Neural Control and Coordination


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 : When higher animals respond to various stimuli, each response to a specific stimulus generally involves many organs (parts) of their bodies. Therefore, it is necessary that all the concerned organs (parts) of the body should work in a systematic manner to produce the response. The working together of various organs (parts) of the body of multicelullar organism in a proper manner to complement the functions of each other is called coordination. This is achieved by three overlapping processes of nervous system-sensory input, integration and motor output.
(b) Forebrain: It consists of: Olfactory lobes, the paired structures concerned with the sense of smell. Cerebrum which is the largest and most complex of all the parts of the human brain. It is divided by a cleft into left and right cerebral hemispheres which are connected by a large bundle of myelinated fibres the. corpus callosum. The outer cover of cerebral hemisphere is called cerebral cortex. It consists of sensory and motor areas. Hypothalamus region of forebrain contains centres which control body temperature, hunger and also contains group of neurosecretory cells.
(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. Midbrain and hindbrain form the brain stem.
(d) Hindbrain: The hindbrain comprises pons, cerebellum and medulla. Pons consists of fibre tracts that interconnect different regions of the brain. Cerebellum has very convoluted surface in order to provide the additional space of many more neurons. The medulla of the brain is connected to the spinal cord. The medulla contains centres which control respiration, cardiovascular reflexes and gastric secretions.
(e) Retina: Retina is the inner layer of an eye 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. The daylight (photopic) vision and colour vision are functions of cones and the twilight (scotopic) vision is the function of the rods. The rods contain a purplish-red protein called the rhodopsin or visual purple, which contains a derivative of Vitamin A. In the human eye, there are three types of cones which possess their own characteristic photopigments that respond to red, green and blue lights. The sensations of different colours are produced by various combinations of these cones and their photopigments. When these cones are stimulated equally, a sensation of white light is produced.
(f) Ear ossicles : There is a small flexible chain of three small bones called as ear ossicles – the malleus (hammer shaped), the incus (anvil shaped) and the stapes (stirrup shaped) in the middle ear. Malleus is attached to the tympanic membrane on one side and incus on the other side. Incus in turn is connected with the stapes. Malleus is the largest ossicle, however stapes is the smallest ossicle.
(g) Cochlea : It is the main hearing organ which is connected with saccule. It is a spirally coiled tube that resembles a snail shell in appearance. It tapers from a broad base to an almost pointed apex.
(h) Organ of Corti: It is a structure located on the basilar membrane 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.
(i) Synapse : It is the junction between the axon of one neuron and the dendrite or cyton of another neuron for transmission of nerve impulse.


Neural Control and Coordination

Q 1.

If someone receives a blow on the back of neck, what would be the effect on the person’s CNS?

Q 2.

Label the following parts in the given diagram using arrow.
(a) Aqueous chamber
(b) Cornea
(c) Lens
(d) Retina
(e) Vitreous chamber
(f) Blind spot

Q 3.

Comment upon the role of ear in maintaining the balance of the body and posture.

Q 4.

Which cells of the retina enable us to see coloured objects around us?

Q 5.

Answer the following.
(a) Which part of the ear determines the pitch ofa sound?
(b) Which part of the human brain is the most developed?
(c) Which part of our central neural system acts as a master clock?

Q 6.

Complete the statement by choosing appropriate match among the following.

Q 7.

The major parts of the human neural system is depicted below. Fill in the empty boxes with appropriate words.

Q 8.

Neural system and computers share certain common features. Comment in five lines. (Hint: CPU, input-output devices).

Q 9.

Name the structures involved in the protection of the brain.

Q 10.

Name the parts of human forebrain indicating their respective functions.

Q 11.

Rearrange the following in the correct order of involvement in electrical impulse movement- Synaptic knob. Dendrites, Cell body. Axon terminal. Axon.

Q 12.

Explain the following.
(a) Role of Na+ in the generation of action potential.
(b) Mechanism of generation of light-induced impulse in the retina.
(c) Mechanism through which a sound produces a nerve impulse in the inner ear.

Q 13.

What do grey and white matter in the brain represent?

Q 14.

6. Give a brief account of
(a) Mechanism of synaptic transmission.
(b) Mechanism of vision.
(c) Mechanism of hearing.

Q 15.

Arrange the following in the order of reception and transmission of sound wave from the ear drum:
Cochlear nerve.External auditoru canal, Ear drum, Stapes, Incus, Malleus, Cochlea.

Q 16.

While travelling at a higher altitude, a person complains of dizziness and vomiting sensation. Which part of the inner ear is disturbed during the journey?

Q 17.

Explain the following.
(a) Role of Na+ in the generation of action potential.
(b) Mechanism of generation of light-induced impulse in the retina.
(c) Mechanism through which a sound produces a nerve impulse in the inner ear.

Q 18.

What is the function ascribed to Eustachian tube?

Q 19.

Which sensory organ is involved in vertigo (sensation of oneself or objects spinning around)?

Q 20.

The region of the vertebrate eye, where the optic nerve passes out of the retina, is called the
(a) fovea (b) iris
(c) blind spot (d) optic chiasma

Q 21.

Our reactions like aggressive behaviour, use of abusive words, restlessness etc. are regulated by brain, name the parts involved.

Q 22.

Briefly describe the structure of the following:
(a) Brain (b) Eye (c) Ear

Q 23.

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

Q 24.

Compare the following:
(a) Central neural system (CNS) and Peripheral neural system (PNS).
(b) Resting potential and action potential.
(c) Choroid and retina.

Q 25.

Answer briefly.
(a) How do you perceive the colour of an object?
(b) Which part of our body helps us in maintaining the body balance?
(c) How does the eye regulate the amount of light that falls on the retina?

Q 26.

Where is the hunger centre located in human brain?

Q 27.

Explain the following processes:
(a) Polarisation of the membrane of a nerve fibre.
(b) Depolarisation of the membrane of a nerve fibre.
(c) Conduction of a nerve impulse along a nerve fibre.
(d) Transmission of a nerve impulse across a chemical synapse.

Q 28.

Explain the structure of middle and internal ear with the help of diagram.

Q 29.

Explain the process of the transport and release of crneurotransmitter with the help of a labelled diagram showing a complete neuron, axon terminal and synapse.

Q 30.

Distinguish between
(a) Afferent neurons and efferent neurons
(b) Impulse conduction in myelinated nerve fibre and unmyelinated nerve fibre
(c) Aqueous humour and vitreous humour
(d) Blind spot and yellow spot
(e) Cranial nerves and spinal nerves

Q 31.

During resting potential, the axonal membrane is polarised, indicate the movefnent of +ve and -ve ions leading to polarisation diagrammatically.

Q 32.

Draw labelled diagrams of the following:
(a) Neuron (b) Brain
(c) Eye (d) Ear

Q 33.

What is the difference between electrical transmission and chemical transmission?

Q 34.

Differentiate between
(a) Myelinated and non-myelinated axons
(b) Dendrites and axons
(c) Rods and cones
(d) Thalamus and Hypothalamus
(e) Cerebrum and Cerebellum