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The Nervous System of Frog
Nervous and Reproductive System of Frog Homework Help: The frog has a well developed nervous system and endocrine glands. The prominent endocrine glands present in the frog are namely, pituitary, thyroid, parathyroid, thymus, pineal body, pancreatic islets, adrenals, and gonads. All these glands together secrete chemicals called as hormones which bring about chemical co-ordination between different parts of the body.
The nervous system is divided into a central nervous system which includes the brain and spinal cord, a peripheral nervous system that includes cranial and spinal nerves, and an autonomic nervous system which includes sympathetic and parasympathetic nerves. The brain of the frog is enclosed in a bony structure called brain box. From the brain, ten pairs of cranial nerves arise.
The brain is divided into three parts namely, fore-brain, mid-brain, and hind-brain. The forebrain includes olfactory lobes, paired cerebral hemispheres, and unpaired diencephalon. The midbrain consists of a pair of optic lobes, that function for vision and the hindbrain consists of the cerebellum and medulla oblongata which passes out through the foramen magnum and runs down as a spinal cord which is enclosed in the vertebral column.
Sensory organs of frog:
Frog has 5 sense organs namely, sensory papillae (organs of touch), taste buds (organs for taste), nasal epithelium (organs for smell), eyes (organs for vision) and tympanum (organs for hearing) and cellular aggregations at the nerve endings, for example, heat, pain etc. External ears are absent in frogs and hence tympanum also plays a role in balancing equilibrium.
Reproductive system in frog:
In male frogs, a pair of testes is located on the upper end of kidneys by a double fold or peritoneum called mesorchium. From the tests, 10-12 vasa efferentia arise which then enter the kidneys and open into Bidder’s canal, thus joining urinogenital duct which then opens into the cloaca. In female frogs, a pair of ovaries is situated near kidneys which are connected through an oviduct. The oviduct opens separately into the cloaca, which is an exterior opening to pass out solid wastes like feces, urine, and sperms.
A. Male B. Female
Under favorable conditions, a female frog lays about 2500-3000 ova which are fertilized in water externally by male frogs. The development is indirect, as a tadpole stage is observed.