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Exam 2 Terms
Fundamentals of Neurobiology
| Term | Definition |
|---|---|
| pupil | opening that allows light to reach the retina |
| iris | circular muscle that controls the diameter of the pupil |
| aqueous humor | fluid behind the cornea |
| sclera | outermost layer that forms the eyeball |
| extraocular muscle | attached to the eye and skull and allow movement |
| conjunctiva | membrane inside eyelid attached to sclera |
| cornea | transparent surface covering iris and pupil |
| optic nerve | axons of the retina leaving the eye |
| optic disk | blind spot where no vision is possible and where blood vessels originate and where optic nerve fibers exit, has no photoreceptors |
| macula | area of the retina responsible for central vision where extending axons lie |
| fovea | center of the retina where most cones are |
| lens | transparent surface that contributes to the formation of images within 9 meters |
| ciliary muscles | change the shape of the lens and allow focusing |
| vitreous humor | more viscous than aqueous humor and lies between lens and retina and provides structural spherical shape |
| retina | inner most layer of cells at the back of the eye that transduces into neural activity, thicker near fovea and thinner near lens |
| parasympathetic ring | surrounds the pupil and when it constricts the pupil constricts |
| sympathetic ring | surrounds the iris so when it constricts it pulls the parasympathetic ring out so the pupil dilates |
| zonule fibers | attached to the lens. contraction of ciliary bodies contract fibers and the lens curves, when wiliary bodies extend then fibers stretch making the lens flat |
| photopic system | light. every photoreceptor is illuminated and activated and light is not amplified. use cones mostly |
| photoreceptors | light sensitive cells in retina that tranduce light energy into neural signals |
| bipolar cells | connect photoreptors to ganglion cells |
| ganglion cells | fire action potential and send axons to to brain |
| horizontal cells | receive inputs from photoreceptors and project laterally to bipolar cells |
| amacrine cells | receive inputs from bipolar cells and project laterally to ganglion cells |
| ganglion cell layer | cell bodies of the ganglion cells |
| inner nuclear layer | cell bodies of the bipolar cells |
| outer nuclear layer | cell bodies of the photoreceptors |
| pigmented epithelium | absorbs any light not absorbed by photoreceptors |
| scotopic system | dark. no photoreceptor is illuminated so photons are harvested and amplified so one rod can activate many ganglion cells (via horizontal and amacrine cells). use rods only |
| bleaching | photoreceptors no longer respond at particular light intensities. activation of rods by light bleaches the photopigment |
| middle ear | air filled cavity within temporal increases the force that has been gathered by the tympanic membrane by the middle ear bones (incus, malleus, stapes--the ossicles) to the oval window |
| tympanic membrane (eardrum) | moves in response to variations in air pressure |
| cochlea | filled with incompressible fluid that requires more force to displace than air which is done by the middle ear bones |
| oval window | smaller hole in the bone of the skull that amplifies pressure from tympanic membrane because the same pressure is pushed through smaller area that causes fluid displacement in the cochlea |
| eustachian tube | connects the air filled middle ear to mouth and contains valve the nasal faranz |
| inner ear | converts physical force of oval window into neural signal. contains the cochlea and vestibular apparatus |
| vestibular apparatus | continuous membranes in loops extended from cochlea that contains the same fluid and is involved in balance and head position in 3D space when stereocilli on apparatus sheer when head moves |
| parts of the cochlea | scala vestibula, scala tympani, scala media, hair cells, basilar membrane, organ of corti, tectorial membrane |
| organ of corti | contains auditory receptor cells and is located in scala media |
| basilar membrane | serparates scala media and scala tympani and has inner hair cells |
| helicotrema | physical connection between scala vestibula and scala tympani where the fluid is continuous |
| hair cells of the basilar membrane | lie between the basilar membrane and tectoral membrane |
| mechanoreceptors | physical distortion |
| nociceptors | pain--free nerve ending. free unmyelinated nerve ending signal body tissue damage |
| thermoreceptors | temperature--free nerve ending. cold and hot receptors and overlaying intermediate receptors. drastic temperatures are perceived as pain. adaptable |
| proprioreceptors | body position |
| chemoreceptors | chemicals |
| types of mechanoreceptors | pacinian, meissner's, ruffini's, mercel's disks |
| pacinian corpuscles | deep pressure/touch and fine discrimination between texture and moving stimuli located in hypodermis and derma |
| meissner's corpuscles | smooth, hairless skin sensitive to lower frequences of vibration, palms of hands and soles of feet, in papillary dermis |
| mercel's disks | light pressures and tactile discrimination and increase surface area that can activate free nerve endings, and epidermis and durma |
| types of proprioreceptors | muscle spindles fibers-detect stretch and contraction of muscle and are activated when stretched has monosynaptic reflex with spinal cord. golgi tendon organs- in tendons and detect muscle tension and have protective role when much tension is on tendon |
| DCML pathway | touch and proprioception |
| ST pathway | pain and temperature |
| alpha motor neurons (lower motor neurons) | final common path for motor behavior, from spinal to muscle |
| spinal cord interneurons | receive sensory inputs as well as descending projection from higher centers and provide much of the reflexive coordination |
| upper motor neurons | cell bodies are in cortex or brain stem and descend to synapse with spinal cord interneurons or alpha motor neurons. there are separate pathways from brain stem and cortical. brain stem involved in posture and cortical involved in voluntary movement |
| cerebellum | primary function is to compare movement commands from brain stem and cortical with sensory feedback about movement (no direct access to alpha motor neurons). coordinates complex movements and motor learning |
| motor pool | group of motor units that control one muscle that run parallel to long axis of spinal cord |
| motor unit | a neuron and the muscle it controls |
| fast fatigable FF motor units | contract and relax rapidly, generate largest force, fatigue after a few minutes of repeated stimulation. ex: extraocular muscles |
| slow motor (S) units | fatigue resistant, contract slowly,fraction of FF's force. muscles involved in posture |
| fast fatigue resistant (FR) motor units | force stronger than slow but still very less than FF motor units but are more fatigue resistant than FF |
| brain stem vestibular nucleus | control 3D position of head and axial muscles |
| brain stem reticular formation | extends from rostral midbrain to caudal medulla and controls axial and proximal muscle limb muscles and respiration and regulation of arousal |
| brain stem superior colliculus | orients movement of head and projects to cervical cord |
| brain stem red nucleus | projects to lateral aspects of cervical cord and controls movement of arms |
| hypothalamus | part of the diencephalon, lies inferior to the thalamus, contributes to the wall of the 3rd ventricle. has nuclei, optic chiasm, and tuber cinereum which is the floor of the 3rd ventricle and has median eminence, and infundibulum |
| infundibiulum | stalk that connects hypothalamus to pituitary |
| pituitary gland | has posterior lobe with infundiblum that make of the neurohypophysis and the anterior lobe or adenohyophysis comprised of glandular tissue |
| SON vs PVN | axons of these neurons terminate in the posterior pituitary and neurohormones released upon electrical stimulation. secretions are released into interstitial tissue and picked up by capillary plexus in posterior pituitary. SON-oxytocin, PVN-ADH |
| connection between hypothalamus and anterior pituitary | vascular. hypophyseal portal system. connects median eminence to secretory cells of the anterior pituitary |
| TRH | localized in PVN and releases TSH that release T3/T4 |
| SST | localized in VM and inhibits GH |
| GHRH | localized in arcuate and secretes GH |
| GnRH | localized in arcuate and secretes FSH and LH that release estrogen |
| CRH | localized in PVNreleases ACTH that releases cortisol |
| PIH | widespread hypothalemic distribution and inhibit PRL |
| anterior pituitary hormones | FSH, LH, TSH, ACTH, GH, PRL, MSH |
| posterior pituitary hormones | OT, AVP, ADH |
Created by:
LittleD331
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