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Nervous system 12-13

The conscious awareness of stimuli received by sensory receptors Sensation; preception
What does sensation require? Stimulus;receptor; conduction of action potential to CNS; translation of action potential; processing of action potential in the CNS
The reduction in sensitivity to a constant stimulus; after exposure to a stimulus for a time, the response of some receptors or sensory pathways to a certain stimulus strength lessens Adaptation
The ability to perceive stimuli. sense
The means by which the brain receives information about the environment and the body. The Senses
Senses are divided into two basic groups General senses; special senses
General senses Somatic senses; visceral senses
Special senses smell; taste; sight; hearing; balance
Senses distributed over a large part of the body. General senses
touch, pressure, proprioception, temperature and pain somatic senses (under general senses)
pain and pressure senses visceral senses (under general senses)
senses that are localized to specific organs special senses
respond to mechanical stimuli (compression, bending or stretching of receptors) Mechanoreceptors
Respond to chemicals(ie. odor molecules, H+ chemoreceptors
respond to light photoreceptors
respond to temperature changes thermoreceptors
respond to painful mechanical, chemical, and thermal stimuli nociceptors (pain receptors)
sensory nerve endings or specialized cells capable of responding to stimuli by developing action potentials sensory receptors
simplest and most common type of receptor. Detect pain, temperature, itch, and movement(proprioception) Free nerve endings
names of touch receptors: merkel disks; hair follicle receptors; Meissner corpuscles; Ruffini end organs; Pacini corpuscles
Awareness of body position and movements. proprioceptors
small superficial nerve endings; respond to light touch and superficial pressure Merkel disks
Wrap around the hair follicle;involved in the sensation of light touch when the hair is bent. Hair follicle receptors
located deep to the epidermis; responsible for two-point discriminative touch Meissner corpuscles
located in the dermis; involved in continuous touch or pressure Ruffini end organs
located in the dermis and subcutaneous tissue; detect deep pressure and vibration; in joints, they serve a proprioceptive function Pacini corpuscles
Major sensory receptors for Proprioception: Muscle spindles; Golgi tendon organs; Pacini corpuscles; Free nerve endings
What provides information about the precise position of body parts; rate of movement of various body parts; weight of an object being held in the hand; range of movement of a joint? sensory receptors for proprioception
have highly localized receptors that provide specific information about the environment. special senses
Interaction of chemicals with sensory receptors Smell and taste
Interaction of light with sensory receptors sight
interaction of mechanical stimulation with sensory receptors hearing and balance
Sense of Smell; response to airborne molecules, called odorants, entering the nasal cavity. Olfaction
7 primary odors: Camphoraceous(moth balls); Musky; Floral; Pepperminty; Ethereal(fresh pears); Pungent; Putrid
Olfactory neurons have very low thresholds and _________ rapidly. accommodate
Olfactory neurons in the olfactory epithelium are __________neurons. bipolar
Distal ends of olfactory neurons have: olfactory hairs
______ _______ have receptors that respond to dissolved substances--approximately 1000 different odorant receptors. Olfactory hairs
What results in ion channels opening and depolarizing in olfactory Epithelium? Receptors activating G proteins
Olfactory neurons are ______ and ____ on a regular basis. lost; replaced
Lost olfactory cells are replaced by __________ ___________. basal cells
Axons from the olfactory neurons extend as _________ _________ to the _________ _________, where they synapse with interneurons. olfactory nerves; olfactory bulb
Axons from interneurons form the _______ ______, which connect to the olfactory cortex. olfactory tracts
Olfactory cortex is part of the: limbic system
Olfactory bulbs and cortex _________ to odors. accommodate
Sensory structures that detect taste are: taste buds
Most taste buds are located in the epithelium of: papillae
Taste buds are found on the: tongue; palate; lips; throat
How many types of papillae are there? 4
How many of the papillae contain taste buds? 3
Does the most numerous papillae have taste buds? no
What gives the tongue its roughness the papillae with no taste buds
What do taste buds consist of? taste cells; basilar cells; supporting cells
have taste hairs that extend into taste pores: taste cells
Cells of taste buds are replaced: 10 days
receptors on the taste hairs detect _________ __________? dissolved substances
What are the 5 basic types of taste? Salty, sour, sweet, bitter, Umami
Gives Salty taste: sodium ions
Gives sour taste: Acids
Gives sweet taste: sugars, some other carbohydrates, and some proteins
Gives bitter taste: Alkaloids (bases)
Elicited by the amino acid glutamate and related compounds? Umami taste
All taste buds can sense the _______ primary taste by tend to be most sensitive to _________. 5; 1
Sensitivity to ________substance is the highest (poisons) bitter
Taste is strongly influenced by ___________ sensations. olfactory
________ ___________ can dampen the taste sensation. Nasal congestion
What other stimuli besides taste can the tongue detect? temperature; texture
What carries taste sensations from the anterior two-thirds of the tongue? facial nerve
What nerve carries taste sensations from the posterior one-third of the tongue and superior pharynx? glossopharyngeal
What nerve carries taste sensations from the epiglottis? vagus
The neural pathways for taste extend from the__________ _________ to the _________ and to the _______ _______. medulla oblongata;thalamus;cerebral cortex
Visual system consists of: eye;accessory structures; sensory neurons
eyebrows, eyelids, conjunctiva, lacrimal apparatus, and extrinsic eye muscles are all: accessory structures of the eye
Prevent perspiration from entering the eyes and help shade the eyes: eyebrows
protect the eyes from foreign objects; help lubricate the eyes by spreading tears over their surface: eyelids
What are the lubricating glands associated with the eyelids called? Meibomian (Tarsal) glands & Ciliary glands
Sebaceous glands that lubricate the eye? Meibomian (Tarsal)
Glands that lie between the hair follicles; modified sweat glands Ciliary glands
Project from the fee margin of each eyelid and initiate reflex blinking: eyelashes
What covers the inner eyelid and the anterior part of the eye? conjunctiva
Inflamed ciliary gland, associated with hair follicle: sty
Infection or blockage of tarsal gland: Chalazion
Infection of the conjunctiva: conjunctivitis
Consists of the lacrimal gland, lacrimal canaliculi, and a nasolacrimal duct: Lacrimal Apparatus
What secretes tears? Lacrimal glands
What do tears contain? mostly water, with some salts, mucus, and lysozyme
Where do tears enter the eye? superolateral lacrimal ducts
Where do tears exit the eye? medially via the lacrimal canaliculi
Where do tears drain? nasolacrimal duct
Six strap-like muscles that enable the eye to follow moving objects; they maintain the shape of the eyeball: extrinsic eye muscles
Name the extrinsic muscles: superior rectus; inferior rectus; medial rectus;lateral rectus; superior oblique; inferior oblique
What extrinsic eye muscle depresses and medially deviates the gaze? inferior rectus
Which extrinsic eye muscle laterally deviates the gaze? Lateral rectus
Which extrinsic eye muscle medially deviates the gaze? Medial rectus
Which extrinsic eye muscle elevates and medially deviates the gaze? superior rectus
Which extrinsic eye muscle elevates and laterally deviates the gaze? Inferior oblique
Which extrinsic eye muscle depresses and laterally deviates the gaze? Superior oblique
Which extrinsic eye muscles are controlled by the oculomotor nerve? Inferior rectus; medial rectus; superior rectus; inferior rectus
Which nerve controls the lateral rectus muscle? Abducent
Which nerve controls the superior oblique? Trochlear
What are the 3 layers of the eyeball? Fibrous; Vascular; nervous
What is the Fibrous layer of the eyeball composed of? Sclera; Cornea
What makes up the Vascular layer of the eyeball? Choroid; Ciliary body; iris
What makes up the nervous layer of the eyeball? retina
What is the internal cavity of the eyeball filled with? fluids called humors
The sclera is the posterior _______ of the eye? 5/6
White connective tissue that maintains the shape of the eyeball; protects internal structures; provides a site for muscle attachments: Sclera
Composes anterior 1/6th of the eye: Cornea
The cornea is ____________ and __________ and refracts light that enters the eye. Avascular; transparent
Vascular network; many melanin-containing pigment cells; appears black in color; prevents the reflection of light inside the eye: choroid
A thickened ring of tissue surrounding the len: Ciliary ring
Ciliary ring is composed of _________ ___________ bundles (ciliary muscles) smooth muscle
The ciliary ring anchors the suspensory ligament that holds the _______ _ _____________. lens in place
Changes the shape of the lens: ciliary ring
What produces aqueous humor? ciliary process
Smooth muscle regulated by the autonomic nervous system; iris
smooth muscle that constricts pupil for close vision and bright light Sphincter pupillae
Smooth muscle of the Iris that dilates pupils for distant vision and dim light: dilator pupillae
What does the pupil do when the subject matter is appealing or requires problem-solving skills? dilates
What controls the amount of light entering the pupil? iris
What determines the color of the iris? amount of melanin present
Large amounts of melanin in the iris make the eye color brown or black
Less melanin in the iris makes the eye color light brown, green, or gray
least melanin makes the eye color: blue
The inner layer of the eyeball. Retina
The retina has over 126 million ___________ cells, which respond to _______. photorecepor; light
What are of the nervous layer(retina) has the greatest sensitivity to light and has the highest concentration of photoreceptor cells? Macula lutea (fovea centralis)
Place where blood vessels enter the eye and axons of neurons converge to form the optic nerve which exits the posterior eye; no photoreceptor cells, known as the "blind spot" of the eye: Optic disc
The eye is composed of 3 chambers: anterior; posterior, vitreous
Chamber of the eye located between the cornea and the iris: Anterior
Chamber of the eye located between the iris and the lens posterior
Largest chamber of the eye; posterior to the lens: Vitreous Chamber
Fills the anterior and posterior chambers of the eye; Aqueous humor
Aqueous humor contributes to ________ pressure. intraocular
What supports, nourishes, and removes wastes for the cornea, which has no blood vessels? Aqueous humor
What produces Aqueous humor as a blood filtrate? ciliary processes
Aqueous humor is returned to the circulation through the __________ ________ ____________. scleral venous sinus
An increase in intraocular pressure due to the build up of aqueous humor: Glaucoma
Fills the vitreous chamber; also contributes to intraocular pressure; helps maintain the shape of the eyeball; holds the lens and retina in place; functions in the refraction of light in the eye: Vitreous humor
A biconvex, transparent, flexible, avascular structure that allows precise focusing of light onto the retina and is composed of epithelium and lens fibers; lens
anterior cells of the lens lens epithelium
lens cells filled with crystallines lens fibers
Ciliary body through suspensory ligaments changes the _______ of the lens. shape
With age, the lens becomes more _________ and _______ and loses its ________. compact; dense; elasticity
All energy waves from short gamma rays to long radio waves: Electromagnetic spectrum
Portion of the electromagnetic spectrum that can be detected by the human eye: visible spectrum
Bending of light refraction
Light striking a concave surface refracts outward divergence
light striking a convex surface refracts inward convergence
converging light rays meet at the _________ _________ and are said to be _____________. focal point: focused
Focusing system of the Eye (light refracting) cornea, aqueous humor, lens, vitreous humor
Responsible for most of the convergence cornea
adjusts the convergence by changing shape lens
looking at objects 20 feet or more from the eye distant vision
looking at objects less than 20 feet from the eye near vision
Relaxation of the ciliary muscles causes the lens to flatten, producing the _________ _______. emmetropic eye
Normal resting condition of the lens emmetropic eye
point at which the lens does not have to thicken for focusing to occur; normal 20 fee or more from the eye: Far point of vision
Closest point an object can come to the eye and still be focused near point of vision
When an object is less than 20 feet from the eye, the image falling on the retina is no longer in focus. What 3 events must occur to bring the image into focus? Accommodation by the lens; Constriction of the Pupil; Convergence of the eyes
Increases the depth of focus constriction of the pupil
Medial rotation of the eyes Convergence of the eyes
Contraction of the ciliary muscles causes the lens to become more spherical which is: accommodation by the lens
___________ layer of the retina provides a black backdrop for increasing visual acuity. Pigmented
Rods and cones synapse with ________ cells. bipolar cells
Bipolar cells synapse with ____________cells, which form the optic nerve. ganglion
Responsible for non-color vision and vision in low illumination (night vision) Rods
Rod-shaped photoreceptive part of the rods contains about _____ double-layered membranous discs. 700
Discs contain: rhodopsin
Rhodopsin is a purple pigment consisting of the protein _______ covalently bound to a yellow photosensitive pigment called ___________ (derived from vitamin A) opsin; retinal
What activates rhodopsin? exposure to light
Rhodopsin is split by light into _______ and ________, eventually resulting in an action potential. retinal; opsin
Light adaptation occurs when the eyes are exposed to _________ light, a person goes from the dark into the sunlight. increased
light adaptation is caused by a reduction of _____________. rhodopsin
Dark adaptation occurs when exposed to ___________ light, such as when a person goes from the sunlight to a dark room. decreased
What causes dark adaptation? increased rhodopsin production
What do both light and dark adaptation involve? pupil reflexes
Created by: tmcr



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