Intergrative Sensory System SEM2

Question 1

What are the different sensory systems

Answer 1

External environment - vision, hearing, taste, smell
Position and movement - balance
Interoceptors - visceral mechanical, thermal + chemical detection

Question 2

What are characteristics of bipolar sensory neurones

Answer 2

Cell body in dorsal root ganglia
Peripheral terminals in dermis/epidermis
Central terminals in dorsal horn of spinal cord

Question 3

What is the types of mechanosensors for touch, vibration, stretch and pressure

Answer 3

Specialised sensory endings - myelinated A β axons for fast conduction of sensory signals

Question 4

What is the type of mechanosensor for pinches, high pressure and trauma

Answer 4

Bare nerve endings - thinly myelinated for faster transmission of pain

Question 5

What do pacinian corpuscles detect

Answer 5

Detect vibrations and deep pressure

Question 6

What is the role of thermal sensors in skin

Answer 6

Distinct sensors for different temperature ranges
Innocuous and noxious ranges covered

Question 7

How do touch pathways ascend

Answer 7

Ascend in ipsilateral dorsal column

Question 8

Where are touch pathways relayed at

Answer 8

Relayed at cuneate/gracile nuclei in medulla

Question 9

Where do touch pathways cross over into

Answer 9

Cross over into the medial lemniscus

Question 10

Where are touch pathways relayed in following being crossed over into the medial lemniscus

Answer 10

Relayed into thalamus and projected to SI cortex

Question 11

Where do pain pathways cross over into

Answer 11

Cross over in the spinal cord

Question 12

Where do pain pathways ascend in

Answer 12

Ascend in contralateral ventrolateral column (spinothalamic tract)

Question 13

Where are pain pathways relayed in

Answer 13

Relayed in thalamus and projected to SI cortex

Question 14

What does stretching of a muscle spindle drive

Answer 14

Drives excitatory input to same muscle to contract and inhibits input to opposing muscle

Question 15

What is the visual pathway

Answer 15

Projection via lateral geniculate nuclei to visual cortex (occipital lobe)

Question 16

What are V1 cells in visual information processing

Answer 16

V1 cells are retinotopic and binocular and important to initial stages of visual processing

Question 17

What causes the movement of the basilar membrane

Answer 17

Inside the cochlea sound waves causes the fluid to move which vibrates the basilar membrane and can respond to different frequencies

Question 18

What is the auditory pathway

Answer 18

Largely crossover in the lower brain stem
Projects to inferior colliculus then medial geniculate nucleus and to auditory cortex A1 (temporal lobe)

Question 19

What does fluid movement in auditory/sensory transduction cause

Answer 19

Fluid movement induced stretch of link fibres opens K+ channels causing depolarisation

Question 20

What does the vestibulo-oculomotor reflex do

Answer 20

Maintains direction of gaze during head rotation

Question 21

What does the righting reflex do

Answer 21

Maintains balance during tilt-induced activity in muscles

Question 22

What is touch processed through

Answer 22

The dorsal column tract

Question 23

What is pain processed through

Answer 23

Ventral spinothalamic tract

Question 24

What does lesions at the forebrain level cause

Answer 24

Contralateral paralysis in the limbs

Question 25

What does lesions at the spinal cord level cause

Answer 25

Ipsilateral paralysis in the limbs

Question 26

What are the three regions of the motor cortex

Answer 26

Primary motor
Premotor
Supplementary motor area (SMA)

Question 27

What does the motor cortex evoke

Answer 27

Evokes muscle contraction directly through the control of lower motor neurones and alters strength of spinal reflexes

Question 28

What is the premotor area involved in

Answer 28

Involved in postural preparation for movement

Question 29

What is the supplementary motor area (SMA) involved in

Answer 29

Involved in planning co-ordinated movements

Question 30

What are properties of the corticospinal tract

Answer 30

Controls voluntary movement
Projects through internal capsule in midbrain
Controls contralateral lower motor neurons in ventral spinal cord

Question 31

What are the effects of a stroke

Answer 31

Occurs near the internal capsule lesioning one or both corticospinal tracts
Causes impairment of voluntary movement with increased muscle tone - spasticity

Question 32

What does the pyramidal pathway control

Answer 32

Controls fine/purposeful movement

Question 33

What tract is used for the pyramidal pathway

Answer 33

Corticospinal tract from motor cortex which descends through the brainstem into the spinal cord

Question 34

What is the purpose of the extrapyramidal pathway

Answer 34

Achieves refelx adjustments of posture/balance
Modulates muscle tone
Delivers coordinated movement

Question 35

What is the pathway of the extrapyramidal pathway

Answer 35

Indirect pathway relaying in the brain stem and regulated by feedback loops from basal ganglia and cerebellum

Question 36

How is the basal ganglia involved in a feedback loop

Answer 36

Forms feedback loop to cerebral cortex to adjust motor output

Question 37

What is the core region of basal ganglia controlled by

Answer 37

The striatum (core region) is controlled by dopamine (DA) contraning neurons that project from substantia nigra