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Biomed Chapter 14&15

biomed chapters 14 and 15, sensory organs

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
Created by: reidabook