Module 7: Sensory System pt.1

Question 1

what are the 4 sensory systems

Answer 1

Somatosensory (touch)

Visual

Olfactory (smell)

Gustatory (taste)

Question 2

Transduction of environmental information

Answer 2

how info from the external envirponment is communicated to the brain (action potentials!)

Question 3

Environmental stimuli

Answer 3

things like heat, light, touch or sound

Question 4

different types of sensory receptors

Answer 4

mechanical
chemical
light
gravity and motion

all produce action potentials

Question 5

Adequate stimulus

Answer 5

specific env. Stimulys the sensory receptor is most sensetive to

Question 6

receptor (generator) potentials similarities to EPSPs

Answer 6

Depolarizing but can be hyperpolarizing

Caused by ^ permeability to Na+ ot K+ ions

Local (don’t propogate)
- Decrease with time and distance

Proportional to stimulus strength
- Larger receptor more likely to fire an AP

Question 7

the somatosensory systemdetects

Answer 7

Tough

Vibration

Temperature

Pain

Question 8

cutaneous receptors types

Answer 8

Receptors in skin = cutaneous receptors

hair follicle
free nerve endings 
meissner's corpuscles
ruffini's corpuscles
pacinian corpuscles

Question 9

hair follicle stimuli

Answer 9

Fine touch

vibration

Question 10

Free nerve endings

Answer 10

pain

temp

Question 11

Meissner’s corpuscles

Answer 11

Low frequency vibrations (30-40 cycles/s)

Touch

Question 12

Ruffini’s corpuscles

Answer 12

touch

Question 13

Pacinian corpuscles

Answer 13

High frequency vibrations (250-300 cycles/sec)

Touch

Question 14

receptive field

Answer 14

Stimuli has to be in range

Question 15

the spinothalamic (anterolateral) tract

Answer 15

Pain, temp, crude touch

First order neuron = sensory neuron sends info to

Spinal cord (synapse with second order neuron)

Second order neuron crosses to opposite side and ascends to

Thalamus (relay station) meets second synapse with third order neuron travel to somatosensory cortex

Question 16

dorsal comumn, medial lemniscal system

Answer 16

Fine touch, proprioception (muscle sense), vibration

…see steps in pic on notes

Question 17

primary somatosensory cortex

Answer 17

In parietal lobe

On postcentral gyrus

Behind central sulcus

Question 18

primary somatosensory cortex – the somatosensory homunculus

Answer 18

see pic - it is like a map of brain correspondance withbody parts

Some are larger than others (seem unproportianate)

Hand, tongue, lips most sensetive so they contain many more sensory receptors than any other body parts

Question 19

visual system

Answer 19

Detect light, convert to AP, send to primary visual areas for processing

Consisnts of: eye (contains photoreceptors that convery light to AP), visual pathway (transmit APs) & primary visual area (in occipital lobe)

Question 20

the eye makes pictures how

Answer 20

1. light pass through cornea
2. amount of light is regulated by iris (constrict when bright or dilate when low light)
3. Lens flips

Question 21

parts of eye

Answer 21

cornea

lens

iris

fovea

optic nerve

retina

Question 22

rod cells

Answer 22

Sensetive to light

Function best in low light

One type potopigment (chemical sensetive to light) - Threfore cannot detect color

Located: outside and around the fovea

Question 23

cone cells

Answer 23

Function best in bright light

Detect detail

3 types, each with different photopigment and each sensetive to one primary color

Question 24

both rod cells and cone cells

Answer 24

No axons, no APs

Generate receptor potentials
- Release inhibitory neurotransmitter

Question 25

when there is no light rod and cone cells

Answer 25

release inhibitory neurotransmitters

• Depolarized
• Na+ flows into photoreceptors

Question 26

when there is light cone and rod cells

Answer 26

shut off

• Hyperpolarize
• Na+ channels shut down

Question 27

types of eye movement

Answer 27

saccades
smooth pursuit
vestibular ocular reflex (VOR)
vergences

Question 28

saccades

Answer 28

Rapid jerky

Look around to object of interest

Ex, looking around room

Question 29

smooth pursuit

Answer 29

Smooth movement to keep things in focus

Ex, following flight of bird through sky while keeping head still

Question 30

Vestibular ocular reflex (VOR)

Answer 30

Focus and then move head

Ex, nodding while agreeing or disagreeing with someone

Question 31

vergences

Answer 31

When something is moving away or closer

Diverge – moving away

Converge – moving forward

Ex, pencil moving away or closer