Question

Pick a topic from the visual system and discuss it .

Answer 1

Visual system consists of eyes, optic nerve,optic chiasma, Laterla geniculate nucleus, visual cortex, visual association area.

Visual system consists of the organs and structures involved including the central nevous system which enables the organism to process the visual details of the surroundings.

Eye structure can be picked as a topic of visual system.

The organ that is present in most of the animals in the visual system is Eye. Vertebrates have well developed eye. The structure of the eye remained mostly stable in all the vertebrates. Certain birds like eagle have sharp eyes for viewing objects from far above the earth. But the basic structure of the eye in all the vertebrates is similar.

Eye consists of eye ball embedded in sockets of the skull. Eye ball is surrounded by muscles which help in rotating the eyes.Eyes are photoreceptors of the visual system. It is these which receive the light rays and convert the visual signals in to nerve impulses and transmit it to the brain through optic nerve.

Eye ball consists of 3 layers. Sclerotic, Choroid and Retina. Sclerotic layer is fibrous and provides shape and protection to the eye. Chorois=d layer is vascular and pigmented layer. The middle layer forms Iris in the exposed part of the eye which has an aperture called pupil.. Pupil is like a window in to the eye through which the light rays enter in to the eye. Inner most layer is retina. This is the layer of photoreceptors called Rods and Cones. Rods are for dim light vision (night vision) and cones are for vision during bright light ( day vision). Rods and cones end in nerve branches. When light falls on rods and cones, the photoreceptors will get stimulated. Stimulation of photoreceptors liberates generation potential. The generation potential produce by the receptors is converted in to action potential. The action potential is carried to the brain as nerve impulse through the optic nerve. When the nerve impulse reaches the visual cortex, we are able to see the object. Association area around the visual cortex of the Occipital lobe of the brain helps us in perceiving the object.