Olfaction in animals Olfaction in animals is defined as the detection of chemicals that are carried in the air. It is the sense of smell. The vertebrates have greater capacity in distinguishing the variety of odorants (chemicals detected by the olfactory system). Olfactory system Olfactory system comprises of the olfactory receptors, supporting cells, and basal […]
Auditory pathway The vestibulo cochlear nerve end up in the cochlear nucleus of the medulla. The impulses from here are transmitted to superior olivary nuclei, inferior colliculus and median geniculate body of thalamus. From thalamus it endsup in temporal lobe of cerebral cortex (auditory cortex) Temporal lobe sends efferent to limbic system for behavioural modification
Process of hearing The pinna concentrates the sound waves to the auditory canal which conducts the sound waves to the ear drum. The sound waves strike the ear drum causing it to vibrate. These vibrations are conducted by the ear ossicles to the inner ear through the oval window. The vibrations cause the perilymph to
Auditory apparatus Auditory apparatus The sense of hearing is the process of detecting and interpretation of sound waves. It is done by the organ called as the ears. Ear The ear consists of three parts: The outer ear, middle ear, and inner ear. The outer ear is of the external pinna and the auditory canal.
Accommodation of the eye Accommodation of the eye is the ability of the eye lens to change its focal length by changing its radius of curvature. In near vision contraction of ciliary muscels causes decreased tension to the suspensory ligament and causes bulging of the anterior curvature of the eye. To cause distant vision ciliary
Types of visions in animals Monocular or periscopic Laterally placed eyes (frog and reptiles) viewing the object independently due to wide visual angle between optic axis and mid line of the eye. Binocular vision Anterio laterally placed eyes (primates, carnivores, birds), both the eyes view the same object simultaneously, overlap of field of vision due
Visual pathway in animals Hyperpolarization of rods and cones alter the activity of bipolar cells. Impulse frequency of ganglion cells too get altered. Horizontal cells influence Bipolar cells, Amacrine cells influence ganglion cells to detect contrast and contour. Axons of ganglion cells project as OPTIC NERVE to the lateral geniculate nucleus of THALAMUS (visual relay
Mechanism of photoreception As the light strikes the photoreceptors, transformation of photo pigment occurs with the resultant HYPERPOLARIZATION of receptor cells. During darkness, the Na+ channel are opened / remain open on rod and cone cell membrane. Na+ leak into rods and lower the membrane potential. As light strikes the rods retinal is released from rhodopsin and
Photo transduction The light falls on the retina by the adjusting the refractive media of the eye. As the light falls on the retina, the rods and cones absorb energy and convert it into electrical signal. The rods and cones are located at the back of the retina synapse with bipolar cells which in turn
Physiological anatomy of eye SCLERA Covering of the eye – Protective in function, Tough in nature. CORNEA (stratified squamous) Transparent Structure, anterior modification of sclera. CHOROID Vascular and Pigmented area of sclera in its posterior part. RETINA Innerside of choroid, has PHOTORECEPTORS. DARK PIGMENT Animal with day light vision, to absorb light which has to
