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Biomed Chapter 14&15
biomed chapters 14 and 15, sensory organs
| Question | Answer |
|---|---|
| Biomed | Chapters 14 and 15 |
| Pairs of spinal nerves | 31 |
| Number of cranial nerves | 12 |
| Spinal nerves | connected to the spinal cord, no special names, but are numbered, 8 cervical nerve pairs, 12 thoracic, 5 lumbar, 5 sacral, 1 coccygeal |
| Cauda equine | Latin for horse’s tail, lower end of the spinal cord with the attached spinal nerves |
| Ventral root | attaches to spinal cord, carry to muscles, autonomic |
| Dorsal root | recognized by ganglion, contain cell bodies of the sensory neurons |
| Mixed nerves | spinal n nerves contain both motor and sensory fibers |
| Ramus | a large branch of nerves formed when the spinal nerves emerge from the cavity |
| Dorsal ramus | supplies somatic motor and sensory fibers to several smaller nerves which innervate eth muscles and skin of the posterior surface of the head, neck, and trunk |
| Ventral ramus | sympathetic chain, some o the autonomic fibers synapse with autonomic neurons that continue on to autonomic effectors by way of splanchnic nerves |
| Splanchic nerves | allow autonomic fibers to continue ton to autonomic effectors |
| Sympathetic rami | two thin rami formed by splitting of autonomic neurons rejoining autonomic fibers |
| Plexus | a complex subdivided networks of nerves, reduces the number of nerves needed to supply each body part |
| 4 plexuses | cervical plexus, brachial plexus, lumbar plexus, and sacral plexus |
| Cervical plexus | in neck, ventral rami of the first four cervical spinal nerves, innervate muscles and skin on neck, shoulders, and part of the head |
| Phrenic nerve | excites the cervical plexus, innervates the diaphragm |
| Brachial plexus | in shoulder, ventral rami of spinal nerves, beneath collarbone towards upper arm, innervate lower part of shoulder and entire arm |
| Lumbar plexus | near psoas muscle, femoral nerve emerges from here, supplies thigh and leg |
| Sacral plexus | in pelvic cavity, combined with lumbar plexus because of proximity to be lumbosacral plexus, tibial and peroneal nerves, forms sciatic nerve, all the skin of the leg, thigh muscles, foot muscles, let muscles |
| Coccygel plexus | innervate the floor of the pelvic cavity and some surrounding areas |
| Dermatome | skin surfaced are supplied by sensoryfibers of a given spinal nerve |
| Myotome | a skeletal muscle or group of muscles that receives motor axons from a given spinal nerve, some overlap |
| Cranial nerves | connect to the undersurface of the brain, mostly on the brainstem, made of axon bundles |
| Mixed cranial nerves | axons of sensory and motor neurons |
| Sensory cranial nerves | sensory axons only |
| Motor cranial nerves | mainly motor axons, contain a small number of proprioceptive fibers |
| Prprioceptive fibers | sensory that are in motor cranial nerves, carry information regarding tension |
| Olfactory nerve | dendrites and cell bodies lie in nasal mucosa up along superior concha, pierce each cribiformplate and terminate in olfactory bulbs, turn to olfactory tracts |
| Optic nerve | from retina to brain, unite at optic chiasma and continue into optic tracts hen entering the brain, terminate in thalamus at lateral geniculate nucleus |
| Oculomotor nerve | move eye muscles, focusing and light |
| Trochlear nerve | midbrain into oblique muscles of eye |
| Trigeminal nerve | three branches, carry impulses from skin and teeth of the head |
| Abducens nerve | originate in pons, abducts the eye |
| Facial nerve | salivary and tear glands |
| Vestibulocochlear nerve | vestibular nerve and cochlear nerve, both sensory |
| Glossopharyngeal nerve | nerves to tongue, pharynx, and blood pressure (carotid sinus) |
| Vagus nerve | sensory and motor, supplies most of gut organs as well as lung and heart, controls swallowing and speaking, heart rate |
| Accessory nerve | motor nerve, go to pharynx and larynx |
| Hypoglossal nerve | motor nerve |
| Final motor pathway | somatic nervous system, each neuron stretches from CNS to muscle |
| Anterior horn neuron | the last neuron in a final common path |
| Reflex | action that results from a nerve impulse passing over a reflex arc |
| Cranial reflex | if the reflex arc is in the brain |
| Somatic reflexes | contraction of skeletal muscles, anterior horn neurons or lower motor neurons produce somatic reflexes |
| Autonomic (visceral) reflexes | contractions of smooth or cardiac muscles or secretion of glands |
| Babinski reflex | Stimulate the outer foot and the big tow comes up |
| Corneal reflex | blinking in response to touch cornea |
| Abdominal reflex | drawing in of the abdominal wall when sides are touched |
| Sympathetic preganglionic neurons | begin in spinal cord, dendrites and cell bodies in lateral gray horns of thoracic and lumbar segments |
| White ramus | very myelinated, at lumbar vertebrae |
| Three paths of preganglionic fiber | synapse with a post gangloinic, send ascending or descending branches in other chain ganglia, not synapse at all |
| Sympathetic postganglionic neurons | in sympathetic chain ganglia, gray ramus, un myelinated |
| Parasympathetic post ganglionic neurons | in parasympathetic ganglia, near autonomic effectors |
| Parasympathetic preganglionic neurons, in brainstem, cranial and pelvic nerves | |
| Norepinephrine | released by adrenergic fibers |
| Acetylcholine | released by cholinergic fibers |
| Norepinephrine | affects visceral effectors by binding to adrenergic receptors, alpha or beta receptors, |
| Alpha receptors | causes smooth muscle to cause blood vessel to constrict |
| Beta receptors | cause blood vessels to dilate |
| How to stop norepinephreine | taken back up by synaptic knobs and broken down by monoamine oxidase, remaining molecules are broken down by catechol-O-methyl transferase |
| Acetylcholine can bond to | nicotinic or muscarinic receptors, broken down by acetylcholinesterase |
| Receptor potential | a potential that develops in the receptor’s membrane, which is graded to the strength of the stimulus |
| Sensation | interpretation of the brain of stimulus |
| Adaptation | the magnitude of the receptor potential decrease over a period in response to a continuous stimulus |
| General sense organs | microscopic receptors widely distributed throughout the body in the skin, mucosa, connective tissues, muscles, tendons, joints, and viscera |
| General sense organs produce | somatic sense, not evenly distributed |
| Three classes of receptors | exorecedptors, visceroceptors, proprioceptors |
| Exteroceptors | located on or near the body surface and respond most frequently to stimuli that arise external to the body itself, detect pressure, pain, touch and temp |
| Cutaneous receptors | also called exteroceptors |
| Visceroceptors | located internally within the organs and provide info about the internal environment, activated by pressure, stretching, and chemical changes, control hunger and thirst |
| Proprioceptors | type of visceroceptors |
| Mechanoreceptors | activated when they are deformed or change position, such as when stretched or touched |
| Chemoreceptors | activated in the changing concentration of chemicals, smell and taste |
| Thermoreceptors | changes in temperature |
| Nociceptors | activated by pain/tissue damage |
| Photoreceptors | only in eye, light stimuli |
| Free nerve endings | most common receptor, are exteroceptors and visceroceptors |
| Nociceptor | free nerve ending, end in dendritic knobs, brain has none |
| Krause’s end bulbs and ruffini’s corpuscles | thermoreceptors, free nerve endings |
| Two types of free nerve endings | A (Acute) and B (chronic) A=sharp intense pain, B=less intense but persistant pain |
| Root hair plexuses | web of free nerve endings that surround hair follicles and detect hair movement |
| Merkel discs | free nerve endings that discriminate light touch in a specific location |
| Pacinican corpuscles | crude touch, harder to deform |
| Encapsulated nerve endings | have a tissue capsule that surrounds their dendritic end, deformed, a tactile corpuscle |
| Mucocutaneous corpuslces | Krause’s end bulbs, discriminate touch and vibration, meissner’s corpuscle |
| Encapsulated endings | meissner corpuscle |
| Ruffini’s corpuscles | variants of meissner’s corpuscles, deep in dermis, crude persistent touch, ability to grasp and object for long periods of time and still be able to sense its presence |
| Pacinian corpuscles | mechano receptors deep in the dermis, hands and feet as well as joint capsules, deep pressure, high frequency vibrations, and stretch |
| Stretch receptors | associated with muscles and tendons and are proprioceptors |
| Two stretch receptors | Golgi tendon receptors, muscle spindles, both operate to provide the body with info concerning muscle length and the strength of muscle contraction |
| Muscle spindle | 5-10 intrafusal fibers in a capsule, can’t contract, lies in between extrafusal fibers, cause muscles to contract when are too flacid |
| Gamma motor neurons | stimulates the intrfusal fibers on the muscle spindle fibers to contract |
| Alpha motor neurons | stimulate the regular muscle fibers to contract |
| Stretch reflex | shortens a muscle or muscle group to aid in posture or positioning |
| Golgi tendon organs | proprioceptors, between muscle tissue and tendon, type Ib nerve fibers in afferent nerves, stimulated by excessive muscle contraction and cause the muscle to relax |
| Golgi tendon reflex | protects muscles from tearing by making them relax |
| Special sense | receptors grouped closely together or located in specialized organs, smell, taste, hearing, equilibrium, and vision |
| Olfactory epithelium | made of epithelial support cells, basal cells, and specialized bipolar olfactory receptor neurons |
| Olfactory receptor neurons | have olfactory cilia which touch the surface of the olfactor yepithelim lining the surface of the nasal cavity, they are chemoreceptors |
| Basal cells | replace the chemo receptors in the olfactory epithelium |
| Cilia function in nose | olfactory cilia help to “mix” the mucus and increases its efficiency as a solvent |
| Location of olfactory epithelium | most superior portion of nasal cavity which is why a sniff is required for smelling, because most air just goes down the nasal passageway without touching them |
| Granule cells | inhibit action potentials when there is a persistent smell |
| Taste buds | sense organs that respond to taste |
| Gustatory stimuli | taste |
| Papillae | elevated projections on the tongue that contain taste buds |
| Where taste buds are located | fungiform circumvallate, and foliate papillae |
| Taste buds are stimulated by | testants (chemicals) dissolved in saliva |
| Gustatory cells | cells on each taste but (50-125) which are surrounded by a supportive epithelial cell capsule, gustatory hairs extend from each cell and project into the taste pore |
| G protein receptor site | when gustatory hairs bind to testants (taste-producing chemicals), which bind to the G protein receptor sites and it determines how fast the receptor potential is generated |
| Ion channels | testants bind to them along with the G protein receptor sites to determine how fast the receptor potential is generated |
| Other tastes | metallic and umami |
| Tastes | sour is H+, salty is Na Cl, bitter and sweet are stimulation of G protein receptors |
| Nerves involved in taste | the facial nerve and glossopharyngeal, vagus only a minor role |
| Parts of the ear | external, middle, and inner |
| Part of external ear | pinna/auricle and the external auditory meatus (ear canal) |
| Ear canal | moves, inward, foreward, and down |
| Tympanic membrane | eardrum |
| Middle ear | tympanic cavity, contains three auditory ossicles |
| Auditory ossicles | malleus, incus, stapes |
| Oval window | opening where the stapes fits in |
| Round window | an opening in the middle ear |
| Eustachian tube | Made of bone and partly cartilage and fibrous tissue, lined with mucosa, into throat behind nose |
| Labrynth | name for inner ear, made of bony labyrinth and membranous labrynth |
| Bony labrynth | made of vestibule, cochlea, and semicircular canals |
| Membranous labrynth | made of utricle and saccule, cochlear duct, and membranous semicircular canals inside the bony ones |
| Endolymph | the clear and potassium-rich fluid that fills the membranous labrynth, allows for very quick refractory periods |
| Perilymph | fluid similar to cerebrospinal fluid, surrounds the membranous labrynth |
| Modiolus | what the cochlea wraps around |
| Cochlear duct | only part of the internal ear concerned with hearing, upper part is scala vestibule, a nd lower section is scala tympani |
| Vestibular membrane | roof of the cochlear duct |
| Basilar membrane | floor of the choclear duct |
| Organ of Corti | hearing sense organ, lies on basilar membrane topped with tectorial membrane, its axons form the cochlear nerve |
| Tectorial membrane | on top of organ of corti |
| Volume | determined by amplitude of the sound waves |
| Pitch | the frequency of the sound waves, number per unit time |
| Basilar membrane width | not the same which causes bulges at different places depending on frequency, lower cause the thicker parts to vibrate, and higher cause the thin ones to vibrate, the higher the upward bulge, the louder the perceived sound that stimulates more cilia |
| Pathway of sound waves | enter in pinna, strike tympanic membrane, moving the malleus, incus, and stapes, stapes moves against oval window, a and pressure is exerted on the perilymph in the cochlea, which starts a ripple to endolymph to basilar membrane |
| Vestibule | the central section of the bony labrynth, semicircular canals |
| Equilibrium | sense of balance, in vestibule and semicircular canals |
| Static equilibrium | utricle and saccule function, sense the position of the head relative to gravity and sense of acceleration |
| Dynamic equilibrium | semicircular canals, maintains balance when the head or body itself is rotated or suddenly moved |
| Macula | strip of epithelium in utricle and saccule, movements of macula provide info related to head position or acceleration, action potentials are generated by movement of the hair cells |
| Otoliths | ear stones, protein and calcium carbonate, in macula, change in position of head produces a change in pressure on the otolith-weighted matrix which stimulates the hair cells, evokes righting reflexes (muscular responses restore body to normal position) |
| Crista ampullaris | dynamic equilibrium, located in ampulla of each semicircular canal, sensory epithelium, made of many hair embedded in cupula |
| Cupula | gelatinous cap where the crista are located, a float that moves with flow of endolymph in semicircular canals, bends the hairs embedded in it producing an action potential, moves in opposite direction of endolymph |
| Amount of eye in orbit | 5/6 |
| Three layers of eyeballs | sclera, choroid, and retina |
| Cornea | anterior portion of the sclera, lies over iris, transparent, no blood vessels |
| Canal of Schlemm | in anterior part of the sclera at the junction with the cornia, ring-shaped venous sinus |
| Choiroid | middle portion of eye, blood vessels and pigment, made ofiris, ciliary body, and suspensory ligament |
| Ciliary body | formed by a thickening of the choroid and fits like a color betweenthe anterior margin of the retina and the posterior margin of the iris, fold in it a ciliary processes |
| Suspensory ligaments | blend with the elastic capsule of the lens and suspend it in place |
| Ciliary muscle | lies in anterior part of ciliary body where cones, the less numerous of the two, are most densely concentrated |
| Iris | colored part of the eye, made of circular and radial smooth muscle fibers to make a doughnut structure, hole in middle I s pupil |
| Retina | incomplete innermost coat of eyeball, no anterior portion, three layers of neurons |
| Nerons of retina | (named in order in which they conduct impulses) photoreceptror neurons, bipolar neurons, and ganglion neurons |
| Dendrites of the photoreceptor neurons | called rods and cones depending on their shape |
| Fovea centralis | where cones, the least numerous of the two, are most densely concentrated, becoming less dense as it reaches the outer eye, macula lutea, yellow area on it |
| Optic disk | circular area in the posterior part of the eyeball where all the axons of ganglion neurons extend to, contains perforations that lead to the optic nerve, also called blind spot |
| Blind spot | no rods or cones, only nerve fibers, where nerves exit to from optic nerve |
| Anterior cavity | eye, two subdivisions known as the anterior and posterior chambers, anterior is in front of the lens, filled with aqueous humor |
| Posterior cavity of eye | larger than anterior, posterior to the lens, contains vitreous humor , soft gelatin, helps maintain interocular pressure |
| Aqueous humor | forms from blood in capillaries in ciliary body, watery |
| Extrinsic eye muscles | skeletal muscles that attach to the outside of the eyeball and to the bones of the orbit that move them voluntarily, 4 strait and 2 oblique |
| Intrinsic eye muscles | smooth, involuntary, iris and ciliary muscles (iris =pupil size, ciliary=lens shape) |
| Accessory structures of eye | eyebrows, lashes, lids, and lacrimal apparatus |
| Eye is the only organ | that voluntary and involuntary muscles are found |
| Eyebrows and lashes | protection against entering of foreign objects in eyes, and prevent direct sunlight |
| Palpebrae | eyelids, voluntary muscle and skin, connective tissue at free nd of lit called tarsal plate |
| Conjunctiva | mucous membrane that lines each eyelid |
| Conjunctivitis | pink eye |
| Palpebral fissure | opening between the eyelids |
| Canthus | the angle in the corner of the eyelid |
| Lacrimal apparatus | structures that secrete tears and train them from surface of eye, lacrimal glands, ducts, sacs, and nasolacrimal ducts |
| Lacrimal glands | small almond, in frontal bone, drain tears onto conjunctiva |
| Lacrimal canals | small chanenels that empty into lacrimal sacs, openings in the canals are punctae, which can be seen as dots on the inner canthus |
| Lacrimal sacs | located in groove of lacrimal bone |
| Nasolacrimal ducts | small tubes that extend from lacrimal secintor inferior meatus of the nose |
| Processes of light on retina | refraction of light, accommodation of the lens, constriction of the pupil, and convergance of the eyes to get it on the retina |
| Refraction | bending of the light rays by cornea, lens, aqueous, and vitreous humor |
| Accommodation | changes the lens depending on the distance of the object, increase in its curvature to achieve greater refraction |
| Contraction of ciliary muscles | contraction pulls choroid layer closer ot the lens which loosens the tension of the suspensory ligaments, allowing lens to bulge |
| Vision vs lens shape | near vision the ciliary muscle is contracted, lens is bulging, for distance it is relaxed. Continual use of eyes for near work produces eye strain |
| Presbyopia | as people grow older lenses lose their elasticity and they lose their ability to see thing nearer |
| Constriction of the pupil | prevents divergent rays from entering the eye through the periphery of the cornea and lens, near reflex=constriction of pupil for near vision |
| Convergence of eyes | movement of the two eyeballs inward so that their visual axes come together at the object viewed, the nearer the object he greater angle of convergance needed |
| Photopigments | light sensitive pigmented compounds found in the outer area of both types of photoreceptors near the pigmented retina, can be broken down in to opsin and retinal |
| Rhodopsin | photopigment found in rods, light sensitive, breaks down into opsin and retinal compounds |
| Cones | three types of cones are present and each contains a different photo pigment, red green and blue cones, function to produce vision in bright light |
| Two types of hearing problems | conduction impairment and nerve impairment |
| Tinnitus | ringing in the ear |
| Otosclerosis | inherited bone disorder which impairs conduction by causing structural irregularities in the stapes |
| Otitis | ear infection |
| Presbycusis | hearing loss due to nerve impairment, aging |
| Myopia | nearsigntedness, concave lenses |
| Satigmatism | irreugularity in the curvature of the cornea or lens |
| Cataracts | cloudy spots on the eye’s lens |
| Diabetic retinopothay | diabetes causes small hemorrhages in retinal blood vessels that disrupt the oxygen supply to photo receptors, the eye responds by building abnormal vessals that block vision |
| Glaucoma | excessive intraocular pressure by abnormal accumulation of aqueous humor, degeneration of the retina due to decrease blood flow |
| Hyperopia | farsightedness, corrected by convex lenses |
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