Sensory receptors and the PNS

Question 1

what are the different kinds of somatosensory recepters ?

Answer 1

• Chemoreceptors detect chemical stimuli for smell taste and internal stimuli like blood pH and metabolite concentrations
• Photo receptors detect light stimuli from the retina
• Thermoreceptors detect temperature and temp changes
• Mechanoreceptors detect physical deformations in tissue (thought, changes in muscle length and tension, auditory and vestibular receptors and others)
• Noiciceptors in general detect pain, from mechanical sources, thermal stimuli

Question 2

What kinds of things that we can’t sense ( and certain animals have them)

Answer 2

• Magnetorecepotrs detect earths magnetic field for navigation
• Infrared receptors detect heart in other organisms (snake)
• Electrorecpotrs detect electricity to help in navigation

Question 3

what kinds of properties that receptors encode ?

Answer 3

Receptors encode stimuli nature, location, intensity and duration

Question 4

What is the adaptation ? and what kinds of adaptation is in receptor and for what purpose ?

Answer 4

During the course of maintained stimulation, receptors begin to adapt and become less sensitive.

Some are slowly adapting (good for detecting static position)

Some are rapidly adapting (good for moving stimuli

Question 5

What are the cell parts of sensory receptors ?

Answer 5

Receptive area (orange)

Mitochondrial area (always near receptive area to supply energy)

Synaptic area (into the CNS)

Question 6

Transduction uses both ___________ and __________ potentials

Answer 6

Transduction uses both : Ionotropic (direct) like somatosensory, and others Metabotropic (2nd messenger systems e.g., olfactory, g-coupled proteins)

Question 7

When receptor potential modulates the AP frequency the receptor potential is also know as a ___________

Answer 7

When receptor potential modulates the AP frequency the receptor potential is also know as a generator potential

Question 8

Somatosensory recptors detect _______ , _______ or _______ changes

Answer 8

Somatosensory recptors detect mechanical, thermal or chemical changes

Answer 9

Somatosensory recptors have

cell body in a dorsal root or cranial nerve ganglion

An axon process that leads to spinal cord or brainstem

And “dendrite” process in the recepotor ending (e.g., skin)

Question 10

Cutaneous Receptors : Our skin is covered with sensory endings, All are either __________ or __________ (whether a capsule covers the ending)

Answer 10

Cutaneous Receptors : Our skin is covered with sensory endings, All are either encapsulated or nonencapsulated (whether a capsule covers the ending)

Question 11

What are the functions of Capsules ?

Answer 11

Capsules serve as filters of sensory information (as in rapidly adapting receptors) and as barriers for fluids (like myelin)

Question 12

Noncapsulated recptors are either _________ or ____________ (but don’t surround the ending)

Answer 12

Noncapsulated recptors are either free nerve endings or endings with accessory structures (but don’t surround the ending)

Question 13

Describe Endings around hair (encapsulated ? what kind of adapting ?)

Answer 13

Noncencapsulated** with accessory structures

Simple spiral ending

Responds to touch

Bending the hair deforms the sensory ending distorts the mechanically sensitive ion channels and leads to a generator potential

Hair receptors are rapidly adapting** because once bent, sensation ends

Question 14

Describe Markel ending (where? encapsulation ? what kind of adaptation ?)

Answer 14

Nonencapsulated receptor endings with accessory structures found in both hairly and glabrous skin

Merkel cells on bottom of dermis (green)

Nerve terminal (blue) synapses onto several merkel cells and sends info about mechanical stimuli (usually pressure

Question 15

Describe Meissner corpuscles. (where ? capsulation? adaptation? .. )

Answer 15

Found in glabrous skil (non hairy) elongated, encapsulated endings in the bottom of the epidermis, runs vertically

Corpuscles run zig-zag between layers of schwann cells (like a stack of pancakes) and respond to pressure/ tough to the skin (usually fingertips in humans)

Rapidly adapting receptors

More and more concentrations of receptors are move from palm to mid finger to fingertips

Question 16

Describe Pacinian corpuscles (where ? adaptation ? … )

Answer 16

Encapsulated ending with distinctive onion layering (concentric layers of very thing epithelial cells and fluid)

Very widespread in body subcutaneous in location

The most rapidly adapting receptros of the body, they transmit quickly applied forced but do not transmit from sustained forces

Also transmit vibration very well

Question 17

Descripe Ruffinin endings

Answer 17

Thin capsule ending that is cigar shaped and contains connective tissue (collogen)

Sensory fiber enters capsule and braches profusely

Slowly adapting

Question 18

____________ are formed by branching terminations of sensory fibers in the skin (no encapsulation)

Answer 18

Free Nerve Endings are formed by branching terminations of sensory fibers in the skin (no encapsulation)

Question 19

Only some form of _________ are free nerve endings

Answer 19

Only some form of mechaniorepectors are free nerve endings

Question 20

Free nerve endings - more commonly are _______ and _______ and respond to pain itch and temperature

Answer 20

More commonly are nociorecepotrs and thermoreceptors and respond to pain itch and temperature

Question 21

Some free nerve endings repond minimally in normal situations but become sensitive after tissue damage and inflammation called ____________

Answer 21

Some free nerve endings repond minimally in normal situations but become sensitive after tissue damage and inflammation called silent or sleeping noiceptros

Question 22

What kinds of necireceptrs and how does mylination affect their function ?

Answer 22

Nociceptors axons are either myelinated or unmyelinated and are responsible for pain stages

Myelinated: fast pain sensation (delta pain)

Unmelinted axons tramit slower signal (slow pain)

Question 23

What is hyperalgesia ? and allodynia?

Answer 23

Injured areas are increased pain levels - this is called (hyperalgesia)

allodynia swallowing hurts when you have a sore throat

Question 24

Area around injury (burn) becomes red (flare) and swollen (edema) produced locally by an ________________ due to self healing mechanisms but restimulate same recepotrs bc AP go up toward skin

Answer 24

Area around injury (burn) becomes red (flare) and swollen (edema) produced locally by an azon relflex due to self healing mechanisms but restimulate same recepotrs bc AP go up toward skin

Question 25

__________ = Long thin stretch receptors found in striated muscles long thing stretch

Answer 25

Muscle Spindles Long thin stretch receptors found in striated muscles long thing stretch

Question 26

Simple structure with a few muscle fibers and capsule surrounding the middle third of the fibers

These fibers are intrafusal muscle fibers (inside the spindle)

The other 2/3 are extrafusal muscle (found outside spindle

Answer 26

Simple structure with a few muscle fibers and capsule surrounding the middle third of the fibers

These fibers are ___________ fibers (inside the spindle)

The other 2/3 are ___________ fibers (found outside spindle

Question 27

What are the two types of intrafusal muscle fibers ?

Answer 27

Two types of intrafusal muscle fibers

Nuclear chain fibers (many cell nuclei that are lines up single file in chain)

Nuclear bag fibers (many cell nuclei arrangied many to a row)

Question 28

what are the two types of sensory endings in muscle spindle ?

Answer 28

Primary endings (called annulospiral endings)

Secondary endings (also called flower-spray endings)

Question 29

_________________ - One very large nerve fiber that enters the capsule and then branches off each branch wrap around on intrafusal fiber in a spinal pattern

Answer 29

Primary endings (called annulospiral endings) : One very large nerve fiber that enters the capsule and then branches off each branch wrap around on intrafusal fiber in a spinal pattern

Question 30

________________ - A few small nerve fibers that branch off and innervate on either side of a primary ending

Answer 30

Secondary endings (also called flower-spray endings) - A few small nerve fibers that branch off and innervate on either side of a primary ending

Question 31

Primary endings most sensitive to the ________________, while secondary endings are sensitive to the _______________

Answer 31

Primary endings most sensitive to the onset of a muscle stretch while secondary endings are sensitive to the maintenance of muscle stretch

Question 32

Muscles spindles receive motor neurons. True or false ?

Answer 32

True

Question 33

describe motoro innervation to muscle spindles :

Answer 33

Motor innervation to muscle spindles:

Alpha motor neurons large motor neurons that supply extrafusal muscle fibers

Gamma motor neurons for fusimotor neurons (smaller motor neurons that innervate those intrafusal fibers

Involved in feedback control of the muscle (at the receptor level) basically how sensitive muscle will be to stretch

Question 34

Whereas muscle spindles detect ________ , golgi tendon organs detect _________

Answer 34

Whereas muscle spindles detect muscle length, golgi tendon organs detect muscle tension

Question 35

____________ - Similar to ruffinin endings in that they have layers of collagen tand very thin capsule and branch out around the collagen in the muscle/ tendon

Answer 35

Golgi Tendon

Question 36

Describe receptors in joints

Answer 36

Similar to those in skin and muscle

Free nerve endings

Ligaments have receptors similar to Golgi tendons organs

Joint capsules have receptors similar to ruffinin endings and few pacinian corpuscles