Special Senses Anatomy & Physiology PDF

Special Senses Anatomy & Physiology Sensory Function Sensation is the raw input from the peripheral nervous system that arrive at the central nervous system.* Perception is the interpretation of the sensations. Sensory receptors are cells that detect stimuli. Mechanoreceptors – respond to...

Special Senses Anatomy & Physiology Sensory Function Sensation is the raw input from the peripheral nervous system that arrive at the central nervous system.* Perception is the interpretation of the sensations. Sensory receptors are cells that detect stimuli. Mechanoreceptors – respond to physical stimuli such as sound or touch Thermoreceptors – respond to temperature Pain Loremreceptors ipsum dolor sit– amet, detect tissue damage, extreme consectetuer heat and adipiscing elit.cold andporttitor Maecenas chemicalscongue released from damaged cells Photoreceptors – respond to light Chemoreceptors – detect chemicals Proprioceptors – detect position of body parts Transduction Transduction is the process by which a sensory receptor converts energy from a stimulus into electrical signals (action potentials). Lorem ipsum dolor sit amet, consectetuer adipiscing elit. Maecenas porttitor congue Sensory Adaptation Sensory adaptation is a phenomenon in which sensations become less noticeable with prolonged exposure to the stimulus.* Sensory receptors generate fewer action potentials under constant stimulation. The response returns only if the intensity of the stimulus changes.** General Senses The general senses detect touch, temperature, or pain with any part of the skin and in the internal organs. Sense Sense Organ Stimulus Type of Receptor Touch* Skin Pressure, vibration Mechanoreceptor Temperature Skin Heat, cold Thermoreceptor Pain Everywhere Damage to body Pain receptor except Lorem ipsum dolor sit amet, the brain consectetuer tissues adipiscing elit. Maecenas porttitor congue Position of body Joints, muscles, Stretching of Proprioceptor parts ligaments muscles and ligaments General Senses Lorem ipsum dolor sit amet, consectetuer adipiscing elit. Maecenas porttitor congue Special Senses The special senses have specialized structures for vision, olfaction, gustation, hearing and equilibrium. Sense Sense Organ Stimulus Type of Receptor Smell Nasal cavity Airborne Chemoreceptor molecules Taste Mouth and Dissolved Chemoreceptor tongue molecules Vision Eyes Light Photoreceptor Lorem ipsum dolor sit amet, consectetuer Hearing adipiscing elit. MaecenasEars porttitor congue Air pressure Mechanoreceptor waves Equilibrium Ears Motion of fluid in Mechanoreceptor inner ear Special Senses Lorem ipsum dolor sit amet, consectetuer adipiscing elit. Maecenas porttitor congue Eye Accessory Structures* 1. Eyelids (Palpebrae) – elastic movable folds of skin over the eyes, protects the eyes from debris and/or trauma 2. Eyelashes – hair that grows at the edge of the eyelids for protection and aesthetics 3. Eyebrows – hairy area of coarse skin above the eye for aesthetics and enhancement of facial expressions 4. Lacrimal Apparatus - consists of the lacrimal gland and ducts that drain Lorem ipsumlacrimal secretions dolor sit amet, into the nasal cavity. Produces tears that consectetuer cleanses, adipiscing lubricates elit. Maecenas and porttitor protects the eyes. Tears contain antibodies congue and enzymes that destroy bacteria. Tears drain to the minute opening called the lacrimal punctum. Eye Accessory Structures 5. Conjunctiva – mucous membrane lines the eyelids and covers part of the outer surface of the eye Bulbar conjunctiva – a thin transparent membrane that covers and protects the anterior portion of the white sclera. Palpebral conjunctiva – coats the insides of the eyelids Fornix conjunctiva – forms the junction between the bulbar and palpebral conjunctivae, loose and flexible, allowing the free movements of the lids and eyeballs Lorem ipsum dolor sit amet, consectetuer adipiscing elit. Maecenas porttitor congue Eye Accessory Structures Lorem ipsum dolor sit amet, consectetuer adipiscing elit. Maecenas porttitor congue Extra-ocular Muscles 6. Extra-ocular Muscles – innervated by the cranial nerves controlling the movement of the eyes. The coordinated action of these muscles allow the eyes to move in tandem, ensuring a clear vision. Superior rectus – CN III Oculomotor – elevation, also contributes in adduction and medial rotation of the eyeball. (upward) Inferior rectus – CN III Oculomotor – depression, also contributes to adduction and lateral rotation of the eyeball. (downward) Medial rectus – CN III Oculomotor – adduction (inward) Lateral Lorem ipsum dolorrectus – CN sit amet, VI Abducens – abduction (outward) consectetuer Superior adipiscing oblique elit. Maecenas – CN porttitor IV Trochlear – depresses, abducts and medially congue rotates the eyeball (downward and outward) Inferior oblique – CN III Oculomotor – elevates, abducts and laterally rotates the eyeball (upward and outward) Extra-ocular Muscles Lorem ipsum dolor sit amet, consectetuer adipiscing elit. Maecenas porttitor congue Eye Tunics 1. Fibrous Layer (Tunica Fibrosa) – fibrous tunic, outer layer, superficial coat of the eyeball Sclera – the white coating of the eye, white tough fibrous connective tissue protecting the inner structures of the eye. It helps maintain the shape of the eyeball. Cornea – a modified part of the sclera toward the front of the eye Lorem which ipsum doloris a sit transparent avascular curved window that bends amet, consectetuer incoming adipiscing light elit. Maecenas rays.congue porttitor Eye Tunics 2. Vascular Tunic (Tunica Vasculosa) – also known as the Uvea, middle layer of the eyeball Choroid – the layer internal to the sclera which is the vascular layer of the eye Ciliary Body – anterior continuation of the choroid that controls the lens’ thickness using its ciliary muscle. With the coordinated actions of the iris’ muscles, it regulates light passing through the lens to the retina. It secretes a fluid called aqueous humor. Lorem ipsum dolor sit amet, consectetuer Iriselit. adipiscing – aMaecenas modified partcongue porttitor of the choroid behind the cornea which is the colored part of the eye and regulates the size of the pupil Pupil – the hole in the middle of the iris that regulates light entering the eye Eye Tunics 3. Nervous Tunic (Tunica Nervosa) – layer that transmits nerve impulses Retina – a sheet of photoreceptors that forms the innermost layer of the eye. The optic nerve connects each retina to the brain. Sensory portion of the eye Macula – located near the center of the retina lateral to the optic disk. The macula is slightly darker than the rest of the retina. The macula provides the sharpest vision, allowing us to read and Lorem recognize ipsum dolor sit faces (central vision). amet, consectetuer Fovea adipiscing Centralis elit. Maecenas – slight porttitor depression within the macula, contains the congue heaviest concentration of cones and provides the clearest vision and color perception. Eye Tunics 3. Nervous Tunic (Tunica Nervosa) – layer that transmit nerve impulses Optic disk – a well-defined round or oval area within the retina. The ganglion nerve fibers (axons) exit the retina through this area to form the optic nerve. Physiologic cup – is a light-colored depression within the temporal side of the optic disk where blood vessels enter the retina. Rod cells* – are photoreceptors which are concentrated around the edges of the retina. These cells provide black and white vision Lorem ipsum dolor sit amet, consectetuer in dim adipiscing light and elit. Maecenas enable porttitor us to see at night (scotopic or night vision). congue Cone cells** – are photoreceptors which are concentrated toward the center of the retina. They require more light and they detect color (photopic or day vision). Eye Tunics Lorem ipsum dolor sit amet, consectetuer adipiscing elit. Maecenas porttitor congue Eye Tunics Lorem ipsum dolor sit amet, consectetuer adipiscing elit. Maecenas porttitor congue Eye Tunics Lorem ipsum dolor sit amet, consectetuer adipiscing elit. Maecenas porttitor congue Eye Refractory Structures 1. Lens - transparent, flexible tissue located directly behind the iris and the pupil which further bends the incoming light to focus light and images. 2. Aqueous humor - fluid found between the cornea and the lens that helps bend light rays and focus them on the retina. This fluid cleanses and nourishes the cornea and the lens and maintains the shape of the eyeball.* Lorem ipsum dolor sit amet, consectetuer 3.adipiscing Vitreous humor - jellylike substance that fills most of the eyeball’s elit. Maecenas porttitor congue volume (vitreous chamber). Eye Refractory Structures Aqueous humor Posterior chamber – the posterior chamber located right in front of the lens, filled with the aqueous humor, as it flows through the pupil into the anterior chamber, the fluid bathes the lens capsule. Aqueous fluid is manufactured in the posterior chamber by the ciliary body. Anterior chamber – The amount of aqueous humor in the anterior chamber varies to maintain the pressure in the eye. Fluid drains from the anterior chamber through collecting channels (trabecular meshwork) Lorem into ipsum dolor sit the amet, Schlemm’s canal. consectetuer adipiscing elit. Maecenas porttitor congue Schlemm's canal – is a circular lymphatic-like vessel in the eye that collects aqueous humor from the anterior chamber and delivers it into the episcleral blood vessels via aqueous veins. Eye Refractory Structures Lorem ipsum dolor sit amet, consectetuer adipiscing elit. Maecenas porttitor congue Visual Pathway The optic nerve leaves the eye and then meets the optic nerve from the other eye at the optic chiasm. The chiasm is the anatomic point at which the nasal fibers from the nasal retina of each eye cross to the opposite side of the brain. The nerve fibers from the temporal retina of each eye remain uncrossed. Fibers from the right half of each eye, which would be the left visual Lorem ipsum dolor sit amet, consectetuer field, carry adipiscing impulses elit. Maecenas to the porttitor right occipital lobe. Fibers from the left half of congue each eye, or the right visual field, carry impulses to the left occipital lobe. Beyond the chiasm, these fibers are known as the optic tract. Visual Pathway Lorem ipsum dolor sit amet, consectetuer adipiscing elit. Maecenas porttitor congue Visual Pathway Lorem ipsum dolor sit amet, consectetuer adipiscing elit. Maecenas porttitor congue Ear Divisions Lorem ipsum dolor sit amet, consectetuer adipiscing elit. Maecenas porttitor congue Outer Ear The outer ear develops in the embryo at the same time as the kidneys and urinary tract. 1. Auricle – shell shaped projecting structure of the external ear that collects and directs sound waves. - helix, antihelix, tragus, earlobe 2.Lorem Auditory Canal – short and narrow sound passageway that leads from ipsum dolor sit amet, consectetuer the outer adipiscing to theporttitor elit. Maecenas inner ear. congue Outer Ear 2. Ceruminous Gland – lines the wall of the auditory canal and secretes a waxy yellow substance called ear wax or cerumen. 3. Mastoid Process – the bony ridge located over the temporal bone and behind the auricle The mastoid air cells are thought to protect the delicate structures of the ear, regulate ear pressure and possibly protect the temporal bone Lorem ipsum trauma. during dolor sit amet, The consectetuer air filled spaces are important for sound adipiscing elit. Maecenas porttitor congue transmission. Outer Ear Lorem ipsum dolor sit amet, consectetuer adipiscing elit. Maecenas porttitor congue Middle Ear The middle ear is an air filled cavity which includes the tympanic membrane. It is connected by the Eustachian tube to the nasopharynx and is continuous with the air filled cells in the adjacent mastoid bone. 1. Ear Drum / Tympanic Membrane – a membrane that vibrates in response to sound waves and is the partition between the external auditory canal and the middle ear. 2.Lorem Auditory ipsum dolorTube / Eustachian sit amet, consectetuer Tube – 1 mm wide and 35 mm long canal that connects adipiscing elit. Maecenasthe ear congue porttitor to the nasopharynx. It controls the pressure within the ear, making it equal with the air pressure outside the body. It also drains normal and abnormal secretions from the middle ear. Middle Ear Lorem ipsum dolor sit amet, consectetuer adipiscing elit. Maecenas porttitor congue Middle Ear 3. Ossicles – 3 smallest bones of the body which amplify the sound and transmit the vibratory motion of the eardrum to the fluids of the inner ear. Malleus (Hammer) – the first bony ossicle where the eardrum is attached Incus (Anvil) – attached to the malleus and stapes Stapes (Stirrups) – attached to the oval window 4. Windows Lorem ipsum dolor–sittwo amet,covered consectetueropenings at the end of the ossicles. It separates adipiscing the elit. Maecenas middle porttitor ear from the inner ear. congue Oval Window – where the vibration enters Round Window – exit point of vibration Middle Ear Lorem ipsum dolor sit amet, consectetuer adipiscing elit. Maecenas porttitor congue Inner Ear The portion of the ear responsible for balance, equilibrium and hearing housed in the temporal bone. It houses the organ of hearing as well as the facial and vestibulocochlear nerves. 1. Cochlea – auditory portion of the inner ear filled with fluids which moves in response to the vibrations coming from the middle ear via the oval window stimulating the hair cells. Perilymph – found in the space between the membranous and Lorem ipsum dolor sit amet, consectetuer bony labyrinth (tunnels & chambers) adipiscing elit. Maecenas porttitor congue Endolymph – found in the membranous labyrinth 2. Organ of Corti – sensorineural organ of the cochlea which is composed of hearing receptors called hair cells. Inner Ear 3. Hair Cells – specialized sensory cells that change the vibrations into electrical signals that are sent to the brain through the cochlear nerve 4. Vestibule – (static equilibrium) sensory apparatus of the inner ear that responds to changes in the position of the head with respect to gravity to maintain body balance, signals that are sent to the brain through the vestibular nerve 5. Semicircular Canal – (kinetic or dynamic equilibrium) sensory Lorem ipsum dolor sit amet, consectetuer apparatus of the inner ear that responds to rotational movements and adipiscing elit. Maecenas porttitor congue helping the body maintain postural equilibrium, signals that are sent to the brain through the vestibular nerve Inner Ear Lorem ipsum dolor sit amet, consectetuer adipiscing elit. Maecenas porttitor congue Inner Ear Lorem ipsum dolor sit amet, consectetuer adipiscing elit. Maecenas porttitor congue Inner Ear Lorem ipsum dolor sit amet, consectetuer adipiscing elit. Maecenas porttitor congue Inner Ear Lorem ipsum dolor sit amet, consectetuer adipiscing elit. Maecenas porttitor congue Auditory Pathway Air conduction – sound travels over the air filled external and middle ear through vibration of the tympanic membrane and ossicles. Bone conduction – sound travels directly through bone to the inner ear bypassing the tympanic membrane and ossicles. Lorem ipsum dolor sit amet, consectetuer adipiscing elit. Maecenas porttitor congue Auditory Pathway Auditory Pathway Lorem ipsum dolor sit amet, consectetuer adipiscing elit. Maecenas porttitor congue Body Equilibrium Body balance is maintained by: 1. Muscles/joints (Proprioception – sense of body position) 2. Eyes (Vision) 3. Ears (Vestibular) 4. Cerebellum (Cerebellar) Any changes in these systems can cause problems with balance. Lorem ipsum dolor sit amet, consectetuer These elit. adipiscing areas sendporttitor Maecenas their congue information about equilibrium to the brain for coordination and interpretation in the cerebral cortex. Body Equilibrium Lorem ipsum dolor sit amet, consectetuer adipiscing elit. Maecenas porttitor congue Body Equilibrium Lorem ipsum dolor sit amet, consectetuer adipiscing elit. Maecenas porttitor congue Vestibular Pathway Lorem ipsum dolor sit amet, consectetuer adipiscing elit. Maecenas porttitor congue Olfactory Structures Nose – a structure projecting from the face for breathing and smelling. 1. Olfactory region – located at the extreme superior region of the nasal cavity that is lined with a specialized epithelium called the olfactory epithelium which contains approximately 10 million olfactory receptor cells. 2. Olfactory receptor cells – olfactory receptor neurons that are Lorem ipsum dolor sit amet, consectetuer responsible adipiscing forporttitor elit. Maecenas the detection congue of odorants (compounds that have an odor) which give rise to the sense of smell. Olfactory Structures 3. Olfactory hairs – long cilia that protrude from olfactory receptors at the nasal epithelium and are continuously bathed by a layer of mucus. The olfactory receptors and hairs once stimulated by chemicals dissolved in the mucus will transmit impulses along the olfactory nerve. 4. Olfactory bulb – a neural structure that transmits smell information Lorem ipsum dolor sit amet, consectetuer from adipiscing elit.the noseporttitor Maecenas to thecongue brain through the olfactory nerve tract. Olfactory Structures Lorem ipsum dolor sit amet, consectetuer adipiscing elit. Maecenas porttitor congue Olfactory Pathway Lorem ipsum dolor sit amet, consectetuer adipiscing elit. Maecenas porttitor congue Gustatory Structures Tongue – a muscular organ in the mouth that manipulates food for mastication and is used in the act of swallowing. It has importance in the digestive system and is the primary organ of taste in the gustatory system. 1. Papillae – are small peg like projections on the dorsal tongue surface that houses the taste buds. Lorem ipsum dolor sit amet, consectetuer 2. Taste adipiscing elit.buds – contain Maecenas the chemoreceptors that detect the flavor of porttitor congue food. The receptor cells that make up a taste bud synapse on sensory neurons, which convey the information to the brain. Gustatory Structures 3. Gustatory cells – are the specific epithelial receptor cells in the taste buds that respond to chemicals dissolved in the saliva. 4. Gustatory hairs – long microvilli protrusions of gustatory cells that transmit taste impulses to the brain. Lorem ipsum dolor sit amet, consectetuer adipiscing elit. Maecenas porttitor congue Gustatory Structures Lorem ipsum dolor sit amet, consectetuer adipiscing elit. Maecenas porttitor congue Gustatory Pathway Lorem ipsum dolor sit amet, consectetuer adipiscing elit. Maecenas porttitor congue