Lecture 6- Somatosensory And Motor Systems

Question 1

Where is somatosensation

Answer 1

All over the body

Question 2

Somatosensory has a closer relationships with what than any other sense

Answer 2

Movement

Question 3

Receptors are

Answer 3

All over skin, muscles, tendons, joints

Question 4

More receptors =

Answer 4

More sensitivity to stimulation

Question 5

What areas have more receptors

Answer 5

Hands, lips

Question 6

What are the two kinds of skin

Answer 6

• Hairy skin

- Glabrous skin

Question 7

Glabrous skin

Answer 7

• Skin that does not have skin follicles

- Larger number of sensory receptors than other skin

Question 8

Hairy skin

Answer 8

Relatively low sensitivity

Question 9

What are most sensitive

Answer 9

• Fingertips
• Higher density of mechanoreceptors
• Receptors with small receptive fields

Question 10

Two point-discrimination test reveals

Answer 10

Differences in skin sensitivity across the body

Question 11

Three main types of somatosensory perception

Answer 11

• Nocioception
• Hapsis
• Proprioception

Question 12

What’s nocioception

Answer 12

Perception of pain and temperature

Question 13

Hapsis

Answer 13

Perception of fine touch and pressure

Question 14

Proprioception

Answer 14

Perception of the location and movement of the body

Question 15

Nocioceptors

Answer 15

• Free nerve endings
• Sharp/dull pain and heat/cold
• Damage to dendrite or surrounding cells release chemicals that stimulate dendrite and produces an action potential

Question 16

Haptic receptors

Answer 16

• Dendrite attached to hair, connective tissue or dendrite encased in capsule of tissue
• Distinguish touch, pull, vibration
• Mechanical stimulation provides action potential
• Composition of capsule determines the type of mechanical energy conducted

Question 17

Proprioceptors

Answer 17

Movements stretch the receptors to mechanically stimulate dendrites and produces an action potential

Question 18

Somatosensory receptors tell us 2 things about a sensory event

Answer 18

• When it occurs

- Whether it’s still occurring

Question 19

Rapidly adapting receptor

Answer 19

Body sensory receptor that responds briefly to the beginning and end of a stimulus on the body

Question 20

Slowly adapting receptor

Answer 20

Body sensory receptor that responds as long as a sensory stimulus is on the body

Question 21

In the dorsal-root ganglion neuron the dendrite and axon are

Answer 21

Continuous and carry sensory information from the skin to the CNS via the spinal cord

Question 22

Each spinal cord segment has one

Answer 22

Dorsal-root ganglion on each side that contains many dorsal-root ganglion neurons

Question 23

In the spinal cord, the axons of these neurons may synapse onto

Answer 23

Other neurons or continue up to the brain

Question 24

Proprioceptive neurons

Answer 24

• Carry information about locations and movement
• Large
• Well myelinated

Question 25

Haptic neurons

Answer 25

- Carry information about touch and pressure - Large - Well myelinated

Question 26

Nocioceptive neurons

Answer 26

- Pain and temp info - Small axons - Little to no Myelination

Question 27

What’s deafferentiation

Answer 27

Loss of incoming sensory input usually due to damage to sensory fibres

Question 28

Dorsal root ganglion neurons consequence of deafferentiation

Answer 28

- Did not lose motor control - Simple actions for prolonged periods needed visual feedback - Couldn’t perform many daily tasks - Afferent feedback is required for fine movement

Question 29

Dorsal spinothalamic tract carries

Answer 29

Haptic and proprioceptive information

Question 30

Axons from the dorsal root ganglion neurons enter the spinal cord and ascend

Answer 30

ipsilaterally until they synapse in the dorsal column nuclei (base of the brain)

Question 31

Axons from the dorsal column cross over to

Answer 31

- opposite side of the brain | - project up through the brain stem as part of the pathway- medial lemniscus

Question 32

Axon synapses with neurons located in the ventrolateral nucleus of the thalamus project

Answer 32

To the somatosensory cortex and motor cortex

Question 33

Ventral/ Anterior Spinothalamic Tract carries

Answer 33

Nocioceptive info

Question 34

Unilateral spinal-cord damage results in

Answer 34

Distinctive sensory losses to both sides of the body below the site of injury

Question 35

Vestibular system

Answer 35

Comprises a set of receptors in each inner ear that responds to body position and to the movement of the head

Question 36

Within each ear, there is a vestibular organ that contains

Answer 36

- Three semicircular canals | - Otolith organs

Question 37

Vestibular organs have which two functions

Answer 37

- Tell is the position of the body in relation to gravity | - Signal changes in the direction and speed of head movements