid
Carbonic acid breaks down to CO2 and water
CO2 diffuses from the blood capillary to the alveoli
The composition of inhaled and exhaled air
Content Inhaled air Exhaled air
Oxygen 21.09 % 16.4 %
Carbon dioxide
0.03 % 4.1 %
Nitrogen 79.0 % 79.0 %
Water vapour
VariesNever
saturated
Saturated
Temperature
RoomTemperature
Body temperature
7.4 Understanding the regulatory
mechanism in respiration
• All metabolic process need energy• The rate of cell respiration is directly related
to the energy requirement of the body• An increase in activity will increase the rate
of ventilation
• 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
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
Correlate the rate of respiration with the rate of heart beat
The change in breathing rate after completing a
vigorous exerciseUnder normal condition - 15 to 20 times per
minuteAfter vigorous exercise – 30 to 35 times per
minute
The change in rate of heartbeat after
completing a vigorous exercise
Under normal condition – 60 to 70 beats per minute
After vigorous exercise – 120 beats per minute
Intercoastal muscles & diaphragm
Respiratory Control Centre
( Medulla oblongata )
impulses
Also helps to monitor CO2
level & regulating the amount of CO2 released during
exhalation
Control the respiration rate
Active cellular activity
CO2 level will
increase
Reduce the pH level of the blood
Detected by the central chemoreceptor in medulla
oblongata
Increase the rate of
breathing and ventilation
Diaphragm and intercoastal
muscles (contract and relax faster)
Normal concentration of
CO2 and pH value
In fear• Breathing and heartbeat rates increase to
increase rate of cellular respiration in cells.• Higher rate of cellular respiration needed to
generate more energy, so 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
Peripheral chemoreceptor• Aortic bodies (aortic arch) and carotid bodies
(carotid artery) • Sensitive to both the CO2 content and pH of
blood.• If level of oxygen is severely low (high
altitudes), peripheral chemoreceptor stimulated and send nerve impulse to respiratory centre
At high altitudes• Atmospheric pressure is low, difficult to
breath• Partial pressure of oxygen decreased, drop in
oxygen level of blood• 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 released to body tissues.
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
6.5 Realising the importance of maintaining a
healthy respiratory system
Why there’s a need to maintain a healthy respiratory system ??
• Try to avoid living in a polluted environment- because poisonous substances from the
atmosphere could damage the lungs
• Wear mask
• Do Not SMOKING !!!!
Healthy lungs Diseased lungs
DON’T SMOKE !!!!!
7.6 Understanding respiration in plants
The energy requirement in plants
• Plants need energy to carry out living processes :
1. Meristems cells - cell division2. Root hair cells – active transport3. Growth4. Reproduction
Aerobic respiration
C6H12O6 + 6O2
6CO2 + 6H2O + 36 ATP
Anaerobic respiration
C6H12O6
2CO2 + 2C2H5OH + 2ATP
ethanol
The intake of oxygen for respiration
Stomata
Lower epidermis
Upper epidermis
Cuticle
Palisade mesophyll
Vascular bundle
Xylem
Phloem
Spongy mesophyll
Air space
stomaO2
CO2
• Photosynthesis occurs during the day• O2 from photosynthesis is used up during
respiration• CO2 from respiration is used in photosynthesis• If photosynthesis rate is higher the excess O2
is removed out• Gaseous exchange also occur through lenticel
(the pores on the surface of root and stem
oxygen
Carbon dioxide
chloroplast mitochondria
Compensation Point
The point reached in a plant when the rate of photosynthesis is equal to the rate of respiration
Night
• Photosynthesis does not take place• Only respiration take place• Carbon dioxide is released to into the
atmosphere
Low light Intensity
• as the light intensity increases, the rate of photosynthesis also increases
• it will come to a certain stage where all the carbon dioxide released during respiration is used up in photosynthesis ( p/s = r )
• at this point there is no accumulation of sugar and oxygen
High Light Intensity
• When the light intensity is higher than the c.p , the rate of photosynthesis is higher than the rate of respiration
• Carbon dioxide is absorbed from the atmosphere
• There is an accumulation of sugar and oxygen
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