physiology quiz 1

sensory receptors can be categorized by

structure and function

structure of sensory receptors

free nerve endings, encapsulated nerve endings, separate cells

Functions of the sensory neurons

type of signal they transduce, type of information they send to the brain, origin of the information

chemoreceptors

sense chemicals in the environment (taste, smell) or blood

Photoreceptors

sense light

Thermoreceptors

respond to cold or heat

Mechanoreceptors

stimulated by mechanical deformation of the receptor (touch, hearing)

Nociceptors

pain receptors

what can nociceptors stimuli include

heat, cold, pressure, chemicals

what are the main neurotransmitters for nociceptors

glutamate and substance P

what are the mechanisms of mechanoreceptors?

deforms plasma membranes of sensory dendrites or deforms hair cells that activate sensory nerve endings

examples of mechanoreceptors

cutaneous touch and pressure receptors; vestibular apparatus and cochlea

what are the mechanisms of nociceptors

damaged tissue release chemicals that excite sensory endings

examples of nociceptors

cutaneous pain receptors

what are the mechanisms of chemoreceptors

chemical interaction affects ionic permeability of sensory cells

Examples of chemoreceptors

smell and taste (exteroceptors), osmoreceptors, and carotid body chemoreceptors (interoceptors)

what are the mechanisms of photoreceptors

photochemical reaction affects ionic permeability of receptor cell

examples of photoreceptors

rods and cones in the retina

proprioceptors

provide a sense of body position and allows fine muscle control

where are proprioceptors found

muscles, tendons, and joints

cutaneous receptors

touch, pressure, head, cold, and pain

special senses

vision, hearing, taste, smell, equilibrium

exteroceptors

Respond to stimuli arising outside the body, includes cutaneous receptors and special senses

interoceptors

respond to internal stimuli

where are interoceptors found

organs

what do interoceptors do

monitor blood pressure, pH, and oxygen concentrations

phasic

adapt quickly

examples of phasic receptors

pressure and smell

tonic

adapt slowly

examples of tonic receptors

pain

what do generator potentials produce

graded response

in a generator potential do receptors and dendrites of neurons behave differently or the similarly

similarly

in a generator potential stimuli produce depolarization or repolarization

depolarization

what produces a small generator potential

light touch on a pacinian corpuscle

what increases the magnitude of the generator potential

pressure

when do action potential occur

when threshold is met

What are cutaneous receptors responsible for?

light touch, pain, cold, and heat

what kind of nerve endings to cutaneous receptors have

free nerve endings (naked dendrites)

what are the special structures around the nerve endings that touch and pressure receptors have

Markel's disk, Meisnner's corpuscles, pacinian corpuscles, and Ruffini corpuscles

what is the structure of a free nerve ending

unmyelinated dendrites of sensory neurons

what are the sensations that free nerve endings respond to

light touch, hot, cold, and nociception (pain)

where are free nerve endings found

around hair follicles, throughout the skin

what is the structure of Merkel's disk

expanded dendritic endings associated with 50 to 70 specialized cells

what are the sensations that Merkel's disk respond to

sustained touching indented depth

where is Merkel's disk located

base of the epidermis (stratum basale)

what is the structure of Ruffini corpuscles?

enlarges dendritic endings with open elongated capsule

what are the sensations that Ruffini corpuscles respond to

skin stretch

Where are Ruffini corpuscles located?

deep dermis and hypodermis

what is the structure of Meissner's corpuscles

dendrites encapsulated in connective tissue

what are the sensations that Meissner's corpuscles respond to

changes in texture, slow vibrations

Where are Meissner's corpuscles located?

upper dermis (papillary layer)

what is the structure of Pacinian corpuscles

dendrites encapsulated by concentric lamellae of connective tissue structures

what is the sensation of Pacinian corpuscles

deep pressure, fast vibrations

Where is the Pacinian corpuscle located?

deep in the dermis

what is the structure of the nerve endings for cold receptors

free nerve endings

are there more cutaneous receptors that respond to hot or cold

cold

Where are cold receptors located?

close to the epidermis

what are cold receptors stimulated by

cold

what are cold receptors inhibited by

heat

Where are warm receptors located?

deeper in the dermis

what are warm receptors excited by

heat

what are warm receptors inhibited by

cold

pain receptors are also called

nociceptors

are nociceptors myelinated or unmyelinated

both

what is dull, persistent pain transmitted by

unmyelinated neurons

what is sudden, sharp pain transmitted by

myelinated neurons

what can nociceptors be activated by

chemicals released by damages tissue, such as ATP or by pH change or mechanical stimuli

what do somatic pain neurons synapse at the same interneuron as

visceral pain neuron

referred pain

heart pain as arm pain or gallbladder pain as back pain

what is acute itch stimulated by

histamine

where is histamine released from during an acute itch

mast cells and basophils

what does chronic itch not respond to

antihistamines

what do itch sensation receptors stimulate

unmyelinated axons to the spinal cord

where does the neural pathway for somatesthetic sensations of cutaneous touch and pressure receptors start?

first order neurons

what are first order neurons in cutaneous touch and pressure receptors?

Large myelinated fibers (A-beta fibers)

where do the first order neurons in cutaneous touch and pressure receptors go?

ascend the dorsal columns of the spinal cord on the ipsilateral side

where do first order neurons in cutaneous touch and pressure receptors synapse

medulla oblongata

what do the second order neurons go in cutaneous touch and pressure receptors?

cross sides as they ascend the medial lemniscus

where do second order neurons go in cutaneous touch and pressure receptors after they ascend the medial lemniscus

thalamus

where do second order neurons in cutaneous touch and pressure receptors synapse?

thalamus

where do third oder neurons go in cutaneous touch and pressure receptors?

post-central gyrus in the parietal lobs

where does the neural pathway for somatesthetic sensations of heat, cold, and pain receptors start?

first carried into the spinal cord

what carries somatesthetic sensations of heat, cold, and pain receptors to the spinal cord

Thin unmyelinated and myelinated neurons

where do the first order neurons synapse in somatesthetic sensations of heat, cold, and pain receptors?

within the spinal cord

where in the spine are somatesthetic sensations of heat, cold, and pain receptors go in the spinal cord

lamina of the dorsal gray horns

where do second order neurons of the somatesthetic sensations of heat, cold, and pain receptors go after the first order neurons are synapsed in the

cross sides and ascend later spinothalamic tract

what neurons do second order neurons in the somatesthetic sensations of heat, cold, and pain receptors synapse

on third order neurons

where are the third order neurons located in the somatesthetic sensations of heat, cold, and pain receptors.

thalamus

where do the third order neurons go to last in the somatesthetic sensations of heat, cold, and pain receptors?

postcentral gyrus

receptive field

area of skin that, when stimulated, changes the firing rate of a neuron

what does the size of the receptive field depend on

density of the receptors

there are few receptors located where?

back of legs

are receptor fields large or small in the back of legs

large

there are many receptors located where?

fingertips

are receptor fields large or small in finger tips

small

two-point threshold

the smallest distance at which two points of contact can be felt

what do two-point thresholds measure?

tactile acuity

what has the most distance between two-point threshold

calf

what has the least distance between two-point threshold

first finger

Where does lateral inhibition occur?

CNS