Chapter 7 : respiration

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


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


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


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


INHALATION/INSPIRATION EXHALATION/EXSPIRATION

Diaphragm


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

Chapter 7 : respiration

Education

Transcript of Chapter 7 : respiration