Write short notes on the following: (a) Neural coordination (b) Forebrain (c) Midbrain (d) Hindbrain (e) Retina (f) Ear ossicles (g) Cochlea (h) Organ of Corti (i) Synapse

(a) Neural Coordination:- The neural system provides rapid coordination among the organs of the body. This coordination is in the form of electric impulses and is quick and short lived. For example, during exercise, our body requires more oxygen and food. Hence, the breathing rate increases automatically and the heart beats faster. This leads to a faster supply of oxygenated blood to the muscles. Moreover, the cellular functions require regulation continuously. These functions are carried out by the hormones. Hence, the neural system along with the endocrine system control and coordinate the physiological processes.
(b) Forebrain:- It is the main thinking part of the brain. It consists of cerebrum, thalamus, and hypothalamus.
1. Cerebrum: Cerebrum is the largest part of the brain and constitutes about four-fifth of its weight. Cerebrum is divided into two cerebral hemispheres by a deep longitudinal cerebral fissure. These hemispheres are joined by a tract of nerve fibres known as corpus callosum. The cerebral hemispheres are covered by a layer of cells known as cerebral cortex or grey matter.The innermost part of cerebrum gives an opaque white appearance to the layer and is known as the white matter.
2. Thalamus: Thalamus is the main centre of coordination for sensory and motor signalling. It is wrapped by cerebrum.
3. Hypothalamus: It lies at the base of thalamus and contains a number of centres that regulate body temperature and the urge for eating and drinking.along with hypothalamus, region of cerebrum are involved in the regulation of sexual behaviour and expression of emotional reactions such as excitement, pleasure, fear, etc.
(c) Midbrain:-It is located between the thalamus region of the forebrain and pons region of hindbrain. The dorsal surface of midbrain consists of superior and inferior corpora bigemina and 4 round lobes called corpora quadrigemina. A canal known as cerebral aqueduct passes through the midbrain. Midbrain is concerned with the sense of sight and hearing.
(d) Hindbrain:- It consists of three regions – pons, cerebellum, and medulla oblongata.
1. Pons is a band of nerve fibres that lies between medulla oblongata and midbrain. It connects the lateral parts of cerebellar hemisphere together.
2. Cerebellum is a large and well developed part of hindbrain. It is located below the posterior sides of cerebral hemispheres and above the medulla oblongata. It is responsible for maintaining posture and equilibrium of the body.
3. Medulla oblongata is the posterior and simplest part of the brain. It is located beneath the cerebellum. Its lower end extends in the form of spinal cord and leaves the skull through foramen magnum.
(e) Retina
Retina is the innermost layer. It contains 3 layers of cells – inner ganglion cells, middle bipolar cells, and outermost photoreceptor cells. The receptor cells present in the retina are of two types – rod cells and cone cells.
1. Rod cells -The rods contain rhodopsin pigment (visual purple), which is highly sensitive to dim light. It is responsible for twilight vision.
2. Cone cells -The cones contain iodopsin pigment (visual violet) and are highly sensitive to high intensity light. They are responsible for daylight and colour visions.

For more answers visit to website:
https://www.tiwariacademy.com/ncert-solutions/class-11/biology/chapter-21/