Frog 1 Flashcards
what are frog
Frogs can live both on land and in freshwater and belong to class Amphibia
of phylum Chordata. The most common species of frog found in India is
Rana tigrina.
give general intro to frogs
They do not have constant body temperature i.e., their body
temperature varies with the temperature of the environment. Such animals
are called cold blooded or poikilotherms. You might have also noticed
changes in the colour of the frogs while they are in grasses and on dry
land. They have the ability to change the colour to hide them from their
enemies (camouflage). This protective coloration is called mimicry. You
may also know that frogs are not seen during peak summer and winter.
During this period they take shelter in deep burrows to protect them
from extreme heat and cold. This is known as summer sleep (aestivation)
and winter sleep (hibernation) respectively.
explai the skin of frogs
The skin is smooth and slippery
due to the presence of mucus. The skin is always maintained in a moist
condition. The colour of dorsal side of body is
generally olive green with dark irregular spots. On
the ventral side the skin is uniformly pale yellow.
The frog never drinks water but absorb it through
the skin
describe the part of the body of the frog ( eyes, nose, ,ear)
Body of a frog is divisible into head and trunk
(Figure 7.1). A neck and tail are absent. Above the
mouth, a pair of nostrils is present. Eyes are bulged
and covered by a nictitating membrane that
protects them while in water. On either side of eyes
a membranous tympanum (ear) receives sound
signals
explain the limbs of a frog
The forelimbs and hind limbs help in swimming, walking, leaping and burrowing. The hind limbs end in five
digits and they are larger and muscular than fore limbs that end in four
digits. Feet have webbed digits that help in swimming.
frogs exhibit sexual dimorphism? what does that mean? what is the difference in male and female frog
When male and female individuals of the same species are differentiated externally, the phenomenon is called sexual dimorphism
Frogs exhibit sexual
dimorphism. Male frogs can be distinguished by the presence of sound
producing vocal sacs and also a copulatory pad on the first digit of the
fore limbs which are absent in female frogs.
give an overview of alimentary canal. why is it relatively short
The alimentary canal is short because frogs are carnivores and hence the
length of intestine is reduced. The mouth opens into the buccal cavity that
leads to the oesophagus through pharynx. Oesophagus is a short tube( due to absence of neck)
that opens into the stomach which in turn continues as the intestine, rectum
and finally opens outside by the cloaca.
what are digestive glands of digestive system
Liver secretes bile that is stored in
the gall bladder. Pancreas, a digestive gland produces pancreatic juice containing digestive enzymes.
explain the process of capture and digestion of food in frog
Food is captured by the bilobed tongue.
Digestion of food takes place by the action of HCl and gastric juices secreted
from the walls of the stomach. Partially digested food called chyme is passed
from stomach to the first part of the small intestine, the duodenum. The
duodenum receives bile from gall bladder and pancreatic juices from the
pancreas through a common bile duct. Bile emulsifies fat and pancreatic
juices digest carbohydrates and proteins. Final digestion takes place in the
intestine. Digested food is absorbed by the numerous finger-like folds in
the inner wall of intestine called villi and microvilli. The undigested solid
waste moves into the rectum and passes out through cloaca.
explain respiratory systen of frog
Frogs respire on land and in the water by two different methods. In
water, skin acts as aquatic respiratory organ (cutaneous respiration).
Dissolved oxygen in the water is exchanged through the skin by diffusion.
On land, the buccal cavity, skin and lungs act as the respiratory organs.
The respiration by lungs is called pulmonary respiration. The lungs are a
pair of elongated, pink coloured sac-like structures present in the upper
part of the trunk region (thorax). Air enters through the nostrils into the
buccal cavity and then to lungs. During aestivation and hibernation
gaseous exchange takes place through skin.
explain the strucuture of heart of frog
Heart is a muscular structure situated in the
upper part of the body cavity. It has three chambers, two atria and one
ventricle and is covered by a membrane called pericardium. A triangular
structure called sinus venosus joins the right atrium. It receives blood
through the major veins called vena cava. The ventricle opens into a saclike truncus arteriosus giving rise a spiral valve called conus arteriosus on the ventral side of the heart. The blood from the
heart is carried to all parts of the body by the arteries (arterial system).
The veins collect blood from different parts of body to the heart and form
the venous system.
explain the flow of blood
vena cava-> R.A -> Ventricle -> Truncus arteriosus-> pulomnary arttery -> pulmonary vein -> L.A -> ventricle -> aortic trunck
Special venous connection between liver and intestine
as well as the kidney and lower parts of the body are present in frogs.The
former is called hepatic portal system and the latter is called renal portal
system.
explain blood composition
The blood is composed of plasma and cells. The blood cells are
RBC (red blood cells) or erythrocytes, WBC (white blood cells) or leucocytes
and platelets. RBC’s are nucleated and contain red coloured pigment
namely haemoglobin.
The vascular system of frog is well-developed closed type.
The blood vascular system involves heart, blood
vessels and blood.
The blood carries nutrients, gases and water to the
respective sites during the circulation. The circulation of blood is achieved
by the pumping action of the muscular heart.
explain lymph and lymphatic system
The lymph is different from blood. It lacks few
proteins and RBCs.The lymphatic system consists of lymph, lymph
channels and lymph nodes.
describe the excretory system
The elimination of nitrogenous wastes is carried out by a well
developed excretory system. The excretory system consists of a pair of
kidneys, ureters, cloaca and urinary bladder.
