Answer:
Neural Coordination The organised network of point-to-point connection for quick coordination provided by neural system is called neural coordination. The mechanism of neural coordination involves transmission of nerve impulse, impulse conduction across a synapse and the physiology of reflex action.
(b) Forebrain It forms, the major part of human brain. The various parts of forebrain are cerebrum, thalamus and hypothalamus. It forms the I major part of the human brain. It consists of two cerebral ' hemispheres connected by a tract of nerve fibres called corpus callosum. The layer of cells which covers the cerebral hemisphere is called cerebral cortex. The cerebral cortex contains motor areas and sensory areas. These regions are responsible for complex functions like intersensory associations, memory and communication.
The cerebrum wraps around a structure called thalamus, which is a major coordinating centre for sensory and motor signaling. The hypothalamus lies at the base of the thalamus. The hypothalamus control body temperature, urge for eating and drinking.
(c) Midbrain The midbrain is located between the thalamus/hypothalamus of the forebrain and pons of the hindbrain. A canal called the cerebral aqueduct passess through the midbrain.
The dorsal portion of the midbrain consists mainly of four round swellings (lobes) called corpora quadrigemina.
(d) Hindbrain The hindbrain comprises pons, cerebellum and medulla (also called the medulla oblongata). Pons consists of fibre tracts that interconnect different regions of the brain. Cerebellum has very convoluted surface and the medulla of the brain is connected to the spinal cord.
(e) Retina The inner layer of eye ball is the retina and it contains three layers of cells from inside to outside - ganglion cells, bipolar cells and photoreceptor cells. There are two types of photoreceptor cells namely, rods and cones. These cells contain the light-sensitive proteins called the photopigments.
(f) Ear ossicles The middle ear contains three ossicles called malleus, incus and stapes which are attached to one another in a chain-like fashion.The malleus is attached to the tympanic membrane and the stapes is attached to the oval window of the cochlea. The ear ossicles increase the efficiency of transmission of sound waves to the inner ear.
(g) Cochlea The membranous labyrinth of inner ear is filled with a fluid called endolymph. The coiled portion of the labyrinth is called cochlea. The membranes constituting cochlea, the reissner's and basilar, divide the surounding perilymph filled bony labyrinth into an upper scala vestibuli and a lower scala tympani. The space within cochlea called scala media is filled with endolymph. At the base of the cochlea, the scala vestibuli ends at the oval window, while the scala tympani terminates at the round window which opens to the middle ear.
(h) Organ of Corti The organ of Corti is a structure located on the basilar membrane of inner ear, which contains hair cells that act as auditory receptors. The hair cells are present in rows on the internal side of the organ of Corti. The basal end of the hair cell is in close contact with the afferent nerve fibres. A large number of processes called stereo cilia are projected from the apical part of each hair cell. Above the rows of the hair cells is a thin elastic membrane called tectorial membrane.
(i) Synapse It is junction between two neurons, where one neuron expands and comes in near contact with another neuron. A synapse is formed by the membranes of a pre-synaptic neuron, and a post-synaptic neuron, which may or may not be separated by a gap called synaptic cleft. There are two types of synapses- an electrical synapse and a chemical synapse. In electrical synapse, membranes of pre and post-synaptic neurons are is very close proximity field. In chemical synapse, there membranes are separated by a fluid filled space called synaptic cleft.
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