anatomy and physiology of frog

1. TYPE STUDY OF FROG
By: Bharathippriyan, Siva Priya,
Ranjani, Isha, Jerlin, Nithyashree,
Shafeen, Yuvasree.

2. Habit and habitat of
frog

3. Habit and habitat
Class : Amphibia
Phylum : Chordata
Kingdom : Animalia
• Frogs in general are found in or near fresh
water and in very damp places on land.
• The most common species of frog in India is
Rana tigrina.
• It moves in two ways by leaping or walking on
land and by swimming in water.
• The frogs swims in water by powerful thrusts of
its hindlimbs which act like propellers.
• Adult frogs are carnivorous.

4. • The characteristic noise or sound made by frogs is
known as croaking.
• Frog is a cold-blooded or poikilothermous animal
i.e., the temperature of its body fluctuates with
that of the environment.
• Frogs have the ability to imitate other organism for
their protection purpose. This protective property
is known as mimicry.
• Frogs exhibit sexual dimorphism.

5. MORPHOLOGY OF
FROG

7. FEATURES OF FROG

8. HEAD

11. TRUNK

14. Digestive system mainly consists of Alimentary
canal and Digestive glands.
Alimentary canal :
The alimentary
canal is short because frogs
are carnivores and the
length of intestine is
reduced but it is complete
ie. from mouth to cloaca.

16. IT CONSISTS OF FOLLOWING PARTS :
MOUTH :
mouth is a wide anterior opening leading
to a spacious buccal cavity that leads to the
oesophagus through Pharynx
OESOPHAGUS :
Because of absence of neck in the
Frog, the oesophagus is only a short tube that
leads to the stomach

17. STOMACH :
 It lies on the left side of the body cavity
 Its large anterior part is called cardiac stomach
 Its short posterior part is called pyloric stomach
 It also contains,
 multicellular gastric glands which secrete the
enzymes pesinogen.
unicellular oxynticglands which secrete
hydrochloric acid
 Its posterior end opens into small indestine

18. INTESTINE :
It is the longest part of alimentary canal
and it is divisble into :
DUODENUM :
It recieves bile from gall bladder and
pancreatic juice from the pancreas through a
common bile duct (hepato pancreatic duct)

19. ILEUM :
The internal lining of ileum is also thrown
into a large number of finger like branched
projections known as villi which increases the
absorptive surface area.
RECTUM :
The ileum leads into a broad ,thin walled
,short but wider tube known as rectum or large
indestine.
It opens outside by cloaca.

21. DIGESTIVE GLANDS :
LIVER :
= It is a reddish brown, multilobed gland located close
to heart and lungs.
= Liver secretes a alkaline fluid ,the bile.
= The bile is transferred to the gall bladder for storage .
PANCREAS :
• It is a branched flat elongated pale-yellow gland .
• It secretes pancreatic juice containing several enzymes.

23. FEED ON
Rapid flicking action

24. Digestion of food
take place by the
action of HCl and
gastric juices
secreted from the
walls of the
stomach
CHYME – Liquified semi digested acidic food

25. In Duodenum, Chyme is mixed with Bile and
Pancreatic juices for futhur digestion to take place.
Bile neutralizes the acidity of Chyme and
Emulsifies the Fat.
Pancreatic juices contain various types of enzymes
to digest carbohydrates and protiens.

26. The digestion is completed in the intestine only
This completely digested food is absorbed by
numerous finger like folds in the inner wall
intestine[ileum]
The undigested solid waste moves into rectum
[where water reabsorption occurs ] and finally passes
out through cloaca

27. RESPIRATION IN FROGS

28. Being amphibious in nature, frogs can utilize the
oxygen present both in atmospheric air and water.
Types of respiration in frogs:
1. Using gills-Tadpole /larval stage
2. Cutaneous respiration- adult frog
3. Pulmonary respiration- adult frog
4. Bucco-pharyngeal respiration- adult frog

29. 1.RESPIRATION THROUGH GILLS
• Takes place in the larval stage ,where the
tadpole are present only in water
• 4 pairs of gills are present for respiration.
• Water containing oxygen is taken through the
mouth ,diffusion takes place at the gills and
co2 is given out.

30. 2.CUTANEOUS RESPIRATION(water)
• Adult frogs use this mode of respiration when
they are in water.
• The skin of the frog provides an extensive surface
for the exchange of gases
It shows certain features:
1. The skin is thin.
2. It is vascular (richly supplied with blood
capillaries)
3. It is kept moist (mucus and water)

31. • Dissolved oxygen in water is exchanged through
the moist surface of the skin by diffusion.
• It is practically the only mode of respiration when
the frog is in water.
• This mode of respiration mostly takes place
during hibernation and aestivation.

32. 3.PULMONARY RESPIRATION(land)
• Adult frogs use this type of respiration when
on land.
• Breathing takes place through the usage of
lungs and respiratory tract ( nostrils, buccal
cavity and glottis).

33. • The lungs are a pair of elongated, thin-walled,
elastic, pink-coloured sacs present in the
upper part of the trunk region. i.e., the thorax
• The inner surface of each lung is divided by a
series of partitions, the septa and further into
many small cavities known as alveoli.

34. • Air enters the nostrils into the buccal cavity
and then into the lungs.

35. 4.BUCCO-PHARYNGEAL
RESPIRATION(land)
• Adult frogs fill its bucco-pharyngeal cavity
with air through the nostrils when on land
• Gaseous exchange takes place through the
moist lining of the buccal cavity and then
expelled out.(similar to cutaneous
respiration).

36. • It brings oxygen to the bloodstream by
dissolving it and diffusing it into the blood
capillaries.
• Mucous membrane blood capillaries

37. CIRCULATORY SYSTEMCIRCULATORY SYSTECIRCULATORY SYSTEMM
CIRCULATORY SYSTEM

38. HEART:
 It is a muscular structure which lies mid-ventrally, inside the
anterior trunk region
 It is enclosed within a thin, transparent, two layered sac
called the pericardium. It protects heart from friction or
mechanical shocks.
 Heart is a three chambered structure in frog, made of two
anterior aria(right and left) and a single posterior ventricle.
 The heart of frog has 2 additional chambers –sinus venosus
and truncus arteriosus(=conus arteriosum).
 Sinus venosus is a thin –walled, triangular chamber attached
dorsally to heart. It opens into the right larger atrium
through an aperture.

40. BLOOD CIRCULATION:
• The right atrium receives deoxygenated blood through
sinus venosus which in turn receives blood from the major
veins called vena cava. While the left atrium receives
oxygenated blood from pulmonary veins. Both right and
left atrium pump blood into single ventricle which opens
into truncus arteriosus. The circulation of blood is achieved
by the pumping action of heart. Various chambers of heart
are separated by valves to keep the blood flowing in one
direction.
• ARTERIAL SYSTEM: Arteries carry blood from the heart. The
arterial system in frog begins with the truncus
arteriosus(=conus arteriosus). The truncus divides into left
and right branches each of which sub-divided into vessels.

42. VENOUS SYSTEM
• It includes veins an or those blood vessels
which carry the blood to the heart. In frog it
can be studied in four parts:
 PULMONARY VEINS: They collect
oxygenated blood from two lungs and open
directly into left auricle.
 VENA CAVA: They carry deoxygenated blood
from the body parts towards heart .

43. RENAL PORTAL VEIN: Renal portal vein carrying
deoxygenated blood from lower part of the body like
hindlimbs, gonads, etc… enters kidney. The blood from
hind parts of the body contains urea and uric acid are first
filtered in the kidneys before the blood goes to the heart.
Thus, the blood going to the heart contains comparatively
less impurities.
HEPATIC PORTAL VEIN: A large hepatic portal vein
confluence of several branches from stomach, intestine,
spleen and pancreas. It carries blood of alimentary canal
and its glands laden with digested foodstuffs, to the liver
into which it breaks as capillaries.

45. BLOOD
• Blood carries nutrients ,gases and water to the
respective sites in the body. Hence it is the
chief circulatory fluid of the body. It contains a
clear liquid, called plasma, in which are
suspended various types of free cells, called
blood substances.
I. Plasma: it is composed of water(dissolved
mineral salts)absorbed foods, excretory
wastes and other soluble substances.
II. Corpuscles: three types of blood corpuscles
are present In the plasma :RBC,WBC OR
PLATELETS.

46. ENDOCRINE SYSTEM

47. ENDOCRINE SYSTEM

48. • The prominent endocrine glands found in frog
are pituitary ,thyroid, parathyroid , thymus,
pineal body , pancreatic islets adrenals and
gonads

50. • Well developed excretory system .
• It is ureotelic organism.
• Excretory system consists of namely:
1. A Pair of kidneys
2. Ureters
3. Urinary bladder
4. cloaca

51. A pair of kidneys
The two mesonephric kidneys, situated one on
either side of the vertebral column in the posterior
part of the body cavity.
Each kidney is a compact mass of innumerable highly
twisted microscropic uriniferous tubules or nephrons
and blood vessels embedded in connective tissue.
Ureters
It is a fine, white tube extends backwards to open
into the dorsal wall of cloaca. In male frog , the
ureters are called urinogenital ducts.

52. Urinary bladder
A large transparent, bilobed, thin walled elastic. It
opens into the ventral wall of cloaca.
Cloaca
Small median chamber into which the anus ,
urinogenital apertures and urinary bladder.

54. PROCESS OF EXCRETION
• Blood is filtered by nephrons in kidney. All the
wastes is filtered out and useful substances
are reabsored into blood. The remaining fluid
forms urine which is carried out in kidney by
collecting vessels into ureter and passes into
cloaca.

55. NERVOUS SYSTEM OF A FROG

56. INTRODUCTION :
• The frog has a highly developed nervous
system. It consists of a brain, a spinal cord, and
nerves.
• The important parts of the frog brain
correspond to comparable parts in the human
brain. The medulla regulates automatic
functions such as digestion and respiration.
Body posture and muscular co-ordination are
controlled by the cerebellum.

58. NERVOUS SYSTEM OF A FROG
• The nervous system of a frog is well developed and is
represented by :
1. Central nervous system comprising brain and spinal cord.
2. Peripheral nervous system including cranial and spinal
nerves.
3. Autonomic nervous system comprises sympathetic and
parasympathetic nervous system .
CENTRAL NERVOUS SYSTEM :
i. Brain : it is enclosed in the cranial cavity of the skull called
brain box. The brain is divisible into three parts.
a) Forebrain :it comprise two olfactory lobes, two cerebral
hemispheres and unpaired diencephalon.

59. b) Mid-brain : It consists of optic lobes and cura cerebri.
c)Hind brain :the posterior part of brain includes cerebellum
and medulla oblongata.
ii)SPINAL CORD:
The spinal cord extends posteriorly from medulla
oblongata through foramen magnum and lies protected
within neural canal of its vertebral column. It is short,
thick, cylindrical somewhat flattened and white in
colour.

60. 2) PERIPHERAL NERVOUS SYSTEM :
i. Cranial nerves : There are 10 pairs of cranial nerves which
originate from brain of the frog.
ii. Spinal nerves : Frog has 10 pairs of spinal nerves. Every
spinal nerves on either side arises from spinal cord.
3)AUTONOMIC NERVOUS SYSTEM :
It is a system of nerve fibres and ganglia which controls and
coordinates the involuntary activities of the visceral organs,
such as secretion of digestive fluid, action of heart etc.

61. Sense organs of a frog

62. SENSE ORGANS
• Sense organs receive stimuli from inside or outside of the
animals and pass impulses to the nervous system.
• Frog has five types of sense organs . They are :
i. Organs of touch : Also known as tangoreceptors. These are
cellular aggregates around nerve endings, found in the skin as
sensory papillae.
ii. Organs of smell : Also known as olfactoreceptors. They are
also cellular aggregates found in the nasal epithelium of the
nasal chambers.
iii. Organs of taste : Also known as gustato receptors. These are
found as taste buds which are present in the epithelium of the
tongue.

63. iv) Eyes are organs of sight.
v) Ears are organs of hearing and balancing.
Out of these, eyes and internal ears are well – organised.
They are described below :
a) EYE : There are two large eyes. Each eyeball is roughly
spherical and lodged inside an orbit in the dorso- lateral side
of head protected by eyelids.
b) EAR : A pair of ears are attached to skull, posterio-laterally
in all vertebrates. They are statoacoustic organs as they help
in both hearing and balancing of body. The ear of a frog
mainly consists of two parts – middle and internal ear.

65. REPRODUCTIVE SYSTEM ..
Frogs have well defined male and female reproductive system.
MALE REPRODUCTIVE SYSTEM ..
• Consists of two testes
• Several vasa efferentia
• And two urinogenital ducts
TESTES.
• It is an elongated and ovoid light yellow body attached to the upper part
of kidney by a double fold peritoneum called mesorchium .
• Seminifereous tubules are coiled within the testes.
VASA EFFERENTIA .
• 10-12 Fine tubes connecting the testes on each side of the kidney
• The vasa efferntia run transversely through the mesorchium and opens
into the bidder’s canal .
• And passes through the urinogenital duct..

66. URINOGENITAL DUCT..
• Arising from the kidney acts as both urinary
and sperm duct .
• Finally opens into the cloaca and passed out
through the cloacal aperture …

68. FEMALE REPRODUCTIVE SYSTEM..
• Comprises a pair of ovaries , oviduct .
OVARIES ..
• Irregular shape ,lobulated structures near the kidneys.
• They have no internal functions and connections with
kidney
• Ovary contains dark round ova in different stages
developments .
• Ovum releases through the oviduct ..
OVIDUCTS..
• Paired ,white , glandular and long coiled tubes on sides of
body cavity
• Posterior ends posses an ovisac where eggs are stored
temporarily..
• Mature female frog lay 2500-3000 ova at a time .

70. MALE URINOGENITAL ORGANS FEMALE URINOGENTAL ORGANS

71. FERTILISATION …
• Onset of rainy season ,frogs emerge out of
aestivation and starts breeding ..
• Male frog starts croaking to attract the female
frog for mating ..
• Male mounts upon the female and grasps with
the help of copulatory pads called amplexus .
• Female release (2500-3000) ova into the water
and sperms discharges over the eggs for
fertilisation .
• exhibits external fertilisation .

72. DEVELOPMENT AND
METAMORPHOSIS .
• Exhibit indirect development
• Within two weeks fertilised eggs develop into
free swimming larvae called tadpoles
• It swims freely on the water and feeding on
planktonic foods .
• Tadpoles has external gills which become
replaced into an internal gills later ,after
metamorphorsis

74. CHANGES THAT CONSTITUTE THE
METAMORPHOSIS …
• Limbs appears and tail shortens .
• Quick growth and movement of the eyes to
higher up the skull
• formation of eyelids , skin glands
• Thickening of skin and development of an
eardrum to lock the middle ear .
• These changes make them into an young adult
frogs.
• finally they disperse into the terrestrial habitat.

75. DID U KNOW ?
• Frogs cannot live away from the aquatic
environment because no means to control the
evaporative water loss through the skin ..
IMPORTANCE TO THE MANKIND …..
• It eats insects and they are harmful to crops
• Saves expenditure on insecticides
• Maintain ecological balance and food chain
• Muscles of frog used as food in other countries
and some parts of india ..
• As an experimental material for teaching nad
researches……..

76. REFERENCE
BOOKS :
NCERT CLASS 11
THE ANATOMY OF FROG BY ALEXANDER ECKER
UNCOVER A FROG BY AIMEE BAKKEN
WEBSITES :
WIKIPEDIA
WWW.ALPHACODERS.COM
https://www.britannica.com

77. …THANK YOU…