Home BIOLOGY TOPIC 5: GASEOUS EXCHANGE AND RESPIRATION | BIOLOGY FORM 2

TOPIC 5: GASEOUS EXCHANGE AND RESPIRATION | BIOLOGY FORM 2

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October 3, 2020

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GASEOUS EXCHANGE AND RESPIRATION

TOPIC 5: GASEOUS EXCHANGE AND RESPIRATION | BIOLOGY FORM 2

The Concept of Gaseous Exchange

Organs Responsible for Gaseous Exchange in Living Organisms

Identify organs responsible for gaseous exchange in living organisms

Organs responsible for gaseous exchange in living organisms include the following:

GASEOUS EXCHANGE AND RESPIRATION

ORGANISM	RESPIRATORY SURFACE
Amoeba	Cell membrane
Insects	Tracheal system
Spider	Book lung
Fish	Gills
Plants	Leaves, stems, roots
Amphibians	Skin, gills and lungs
Mammals	Lungs
Birds	Lungs
reptiles	Lungs

GASEOUS EXCHANGE AND RESPIRATION

Features of Respiratory Surface

They are thin to reduce diffusion distance

They are moist to dissolve gaseous so that they dissolve and diffuse in solution form

GASEOUS EXCHANGE AND RESPIRATION

They are highly braced, folded or flattened in order to increase the surface area for gaseous exchange

They are close to efficient transport and exchange easily by the cells

They are well ventilated so that gaseous passes easily

The Concept of Gaseous Exchange

Explain the concept of gaseous exchange

Gaseous
exchange refers to the movement of oxygen and carbon dioxide across the
respiratory surface.

GASEOUS EXCHANGE AND RESPIRATION

Is the process through which respiratory gaseous
are passed through the respiratory surface. Respiratory surface are
specialized organs for gaseous exchange.

Gaseous exchange takes place
through a process of diffusion.

Gaseous Exchange in Mammals

Parts of the Respiratory System

Identify parts of the respiratory system

The gaseous exchange in mammals takes place in the lungs.

GASEOUS EXCHANGE AND RESPIRATION

The Features of Different Parts of the Respiratory System and their Adaptive Features

Describe the features of different parts of the respiratory system and their adaptive features

The Features of Different Parts of the Respiratory System include the following:

GASEOUS EXCHANGE AND RESPIRATION

Nose and nasal cavity:It has mucus and hair which trap dust and microorganisms

Glottis:
It is situated in the epiglottis which closes the trachea during
swallowing to prevent food from entering the respiratory system

Trachea, Bronchus, and Bronchioles:
They have blood vessel which have ring cartilage and mucus which warm
hair and prevent collapse of respiratory track also they trap and fitter
dust and micro organisms

GASEOUS EXCHANGE AND RESPIRATION

Lungs:They are sponge with air space (alveoli) which is the main organ of mammalian gaseous exchange

Ribs:They are made up of hard bone tissues which protect the lungs from injury.

Intercostal muscles:They more antagonistically to allow expansion and relaxation of the thoraic cavity

Diaphragm: is the muscular sheet of tissue which separate thorax from abdomen

GASEOUS EXCHANGE AND RESPIRATION

Alveoli: they are numerous in number; they are moist and thin membranes

Functions of alveolus

Provide surface area for gaseous exchange

Reduce distance for diffusion of gaseous

Enable gaseous to dissolve into solution before diffusing

Transport oxygen from the alveoli to the tissues and carbon dioxide to the alveoli

GASEOUS EXCHANGE AND RESPIRATION

Maintain the shape and avoid collapsing

The Mechanism of Gaseous Exchange in Mammals

Describe the mechanism of gaseous exchange in mammals

Gaseous
exchange in mammals happens as a result of inhalation and exhalation.

Inhalation is breathing in air in to the lungs.

Exhalation is the
breathing out of air from the lungs.

GASEOUS EXCHANGE AND RESPIRATION

During inhalation the muscle of the
diaphragm contract pulling the diaphragm downwards.

As this happens,
the external inter costal muscle contract and pull the rib cage upward
and outwards.

GASEOUS EXCHANGE AND RESPIRATION

This increase volume and decreases pressure in the thorax.
This makes air rush in the lungs.

During
exhalation the muscles of the diaphragm resumes its dome shape.

The
external intercostal muscles relax pulling the rib cage inwards and
downwards.

This decreases volume and increases pressure.

This forces air
out through the bronchioles, trachea and nostrils

GASEOUS EXCHANGE AND RESPIRATION

Gaseous Exchange Across the Alveolus

Describe gaseous exchange across the alveolus

The
actual exchange of oxygen and carbon dioxide takes place in the
alveoli.

One mammalian lung has millions of alveoli. When we breathe air
in it accumulates in the alveoli.

There is higher concentration of
oxygen in the alveoli than in the blood stream.

The oxygen combines with
hemoglobin to form oxy hemoglobin.

GASEOUS EXCHANGE AND RESPIRATION

Oxygen is then transported to the
tissues

The
tissue use oxygen and release carbon dioxide which diffuses in blood
capillaries and combine with hemoglobin to form carbon hemoglobin.

Capillaries transform this form to alveoli as it is then transported
through the bronchioles trachea, glottis, pharynx, and finally nostrils
into the atmosphere.

GASEOUS EXCHANGE AND RESPIRATION

Factors Affecting Gaseous Exchange in Mammals

Outline factors affecting gaseous exchange in mammals

Factors affecting gaseous exchange in mammals include the following:

GASEOUS EXCHANGE AND RESPIRATION

Exercise or physical activities

Age

Emotions

Temperature

Health

Carbon dioxide concentration

Hemoglobin concentration

Altitude

Gaseous Exchange in Plants

In
plants gaseous exchange takes place through the stomata on the leaves
and lenticels on the stem.

GASEOUS EXCHANGE AND RESPIRATION

But some plants such as mangrove also carry
out gaseous exchange through breathing roots.

Parts of Plant Responsible for Gaseous Exchange

Identify parts of plant responsible for gaseous exchange

In
plants gaseous exchange takes place through the stomata on the leaves
and lenticels on the stem.

GASEOUS EXCHANGE AND RESPIRATION

But some plants such as mangrove also carry
out gaseous exchange through breathing roots.

The Process of Gaseous Exchange in Plants

Describe the process of gseous exchange in plants

Gaseous exchange in leaves:

Through stomata, atmospheric air moves in and out of the leaf.

Gaseous
exchange mostly takes place in the air spaces in the spongy mesophyll.

GASEOUS EXCHANGE AND RESPIRATION

During
the day, green plants carry out photosynthesis to produce glucose and
this takes place within the guard cells that surround the stomata then
the cell sap of the guard cells becomes hypertonic and draws in water
from the neighboring cells by osmosis.

The
guard cells become turgid and the stomata open whereby the air from the
atmosphere such as carbon dioxide enters into the air spaces in the
spongy mesophyll.

GASEOUS EXCHANGE AND RESPIRATION

In this case carbon dioxide (CO₂)

is more in the air within the air space but oxygen is less.

Then the
carbon dioxide and oxygen diffuse in opposite direction depending on
their concentration gradients (such as oxygen out and carbon dioxide
in).

GASEOUS EXCHANGE AND RESPIRATION

The carbon dioxide diffuses into neighboring cells until it reaches
the site for photosynthesis and oxygen moves out through the open
stomata to the atmosphere.

During
the night there is no light so that photosynthesis ceases and there is
no production of glucose. Therefore the guard cells do not absorb water
by osmosis hence the stomata remain partially closed.

However
respiration process takes place at night in plants.

The partially open
stomata allow small amount of air to enter and accumulate in the air
spaces.

GASEOUS EXCHANGE AND RESPIRATION

In this case there is more oxygen and less carbon dioxide in the
air spaces compared to plant cells.

Oxygen
moves into the plant cells while carbon dioxide moves into the air
spaces and eventually into the atmosphere through the partially open
stomata.

This explains why green plants produce carbon dioxide at night
and oxygen during the day.

Importance of Gaseous Exchange in Plants

Explain the importance of gaseous exchange in plants

Importance of Gaseous Exchange in Plants include the following:

GASEOUS EXCHANGE AND RESPIRATION

It enables the plants to eliminate excess carbon dioxide at night of which if left will harm the plants

It enables plants to obtain carbon dioxide which is one of the raw materials necessary for photosynthesis

Plants obtain oxygen which is necessary for production of energy which is produced during respiration through gaseous exchange

Respiration

The concept of Respiration

Explain the concept of respiration

Respiration:

Is
the metabolic activity or reaction in which complex food substances are
broken down step by step to release energy within a cell.

Cellular Respiration:Is
a set of metabolic reaction and process that takes place in the cell of
organisms to convert biochemical energy from nutrients into ATP.

NB:
The reaction involved is catabolic reaction, which breaks larger
molecules into smaller ones to release energy.

Cellular respiration is
considered as exothermic reaction.

GASEOUS EXCHANGE AND RESPIRATION

Exothermic reaction is the process
whereby energy is released out.

Types of Respiration

Mention types of respiration

There are two types of respiration

Aerobic Respiration

Anaerobic Respiration

Aerobic Respiration

The Concept of Aerobic Respiration

Explain the concept of aerobic respiration

This
is the combustion reaction.

This means that oxygen is required in order
to generate ATP.

GASEOUS EXCHANGE AND RESPIRATION

The simplified reaction of respiration of
carbohydrates is C₆H₁₂O_6.

Aerobic respiration – In the presence of oxygen glucose molecules are broken down into carbon dioxide water and energy

Equation of Aerobic respiration

C₆H₁₂O₆ + 6O₂→ 6CO₂ + 6H₂O + Energy (38ATP)

The Mechanism of Aerobic Respiration

Outline the mechanism of aerobic respiration

Respiration
starts with glucose (usually).

GASEOUS EXCHANGE AND RESPIRATION

In aerobic and anaerobic respiration
initial reactions are common as a result of which pyruvic acid is formed
by breakdown of glucose.

The
process is called Glycolysis or EMP Pathway (Embden-Meyerhof-Parnas
Pathway).

GASEOUS EXCHANGE AND RESPIRATION

This process does not require O2although this can take place
in the presence of oxygen.

After this stage, the fate of pyruvic acid is
different depending upon the presence or absence of oxygen.

If
oxygen is present there is complete oxidation of pyruvic acid into H2O
and CO2and chemical reactions through which this occurs is called
Tri-Carboxylic Acid cycle (TCA Cycle) or Krebs Cycle.

This cycle occurs
in mitochondria.

GASEOUS EXCHANGE AND RESPIRATION

If oxygen is absent, pyruvic acid forms ethyl alcohol
(C2H5OH) and CO2without the help of any cell organelle.

This process is
called anaerobic respiration.

Experiments on Aerobic Respiration

Carry out experiments on aerobic respiration

Respiration
by living organisms can be investigated by carrying out experiments to
show the production of carbon dioxide and heat.

Investigating carbon dioxide production

GASEOUS EXCHANGE AND RESPIRATION

Limewaterturns
milky in the presence of carbon dioxide.

It can be used to show that
exhaled air contains more carbon dioxide than inhaled air.

Carbon dioxide dissolves in water to form a weaklyacidicsolution.

Hydrogencarbonate indicatoris used to show the presence of carbon dioxide in solution. It is:

red at neutralpH(no carbon dioxide)

yellow at low pH (carbon dioxide present)

GASEOUS EXCHANGE AND RESPIRATION

Investigating heat production

The release of heat can be shown by carrying out an experiment usinggerminatingseeds. Twovacuum flasksare used:

one containing living plant material

GASEOUS EXCHANGE AND RESPIRATION

one containing dead plant material (thecontrol)

Contents	Start temp (°C)	End temp (°C)	Temp change (°C)
Living plant material	21	29	8
Dead plant material	21	21	0

GASEOUS EXCHANGE AND RESPIRATION

Factors which Affect the Rate of Respiration

Describe factors which affect the rate of respiration

The
rate of respiration in organisms is rarely constant.

There are several
factors in that affect rate of respiration.

These apply equally to
aerobic and anaerobic respiration although the examples given here refer
to aerobic respiration

GASEOUS EXCHANGE AND RESPIRATION

Temperature:Respiration
is a chemical process therefore its rate increases with increasing body
temperature as an increasing in temperature increases the rate of
chemical change.

Activity:All body activity
requires energy.

When an organism becomes active it requires more energy
than when it’s inactive. Since respiration provides energy required for
the activity the rate of respiration will correspondingly increase.

Body Size:Small
organisms have high surface area to volume ratio.

Heat loss occurs at
the surface; therefore small organisms tend to lose heat more rapidly
than larger ones. Small animals e.g. shrews, have to maintain higher
rate of respiration than larger ones to maintain their body temperature.

GASEOUS EXCHANGE AND RESPIRATION

Age:Young
organisms are growing and as a result require more energy than older
mature individual whose growth may slow down or stopped.

Younger
individual tend to be more physically active also.

Both of these rate
factors lead to increased rates of respiration in younger organism

AnAerobic Respiration

The Concept of Anaerobic Respiration

Explain the concept of anaerobic respiration

GASEOUS EXCHANGE AND RESPIRATION

This
is the process whereby energy is released in absence of oxygen although
the energy outcome in anaerobic respiration is much less than aerobic
respiration.

Anaerobic respiration differs in plant and animal.

Anaerobic Alcoholic fermentation in plant cell and yeast

Anaerobic lactic fermentation

GASEOUS EXCHANGE AND RESPIRATION

The Mechanism of Anaerobic Respiration

Outline the mechanism of anaerobic respiration

Anaerobic respiration differs in plant and animal.

Anaerobic Alcoholic fermentation in plant cell and yeast

Anaerobic lactic fermentation

Anaerobic Alcoholic fermentation in plant and yeast

In the presence of Alcoholic fermentation glucose molecule is broken down into ethanol and carbon dioxide and energy.

Glucose → Ethanol + Carbon dioxide + Energy

C₆H₁₂O₆ → 2C₂H₅OH + 2CO₂ + 2 ATP

Raw Material → End Product

Anaerobic Lactic Fermentation

If there is lack of oxygen carbohydrate molecule is broken down to lactic acid and energy outcome only 2ATP.

GASEOUS EXCHANGE AND RESPIRATION

C₆H₁₂O_{6 (Glucose)}→ C₃H₆O₃ + 2ATP Energy (Lactic Acid)

Raw Material → End Product

A
more common occurrence of lactic acid fermentation is in muscles;
during exercise.

During this period the respiratory surface is incapable
of supplying oxygen to the molecule, which is requirement.

Hence due to
this lactic acid is produced.

GASEOUS EXCHANGE AND RESPIRATION

Accumulation of lactic acid will cause
muscle cramp and so prevent muscles from operating.

The End Products of Anaerobic Respiration

Mention the end products of anaerobic respiration

The following are the End Product of Anaerobic Respiration:

In plants

Ethanol

Carbon dioxide

Energy

In Animals

Lactic Acid

Energy (2ATP)

Importance of Anaerobic Respiration

This
process brings about fermentation.

GASEOUS EXCHANGE AND RESPIRATION

Fermentation occurs when simple
sugar (glucose) is broken down by bacterial in absence of oxygen

Bacteria break down milk sugar to reduce lactic acid

Production of composite manure

Oxygen debt

During
heavy exercise, oxygen supply is less than what is required by the
body.

As a result of anaerobic respiration taking place and lactic acid
accumulates.

GASEOUS EXCHANGE AND RESPIRATION

This creates oxygen deficit.

Oxygen debt refers to the amount of oxygen required to convert lactic acid into carbon dioxide, water and energy.

An Experiment to Demonstrate the Application of Anaerobic Respiration

Carry out an experiment to demonstrate the application of anaerobic respiration

Application of Anaerobic respiration in industry and home

Alcohol brewing e.g. making beer and wine

Production of acetic acid and other acid such as citric acid

Production of biogas from cooking and lighting

Bread making process

GASEOUS EXCHANGE AND RESPIRATION

Production of composite manure

The Difference Between Aerobic Respiration and Anaerobic Respiration

Distinguish between aerobic respiration and anaerobic respiration

Differences between Aerobic Respiration and Anaerobic Respiration include the following

Aerobic Respiration	Anaerobic Respiration
Oxygen is used up	Oxygen is not used
Larger amount of energy is released	Less amount of energy is released
Water molecules are produced	Water molecules are not produced
Takes place in mitochondria	Takes place in cytoplasm
Products produced are not harmful	Products produced are harmful example lactic acid

GASEOUS EXCHANGE AND RESPIRATION

Infection and Diseases of the Respiratory System

Common Airborne Infections and Diseases which Affect the Respiratory System

Mention common airborne infections and diseases which affect the respiratory system

There
are several airborne infections, which affect the human respiratory
system.

The common ones are influenza, pneumonia, common cold and
tuberculosis.

GASEOUS EXCHANGE AND RESPIRATION

Most
of the airborne infections are a result of close contact with an
infected person.

When the sick person breathes out, coughs or sneezes,
the pathogens are released into the air.

Airborne
infections can be controlled by isolation of the infected patients,
proper disposal of infected secretion such as sputum, living in a
well-ventilated house and avoiding overcrowding especially in bedrooms.

The Causes, Symptoms, Effects and Control Measures of Common

Infections and Diseases of the Respiratory System

Explain the causes, symptoms, effects and control measures of common infections and diseases of the respiratory system

GASEOUS EXCHANGE AND RESPIRATION

Disorders of the Respiratory System

Disorders of the Respiratory System

Mention disorders of the respiratory system

GASEOUS EXCHANGE AND RESPIRATION

Disorders of the Respiratory System include the following:

PNEUMONIA

BRONCHITIS

ASTHMA

LUNG CANCER

EMPHYSEMA

TUBERCULOSIS

Causes, Symptoms and Effects of the Disorders of the Respiratory System

Explain causes, symptoms and effects of the disorders of the respiratory system

PNEUMONIA

Pneumonia
is inflammation of the lung.

It is caused by bacteria, viruses, fungi
or by inhaling chemical toxins or irritants.

GASEOUS EXCHANGE AND RESPIRATION

Pneumonia is normally
followed by other illnesses such as cold or flu.

SIGNS AND SYMPTOMS OF PNEUMONIA

Fever

Chills

Shortness of breath associated with pain

Increase of mucus production

GASEOUS EXCHANGE AND RESPIRATION

Cough

PREVENTION AND TREATMENT OF PNEUMONIA

Staying warm

Avoiding overcrowded areas

Avoiding cold food and drinks, hot drinks are preferred more as they loosen secretions

Get treatment as early as possible since it is curable by antibiotics

BRONCHITIS

Bacteria,
viruses and inhaling of irritating substances can cause the lining of
the respiratory system to become inflamed.

This causes an infection
called bronchitis.

Bronchitis can be acute or chronic.

ACUTE BRONCHITIS

This is caused by whooping cough or recurrent attacks of influenza; smoking can also cause acute bronchitis.

SIGNS AND SYMPTOMS OF ACUTE BRONCHITITS

Pain in the chest

Rapid breathing

Fever

Coughing

Headache

CHRONIC BRONCHITIS

Heavy smoking and recurrent acute bronchitis cause chronic Bronchitis.

SIGNS AND SYMPTOMS OF CHRONIC BRONCHITIS

Coughing with the production of thick sputum

Breathing difficulties

PREVENTION AND TREATMENT OF CHRONIC BRONCHITIS

Avoiding smoking

Avoid very smoky or dusty areas

Live in a well-ventilated house

Keep your body warm

GASEOUS EXCHANGE AND RESPIRATION

Seek medical help

ASTHMA

Asthma
is characterized by inflamed and constricted airways.

The narrowing of
the airways restricts the flow of air into the lungs.

Asthma can be caused by:

Allergic reactions to dust, pollen, spores or animal fur

Herediroty diseases of the respiratory system

Extremely cold weather

GASEOUS EXCHANGE AND RESPIRATION

Frequent viral or bacteria lung infection

SIGNS AND SYMPTOMS OF ASTHMA

Narrowing of bronchioles resulting in breathing difficulties and a wheezing or hissing sound when breathing

Coughing

Shortness of breath

Excessive production of mucus

Dilation of blood vessels leading to low blood pressure, low blood pressure can be fatal

GASEOUS EXCHANGE AND RESPIRATION

Chest tightness

PREVENTION AND TREATMENT OF ASTHMA

Avoid allergens (things that cause allergenic reaction)

Get treatment for respiratory infections as early as possible

Keep the body warm

Muscle relaxants in the form of sprays, pills and injections are used to prevent the narrowing of bronchitis

LUNG CANCER

The
main cause of lung cancer is smoking.

The nicotine in cigarette smoke
stops the cilia in the trachea from expelling foreign materials leading
to respiratory infection.

SIGNS AND SYMPTOMS OF LUNG CANCER

Chest pain

Breathing difficulty

GASEOUS EXCHANGE AND RESPIRATION

Weight Loss

Persistent Cough

Abnormal Production of Mucus

PREVENTION AND TREATMENT OF LUNG CANCER

Stop smoking

There is no cure for cancer. However chemotherapy and physiotherapy are used to control the disease

EMPHYSEMA

This
is a lung disease, which results from destruction of the structure
supporting the alveoli leading to these collapse.

This significantly
reduces the surface area available for gaseous exchange.

CAUSES OF EMPHYSEMA

Mainly cigarette smoke

Air pollution

Hereditary

Old age

SIGNS AND SYMPTOMS OF EMPHYSEMA

Shortness of breath

Coughing

Obstructive lung disease

Difficulties when breathing especially during exercise

GASEOUS EXCHANGE AND RESPIRATION

Wheezing during breathing

PREVENTION AND TREATMENT OF EMPHYSEMA

Avoid cigarette smoking and exposure to smoke

Lung surgery is usually done to relieve the symptoms

Use of medical drugs

In severe cases, lung transplant is necessary

TUBERCULOSIS

Tuberculosis
is highly infections disease. The causal organism for TB is one of the
strains of bacteria belonging to the Mycobacterium tuberculosis.

GASEOUS EXCHANGE AND RESPIRATION

Tuberculosis can be spread from one person to another person, when the
bacteria become airborne.

SIGNS AND SYMPTOMS OF TUBERCULOSIS

Cough

Fever

Weight Loss

Loss of appetite

Disorders of the Respiratory System and HIV/AIDS

Relate disorders of the respiratory system and HIV/AIDS

Tuberculosis
is the most common opportunistic infection associated with HIV
worldwide.

GASEOUS EXCHANGE AND RESPIRATION

Tuberculosis is an infection by the tuberculosis bacterium
that predominantly affects the lungs, but it can spread through the
blood and lymph nodes to the rest of the body in people with HIV.

The
disease can strike people with HIV no matter what the level of the CD4
count, which means that TB can often occur years before other problems
associated with HIV develop.

Pneumocystis Carinii Pneumonia (PCP)

This
is the most common opportunistic infection that occurs with AIDS the
fungus that causes the PCP infection is spread through breathing or
coughing.

GASEOUS EXCHANGE AND RESPIRATION

Symptoms include cough, fever, trouble breathing and loss of
weight.

Cryptococci Meningitis

This
is caused by fungus and it is the most common central nervous system
infection associated with HIV.

Meningitis is an inflammation of the
membranes and fluid surrounding the brain and spinal cord.

Ways of Preventing and Controlling Disorders of the Respiratory System

GASEOUS EXCHANGE AND RESPIRATION

Suggest ways of preventing and controlling disorders of the respiratory system

Activity 1

Suggest other ways of preventing and controlling disorders of the respiratory system.

GASEOUS EXCHANGE AND RESPIRATION

TOPIC 5: GASEOUS EXCHANGE AND RESPIRATION | BIOLOGY FORM 2

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