Exam 4.4 - Reduced Senses

Sensory receptors

provide info about external and internal environments and respond to specific stimuli

Transducers

convert stimulus energy into electrical energy

Receptors have…

resting membrane potential and modality gated channels

Final signal pathway order

Receptor → action potential → CNS for interpretation

Receptive field

area monitored by one sensory neuron

Smaller receptive fields result in more precise…

localization

Sensation

conscious awareness of a stimulus

Requirement for sensation

signal must reach cerebral cortex

A lot of sensory input goes to…

other areas of brain

Receptors are categorized by…

distribution, stimulus origin, and stimulus modality

General sense receptors

simple structures distributed throughout body

Special sense receptors are located in…

complex organs of head

5 special senses

smell, taste, vision, hearing, equilibrium

Exteroceptors detect…

external stimuli from environment

Interoceptors detect…

internal organ conditions

Proprioceptors detect…

body and limb position

Chemoreceptors detect…

chemicals in fluids

Thermoreceptors detect…

temperature changes

Photoreceptors detect…

light intensity, color, movement

Mechanoreceptors detect…

distortion such as pressure, vibration, stretch

Nociceptors detect…

pain from tissue damage

Somatic nociceptors detect…

surface and skeletal muscle damage

Visceral nociceptors detect…

internal organ damage

Free nerve endings are located near…

skin surface and mucous membranes

Free nerve endings detect…

pain temperature, light, touch, pressure

Root hair plexuses are located in…

the deeper dermis

Root hair plexus detect…

hair movement

Tactile discs connect to…

merkel (tactile) cells

Tactile discs respond to…

light touch and tonic

End bulbs detect…

pressure and low-frequency vibration

End bulbs are…

ensheathed in connective tissue

Lamellated corpuscles detect…

deep pressure, coarse touch, high-frequency vibration

Lamellated corpuscles are wrapped in…

neurolemmocytes and concentric layers of connective tissue

Bulbous corpuscles

wrapped in CT, detect deep pressure and skin distortion

Tactile corpuscles

are intertwined endings wrapped in modified neurolemmocytes, covered in connective tissue

Phantom pain

stimulation of sensory pathway after limb removal; neuron cell body still alive

Olfactory receptors type

chemoreceptors exposed to air

Gustatory cell are…

chemoreceptors in taste buds

Filiform papillae location

anterior 2/3 tongue

Foliate papillae location

posterior lateral tongue

Vallate papillae location

posterior tongue row

Taste bud

onion-shaped organs housing taste receptors

5 main tastes

sweet, salty, sour, bitter, umami

Sweet caused by…

organic compounds

Salty caused by…

metal ions

Sour caused by…

acids

Bitter caused by…

alkaloids

Umami caused by…

amino acids

For sweet, bitter, and umami the tastants are…

molecules

For salt and sour the tastants are…

ions

Taste integration depends on…

smell, temperature, texture

Conjuctiva layers

ocular and palpebral

Lacrimal fluid

lubricates, cleans, protects, nourishes

Blink rate

15-20 per minute

Eye diameter

2.5 cm

Eye cavities

anterior aqueous, posterior vitreous

3 eye tunics

fibrous, vascular, retina

Cornea

refracts light

Conjuctiva

transparent lining of eye and lid surfaces

Ocular conjuctiva covers…

anterior sclera (white of eye)

Palpebral conjuctiva covers…

internal surface of eyelid

Choroid contains

capillaries and melanocytes

Ciliary muscle

changes lens shape

Posterior cavity contains __ ___ humor

permanent vitreous

Anterior cavity contains __ ___ humor

circulating aqueous

Fibrous tunic contains

sclera, cornea

Vascular tunic contains

iris, ciliary body, choroid

Retina tunic contains

pigmented layer, neural layer

Sphincter pupillae causes…

constriction parasympathetic

Dilator pupillae causes…

dilation sympathetic

Pigmented layer

absorb light, provide vitamin A

Neural layer

convert light to signals

Optic disc

blind spot

Macula lutea

central vision

Fovea centralis

highest acuity

Peripheral retina

low light vision rods

Vitreous humor

maintains shape, supports retina

Aqueous humor

nourishes lens and cornea

Glaucoma cause

drainage failure, increases pressure

Hyperopia

farsighted; short eyeball

Myopia

nearsighted; long eyeball

Astigmatism

uneven curvature causes blurred vision

Presbyopia

age-related loss of near vision

Image on retina is…

inverted and reversed

Hearing

perception of sound

Sound

the perception of pressure waves established from vibrating objects

Conductive deafness

problem in outer or middle ear

Sensorineural deafness

problem in inner ear or nerve

Equilibrium

coordination, balance, and orientation in three-dimensional space

Vestibular apparatus

responsible for sensing equilibrium