Chapter 16 Nervous System: Senses

place the structures of CN II in order from anterior to posterior

1. optic nerve 2. optic chiasm 3. optic tract

light rays are refracted when:

1. they pass between two media of different densities 2. these media meet at a curved surface

dark adaptation

The process in which the eyes become more sensitive to light in low illumination.

lamellated corpuscles

The receptors for deep pressure and vibration in the dermis and subcutaneous tissue (pacinian corpuscles)

which taste sensation translates as "delicious flavor" and is perceived as a meaty flavor?

Umami

photopsin of cone cells

cis-retinal transforms to trans-retinal and a bleaching reaction occurs, but a more intense light is required the regeneration of photopsin occurs much more quickly than the regeneration of rhodopsin

as we adjust to low light, our ______ become nonfunctional and it may take _________ for rhodopsin to become regenerated sufficiently so that you can see well in low-light conditions

cones, 20-30 minutes

inner segment

contains the organelles for the cell, such as mitochondria connects to the cell body, which contain the nucleus

superior colliculli

coordinates reflexive movements of the head, eyes, and neck

gustatory cells

detect tastants in our food have a 7-10 day lifespan are chemoreceptors located within taste buds on the tongue and soft palate

synaptic terminals

house synaptic vesicles with glutamate neurotransmitter

light causes the photoreceptor plasma membranes to

hyperpolarize

presbyopia

impaired vision as a result of aging lens loses elasticity

rods are essentially nonfunctional in bright light because

in bright light, rhodopsin will bleach as fast as it is reformed

the majority of the optic tract axons extend to the thalamus, specifically to the

lateral geniculate nucleus

Refraction of light

light rays are straight as they first enter the eye, but the ability to see clearly requires refraction of the light rays so that they hit on the retina

myopia

nearsighted, have trouble seeing faraway objects, only rays relatively close to the eye focus on the retina, the cause is a long eyeball

Which are cells found in the olfactory epithelium

olfactory receptor cells- which detect odors supporting cells- which sustain the olfactory receptor cells basal cells- which function as neural stem cells to continually replace olfactory receptor cells

olfactory hairs house receptor proteins for detecting ________ specific odorant molecules

one

ganglion axons of the retina converge to form the-

optic nerve

where is the trans-retinal transported so that the retinal can be reconverted back to its cis formation?

pigment epithelium

Rods

primarily located in the peripheral retina rods are activated by dim light and provide no color recognition

some individuals experience pain in their left shoulder during a heart attack. this is an example of

referred pain

root hair plexuses are usually found in the

reticular layer of the dermis

which events occur during bright light adaptation?

rods become inactive pupils constrict cones gradually adjust

tactile cells associated with tactile discs are located in the

stratum basale of the epidermis

supporting cells

sustain the gustatory cells

what type of phasic receptors detects light touch, shapes, textures?

tactile corpuscles

the dendritic ending of each gustatory cell is formed by a slender gustatory microvillus, also called a

taste hair

phototransduction

the process by which photoreceptors become activated when the photopigments are altered by light entering the eye is

which are true of the olfactory hairs?

they are immobile they are unmyelinated

unlike other sensory information, olfactory pathways do not project to the thalamus

true

convex lens

used to treat hyperopia

concave lens

used to treat myopia

axons of olfactory cells form fascicles of cranial nerve number

CN I

gustatory information travels through which cranial nerves?

CN VII and CN IX

glutamate neurotransmitter

binds with receptors of the bipolar cells to cause hyperpolarization in nerve signals

olfactory receptor cells are

bipolar neurons with radiating olfactory cilia

olfactory glands are also known as _______ glands

bowman

which is a type of tonic receptor that detects both continuous deep pressure and distortion of the skin?

bulbous corpuscles

astigmatism

causes unequal focusing and blurred images due to unequal curvatures in one or more of the refractive surfaces

photopigments

chemicals in photoreceptors that respond to light and assist in converting light into neural activity composed of an opsin and a retinal

Glaucoma

disease that causes fluid build up in the eye, dislocating the lens

taste buds

each taste bud is composed of three distinct cells: gustatory cells, supporting cells, basal cells

which are examples of encapsulated receptors?

end bulbs (krause bulbs) lamellated corpuscles bulbous corpuscles tactile corpuscles

outer segment

extends into the pigmented layer of the retina (rod-shaped in rods and conical-shaped in cones) composed of hundreds of discs that are flattened, membranous sacs, which are constantly being replaced.

light adaptation

eyes adjust from low light to bright light conditions

hyperopia

farsighted, have trouble seeing close-up objects, only convergent rays can be brought to focus on the retina, the cause is a short eyeball

what are types of papillae?

filiform, fungiform, foliate, and vallate

basal cells

function as neural stem cells to continually replace the relatively short-lived gustatory cells

as a consequence of the dark current, _________ channels in the photoreceptor open

glutamate

emmetropia

normal vision, parallel rays of light are focused exactly on the retina

optic tracts ultimately are directed to the primary visual cortex in the:

occipital lobe

cones

occur at a density of less than 10 million per eye and are concentrated in the fovea centralis activated by high-intensity light and provide color recognition and precise visual sharpness

referred pain

occurs when impulses from an organ are perceived as originating from the skin

dark current

when elevated levels of cGMP are present, Na+ channels in the photoreceptor membrane are kept open and Na+ enter the photoreceptor the bipolar cells are inhibited, so the brain does not perceive light