Somatic Sensory System

Question 1

Comprises specialized nerve cells that respond to stimuli within or outside the body

Answer 1

Sensory Receptors

Question 2

What is the job of sensory receptors?

Answer 2

Convert stimulus energy to electrical energy –> action potentials.

Question 3

What means that a sensory signal reached CNS?

Answer 3

Perception

Question 4

Nervous system responsible for taking in information from the environment and relaying it to the CNS.

Answer 4

Sensory System

Question 5

Basic Pathway of Sensory System.

Answer 5

Stimulus Energy –> Transduction –> Sensory Receptor –> Output to CNS —> Perception

Question 6

Overview of somatic sensations conveying to the CNS and the brain?

Answer 6

receptor endings –> mechanosensory afferent fiber –> dorsal root ganglion cells –> then travels up the spine.

Question 7

The pathway depends on modality. What are the two types of modalities?

Answer 7

Discriminative touch.

Pain and Temperature

Question 8

What are the First Order Neurons?

Answer 8

Mechanosensory Receptors From the Lower Body

Mechanosensory Receptors From the Upper Body

Question 9

What are the Second Order Neurons?

Answer 9

Cuneate Nucleus

Gracil Nucelus

Question 10

What are the Third Order Neurons?

Answer 10

Ventral Posterior Lateral Nucleus of Thalamus

Question 11

Where does discriminative touch cross?

Answer 11

High in the Medulla Oblongata

Question 12

Mechanosensory receptors from the upper body come in the level of?

Answer 12

Cervical Spinal Cord

Question 13

Mechanosensory receptors from the lower body come in the level of?

Answer 13

Lumbar Spinal Cord

Question 14

Gracile nucleus (pathways from _______ ________)

Answer 14

Lower Body

Question 15

Cuneate nucleus (pathways from _______ _______)

Answer 15

Upper Body

Question 16

What does decussate mean?

Answer 16

2nd order neurons projecting axons across the midline

Question 17

Where does 2nd order nuerons synapse? What general location?

Answer 17

Caudal medulla (Gracile or Cuneate)

Question 18

Where is the primary somatic sensory cortex located?

Answer 18

Post-Central gyrus

Question 19

What is the dividing line of the brain?

Answer 19

Central Sulcus

Question 20

Pathway for the face to the primary somatic sensory?

Answer 20

Mechanosensory receptors from face (Trigeminal ganglion) –> principal nucleus of trigeminal complex –> medial lemniscus –> trigeminal lemiscus –> Thalamus –> Primary Somatic Sensory Cortex

Question 21

Somatosensory cortex is subdivided into ________ ______?

Answer 21

Brodmann’s Areas

Question 22

What are the four areas of Brodmann?

Answer 22

1
2
3a
3b

Question 23

What does cutaneous mean?

Answer 23

sensations coming through the skin

Question 24

What does proprioceptive mean?

Answer 24

Where your body is in space. (sensations coming through the muscles, tendons)

Question 25

What areas are cutaneous?

Answer 25

1 and 3b

Question 26

What area(s) are proprioceptive?

Answer 26

3a

Question 27

What area(s) are both cutaneous and proprioceptive?

Answer 27

2

Question 28

What is the order of the areas from anterior to posterior?

Answer 28

3a 3b 1 2

Question 29

Info from body comes through ______ of the thalamus?

Answer 29

VPL (Ventral Posterior Lateral Nucleus)

Question 30

Info from face comes through _______ of the thalamus?

Answer 30

VPM (Ventral Posterior Medial Nucleus)

Question 31

Primary Somatic Sensory Cortex: Number of neurons (or size of the cortex) is not proportional to ?

Answer 31

the size of that part of the body

Question 32

Somatic sensory system sensory receptors specialized to transduce?

Answer 32

mechanical (kinetic) energy

Question 33

Stimuli leads to ?

Answer 33

Deformation (changes in the shape of the cell membrane of the receptor)

Question 34

Deformation leads to ?

Answer 34

Changes in the conductance of nerve ending

Question 35

What causes changes in the conductance of nerve endings?

Answer 35

Altering the permeability of ion channels

Question 36

What causes changes in the membrane?

Answer 36

Stimuli (Mechanically gated channels open)

Question 37

After deformation what will you get?

Answer 37

A receptor (generator) potential

Question 38

What is a receptor potential?

Answer 38

Changes of the membrane potential of the receptor.

Question 39

What will cause an action potential?

Answer 39

Receptor potential is threshold or suprathreshold.

Question 40

Action potential is conducted?

Answer 40

Centrally

Question 41

What is signal transduction?

Answer 41

Conversion of stimulus energy to electrical energy

Question 42

Receptors are ?

Answer 42

Transducers

Question 43

CNS interprets stimulus ______ and _______.

Answer 43

quality and quantity.

Question 44

What does it mean by quality?

Answer 44

What and where the stimulus is.

Question 45

What is quality determined by? (two things)

Answer 45

1. Type of receptor responding | 2. Location of central target

Question 46

What does it mean by quantity?

Answer 46

Strength of stimulus

Question 47

What is quantity determined by?

Answer 47

Frequency of action potentials

Question 48

Quality of stimulus is the # of ______ ______ _____ that respond to a stimulus.

Answer 48

Different receptor cells

Question 49

Receptive Field =

Answer 49

Area of skin that sensory neuron innervates (is supplied)

Question 50

Receptive fields are usually small when ?

Answer 50

High receptor density

Question 51

Two-point discrimination:

Answer 51

Method of measuring minimal distance needed to sense two different and simultaneous stimuli.

Question 52

What two things does the two-point discrimination depend on?

Answer 52

1. Receptor density | 2. Receptive fields

Question 53

Sensory Adaptation:

Answer 53

Size of receptor potential and frequency of AP can decline if the stimulus persists

Question 54

What are the two types of receptor classification based on response to enduring stimuli?

Answer 54

Phasic | Tonic

Question 55

Phasic:

Answer 55

Rapidly Adapting

Question 56

Tonic:

Answer 56

Slowly Adapting

Question 57

Phasic responds to ________ stimuli.

Answer 57

Dynamic

Question 58

What are the major subsystems of the SSS?

Answer 58

Mechanosensory | Pain/Thermal

Question 59

Mechanosensory:

Answer 59

Detects mechanical stimuli | Receptors have nerve endings encapsulated in CT to modulate inputs

Question 60

Pain/Thermal

Answer 60

Detects painful and thermal stimuli | Receptors have free nerve endings

Question 61

In mechanosensory external stimuli receptors are found in?

Answer 61

Skin

Question 62

In mechanosensory internal stimuli receptors are found in?

Answer 62

Muscles, joints, bonds and other deep tissues

Question 63

Internal stimuli has to do with?

Answer 63

Proprioception

Question 64

Examples of encapsulated nerve endings.

Answer 64

Meissner corpuscle | Merkel cell

Question 65

``` Myelinated Type AB fibers Dermal papillae of glabrous skin Encapsulated by Schwann Cells Most common mechanoreceptor fo glabrous kin Stimulus - Light touch Phasic ```

Answer 65

Meissner's Corpuscles

Question 66

``` Myelinated Type AB fibers Dermis of glabrous skin Encapsulated Stimulus - Deep touch, ticklish (response) Phasic ```

Answer 66

Pacinian Corpuscle

Question 67

``` Myelinated Type AB fibers Dermis of glabrous skin, ligaments and tendons Encapsulated Stimulus -Stretch Tonic ```

Answer 67

Ruffini's Corpuscles

Question 68

Myelinated Type AB fibers Location - In epidermis (Deep folds) Encapsulated and in close apposition to modulating cell that secretes neuromodulator Stimulus - Shapes, edges, and rough textures Tonic

Answer 68

Merkel's Disk

Question 69

List (of most used to least used) receptor to read braille.

Answer 69

Merkel Cell Meisnner Corpuscle Ruffini Corpuscle Pacianian Corpuscle