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Abhishek Jhunjhunwala

Class 11th
Biology
2 years ago

Write short notes on the following: (a) Neural coordination (b) Forebrain (c) Midbrain (d) Hindbrain (e) Retina (f) Ear ossicles

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Muskan Anand

2 years ago

(a) Neural coordination The neural gadget gives speedy coordination the various organs of the frame. This coordination is withinside the shape of electric powered impulses and is short and brief lived. All the physiological strategies withinside the frame are closed related and based upon every other. For example, at some stage in exercise, our frame calls for extra oxygen and food. Hence, the respiration price will increase routinely and the coronary heart beats quicker. This ends in a quicker deliver of oxygenated blood to the muscles. Moreover, the mobile features require law continuously. These features are achieved through the hormones. Hence, the neural device in conjunction with the endocrine gadget manage and coordinate the physiological tactics. (b) Forebrain It is the principle questioning a part of the mind. It includes cerebrum, thalamus, and hypothalamus. (i) Cerebrum: Cerebrum is the most important a part of the mind and constitutes approximately 4-5th of its weight. Cerebrum is split into cerebral hemispheres via way of means of a deep longitudinal cerebral fissure. These hemispheres are joined through a tract of nerve fibres referred to as corpus callosum. The cerebral hemispheres are blanketed with the aid of using a layer of cells referred to as cerebral cortex or gray matter. Cerebrum has sensory areas called affiliation regions that acquire sensory impulses from diverse receptors in addition to from motor areas that manage the motion of diverse muscles. The innermost a part of cerebrum offers an opaque white look to the layer and is called the white matter. (ii) Thalamus: Thalamus is the primary centre of coordination for sensory and motor signalling. It is wrapped through cerebrum. (iii) Hypothalamus: It lies at the bottom of thalamus and consists of some of centres that adjust frame temperature and the urge for consuming and drinking. Some areas of cerebrum, at the side of hypothalamus, are concerned withinside the law of sexual behaviour and expression of emotional reactions inclusive of excitement, pleasure, fear, etc. (c) Midbrain It is positioned among the thalamus place of the forebrain and pons location of hindbrain. The dorsal floor of midbrain includes advanced and inferior corpora bigemina and 4 spherical lobes known as corpora quadrigemina. A canal called cerebral aqueduct passes via the midbrain. Midbrain is involved with the feel of sight and hearing. (d) Hindbrain It includes 3 areas - pons, cerebellum, and medulla oblongata. (i) Pons is a band of nerve fibres that lies among medulla oblongata and midbrain. It connects the lateral components of cerebellar hemisphere together. (ii) Cerebellum is a big and properly evolved a part of hindbrain. It is placed under the posterior facets of cerebral hemispheres and above the medulla oblongata. It is liable for keeping posture and equilibrium of the frame. (iii) Medulla oblongata is the posterior and best a part of the mind. It is placed under the cerebellum. Its lower give up extends withinside the shape of spinal twine and leaves the cranium thru foramen magnum. (e) RetinaRetina is the innermost layer. It consists of 3 layers of cells - internal ganglion cells, center bipolar cells, and outermost photoreceptor cells. The receptor cells gift withinside the retina are of types - rod cells and cone cells. (i) Rod cells -The rods include rhodopsin pigment (visible purple), that is exceptionally touchy to dim light. It is answerable for twilight vision. (ii) Cone cells -The cones comprise iodopsin pigment (visible violet) and are fantastically touchy to excessive depth light. They are accountable for daytime and color visions. The innermost ganglionic cells deliver upward push to optic nerve fibre that bureaucracy optic nerve in every eye and is hooked up with the mind. In this area, the photoreceptor cells are absent. Hence, it's far called the blind spot. At the posterior part, lateral to blind spot, there's a pigmented spot referred to as macula lutea. This spot has a shallow melancholy at its center called fovea. Fovea has handiest cone cells. They are without rod cells. Hence, it's far the area of maximum wonderful vision. (f) Ear ossicles The center ear carries a bendy chain of 3 center bones referred to as ear ossicles. The 3 ear ossicles are as follows. (i) Malleus (ii) Incus (iii) Stapes The malleus is hooked up to tympanic membrane on one facet and to incus on the alternative facet. The incus is hooked up with stapes. Stapes, in turn, are connected with an oval membrane, fenestra ovalis, of inner ear. The ear ossicles act as a lever that transmits sound waves from outside ear to inner ear

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