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outer synaptic layer : layer in the retina at which photoreceptors connect to bipolar cells
https://openstax.org/books/anatomy-and-physiology-2e/pages/14-key-terms
oval window : membrane at the base of the cochlea where the stapes attaches, marking the beginning of the scala vestibuli
https://openstax.org/books/anatomy-and-physiology-2e/pages/14-key-terms
palpebral conjunctiva : membrane attached to the inner surface of the eyelids that covers the anterior surface of the cornea
https://openstax.org/books/anatomy-and-physiology-2e/pages/14-key-terms
papilla : for gustation, a bump-like projection on the surface of the tongue that contains taste buds
https://openstax.org/books/anatomy-and-physiology-2e/pages/14-key-terms
photoisomerization : chemical change in the retinal molecule that alters the bonding so that it switches from the 11-cis-retinal isomer to the all-trans-retinal isomer
https://openstax.org/books/anatomy-and-physiology-2e/pages/14-key-terms
photon : individual “packet” of light
https://openstax.org/books/anatomy-and-physiology-2e/pages/14-key-terms
photoreceptor : receptor cell specialized to respond to light stimuli
https://openstax.org/books/anatomy-and-physiology-2e/pages/14-key-terms
premotor cortex : cortical area anterior to the primary motor cortex that is responsible for planning movements
https://openstax.org/books/anatomy-and-physiology-2e/pages/14-key-terms
primary sensory cortex : region of the cerebral cortex that initially receives sensory input from an ascending pathway from the thalamus and begins the processing that will result in conscious perception of that modality
https://openstax.org/books/anatomy-and-physiology-2e/pages/14-key-terms
proprioception : sense of position and movement of the body
https://openstax.org/books/anatomy-and-physiology-2e/pages/14-key-terms
proprioceptor : receptor cell that senses changes in the position and kinesthetic aspects of the body
https://openstax.org/books/anatomy-and-physiology-2e/pages/14-key-terms
pupil : open hole at the center of the iris that light passes through into the eye
https://openstax.org/books/anatomy-and-physiology-2e/pages/14-key-terms
pyramidal decussation : location at which corticospinal tract fibers cross the midline and segregate into the anterior and lateral divisions of the pathway
https://openstax.org/books/anatomy-and-physiology-2e/pages/14-key-terms
pyramids : segment of the descending motor pathway that travels in the anterior position of the medulla
https://openstax.org/books/anatomy-and-physiology-2e/pages/14-key-terms
receptor cell : cell that transduces environmental stimuli into neural signals
https://openstax.org/books/anatomy-and-physiology-2e/pages/14-key-terms
red nucleus : midbrain nucleus that sends corrective commands to the spinal cord along the rubrospinal tract, based on disparity between an original command and the sensory feedback from movement
https://openstax.org/books/anatomy-and-physiology-2e/pages/14-key-terms
reticulospinal tract : extrapyramidal connections between the brain stem and spinal cord that modulate movement, contribute to posture, and regulate muscle tone
https://openstax.org/books/anatomy-and-physiology-2e/pages/14-key-terms
retina : nervous tissue of the eye at which phototransduction takes place
https://openstax.org/books/anatomy-and-physiology-2e/pages/14-key-terms
retinal : cofactor in an opsin molecule that undergoes a biochemical change when struck by a photon (pronounced with a stress on the last syllable)
https://openstax.org/books/anatomy-and-physiology-2e/pages/14-key-terms
retinal ganglion cell (RGC) : neuron of the retina that projects along the second cranial nerve
https://openstax.org/books/anatomy-and-physiology-2e/pages/14-key-terms
rhodopsin : photopigment molecule found in the rod photoreceptors
https://openstax.org/books/anatomy-and-physiology-2e/pages/14-key-terms
rod photoreceptor : one of the two types of retinal receptor cell that is specialized for low-light vision
https://openstax.org/books/anatomy-and-physiology-2e/pages/14-key-terms
round window : membrane that marks the end of the scala tympani
https://openstax.org/books/anatomy-and-physiology-2e/pages/14-key-terms
rubrospinal tract : descending motor control pathway, originating in the red nucleus, that mediates control of the limbs on the basis of cerebellar processing
https://openstax.org/books/anatomy-and-physiology-2e/pages/14-key-terms
saccule : structure of the inner ear responsible for transducing linear acceleration in the vertical plane
https://openstax.org/books/anatomy-and-physiology-2e/pages/14-key-terms
scala tympani : portion of the cochlea that extends from the apex to the round window
https://openstax.org/books/anatomy-and-physiology-2e/pages/14-key-terms
scala vestibuli : portion of the cochlea that extends from the oval window to the apex
https://openstax.org/books/anatomy-and-physiology-2e/pages/14-key-terms
sclera : white of the eye
https://openstax.org/books/anatomy-and-physiology-2e/pages/14-key-terms
semicircular canals : structures within the inner ear responsible for transducing rotational movement information
https://openstax.org/books/anatomy-and-physiology-2e/pages/14-key-terms
sensory homunculus : topographic representation of the body within the somatosensory cortex demonstrating the correspondence between neurons processing stimuli and sensitivity
https://openstax.org/books/anatomy-and-physiology-2e/pages/14-key-terms
sensory modality : a particular system for interpreting and perceiving environmental stimuli by the nervous system
https://openstax.org/books/anatomy-and-physiology-2e/pages/14-key-terms
solitary nucleus : medullar nucleus that receives taste information from the facial and glossopharyngeal nerves
https://openstax.org/books/anatomy-and-physiology-2e/pages/14-key-terms
somatosensation : general sense associated with modalities lumped together as touch
https://openstax.org/books/anatomy-and-physiology-2e/pages/14-key-terms
special sense : any sensory system associated with a specific organ structure, namely smell, taste, sight, hearing, and balance
https://openstax.org/books/anatomy-and-physiology-2e/pages/14-key-terms
spinal trigeminal nucleus : component of the trigeminal nuclei that is found in the medulla
https://openstax.org/books/anatomy-and-physiology-2e/pages/14-key-terms
spinothalamic tract : ascending tract of the spinal cord associated with pain and temperature sensations
https://openstax.org/books/anatomy-and-physiology-2e/pages/14-key-terms
spiral ganglion : location of neuronal cell bodies that transmit auditory information along the eighth cranial nerve
https://openstax.org/books/anatomy-and-physiology-2e/pages/14-key-terms
stapes : (also, stirrup) ossicle of the middle ear that is attached to the inner ear
https://openstax.org/books/anatomy-and-physiology-2e/pages/14-key-terms
stereocilia : array of apical membrane extensions in a hair cell that transduce movements when they are bent
https://openstax.org/books/anatomy-and-physiology-2e/pages/14-key-terms
stretch reflex : response to activation of the muscle spindle stretch receptor that causes contraction of the muscle to maintain a constant length
https://openstax.org/books/anatomy-and-physiology-2e/pages/14-key-terms
submodality : specific sense within a broader major sense such as sweet as a part of the sense of taste, or color as a part of vision
https://openstax.org/books/anatomy-and-physiology-2e/pages/14-key-terms
superior colliculus : structure in the midbrain that combines visual, auditory, and somatosensory input to coordinate spatial and topographic representations of the three sensory systems
https://openstax.org/books/anatomy-and-physiology-2e/pages/14-key-terms
superior oblique : extraocular muscle responsible for medial rotation of the eye
https://openstax.org/books/anatomy-and-physiology-2e/pages/14-key-terms
superior rectus : extraocular muscle responsible for looking up
https://openstax.org/books/anatomy-and-physiology-2e/pages/14-key-terms
supplemental motor area : cortical area anterior to the primary motor cortex that is responsible for planning movements
https://openstax.org/books/anatomy-and-physiology-2e/pages/14-key-terms
suprachiasmatic nucleus : hypothalamic target of the retina that helps to establish the circadian rhythm of the body on the basis of the presence or absence of daylight
https://openstax.org/books/anatomy-and-physiology-2e/pages/14-key-terms
taste buds : structures within a papilla on the tongue that contain gustatory receptor cells
https://openstax.org/books/anatomy-and-physiology-2e/pages/14-key-terms
tectorial membrane : component of the organ of Corti that lays over the hair cells, into which the stereocilia are embedded
https://openstax.org/books/anatomy-and-physiology-2e/pages/14-key-terms
tectospinal tract : extrapyramidal connections between the superior colliculus and spinal cord
https://openstax.org/books/anatomy-and-physiology-2e/pages/14-key-terms
thermoreceptor : sensory receptor specialized for temperature stimuli
https://openstax.org/books/anatomy-and-physiology-2e/pages/14-key-terms
topographical : relating to positional information
https://openstax.org/books/anatomy-and-physiology-2e/pages/14-key-terms
transduction : process of changing an environmental stimulus into the electrochemical signals of the nervous system
https://openstax.org/books/anatomy-and-physiology-2e/pages/14-key-terms
trochlea : cartilaginous structure that acts like a pulley for the superior oblique muscle
https://openstax.org/books/anatomy-and-physiology-2e/pages/14-key-terms
tympanic membrane : ear drum
https://openstax.org/books/anatomy-and-physiology-2e/pages/14-key-terms
umami : taste submodality for sensitivity to the concentration of amino acids; also called the savory sense
https://openstax.org/books/anatomy-and-physiology-2e/pages/14-key-terms
utricle : structure of the inner ear responsible for transducing linear acceleration in the horizontal plane
https://openstax.org/books/anatomy-and-physiology-2e/pages/14-key-terms
vascular tunic : middle layer of the eye primarily composed of connective tissue with a rich blood supply
https://openstax.org/books/anatomy-and-physiology-2e/pages/14-key-terms
ventral posterior nucleus : nucleus in the thalamus that is the target of gustatory sensations and projects to the cerebral cortex
https://openstax.org/books/anatomy-and-physiology-2e/pages/14-key-terms
ventral stream : connections between cortical areas from the occipital lobe to the temporal lobe that are responsible for identification of visual stimuli
https://openstax.org/books/anatomy-and-physiology-2e/pages/14-key-terms
vestibular ganglion : location of neuronal cell bodies that transmit equilibrium information along the eighth cranial nerve
https://openstax.org/books/anatomy-and-physiology-2e/pages/14-key-terms
vestibular nuclei : targets of the vestibular component of the eighth cranial nerve
https://openstax.org/books/anatomy-and-physiology-2e/pages/14-key-terms
vestibule : in the ear, the portion of the inner ear responsible for the sense of equilibrium
https://openstax.org/books/anatomy-and-physiology-2e/pages/14-key-terms
vestibulo-ocular reflex (VOR) : reflex based on connections between the vestibular system and the cranial nerves of eye movements that ensures images are stabilized on the retina as the head and body move
https://openstax.org/books/anatomy-and-physiology-2e/pages/14-key-terms
vestibulospinal tract : extrapyramidal connections between the vestibular nuclei in the brain stem and spinal cord that modulate movement and contribute to balance on the basis of the sense of equilibrium
https://openstax.org/books/anatomy-and-physiology-2e/pages/14-key-terms
visceral sense : sense associated with the internal organs
https://openstax.org/books/anatomy-and-physiology-2e/pages/14-key-terms
vision : special sense of sight based on transduction of light stimuli
https://openstax.org/books/anatomy-and-physiology-2e/pages/14-key-terms
visual acuity : property of vision related to the sharpness of focus, which varies in relation to retinal position
https://openstax.org/books/anatomy-and-physiology-2e/pages/14-key-terms
vitreous humor : viscous fluid that fills the posterior chamber of the eye
https://openstax.org/books/anatomy-and-physiology-2e/pages/14-key-terms
working memory : function of the prefrontal cortex to maintain a representation of information that is not in the immediate environment
https://openstax.org/books/anatomy-and-physiology-2e/pages/14-key-terms
zonule fibers : fibrous connections between the ciliary body and the lens
https://openstax.org/books/anatomy-and-physiology-2e/pages/14-key-terms
The primary responsibilities of the autonomic nervous system are to regulate homeostatic mechanisms in the body, which is also part of what the endocrine system does. The key to understanding the autonomic system is to explore the response pathways—the output of the nervous system. The way we respond to the world aro...
https://openstax.org/books/anatomy-and-physiology-2e/pages/15-chapter-review
The sympathetic output of the nervous system originates out of the lateral horn of the thoracolumbar spinal cord. An axon from one of these central neurons projects by way of the ventral spinal nerve root and spinal nerve to a sympathetic ganglion, either in the sympathetic chain ganglia or one of the collateral locati...
https://openstax.org/books/anatomy-and-physiology-2e/pages/15-chapter-review
The parasympathetic output is based in the brain stem and sacral spinal cord. Neurons from particular nuclei in the brain stem or from the lateral horn of the sacral spinal cord (preganglionic neurons) project to terminal (intramural) ganglia located close to or within the wall of target effectors. These preganglionic ...
https://openstax.org/books/anatomy-and-physiology-2e/pages/15-chapter-review
Signaling molecules utilized by the autonomic nervous system are released from axons and can be considered as either neurotransmitters (when they directly interact with the effector) or as hormones (when they are released into the bloodstream). The same molecule, such as norepinephrine, could be considered either a neu...
https://openstax.org/books/anatomy-and-physiology-2e/pages/15-chapter-review
Autonomic nervous system function is based on the visceral reflex. This reflex is similar to the somatic reflex, but the efferent branch is composed of two neurons. The central neuron projects from the spinal cord or brain stem to synapse on the ganglionic neuron that projects to the effector. The afferent branch of th...
https://openstax.org/books/anatomy-and-physiology-2e/pages/15-chapter-review
The role of visceral reflexes is to maintain a balance of function in the organ systems of the body. The two divisions of the autonomic system each play a role in effecting change, usually in competing directions. The sympathetic system increases heart rate, whereas the parasympathetic system decreases heart rate. The ...
https://openstax.org/books/anatomy-and-physiology-2e/pages/15-chapter-review
In a few systems of the body, the competing input from the two divisions is not the norm. The sympathetic tone of blood vessels is caused by the lack of parasympathetic input to the systemic circulatory system. Only certain regions receive parasympathetic input that relaxes the smooth muscle wall of the blood vessels. ...
https://openstax.org/books/anatomy-and-physiology-2e/pages/15-chapter-review
The autonomic system integrates sensory information and higher cognitive processes to generate output, which balances homeostatic mechanisms. The central autonomic structure is the hypothalamus, which coordinates sympathetic and parasympathetic efferent pathways to regulate activities of the organ systems of the body. ...
https://openstax.org/books/anatomy-and-physiology-2e/pages/15-chapter-review
These higher centers have descending control of the autonomic system through brain stem centers, primarily in the medulla, such as the cardiovascular center. This collection of medullary nuclei regulates cardiac function, as well as blood pressure. Sensory input from the heart, aorta, and carotid sinuses project to the...
https://openstax.org/books/anatomy-and-physiology-2e/pages/15-chapter-review
The autonomic system is affected by a number of exogenous agents, including some that are therapeutic and some that are illicit. These drugs affect the autonomic system by mimicking or interfering with the endogenous agents or their receptors. A survey of how different drugs affect autonomic function illustrates the ro...
https://openstax.org/books/anatomy-and-physiology-2e/pages/15-chapter-review
Nicotine is not a drug that is used therapeutically, except for smoking cessation. When it is introduced into the body via products, it has broad effects on the autonomic system. Nicotine carries a risk for cardiovascular disease because of these broad effects. The drug stimulates both sympathetic and parasympathetic g...
https://openstax.org/books/anatomy-and-physiology-2e/pages/15-chapter-review
Other drugs affect one division of the autonomic system or the other. The sympathetic system is affected by drugs that mimic the actions of adrenergic molecules (norepinephrine and epinephrine) and are called sympathomimetic drugs. Drugs such as phenylephrine bind to the adrenergic receptors and stimulate target organs...
https://openstax.org/books/anatomy-and-physiology-2e/pages/15-chapter-review
acetylcholine (ACh) : neurotransmitter that binds at a motor end-plate to trigger depolarization
https://openstax.org/books/anatomy-and-physiology-2e/pages/15-key-terms
adrenal medulla : interior portion of the adrenal (or suprarenal) gland that releases epinephrine and norepinephrine into the bloodstream as hormones
https://openstax.org/books/anatomy-and-physiology-2e/pages/15-key-terms
adrenergic : synapse where norepinephrine is released, which binds to α- or β-adrenergic receptors
https://openstax.org/books/anatomy-and-physiology-2e/pages/15-key-terms
afferent branch : component of a reflex arc that represents the input from a sensory neuron, for either a special or general sense
https://openstax.org/books/anatomy-and-physiology-2e/pages/15-key-terms
agonist : any exogenous substance that binds to a receptor and produces a similar effect to the endogenous ligand
https://openstax.org/books/anatomy-and-physiology-2e/pages/15-key-terms
alpha (α)-adrenergic receptor : one of the receptors to which epinephrine and norepinephrine bind, which comes in two subtypes: α1and α2
https://openstax.org/books/anatomy-and-physiology-2e/pages/15-key-terms
antagonist : any exogenous substance that binds to a receptor and produces an opposing effect to the endogenous ligand
https://openstax.org/books/anatomy-and-physiology-2e/pages/15-key-terms
anticholinergic drugs : drugs that interrupt or reduce the function of the parasympathetic system
https://openstax.org/books/anatomy-and-physiology-2e/pages/15-key-terms
autonomic tone : tendency of an organ system to be governed by one division of the autonomic nervous system over the other, such as heart rate being lowered by parasympathetic input at rest
https://openstax.org/books/anatomy-and-physiology-2e/pages/15-key-terms
baroreceptor : mechanoreceptor that senses the stretch of blood vessels to indicate changes in blood pressure
https://openstax.org/books/anatomy-and-physiology-2e/pages/15-key-terms
beta (β)-adrenergic receptor : one of the receptors to which epinephrine and norepinephrine bind, which comes in three subtypes: β1, β2, and β3
https://openstax.org/books/anatomy-and-physiology-2e/pages/15-key-terms
cardiac accelerator nerves : preganglionic sympathetic fibers that cause the heart rate to increase when the cardiovascular center in the medulla initiates a signal
https://openstax.org/books/anatomy-and-physiology-2e/pages/15-key-terms
cardiovascular center : region in the medulla that controls the cardiovascular system through cardiac accelerator nerves and vasomotor nerves, which are components of the sympathetic division of the autonomic nervous system
https://openstax.org/books/anatomy-and-physiology-2e/pages/15-key-terms
celiac ganglion : one of the collateral ganglia of the sympathetic system that projects to the digestive system
https://openstax.org/books/anatomy-and-physiology-2e/pages/15-key-terms
central neuron : specifically referring to the cell body of a neuron in the autonomic system that is located in the central nervous system, specifically the lateral horn of the spinal cord or a brain stem nucleus
https://openstax.org/books/anatomy-and-physiology-2e/pages/15-key-terms
cholinergic : synapse at which acetylcholine is released and binds to the nicotinic or muscarinic receptor
https://openstax.org/books/anatomy-and-physiology-2e/pages/15-key-terms
chromaffin cells : neuroendocrine cells of the adrenal medulla that release epinephrine and norepinephrine into the bloodstream as part of sympathetic system activity
https://openstax.org/books/anatomy-and-physiology-2e/pages/15-key-terms
ciliary ganglion : one of the terminal ganglia of the parasympathetic system, located in the posterior orbit, axons from which project to the iris
https://openstax.org/books/anatomy-and-physiology-2e/pages/15-key-terms