A Frog and It's Systems

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The frog has many systems with different functions. The frogs systems include the Internal Transport System (Circulatory System), Reproductive System, Feeding and Digestion System. As well as the less known Gas Exchange System, Sensory System and the Loco


The frog is an interesting species that not many people know much about. Here is some information regarding the frogs systems and how they function.


A frog uses its four appendages to move. They use their strong large hind legs which are specialized for leaping makes the frog fast and evasive, the weaker front legs are for control. The frog uses a network of muscles to make very precise leaps, allowing the frog to move quickly. 

When in water the webbing on the frogs toes allow the frog to use its powerful hind legs like flippers propelling the frog’s streamlined body through the water, the smaller front appendages allow for control through the water.

Feeding and Digestion

Frogs are carnivorous. Small frogs eat insects, worms and snails. Larger frog species eat small reptiles and mammals. Frogs do not chew their food; all of their prey is swallowed whole.

Frog teeth (note: there are two type of frog teeth Vomarine and Maxillary, both have the same purpose) are extremely weak nearly useless for biting, they are only used for holding prey that are in  the mouth, a sticky tongue can snatch food and swallow it.

Food passes on to stomach then to the small intestine where nutrients are absorbed with the help of the insulin made by the pancreas and bile made by the liver and stored by the gall bladder which is attached to the digestive system by ducts.    

The food then passes on to the large intestine and water is extracted waste is collected, any remains pass through the cloaca and are pushed out the anus. Liquid waste is collected by the kidneys stored in the Urinary Bladder (being sent by the ureters), and exits through the cloaca.

Frogs bodies retain water when on land but not when they are in water. Frogs can only spend so much time underwater, and so much time on dry land.

Reproductive system

The reproductive system is very closely related to the urinary system, the cloaca not only allows feces and urine to exit it also expels sperm and eggs.

In the male frogs contribution to reproduction the testes create sperm which can move on through the cloaca. In the female frogs reproduction process the ovary makes eggs which can be passed through and out the cloaca through the oviducts.

Sensing the Environment

The frog has a highly developed nervous system that includes a brain, spinal cord and nerves. Parts of the frog’s brain are similar and comparable to the human brain. The medulla controls automatic functions like breathing, posture and muscles are controlled by the cerebrum. The frog has 10 cranial nerves and 10 spinal nerves. (Man has 12 and 30, respectively) The sense of smell is registered in the brain by olfactory lobes through the nostrils. The frog has poor eyesight because it has a fixed lens; it can however draw the eye further in or out of its socket. There is no external ear, Eardrums and tympanic membranes are exposed the ear only has one. Just like a human the semicircular canals help maintain body balance.

Gas Exchange

The frog has a two layered skin, the outer epidermis and inner dermis used for protection and breathing. On land frogs breathes through their lungs, but underwater frogs breathe through pores in membranous skin into their blood stream.

The Lungs operate similarly to that of a man except without the assistance of a diaphragm ribs and chest muscles that assist a human in breathing. Frogs lungs are used by opening the mouth or through the internal nares (nostrils) and allowing air to flow.

Internal Transport System (Circulatory System)

The frog has a closed circulatory system. The heart has 3 main chambers; its heart is also a frog’s only organ with its own protective covering. Air gets into the blood from the skin as well, not just the heart. Frogs have mixed blood, blood with and without oxygen that can be in the same place (although they themselves will mix it to form half- oxygen rich blood), the blood is part liquid part solid. 


I hope by the end of this article your knowledge has grown pertaining to the frog and its functioning systems. 

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Posted on Apr 4, 2012