Class Notes (810,035)
Canada (493,928)
BIOB32H3 (79)

special senses.docx

5 Pages
Unlock Document

University of Toronto Scarborough
Biological Sciences
Kenneth Welch

The Special Senses Olfaction Olfactory organs • Contain olfactory epithelium with olfactory receptors, supporting cells, basal cells • Olfactory receptors are modified neurons • Surfaces are coated with secretions from olfactory glands • Olfactory reception involved detecting dissolved chemicals as they interact with odorant binding proteins Olfaction • Olfactory pathways • No synapse in the thalamus for arriving information • Olfactory discrimination • Can distinguish thousands of chemical stimuli • CNS interprets smells by pattern of receptor activity • Olfactory receptor population shows considerable turnover • Number of receptors declines with age Gustation Taste receptors • Clustered in taste buds • Associated with lingual papillae Taste buds • Contain basal cells which appear to be stem cells • Gustatory cells extend taste hairs through a narrow taste pore Gustatory pathways • Taste buds are monitored by cranial nerves • Synapse within the solitary nucleus of the medulla oblongata • Then on to the thalamus and the primary sensory cortex Gustatory discrimination • Primary taste sensations • Sweet, sour, salty, bitter • Receptors also exist for umami and water • Taste sensitivity shows significant individual differences, some of which are inherited • The number of taste buds declines with age Vision Accessory structures of the eye • Eyelids (palpebrae) separated by the palpebral fissue • Eyelashes • Tarsal glands • Lacrimal apparatus external structures of the eye • Conjunctiva covers most of eye • Cornea is transparent anterior portion Lacrimal apparatus • Secretions from the lacrimal gland contain lysozyme • Tears form in the lacrimal glands, wash across the eye and collect in the lacrimal lake • Pass through the lacrimal punctae, lacrimal canaliculi, lacrimal sac and nasolacrimal duct The eye • Three layers • Outer fibrous tunic • Sclera, cornea, limbus • Middle vascular tunic • Iris, ciliary body, choroid • Inner nervous tunic • Retina internal structures of the eye • Ciliary body • Ciliary muscles and ciliary processes, which attach to suspensory ligaments of lens • Retina • Outer pigmented portion • Inner neural part • Rods and cones The Special Senses retina • Retina contains rods and cones • Cones densely packed at fovea (center of the macula lutea) • Retinal pathway • Photoreceptors to bipolar cells to ganglion cells, to the brain via the optic nerve • Axons of ganglion cells converge at blind spot (optic disc) • Horizontal cells and amacrine cells modify the signal passed along the retinal neurons Eye anatomy • Ciliary body and lens divide the anterior cavity of the eye into posterior (vitreous) cavity and anterior cavity • Anterior cavity further divided • anterior chamber in front of eye • posterior chamber between the iris and the lens Fluids in the eye • Aqueous humor circulates within the eye • diffuses through the walls of anterior chamber • passes through canal of Schlemm • re-enters circulation • Vitreous humor fills the posterior cavity. • Not recycled – permanent fluid Lens • Posterior to the cornea and forms anterior boundary of posterior cavity • Posterior cavity contains vitreous humor • Lens helps focus • Light is refracted as it passes through lens • Accommodation is the process by which the lens adjusts to focus images • Normal visual acuity is 20/20
More Less

Related notes for BIOB32H3

Log In


Don't have an account?

Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.