Digestive system of frog
Digestion
 The process in which the complex insoluble substance are converted
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into soluble form by the action of enzymes.
Digestive system of frog consists of :
(1) Alimentary canal
(2) Digestive glands
Food is captured by a sticky tongue & taken into the mouth.The
upper jaw consists small pointed teeth which present the
food particles from slipping out side the tongue of frog is
attached in front and free behind.
It is then swallowed & moves through the pharynx & elastic
esophagus.
Oesophagus: It is broad, short muscular tube which opens into stomach.
Stomach: The stomach is large, thick walled muscular bag. Anterior part
of stomach is called cardiac part and posterior part is called pyloric
part. It is internally folded. It stores ingested food. Posterior part
consists of pyloric constriction through which food is slowly passed.
 A muscle at the base of the stomach opens & allows the food to
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move into the first section of the intestines: the duodenum
From the duodenum it moves to the ileum where the nutrients
released from the food is absorbed into the blood stream
The duodenum and the ileum make up the small intestine.
The indigestible parts of the food move into the large intestine
where any extra water is reabsorbed & the leftover waste is
pushed into the cloaca & out through the vent
The intestines are held in place by a thin but strong membrane
called the mesentery.
 The frog has many accessory glands like humans that aid the digestion process
 Liver: produces bile which breaks down fat
 Gallbladder: bile is stored here until it is needed
 Pancreas: secretes enzymes that help further digest the food.
 Functions of liver.
 · The liver secrets bile, which is used in small intestine for
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digestion of food.
· It regulates the amount of sugar in the blood.
· It maintains the protein concentration in blood.
· It stores copper and iron and forms vitamin A.
· It kills many bacteria.
Digestion system of frog
Respiration system of frog
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Respiration
 The process in which inhaling oxygen and exhalling carbon dioxide is known as
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respiration.
Respiration divided into two phases
(i) Gases exchanges or extra cellular respiration.( in lungs)
(ii) Cellular respiration: It is produced by the oxidation of food specially
glucose.
In the frog process of respiration is brought about by three types.
(1) Pulmonary respiration (through lungs)
(2) Cutaneous respiration (through skin)
(3) Buccal respiration (through buccal cavity)
(1) Pulmonary respiration: The gases exchanges which takes place in
lungs is called Pulmonary respiration.
The Frog has two lungs, which are
balloon like structures.
The outer surface is smooth but their
inner surface has numerous folds
which increase the area for gases
exchanges the lungs are richly
supplied with blood vessels .
Each lung has a bronchus at its upper
end. The two bronchi open into a
larynx. The glottis opens into the
larynx.
During respiration air is taken in by the
external nostrils.
It passes into the buccal cavity
through the internal nostrils.
From here it enters the glottis, passes
through the larynx and bronchi finally
reaches the lungs.
In the lungs exchange of gases b/w air
and blood.
Cutaneous respiration:
Gases exchanges carried out by
skin.
Frog uses skin as a respiratory
organ during swimming and
hibernation.
Oxygen diffuse in blood
through skin while Carbon
dioxide diffuse out from
network blood capillaries in
skin.
 Buccal respiration:
 Respiration through mucous membrane of the buccal
cavityis called buccal respiration. When the frog is at rest the
air is not driven in to the lungs but is simply drawn into and
forced out of the buccal cavity through the nostrils. Here also
exchange of gases takes place b/w air and blood.
Viruses:
 Viruses are the smallest, the simplest and
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perhaps the most primitive living things. The
word Viruses derived from (Latin word Viron=
Poison)
By 1800’s many biologists had demonstrate that
many disease man and other organisms were
caused by bacteria.
Mayer in 1886 mention about disease was
tobacco mosaic disease occurring in tobacco
plant leaves. In 1892 Russian Biologist
Iwanowsky showed that disease was due to
something smaller than bacteria. He named
that Viruses. No one had seen them b/c they
were to smallest to be seen ever with the
compound microscope.
An American scientist W. Stanely isolated
tobacco mosaic virus in 1935 for the first time.
Viruses are obligate and reproduce only in the
living cell.
Characteristics of viruses
 Viruses are non-cellular parasitic organisms that always have
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a protein coat and nucleic acid core.
They range in size 20nm to 250nm.
They are considerd on the border of living and non-living
b/c they are alivein the body of living organisms and dead
out side the living body.
They are sub-microscopic.
There no asexual and sexual reproduction. They reproduce
by replication.
They are composed of nucleic acid and proteins.
Shapes of viruses:
 Viruses are different size and
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shapes,
Some of rounded, (polio
virus)
Few are rod shapes, (Tobacco
mosaic virus)
Few polyhedral, (Tumor
virus)
Some look like tadpoles.
( Bacteriophage)
Bullet Shaped.
Structure of viruses:
 Viruses consist of Nucleic acid, Capsids , Envelope and tail fiber.
 Their nucleic acid may consists of a single or several molecules of DNA
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or RNA. The smallest viruses have four genes while the largest have up
to two hundreds.
Capsid : The protein coat that encloses the nucleic acid is called a
capsid.It may be are different shapes.
Capsid is made up of protein subunits called capsomeres
The number of capsomers is characteristics of a perticular virus.
Viral envelopes: These are membranous covering around the capsid.
It is found some viruses.
This covering helps them to infect their hosts.
Tail fibers: In bacteriophage virus lower part is tail like. At the posterior
end of tail some fibre like structures are present called tail fiber. These
fibers take part in the attachment of virus with host cell.
Types of viruses:
 Plant viruses = Infecting plants.
 Animal viruses = infecting animals and men.
 Bacteriophages = which infect bacteria.
Viruses are living and non-living:
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Living
1. Viruses with their core of DNA or RNA surrounded by
protein coat. Some what resemble the chromosomes of other
living organisms.
They have the ability to reproduce. ( Properties of replication
of reproduction)
Many kinds of viruses are known to undergo mutations.
Viruses show genetic recombination.
Non-living
Non-cellular structure .
Undergo crystallization.
Completely in active out side host’s cell.
Viral disease:
 Viruses caused many disease s in human beings . Animals and
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plants. They are also involved in the development of cancer.
ANIMALS DISEASE:
Poliomylitis ( Disease by polio viruses)
Symptoms: Fever, Headache, Indigestion, Vomitng, Stiffness in
neck and back.
Control :Vaccination of babies, Contaminted food and water
should not be used.
COLD:
Flue:
Retroviruse (Tumor virus)
HIV (AIDS)
Plant Disease caused by virus:
 Tobacco Mossaic Virus