7.1 The Respiratory Process in Energy Production

All living processes require energy.Eg:

o Muscle contractiono Active transporto Transmission of nerve impulseo Synthesis proteinso Formation new protoplasm for

growtho Cell division

Two types of respiration:o External resp. : a mechanical process

that maintain a continuous exchangeof gases between the respiratorysurfaces on an organism and utsenvironment.

o Internal resp. (cellular respiration) :biochemical process in which energyis made available to all living cells.

RESPIRATION : process of obtaining O2 anddelivering it to the cells for cellular respirationand removing CO2 produced by the cells.

Main substrate for producing energy glucose.

TWO types of cellular respiration:o Aerobic respirationo Anaerobic respiration

Explain the energy production from glucose duringthe process of aerobic respiration

- A process where the breakdown of glucoseinvolves the use of O2.

- Requires continuous supply of O2 whichobtained from the air during externalrespiration.

- CO2 and H2O always produced as wasteproducts.

- Occurs in the mitochondria.- Can be represented by:

- Organisms showing aerobic respiration arecalled aerobes.

- Energy released used to convert ADP to ATP(instant energy).

- To use energy stored in ATP, the ATPmolecule must be broken down again to ADP.

State the condition leading to anaerobic respiration incells

- Prolonged physical activity: cells are forced todo work without enough O2 supply. Bodyusing more ATP quickly than the lungs andcirculatory system can deliver O2 to the cellsfor cellular respiration.

- Cells continue generating ATP without usingO2.

Explain the process of anaerobic respiration in humanmuscles

- Anaerobic respiration occurs in cytoplasm.- Occurs in condition: fast running, fast walking,

swimming.- Vigorous exercise causing an increased in

heartbeat rate, breathing rate.- Blood cannot supply O2 fast enough to meet

demand for ATP (O2 debt).- Therefore, muscles obtain the extra energy

from anaerobic respiration.o Glucose molecules break down

partially into lactic acid.o can be represented by :

- When level of lactic acid concentration is high,causing muscular cramps and fatigue.

- When one rests after an exercise, the lacticacid gets slowly oxidized by the O2 which isavailable later on.

- O2 debt is said to have been paid (cleared)when all the lactic acid has been eliminatedthrough increased breathing.

- Can be represented by:

C6H12O6 + 6O2 6CO2 + 6H2O + 2898kJ (38 ATP)Glucose oxygen carbon water energy

dioxide

C6H12O6 2C3H6O3 + 150kJ (2 ATP)Glucose lactic acid

2C3H6O3 + 6O2 6CO2 + 6H2O + energyLactic acid oxygen carbon dioxide water

Explain the process of anaerobic respiration inyeast

- Organims respire anaerobically known asanaerobes.

o Eg: bacteria, yeast.- Occurs in cytoplasm.- Producing ethanol.- Catalysed by zymase enzyme (fermentation

process).

Compare and contrast aerobic respiration withanaerobic respiration

DifferencesAerobic respiration Anaerobic respiration

Glucose are oxidized inthe presence of O2

Glucose are oxidized inthe absence of O2

Occurs in mitochondria Occurs in cytoplasmComplete oxidation ofglucose to CO2 and H2O

Incomplete oxidation ofglucose into lactic acid or

ethanol.38 ATP molecules

released2 ATP molecules released

Occurs in most animalsand all higher organisms

Occurs in lowerorganisms such as yeast,

bacteria, germinatingseeds and cells of higher

organisms such asskeletal muscles.

7.2 The Respiratory Structures and Breathingmechanisms in Humans and Animals

Adaptation of RESPIRATION: GAS EXCHANGE

- Supplies oxygen for cellular respiration(metabolism) and disposes of waste (CO2)

- gas travels through resp. surface via diffusion- vertebrates are large, so must have a complex

system of respiration- Aquatic animals: Gills- Terrestrial animals: Lungs- Unicellular organism (eg: Amoeba sp.) :

gaseous exchange occurs over the wholeplasma membrane.

Characteristics of respiratory surfaces in humans andother organisms1 The resp. surface is moist2 Cells lining the respiratory surface are thin3 The respiratory structure has a large surface area4 The resp. surface are permeable to the

respiratory gases (O2 and CO2)

Adaptation of respiration for insects1. Respiratory system of insects is tracheal

system.2. Tracheal system of insect consists of spiracle,

trachea, air sac and tracheoles.

3. Tracheal system consists of air tubes calledtracheae

4. Air enters the tracheae through spiracles5. Spiracles have valves which allow air, go in

and out of the body6. Tracheae reinforced with rings of chitin which

prevent them from collapsing7. Trachea split into numerous finer tubes called

tracheoles8. Large number of tracheoles provides large

surface area for diffusion of gases9. Tracheoles :10. So tiny, can channel O2 directly to the cells in

the different parts of body11. Are numerous , increase total surface area12. Have thin and moist wall at the end of tip ,

make it easy for respiratory gases to bedissolved

13. Larger insects like grasshoppers have air sacsin their tracheal system to speed upmovement of gases to and from the insect’stissue

both are cellularrespiration

both use glucose asthe source of energy

energy is stored inATP molecules

both are catalysed byenzymes

similarities

C6H12O6 zymase 2C2H5OH + 2CO2 + 210 kJGlucose ethanol carbon energy

dioxide

Adaptation of respiration for fish1. Respiratory structures of fish – gills2. Bony fish have 4 pairs of gills which are protected

by operculum3. Gill consist of filaments which supported by gill

arch4. Filament s have a thin wall called lamellae5. Structural adaptation of the gills: Thin membranes allow the absorption of

respiratory gases into the blood capillaries Rich of blood capillaries – efficient and

transport of respiratory gases Surrounded by water – enable respiratory

gases to be dissolve Large surface area of filaments and lamellae

for efficient gases exchange6. Efficiency of gaseous exchange is further

enhanced by countercurrent exchangemechanism

7. Mechanism of Countercurrent Exchange- Water flows over the gills in one direction- Blood flows in the opposite direction

through blood capillaries in the lamellae- As deoxygenated blood enters the blood

capillaries, it encounters water with higherO2 content

- Along the blood capillaries, conc gradientallows the transfer of O2 into the blood

- However, conc of CO2 in blood is higherthan in water. So CO2 diffused from bloodinto water

8. Breathing mechanism of fishWhen Inhale

- Its mouth opens, buccal cavitylowered.

- Operculum closes, opercular cavitybecomes bigger

- Resulted in lower pressure in thebuccal cacity

- Water is then drawn into its mouthalong with dissolved O2.

When exhale

- Its mouth closes, raising buccal cavityfloor.

- As water flows through lamellae,respiratory gases are exchangesbetween blood capillaries and water.

- As this occurs, the opercular cavitybecomes smaller.

- High pressure in buccal cavity forcesthe operculum to open allowingwater to flow out.

Adaptation of respiration for amphibian (Eg: Frog)1. Amphibians such as frog live on land and in

water2. Gaseous exchange occur through skin and

lungs3. Adaptation of the skin for gaseous exchange:

o skin is thin and highly permeable – allowthe absorption of respiratory gases intothe blood capillaries

o beneath the skin is a network of bloodcapillaries – to receive O2 and transport itto body cells

o skin is moist by secretion of mucus –facilitate rapid and efficient exchange ofgases between the skin and theenvironment

4. Adaptation of the lung for gaseous exchange:- Surface area for gases exchange is

increased by numerous inner partition –facilitate the efficient diffusion ofrespiratory gases in and out rapidly

- Covered with a rich network of bloodcapillaries – to receive O2 and transport itto body cells

- Membrane of the lungs are thin and moistto increase the surface area for gasesexchange

5. Breathing mechanism of amphibianWhen inhale- When a frog inhales, it breathes in

through its nostrils.- The bucco-pharyngeal floor is lowered

and fresh air is drawn in.- At the same time, its glottis closes, and air

remains in the lungs.- Afterwards, the glottis opens.- Its nostrils are then closed and bucco-

pharyngeal floor is raised.- This causes high air pressure which forces

air into its lungs thus expanding them.

When Exhale

- Its lungs muscles contract, expelling airfrom its lungs

- A frog does this by the abdominalpressure and elasticity of the lungs.

- Some of the air flows out of its nostrilsand some mixes with air in the bucco-pharyngeal cavity.

Adaptation of Respiration for Humans

1. Gaseous exchange in humans take place inthe lungs

2. Air enters lungs through :trachea bronchi bronchioles alveoli

3. Trachea is supported by cartilage to prevent itfrom collapse during inhalation

4. Features Of Alveoli And The Function InGaseous Exchange

- A large number of alveoli in the lungsto increase the surface area forexchange of gases

- Walls are made up of a single layer ofcells – gases can diffuse easily acrossthe thin walls

- Walls secrete a thin lining of moisture– gases can dissolve in moisture anddiffuse easily across walls

- Surrounded by a network of bloodcapillaries – can transport O2 to andCO2 away from the cells

5. Breathing mechanism in human

EXHALATION

External intercostal muscles relaxInternal intercostal muscles contractRib cage move downwards and inwards

Diaphragm relaxes and returns to dome-shapedVolume of thoracic cavity decrease resulting inhigher air pressure in alveoli

Air is force out of lungs

INHALATION

External intercostal muscles contract

Internal intercostal muscles relax

Rib cage move upwards and outwards

Diaphragm contracts and flattens

Volume of thoracic cavity increase resulting inreduced air pressure in alveoli

Higher atmospheric pressure outside causes airto rush in

7.3 GASEOUS EXCHANGES ACROSS RESPIRATORYSURFACES & TRANSPORT OF GASES IN HUMANS

How does the gaseous exchange happen betweenthe alveolus and the blood capillaries?

Gaseous exchange happens between thealveolus and the blood capillaries throughdiffusion.

The O2 concentration or partial pressure ofO2 in the alveolus is higher than the bloodcapillaries.

O2 from the alveolus diffuses into the bloodcapillaries.

The blood capillaries carry CO2 from bodycells to the alveolus.

So, it has a higher partial pressure of CO2compared to the air in the alveolus.

CO2 diffuses into the alveolus and then it isbreathed out through the nose or mouth.

TRANSPORT OF RESPIRATORY GASES IN HUMAN

a) Transport of O2 from lungs to body cell

After the gaseous exchange happens betweenthe alveolus and the blood capillary, the O2from the blood capillaries must betransported to the body cells and tissues forcellular respiration.

O2 combines with haemoglobin (Hb) to formOxyhaemoglobin.

Hb is the red pigment in the red blood cells. O2 in the form of Oxyhaemoglobin is caries to

the cells and tissues. For the O2 to dissolve in the cells and tissues

that need them, partial pressure of O2 playsan important role.

The Oxyhaemoglobin is not stable, so it will bebroken down into Hb and O2 when it reachesthe cell or tissue with low partial pressure ofO2.

b) Transport of CO2 from body cells to lungs

At the same time the CO2 will diffuse into theblood capillary.

CO2 released by respiring cells diffuses intothe blood plasma and into the red blood cells(RBC).

CO2 can be transported from the body cells tothe lungs through three ways.

7% dissolves into the plasma. 23% binds to the multiple amino groups of Hb

(Carbaminohaemoglobin). And 70% is carried as bicarbonate ions. The reaction between the CO2 with water

forms carbonic acid. Carbonic anhydrase, an enzyme in the RBC

catalysed the reaction. The carbonic acid then breaks into a

hyf\drogen ion and a bicarbonate ion. The bicarbonate ions diffuse into the blood

plasma and carried to the lungs. At the lungs, the process that happens is the

reverse of what happens in the tissue.

Process1 The bicarbonate ions diffuse from the

blood plasma into the RBC and formcarbonic acid.

2 Carbonic acid breaks down to CO2 andwater.

3 CO2 diffuse from the blood capillariesinto the alveolus.

4 CO2 is breathed out through the nose ormouth.

The CO2 than is carried through the plasmadiffuses into the alveolus.

The carboxyhaemoglobin that is carried byRBC will break down intoCO2 and Hb and CO2diffuses into the alveolus.

7.4 THE REGULATION MECHANISM IN RESPIRATION

CORRELATION RATE OF RESPIRATION WITH O2 ANDCO2 CONTENTS IN THE BODY

1. During vigorous exercise, muscles requiremore O2 and glucose to release E duringcellular respiration. So, rate of respirationincrease.

2. Thus, to supply more O2, rate and depth ofbreathing increase.

3. At the same time, the heartbeat increase topump more blood into circulation.

o this enable more O2 and glucose to besupplied for cellular respiration and moreCO2 removed from the cells.

o rate of ventilation increase.rate ofventilation is the rate of gaseousexchange between alveoli and bloodcapillaries

REGULATORY MECHANISM OF O2 CONTENT IN THEBODY

HUMAN RESPIRATORY RESPONSE & RATE OFRESPIRATION IN DIFFERENT SITUATIONS

MAINTAINING A HEALTHY RESPIRATORY SYSTEM

Do not smoke Smoking can causes emphysema, bronchitis,

and lung cancer. Smoking also can cause laryngitis which

makes speaking painful. There are lots more effects of smoking to

lungs. Not only the smokers suffer, but those who

breathe the smoke also can be affected.

7.6 RESPIRATION IN PLANTS

ENERGY REQUIREMENT IN PLANT

Plant require energy from cellular respiration During cellular respiration, plant cells take in

O2 and produce CO2. Photosynthesis only occurs in the presence of

light. In darkness, plants carry out respiration.

Plants need energy continuously to sustaintheir living process

Intake of O2 for respiration Stomata and lenticels are structures

that are related to the gaseousexchange in plants.

Stomata are openings in theepidermis of a leaf.

They have a mechanism for openingand closing. They open to let in O2

and release CO2. Lenticels are small openings on the

surface that usually found in stems.

Plants do not have specialized organsfor gaseous exchange.

Most plants take in O2 through leaves,stems and roots because they havelarge surface area for gaseousexchange.

Gaseous exchange happens by simplediffusion through stomata in theleaves and lenticels on the stems androots.

The exchange of O2 in plants can occurin the day or at night.

In general, stomata are open duringthe daytime when photosynthesis isactive, and then closed at night, whenopen stomata would only lead towater loss.

However, stomata may be closedeven in bright sunlight under hot, dryconditions in which waterconservation is a matter of life anddeath.

O2 from the atmosphere goes into thelead through stomata into the airspace in leaf.

O2 is also given out as a waste productof photosynthesis during the day.

The concentrations of O2 in the airspaces become higher than thesurrounding cells.

As a result, O2 diffuses into the cells.

The differences in concentrationgradient of O2 facilitate O2 to diffusecontinuously into the cell.

AEROBIC AND ANAEROBIC RESPIRATION INPLANTS

1. Types of respiration in plantsa. Aerobic respirationb. Anaerobic respiration

Aerobic respiration in plants

Aerobic respiration is carried out byplants in the presence of O2.

During aerobic respiration, O2

concentration in the cell is lower than theconcentration of O2 in the air spaces.

It causes O2 to diffuse continuously intothe cell.

It combines with glucose to produceenergy.

This type of respiration is frequentlycarried out by plants throughout the dayand night.

CO2 produced during aerobic respirationis used in photosynthesis during the daybecause photosynthesis is faster thanrespiration.

equation:

Anaerobic respiration in plants

Under certain circumstances, plantscan also carry out anaerobicrespiration for short period.

Basically, anaerobic respirationhappens during the absence of O2.

During floods, plants can survive formany days submerged in the waterrespiring anaerobically.

Rice plants are one good example ofanaerobic respiration.

Young rice plants can respireanaerobically using its roots in thewaterlogged field which have little orno O2.

Anaerobic respiration also happensduring early stages of germinationwhen the embryo is completelyenclosed within airtight seed coat.

Equation:

SIMILARITIES AND DIFFERENCES OFPHOTOSYNTHESIS AND RESPIRATION

Photosynthesis RespirationSimilarities

Both are metabolic processes.Both processes are needed to sustain life.

Both are needed to maintain composition of CO2

and O2 in the air.Differences

Occurs in chloroplast Occurs in mitochondriaOccurs in sunlight Occurs in the dark as

well as in sunlightSolar energy is

converted into chemicalenergy and stored in the

form of glucose.

Chemical energy inglucose is converted intoheat and useful energy,

the ATP releasedReleases O2 Uses O2

Combines CO2 andwater to produce

glucose. It is an anabolicprocess.

Breaks down glucose toproduce CO2, water andenergy. It is a catabolic

process.

Graph shows CO2 uptake in plants related tolight intensity

At night, photosynthesis does not take place.Only respiration takes place. CO2 is releasedinto the atmosphere.

So, the CO2 uptake is denoted as negative. As light intensity increases during the day

light, the rate of photosynthesis alsoincreases. It causes the quantity of CO2

released into the atmosphere to decrease. This is because CO2 released during

respiration is used for photosynthesis. This correlation continues until it reaches a

certain point of light intensity whereby therate of photosynthesis is equal to the rate ofrespiration.

At this point, all the CO2 released fromrespiration is equal to the CO2 used up forphotosynthesis.

This point of equilibrium is called thecompensation point.