chapter7 respiration f4 bio

RESPIRATION

•Two stages of respiration:

1.External respiration

2.Internal respiration

•External respiration

- a mechanical process that enable exchange of gases between the respiratory surfaces of an organism and the environment

•Internal respiration / cellular respiration

- biochemical process that produce energy

to the cells

- organic molecules are oxidised to

release chemical energy

Cellular respiration

Aerobic respiration Anaerobic respiration

Energy production in aerobic respiration

•Aerobic respiration require oxygen from the air or water

oxygenBlood

Circulatorysystem

Cells

Glucose

•Inside the cells oxygen are used to oxidized glucose molecules and release energy

oxygen

glucose

C6H12O6 + 602 6CO2 + 6H2O + 2898 kJ energy

•Energy stored inside the glucose molecules are fully release in aerobic respiration

oxygen

glucose

energy

•ATP are synthesized by from the energy released by aerobic respiration

ADP + phosphate + energy ATP

- Living things needs ATP as the main energy supply

ATP ADP + phosphate + energy

Energy released

Anaerobic respiration

•The break down of glucose when there is no oxygen or low concentration of oxygen

•Anaerobes are organisms that does not use oxygen to respire

•Examples – yeast, bacteria, contracting muscle

•The site for anaerobic respiration is the cytoplasm

Anaerobic respiration in human muscles

•When the body is not doing rigorous activity, aerobic respiration is able to supply the body cells with oxygen and produce energy for synthesizing enough ATP

•High rate physical activity (running )

- ATP is used in higher rate

- energy supply are not enough for the

muscle to do work

- Respiratory system and circulatory system cannot deliver enough oxygen for the cells for cellular respiration

•Muscle cells generate ATP without oxygen through anaerobic respiration

•Running

- increased breathing rate, heartbeat rate

- blood cannot supply enough oxygen to

the muscle

- the rate of oxygen used exceeds the

amount of energy supply

-The muscle are in state of oxygen

deficiency, an oxygen debt occur

- muscle obtain extra energy from

anaerobic respiration

- the glucose molecules break down

partially into lactic acids

- energy released in anaerobic respiration

is less than the energy released during

aerobic respiration

C6H12O6 2C3H6O3 + 150 kJ

lactic

acid

•Much of energy is still trapped within the molecules of lactic acid

•The accumulation of lactic acid can reach a high level and cause muscle cramps and fatigue

•After running a person need to breathe in deeply and rapidly to inhale more oxygen

•Excess oxygen is used to oxidize the lactic acid to carbon dioxide and water

Lactic acid + oxygen carbon dioxide + water + energy

•Oxidation of lactic acids occurs mainly in the liver

Lactic acidLiver

Energy Glycogen stored in

muscle

•The oxygen debt is paid off when all the lactic acid is removed

•Oxygen debt is the amount of oxygen needed to remove lactic acid from the muscle

Anaerobic respiration in yeast

•Yeast normally respires aerobically

•Anaerobic respiration in yeast produces ethanol, carbon dioxide and energy

•C6H12O6 2C2H5OH + 2CO2 + 210 kJ

ethanol energy

•Anaerobic respiration in yeast also known as fermentation, catalyzed by enzyme zymase

•Ethanol - wine, beer

•Carbon dioxide – used in bread making

- cause the dough to rise

Assignment

List the differences between aerobic and anaerobic respiration

The respiratory structure and breathing mechanisms in humans and animals

•The respiratory structure have structural adaptations to maximize the rate of gaseous exchange

•Gaseous exchange between the respiratory surface and the environment takes place by diffusion

•Cellular respiration depletes the oxygen in cells, increase the carbon dioxide levels

•The concentration gradient result in the diffusion of oxygen into the cells and the diffusion of carbon dioxide out of the cells

Unicellular organisms

-Amoeba sp.

-Respiratory surface is the entire plasma membrane

-Have a large surface area compared to the volume of their bodies

-Gases exchange through simple diffusion

- Aquatic habitat – plasma membrane is constantly moist – respiratory gases easily dissolve across respiratory surface

-Thin plasma membrane – rapid diffusion of gas

-Small multicellular organisms also do not require a specialised gaseous exchange system

•Examples : flatworms

•Large size organisms – smaller surface to volume ratio

- the volume of the body that require oxygen is greater than its surface area

•Oxygen cannot be deliver to the internal organs effectively

•Complex multicellular organisms need specialized respiratory structure for efficient gaseous exchange

The characteristics of respiratory structure in complex multicellular organisms

a.High surface to volume ratio for efficient gaseous exchange

b.Cell lining the respiratory structure are thin

c. The surface of the gaseous exchange are constantly moist for respiratory gases to dissolve

The respiratory structure and breathing mechanism of insect

•Known as tracheal system

•Composes of a network of air tubes called tracheae

Air Spiracles

Have valves

trachea Tracheoles

•Certain insects have air sacs in the tracheal system that speeds up the movement of gases to the tissues and from the tissues

Structural adaptations of tracheoles for gaseous exchange

•Tracheoles branch intricately throughout the body and penetrate the body tissues

•Can channel oxygen directly to the cells in different parts of the body

•Large number of tracheoles provide large surface area for the diffusion of gases

•The tips of the tracheoles have thin permeable walls and contain fluid in which the respiratory gases can dissolve

Breathing mechanism of insects

•Inhale and exhale through contraction and expansion of their abdominal muscle and body movements

•Inhales – abdominal muscles relax and the spiracles open

•Air pressure inside the trachea decrease – air is drawn in

•Exhales – abdominal muscles contract

•Air pressure increase – air is forced out through the spiracles

•The tracheal tubes carry oxygen from the air directly to the body cells

•No need for circulatory system

The respiratory structure and breathing mechanism in fish

•Gills are specialised respiratory structures for gaseous exchange in water

•Gills are supported by a gill arch and protected by the operculum

Structural adaptation of gills for gaseous exchange

1. Large surface area of the filaments and lamellae increases the efficiency of gaseous exchange in fish

2. The membrane of the gills filaments is thin – allow absorption of respiratory gases

3. Filaments supplied with blood capillaries – efficient exchange and transport of gases

4. Countercurrent exchange mechanisms – the blood in the blood capillaries flows in opposite direction of the water flows through the gills

•Deoxygenated blood enters the blood capillaries, encounters water with a higher oxygen content

•

Concentration gradient in the blood capillaries allows the diffusion of oxygen into the blood

•Ventilation – increase in the flow of water over respiratory surfaces

- swimming

- opening and closing of the operculum

The breathing mechanism of fish

Inhalation

-The floor of the buccal cavity lower

-The opercular cavity enlarges and the operculum closes

Opercular cavity

operculum

-This lowers the pressure in the buccal cavity

- Water with dissolved oxygen is drawn into the mouth

Exhalation

-Mouth closes, the floor of the buccal cavity raises

-Water flows through lamellae –gaseous exchange between blood capillaries and water

-Opercular cavity becomes smaller

-Pressure inside buccal cavity higher than the pressure outside

- Higher water pressure forces operculum to open – water flow out through operculum

The respiratory structure and breathing mechanism of amphibians

•Frogs live – land & water

•Respiratory structure & body surface – adaptation – for land and water

Skin

-thin, permeable, moist

- efficient exchange of gas

- Mucus secreted by glands on the surface of the body

- Network of blood capillaries – under the skin – transport respiratory gases

Lung

-Surface area is increased by numerous inner partitions

-Membranes – thin and moist

- efficient diffusion of gases

- Rich with network of blood capillaries – transport respiratory gases to the body cells

The breathing mechanism of frogs

Inhalation

-Breath through nostrils – bucco pharyngeal floor lowers and the glottis closes

-Fresh air drawn into bucco pharyngeal cavity

-Glottis open – nostril close, bucco pharyngeal cavity floor raises

-Air pressure increased – air is forced into the lungs

-lungs expand

- Rapid movement of bucco pharyngeal floor – accumulate fresh air for lung ventilation

Exhalation

-Lungs muscle contract

-Air is expelled from the lungs

-Helped by the abdominal pressure and elasticity of the lungs

- air escapes through the nostril

The respiratory structure and the breathing mechanisms of humans

Buccal cavity

pharynx

Larynx

trachea

Bronchus

diaphragm

bronchus

Intercostal

muscle

lung

epoglottis

Nasal cavity

•Epiglottis –flap that closes the air passage during swallowing to prevent food and water from entering trachea

•Trachea is supported by c shaped cartilage rings which keep the trachea open

The structural adaptations of the alveoli for gaseous exchange

1. Large number of alveoli to provides a large surface for gaseous exchange

2. Inner layer of alveolus is lined with a layer of moist epithelial cells which enable oxygen and carbon dioxide to dissolve and diffuse

3. Entire surface of alveolus is covered by dense network of blood capillaries

- rapid diffusion and transport of

respiratory gases

4. The wall of alveolus is very thin, one cell thick

- diffusion of gases across the membranes take place easily

The human breathing mechanism

Inhalation

-External intercostal muscle contract

-Internal intercostal muscle relax

-This action causes the rib cage to move upwards and outwards

-The diaphragm muscle contract, the diaphragm lowers and flattens

-The volume of the thoracic cavity increase

-The pressure of the thoracic cavity decreases

-Higher atmosphere pressure on the outside forces air into the lung

Exhalation

-External intercostal muscle relax,internal intercostal muscle contract

-Rib cage move downwards and inwards

-Diaphragm muscle relax, curves upwards

-Volume of thoracic cavity decrease, pressure in the thoracic cavity increases

- Higher atmospheric pressure in the lungs forces the air out of the lungs

Gaseous exchange across the respiratory surfaces and transport of gases in human

•Gaseous exchange across the alveolus occurs by diffusion

•The greater the partial pressure gradient of respiratory gases across the respiratory surface the greater the rate of diffusion

Partial pressure of carbonDioxide is higher becauseOf cellular respiration

Carbon dioxide diffusesOut of the cells into theBlood capillaries

Partial pressure of oxygenIncreased but the partialPressure of carbon dioxideIs lower

Partial pressure of oxygen in theBlood is higher than partial pressureIn the cells

Oxyhaemoglobin break down andRelease oxygen.

Oxygen diffuse through the capillaryWalls into the cells

The transport of respiratory gases in humans

alveoli Blood circulstory

system

Oxygen combines with

haemoglobin to form

oxyhaemoglobin

Oxyhaemoglobin is

carried to every part of

the body

•Blood passes the tissues with low partial pressure of oxygen, the oxyhaemoglobin release oxygen to the tissues

•Each hemoglobin molecule carry four molecules of oxygen

Transport of carbon dioxide

•Carbon dioxide release by the cells can be transported in three ways

1.7 % - transported as dissolved carbon dioxide in blood plasma

2.23% - binds to hemoglobin to form carbaminohemoglobin and transported through blood

3.70% - transported in the form of bicarbonate ions (HCO3-)

Carbon dioxide Reacts with water to form carbonic acid

Enzyme carbonic anhydrase from red blood cells catalyse this reaction

Carbonic acids dissociates into hydrogen ions and bicarbonate ion (HCO3)

Bicarbonate ions diffuse into blood plasma and carried into the lungs

From body cells to the tissue capillaries

From the blood capillaries to the alveoli

Bicarbonate ions diffuse from the blood plasma into the red blood cells and forming carbonic acids

Carbonic acid break down to form carbon dioxide and water

Carbon dioxide diffuses from the blood capillaries into the alveoli and expelled during exhalation

Bicarbonate ions

Red blood cells

Carbonic acids

alveolusCarbonic acid break

down to form carbon dioxide and water

The regulatory mechanism in respiration

● During exercise :● Rate of respiration increase● Oxygen content decrease, carbon

dioxide content increase●

● Breathing rate increase● Heart beat increase●

● More oxygen and glucose are used in cellular respiration

● More carbon dioxide removed from the body

● Ventilation rate● The rate of gaseous exchange between

alveoli and blood capillaries

● In fear● Breathing rate and heart beat rate increase● Adrenal glands secrete adrenaline

hormone that increase heartbeat and breathing rate

●

● More oxygen and glucose is supplied to the muscle

● Body is prepared to response on dangerous situation

● At high altitudes● Decreased partial pressure of oxygen● Difficult to breath

● Headaches, nausea, dizziness● After a few days human body can adapt to

low concentration of oxygen

The regulatory mechanism of the carbon dioxide content in the body● Exercise

● Partial pressure of carbon dioxide increase● Carbon dioxide convert into carbonic acids● High concentration of CO2 drops the pH

value of the blood and tissue fluid

● Central chemoreceptor detect the drop of pH and send impulses to respiratory centre

●

● Respiratory centre sends nerve impulses to the muscle of intercostal and diaphragm

Respiratorycentre

● Respiratory muscle contract and relax rapidly

● Breathing rate and ventilation rate increase

● Peripheral chemoreceptors also detected drop in pH

● Peripheral chemoreceptor are the aortic bodies and the carotid bodies

The regulatory mechanism of oxygen content in the body

● High altitude● Decreased oxygen concentration in the

blood● Peripheral chemoreceptor detect the

decrease of oxygen in the blood

● Nerve impulses is send to the respiratory centre

●

● Concentration of oxygen in blood return to normal

● Diaphragm and intercostal muscle receive impulses from respiratory centre

● Breathing rate and ventilation rate increase

Respiration in plants

● Plants also respire aerobically to obtain energy for metabolism

● Energy produced by cellular respiration

● Respiratory gases enter and leave the plants through stomata and lenticels

● Lenticels are raised pores found on stems and roots

The intake of oxygen by plants

● Oxygen enter the plant through stomata●

● Oxygen diffuses into the air spaces and dissolves in the film of water around the mesophyll cells

● Oxygen is used up in the cells respiration●

● The oxygen concentration in the cells is lower than in the air spaces

● Concentration gradient occur, this allow the continous diffusion of air from the air spaces into the cells

● During the day, carbon dioxide produced by aerobic respiration is used in photosynthesis

CO

2

Anaerobic respiration in plants

● In certain condition plants can carry out anaerobic respiration

● Flooding condition - plants can survive when submerged for a few days

●

● Seed germination – seed is enclosed in air tight seed coat

● Anaerobic respiration occur

● Photosynthesis produce raw materials required by respiration

● Respiration produce raw materials required for photosynthesis

● Low light intensity● All carbon dioxide produced by respiration

is used in photosynthesis● No net gain or net loss in carbon dioxide

and glucose by plants

● Plants has reached compensation point●

● The rate of carbon dioxide produced during respiration is equal to the carbon dioxide consumption during photosynthesis

● High light intensity● The rate of photosynthesis exceeds the

rate of respiration●

● Carbon dioxide produced during respiration is no longer sufficent for the plants

● Plant has to take carbon dioxide from the atmosphere

●

● The rate of photosynthesis must exceed the rate of respiration for the growth and reproduction of the plants

● The rate of sugar reproduction will exceed the rate of sugar consumption