Sensory Perception

Question 1

What are the steps to sensation?

Answer 1

1. Stimulation
2. Transduction
3. Conduction
4. Perception

Question 2

Stimulation

Answer 2

Application of stimulus

Question 3

Transduction

Answer 3

Induction of AP (if strong enough depolarization)
Increased stimulus strength above threshold leads to increase AP

Question 4

Conduction

Answer 4

Relay of info through a sensory pathway to specific region of CNS
1st, 2nd and 3rd order neuron

Question 5

1st, 2nd and 3rd order neuron

Answer 5

1. From stimulation point to CNS
2. From entry into CNS to thalamus
3. From thalamus to perception site

Question 6

Perception

Answer 6

Detection of environmental change by the CNS

Question 7

Adequate stimulus

Answer 7

Sensors most sensitive to one particular stimulus modality

Question 8

Phasic receptors

Answer 8

Exhibits sensory adaptation (response of sensors to constant stimulation)
Decrease with constant stimulus
Ex: don’t feel a shirt after a while

Question 9

Tonic receptors

Answer 9

Exhibit little adaptation
Maintain constant firing rate as long as stimulus is applied

Question 10

Sensory system (receptor types)

Answer 10

Touch (mechanoreceptor)
Temperature (thermoreceptor)
Pain (nociceptors)
Body position (proprioceptors)
Photoreceptors
Osmoreceptors
Chemoreceptors

Question 11

What re the receptors of the skin?

Answer 11

Free nerve endings for heat, cold, and pain:
Expanded dendritic endings
Encapsulated endings
Bundled receptors

Question 12

Expanded dendritic endings

Answer 12

Ruffini endings and Merkel’s disks (touch)

Question 13

Encapsulated endings

Answer 13

Meissener’s corpuscles, krause’s corpuscles, pacinian corpuscles (touch and pressure)

Question 14

Bundled receptors

Answer 14

Spindle fibers, golgi tendon organs

Question 15

Tactile sensory input

Answer 15

Responds to pressure and movement of skin
Specialized receptors that respond to particular types of inputs

Question 16

Pacinian

Answer 16

Heavy pressure and rapid vibration (300 hz)

Question 17

Meissener’s

Answer 17

Light pressure
Slow vibration (50 Hz)

Question 18

Acuity

Answer 18

Ability to discriminate size and shape of an object in the environment

Question 19

When is acuity increased?

Answer 19

With increase in receptor density and decrease in receptive field size

Question 20

Receptive field

Answer 20

The region of the skin in which a stimulus evokes a response in a sing,e sensory neuron
Discrimination depends on the density of receptors

Question 21

Thermoreception

Answer 21

Responds to not painful temperatures
Warm and cold thermoreceptors

Question 22

Where are thermosensitive neurons present?

Answer 22

Skin, hypothalamus and spinal cord

Question 23

Proprioception

Answer 23

Internal awareness of body position in relation to the environment

Question 24

What are the 2 types of proprioceptors?

Answer 24

1. Muscle spindle and golgi tendon organs found in skeletal muscle
2. Mechanoreceptors found in CT, ligaments and joint capsules

Question 25

Myelinated sensory functions

Answer 25

Muscle spindle- primary (slowest condition velocity) Muscle tendon Hair receptors (slowest CV) Vibration (pacinian corpuscle) High discrimination touch Deep pressure touch Picking pain Cold Warm

Question 26

Unmyelinated motor function

Answer 26

Cold Warm Acting pain Tickle (fastest condition velocity) Crude touch and pressure

Question 27

Nociceptors

Answer 27

Respond to painful stimulus Carried by non-myelinated C fiber sensory neurons Painful heat, acids, mechanical damage all activate non-specific cation channels

Question 28

What substances are released from damaged cells?

Answer 28

ATP Bradykinin Substance P

Question 29

How is transduction of warm temperatures carried out?

Answer 29

By several types of TRPV cation channels

Question 30

TRPV1

Answer 30

Receptor that's activated by the vanilloid class of compounds (capsaicin, spicy food ingredient)

Question 31

Segmental pain modulation

Answer 31

Pain control when there's not too much damage, the body will take care of it automatically Body will inhibit the pain receptor

Question 32

Descending pain modulation

Answer 32

Pain in the brain 1. C fiber (dorsal horn) 2. Medulla (Nucleus raphe magnus and nucleus paragigantocellularis 3. Periaqueductal gray

Question 33

Referred pain

Answer 33

Feel pain in a part of the body that is fairly remote from the tissue causing the pain Due to lack of precision in the central organization of pain pathways Ex; heart attack, feeling pain in left shoulder)

Question 34

Dorsal column-medial lemniscal pathway

Answer 34

Propioceptors or mechanoceptors Crosses over @ the medulla and will synapse at the dorsal column nuceli (2nd order neuron)

Question 35

Spinothalamic tract

Answer 35

Nociceptors or thermoreceptors Crosses over @ the SC (synapse @ first order neuron)

Question 36

Spinocerebellar tracts

Answer 36

Prorioceptive to cerebellum Ipsillateral Keeps track of movement

Question 37

Spinoreticular tract

Answer 37

Conveys deep and chronic pain