Biology, asked by Rittikahazra, 1 year ago

Hi friends,,,1)short note on Neuron 2)short note on corpus callosum,,marks-6 3)Name the three compartments of cochlea,,marks-2,,,answered all the question not any one. Best answer will be mark as brainlest.

Answers

Answered by DavidOtunga

Answer 1)

Neurons are the structural and functional units of the nervous system. Over 100 billion Neurons occur in human body, 98% in brain out of which 9-10 billion are found in cerebral cortex alone. Each neuron is connected to as many as 25000 cells so that there are 2.5*10^15 nerve connections. Neurons are accompanied by companion cells called as glial cells for house keeping functions, nourishment, consuming waste products and for providing insulation.

Their number is 10 times the number of neurons, that is, about one trillion. Neurons are the largest cells in the body (size collectively are upto 90 centimeters).

A neuron or nerve cell has three parts in total: cell body or cyton, dendron and axon. Cell body contains nucleus, nueroplasm, Nissil granules, nuerofibrils and other cell organelles. Nissil granules are riboprotein entities connected with enzyme formation required for synthesis of neurotransmitter.

Answer 2)

Corpus Callosum belongs to cerebrum. It consists of left and right hemispheres connected by a large bundle of myelinated fibres called corpus callosum and other small fiber bundles. It is a deep longitudinal cerebral fissure which also has a thick curved Fibre (in the inferior region). It has the function of connecting the two hemispheres.

Answer 3)

Cochela is the main hearing organ which is connected with a saccule by a short $\textbf{ductus reuniens}$ leading from the saccule itself. It is a spirally coiled shaped which resembles the shell similar to a snail in appearance. It tapers or forms an end to form a broad base to an almost pointed apex. Internally it consists of three fluid filled chambers or fluid filled canals, the upper one $\textbf{scala vestibuli}$ , lower one as $\textbf{scala tympani}$ , and the middle one as $\textbf{scala media}$ (or cochlear duct).

Both scala vestibuli and scala tympani are filled with a fluid called as $\textbf{perilymph}$ . However scala media is filled with a fluid called as $\textbf{endolymph}$ . Both the scala vestibuli and scala tympani are connected with each other at the top or apex of the cochlea by a small canal, known as the $\textbf{helicotrema}$ . It is equally important to mention that near the base of the scala vestibuli the wall of the membranous labyrinth comes into with a contact with the fenestra ovalis, while at the lower end of the scala tympani their lies the fenestra rotunda.

The scala media is a very important canal or channel of the cochlea. It bears an upper membrane called the $\textbf{Reissner's membrane}$ , and the lower membrane called the $\textbf{basilar membrane}$ . On the basilar membrane a sensory ridge, the special $\textbf{organ of Corti}$ is present. The organ of Corti consists primarily of outer hair cells, inner hair cells, inner pillar cells, outer pillar cells, tunnel of Corti, phalangel cells (cells of Deiters), cells of Hensen and cells of Claudius. The sensory hairs of it project From the outer ends of the hair cells into the scala media, while from the inner end of it, the cells arise with nerve fibres, which unite to form the cochlear nerve. The tectorial membrane overhangs itself from the sensory hair in the scala media. Its prime property is to determine the patterns of vibration of the incoming sound waves.