Home
Class 11
BIOLOGY
Explain the following : (a) Role of Na...

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

Text Solution

Verified by Experts

(a) In a stimulated nerve fibre, sodium channels of the neurilemma come in activated state and open. Sodium ions rapidly diffuse from outside to interacellular fluid due to their electrochemical gradient. The potential difference first increases to zero and then rises to `+45 mV` and is called action potential. This causes depolarization of nerve fibre.
(b) When the light rays are foccused on the photoreceptors (rods and cones), then their photopigments are dissociated which activate the transduction protein which activates phosphodiesterase enzyme which changes C - GMP into 5. - GMP. Declined level of C - GMP causes closing of `Na^(+)` channels and hyperpolarisation of photoreceptors and an action potential is generated.
Promotional Banner

Topper's Solved these Questions

  • NEURAL CONTROL AND COORDINATION

    MODERN PUBLICATION|Exercise NCERT Exemplar Problems (A. MULTIPLE CHOICE QUESTIONS)|11 Videos

  • NEURAL CONTROL AND COORDINATION

    MODERN PUBLICATION|Exercise NCERT Exemplar Problems (B. VERY SHORT ANSWER TYPE QUESTIONS)|12 Videos

  • NEURAL CONTROL AND COORDINATION

    MODERN PUBLICATION|Exercise PRACTICE PROBLEMS - RECEPTORS|23 Videos

  • MORPHOLOGY OF FLOWERING PLANTS

    MODERN PUBLICATION|Exercise CASE BASED SHORT ANSWER TYPE QUESTIONS|2 Videos

  • PHOTOSYNTHESIS IN HIGHER PLANTS

    MODERN PUBLICATION|Exercise CHAPTER PRACTICE TEST|9 Videos

Similar Questions

Explore conceptually related problems

The steps involved in the mechanism of vision are given below. Arrange them in proper sequence and select the correct option. A. Dissociation of retinal from opsin and generation of potential difference in photoreceptor cells. B. Focusing of the light rays in visible wavelength on the corner through the lens. C. Generation of the action potential in ganglion cells through bipolar cells. D. Analysis of neural impulse and formation of aa image on the retina. E. Transmission of the action potential by the optic nerve to the visual cortex.

Explain the following : (a) How does the middle ear help in hearing ? (b) Why does vitamin A deficiency produce night-blindness ? (c ) What is the role of lacrimal gland ? (d) How does the iris adjust the size of the pupil ?

Given below are some of the process which takes place in our ear when we are exposed to any sound. Arrange these in the correct order of sequence. (a)The eardrum vibrates the transmits the sound wave to the ear ossicles. (b) Vibration travel from oval window to the fluid of cochlea. (c) Ripples in the basilar membrane band the hair cell against the tectorial membrane (d) Generation of waves in the lymphs. (e ) sound waves are collected by the pinna. (f) generation of nerve impulse and transmission through auditory nerves to the brain

Given below are the steps involved in the generation and conduction of nerve impulse. Arrange them in proper sequence and select the correct option. I. Rapid influx of Na^+ ions followed by reversal of polarity at the site of application of stimulus. II. Reversal of polarity and generation of action potential at a point ahead of the point of application of stimulus. III. Development of free permeability to Na^+ ions at the site of application of stimulus. IV. Arrival of the impulse generated at the first site to the second site. V. Rise in permeability of K^+ ions and restoration of the resting potential of the membrane.