0-1 Chapter 16 - sense Organs Flashcards Preview

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1

sense organs

nerve tissue surrounded by other tissues that enhance response to certain type of stimulus
•added epithelium, muscle or connective tissue

2

transduction

the conversion of one form of energy to another
–fundamental purpose of any sensory receptor

3

receptor potential

small, local electrical change on a receptor cell brought about by an initial stimulus
•results in release of neurotransmitter or a volley of action potentials that generates nerve signals to the CNS

4

sensation

a subjective awareness of the stimulus
–most sensory signals delivered to the CNS produce no conscious sensation

5

Receptors Transmit Four Kinds of Information

Modality
Location
Intensity
Duration

6

Modality

type of stimulus or the sensation it produces
–vision, hearing, taste

7

labeled line code

all action potentials are identical. Each nerve pathway from sensory cells to the brain is labeled to identify its origin, and the brain uses these labels to interpret what modality the signal represents

8

Location

encoded by which nerve fibers are issuing signals to the brain

9

receptive field

area that detects stimuli for a sensory neuron

10

sensory projection

brain identifies site of stimulation

11

projection pathways

the pathways followed by sensory signals to their ultimate destination in the CNS

12

Intensity

encoded in 2 ways

Strength
frequency

13

Duration

how long the stimulus lasts

14

sensory adaptation

if stimulus is prolonged, the firing of the neuron gets slower over time, and we become less aware of the stimulus

15

phasic receptor

generate a burst of action potentials when first stimulated, then quickly adapt and sharply reduce or stop signaling even though the stimulus continues

16

tonic receptor

adapt slowly, generate nerve signals more steadily

17

Classification of Receptors by

modality
origin of stimuli
distribution

18

by modality

–thermoreceptors, photoreceptors, nociceptors, chemoreceptors, and mechanoreceptors

19

origin of stimuli

–exteroceptors -detect external stimuli
–interoceptors -detect internal stimuli
–proprioceptors -sense body position and movements

20

by distribution

–general (somesthetic) senses -widely distributed
–special senses -limited to head
•vision, hearing, equilibrium, taste, and smell

21

General Senses

structurally simple receptors
–one or a few sensory fibers and a little connective tissue

22

unencapsulated nerve endings

•dendrites not wrapped in connective tissue
–free nerve endings
–tactile (Merkel) discs
–hair receptors (peritrichial endings

23

free nerve endings

–for pain and temperature
–skin and mucous membrane

24

tactile discs

–for light touch and texture
–associated with Merkel cells at base of epidermis

25

hair receptors

–wrap around base of hair follicle
–monitor movement of hair

26

encapsulated nerve endings

•dendrites wrapped by glial cells or connective tissue
•connective tissue enhances sensitivity or selectivity of response

27

encapsulated nerve endings

types

–tactile (Meissner) corpuscles
–Krause end bulbs
–bulbous (Ruffini) corpuscles
–lamellar (pacinian) corpuscles
–muscle spindles
–golgi tendon organs

28

tactile (Meissner) corpuscles

–light touch and texture
–dermal papillae of hairless skin

29

Krause end bulb

–tactile; in mucous membranes

30

lamellated (pacinian) corpuscles

phasic
–deep pressure, stretch, tickle and vibration
–periosteum of bone, and deep dermis of skin