Lecture 2 (Receptors And Afferent Pathways)

Question 1

What does sensory information promote? Where is sensory info from?**

Answer 1

-adaptations in posture and movement (planned and reactive)
-sent from peripheral receptors

Question 2

What is perception? What does it interpret?**

Answer 2

-Awareness of stimuli
-Interprets sensory info into meaningful forms (ex. Reaching for keys)

Question 3

What type of process is perception? What are 3 examples?**

Answer 3

-active and ongoing process: perception involves acting within the environment
-proprioception, visual, vestibular

Question 4

What are 3 cutaneous sensory receptors? Examples of each**

Answer 4

-mechanoreceptors (pressure, touch, vibration, proprioception)
-thermoreceptors (heat, cold)
-nociceptive (pain)

Question 5

What are 5 cutaneous receptors?**

Answer 5

Meissner corpuscle
Pacinian corpuscle
Ruffini’s corpuscles
Merkel’s disks
Free nerve endings

Question 6

What does Meissner corpuscle sense?**

Answer 6

Discriminative touch and low frequency vibrations

Question 7

What does Pacinian corpuscle sense?**

Answer 7

High vibration and sudden stimuli

Question 8

What does Ruffini’s corpuscle sense?**

Answer 8

Stretch

Question 9

What does Merkel’s disks sense?

Answer 9

Surface pressure, static touch, hair follicles

Question 10

What do free nerve endings sense?**

Answer 10

Pain, heat, cold

Question 11

Where are Meissner’s corpuscles found? What vibration level does it sense? Velocity?

Answer 11

-superficial skin, greater density at fingertips
-30-50 Hz (flutter)
-velocity sensitive 2-40 mm/s

Question 12

Where are Pacinian corpuscles found? Higher density found? What type of receptive fields?

Answer 12

-subcutaneous
-in fingertips
-large receptive fields (>4mm)

Question 13

Where are Merkel’s Discs found? What is the receptive field range? What do they respond to?

Answer 13

-found in superficial skin (greater density at fingertips); dermis and hair follicles
-small receptive field (2-4mm)
-responds to pressure, touch and form

Question 14

What is glamorous skin?

Answer 14

Has no hair

Question 15

Where are free nerve endings found? What do they detect?

Answer 15

-throughout the skin and viscera (internal organs); in epidermis
-detects temp, pain, tickle and itch

Question 16

What does pain stimulus do? What type of stimuli set it off?

Answer 16

-Translate potentially damaging stimuli into electrochemical signals
-mechanical, thermal, or chemical stimuli

Question 17

What are two types of pain?

Answer 17

Nociceptive and neuropathic

Question 18

What is nociceptive pain a result from? Is it a normal or abnormal response?

Answer 18

Activation of pain receptors in body due to tissue injury/inflammation; normal

Question 19

What is neuropathic pain?

Answer 19

Direct injury to neural tissue, typically results in burning, radiating, following peripheral nerve

Question 20

What do pain receptors transmit? Give examples

Answer 20

-precise information
-where injury is located
-characterized as sharp or dull (pressure, heat, cold)

Question 21

What do pain receptors in organs do?

Answer 21

Refer pain to other locations since pain receptors in organs are not precise

Question 22

What are myelinated delta free nerve endings? What types of sensations do they carry? Sense pain immediately or over time?

Answer 22

-afferent fibers
-carry sharp, stabbing, pricking pain or cold
-immediately

Question 23

What type of pain does unmyelinated C fibers carry? What is the activation threshold like? Polymodal pain receptors?

Answer 23

-dull ache pain
-threshold is higher since info travels slower
-chemical, heat thermal, mechanical, hypoxia

Question 24

What are the 4 different sizes of axons (motor and sensory)

Answer 24

-Alpha (motor neuron): highly myelinated, high speed transmission
-Beta (sensory neuron): Pacinian, Ruffini, Meissner, Merkel
-Delta: myelinated free nerve ending
-C fibers: free nerve ending

Question 25

What is a muscle spindle and where is it found? Function?

Answer 25

-Sensory proprioception within muscle belly
-Gives feedback about muscle performance and speed

Question 26

Which is intrafusal and extrafusal: muscle spindle and muscle

Answer 26

MS = intrafusal
Muscle = extrafusal

Question 27

Where does MS send info to? What does that structure do with the info? **

Answer 27

-cerebellum
-calculate joint position and other variables to make appropriate movement

Question 28

What does the cerebellum house, regarding muscle spindles?**

Answer 28

Motor memory (length and velocity)

Question 29

What do muscle spindles respond to?**

Answer 29

Length and velocity of stx

Question 30

Does muscle spindle contribute to force generation?

Answer 30

No, GTOs do

Question 31

What do tendon reflexes assess?

Answer 31

The integrity of the MS system

Question 32

What do GTOs give feedback about

Answer 32

Amount of force in a tendon

Question 33

Describe how the patellar tendon reflex happens

Answer 33

Tendon tap = stimulus
Muscle spindle = receptor
Afferent neuron 1a (sensory neuron) sends info to SC
SC synapses synapse w/ other neurons
Two motor (effector) neurons activate muscles (one contracts quad, the other inhibits hs)

Question 34

What is an order neuron?

Answer 34

Delivery of sensory info from periphery to cortex

Question 35

How does stimulus travel to cortex?

Answer 35

-through PNS - dorsal root ganglion (1st order neuron)
-SC (2nd order neuron)
-Thalamus (relay; 3rd order neuron)
-Cortex

Question 36

What are the two major sensory pathways?

Answer 36

Anterolateral (spinothroacic tract)
Posterior (dorsal) Columns (medial lemniscal pathway)

Question 37

What does the anterolateral pathway sense? Where is the Decussation?

Answer 37

-pain, temp, crude touch
-SC

Question 38

What info does the posterior (dorsal) column sense? Where is the Decussation?

Answer 38

-vibration, joint position, fine touch
-medulla