topic 6 (senses) Flashcards
Describe the macroscopic structure of the eye.
Sclera: The white, outer layer of the eye.
Cornea: Transparent front part of the eye that covers the iris, pupil, and anterior chamber.
Iris: Colored part of the eye, controlling the diameter of the pupil.
Pupil: Opening in the center of the iris, regulates the amount of light entering the eye.
Lens: Transparent structure behind the iris, focuses light onto the retina.
Retina: Light-sensitive inner surface at the back of the eye, contains photoreceptors (rods and cones).
Optic Nerve: Transmits visual information from the retina to the brain.
Macula: Central part of the retina, responsible for detailed central vision.
Fovea: Small depression in the macula, highest visual acuity.
Outline the causes of cataracts and glaucoma.
Cataracts: Caused by the clouding of the eye’s lens, leading to vision impairment. Risk factors include aging, diabetes, excessive UV exposure, smoking, and prolonged use of corticosteroids.
Glaucoma: A group of eye conditions resulting in optic nerve damage, often due to increased intraocular pressure. Causes include genetic predisposition, age, severe myopia, and conditions like diabetes and hypertension.
Describe the pathway of visual processing.
Light enters the eye through the cornea.
Passes through the aqueous humor, pupil, lens, and vitreous humor.
Focused onto the retina, where photoreceptors (rods and cones) convert light into electrical signals.
Signals travel through the optic nerve.
Optic nerves converge at the optic chiasm.
Processed by the lateral geniculate nucleus of the thalamus.
Signals are relayed to the primary visual cortex in the occipital lobe for interpretation.
Describe the location and activation of smell receptors and the afferent pathways for this sense.
Location: Olfactory epithelium in the roof of the nasal cavity.
Activation: Odor molecules bind to receptors on the cilia of olfactory receptor neurons.
Afferent Pathway: Activated neurons send signals through the olfactory nerve (cranial nerve I) to the olfactory bulb. Signals are then relayed to the olfactory tract and further processed in the olfactory cortex, limbic system, and frontal cortex.
Describe the location, types, and activation of taste receptors and the afferent pathways for this sense.
Location: Taste buds on the tongue, soft palate, pharynx, and epiglottis.
Types of Receptors: Sweet, salty, sour, bitter, and umami.
Activation: Chemicals in food dissolve in saliva, bind to receptors on taste bud cells.
Afferent Pathway: Signals are transmitted via the facial nerve (cranial nerve VII), glossopharyngeal nerve (cranial nerve IX), and vagus nerve (cranial nerve X) to the gustatory cortex in the brain.
Describe the structure and general function of the outer, middle, and internal ears.
Back
Outer Ear: Includes the pinna (auricle) and external auditory canal; captures sound waves and directs them to the eardrum.
Middle Ear: Contains the tympanic membrane (eardrum) and ossicles (malleus, incus, stapes); amplifies and transmits sound vibrations to the inner ear.
Inner Ear: Includes the cochlea (hearing) and vestibular system (balance); converts sound vibrations to neural signals and detects head movements for balance.
Explain how balance organs of the semicircular canals and the vestibule help maintain equilibrium.
Semicircular Canals: Three fluid-filled loops oriented in different planes; detect rotational head movements. Movement of endolymph within the canals bends hair cells in the crista ampullaris, sending signals to the brain.
Vestibule: Contains the utricle and saccule; detects linear accelerations and head position relative to gravity. Otoliths (calcium carbonate crystals) shift with movement, bending hair cells and sending signals to the brain.
Combined Function: These structures send information via the vestibular nerve to the brainstem and cerebellum, helping maintain balance and coordinate head and eye movements.
How is smell perceived?
Odour Molecules: Enter the nasal cavity and dissolve in the mucus.
Olfactory Receptors: Located in the olfactory epithelium, these receptors detect odour molecules.
Signal Transmission: Activated receptors send signals via the olfactory nerve (cranial nerve I) to the olfactory bulb.
Processing: Signals are relayed from the olfactory bulb to the olfactory tract and then to the olfactory cortex, limbic system, and frontal cortex for perception and emotional response.
How is taste perceived?
Taste Buds: Located on the tongue, soft palate, pharynx, and epiglottis.
Taste Receptors: Detect five basic tastes - sweet, salty, sour, bitter, and umami.
Signal Activation: Chemicals in food dissolve in saliva and bind to taste receptors on taste bud cells.
Afferent Pathways: Signals are transmitted via the facial nerve (cranial nerve VII), glossopharyngeal nerve (cranial nerve IX), and vagus nerve (cranial nerve X) to the gustatory cortex for processing.
Function of different structures of the ear in hearing.
Outer Ear (Pinna and External Auditory Canal): Captures sound waves and directs them to the eardrum.
Middle Ear (Tympanic Membrane and Ossicles): Amplifies and transmits sound vibrations to the inner ear.
Inner Ear (Cochlea): Converts sound vibrations into neural signals through the movement of hair cells in response to fluid vibrations.
Function of different structures of the ear in balance.
Semicircular Canals: Detect rotational movements. Endolymph movement bends hair cells in the crista ampullaris, sending signals to the brain about head rotation.
Vestibule (Utricle and Saccule): Detect linear acceleration and head position relative to gravity. Otoliths shift with movement, bending hair cells and sending signals to the brain.
Afferent Pathways: Balance information is transmitted via the vestibular nerve to the brainstem and cerebellum, aiding in the maintenance of equilibrium and coordination of movements.
Explain how balance organs of the semicircular canals and the vestibule help maintain equilibrium.
Semicircular Canals: Detect rotational head movements through the movement of endolymph, which bends hair cells in the crista ampullaris.
Vestibule: Contains utricle and saccule, which detect linear accelerations and head position relative to gravity via shifting otoliths.
Combined Function: Send balance information through the vestibular nerve to the brainstem and cerebellum, maintaining balance and coordinating head and eye movements.
