physiology : Sensory Perception

Question 1

Peripheral Nervous System

Answer 1

fibres other than brain and spinal cord , that are carry info to CNS and other parts of the body

Question 2

in the PNS there is
efferent division
afferent division

Answer 2

• sends info FROM CNS to muscles and glands

- sends info TO CNS from external and internal enviroment

Question 3

afferent division is split up into

Answer 3

visceral afferent - info from internal viscera ( soft internal organs)

sensory afferent - split into ….somatic and sensory senses

Question 4

somatic

sensory sense

Answer 4

sensation from body surface and proprioception (ability to sense movement, action, and location)

vision , hearing , smell and taste

Question 5

Stimulus
what
received by

Answer 5

• a change detected by body

- receptors ( structures at peripheral endings of afferent nuerons)

Question 6

function of receptors

Answer 6

convert stimuli into electric signals

Question 7

what is the sensory system made up of

Answer 7

sensory receptors , their axonal pathways and target areas in brain involved w perception

Question 8

Specialized sensory receptors…

Answer 8

detect different modalities.....
light
sound
sight
taste
pressure

Question 9

transduction

types of transduction depends on

Answer 9

Specialized neurons on outside or inside of body CONVERT physical stimulus into electric signals

type of receptor

Question 10

Specialized neurons on
outside
inside

Answer 10

exteroceptors

interoceptors

Question 11

the stimulus and sense of :
photoreceptors
mechanoreceptors

Answer 11

• ST= light. SE=vision

- ST=mechinal en (stretching muscle ect.) SE= touch , balance , proprioception ,hearing

Question 12

the stimulus and sense of :
thermoreceptors
chemoreceptors
nocicoreceptors

Answer 12

ST= heat and cold. SE=temperature
ST=specific chem SE= smell and taste
ST= Excessive pressure&temp. SE= pain

Question 13

Primary afferent axons enter spinal cord

Answer 13

thru dorsal roots and have their somas (cell bodies) in dorsal root ganglia

Question 14

Nerve Fibre types: velocity

axon diameter

Answer 14

larger diamater = less resistance to current flow down axon

therefore larger diameter means the fastest

Question 15

Nerve Fibre types: velocity

Unmyelinated sheaths have

Answer 15

they have voltage regulated channels close to eachother to take into account for ion leakage across membrane

therefore impulse are quite slow

Question 16

ion leakage
occurs at
action potentials

Answer 16

• nodes of ranvier

- only generated at nodes and travel from node to node (saltatory conduction )

Question 17

Receptors: transduction

where
stimulus

Answer 17

• receptor cell or free nerve ending

- the stimulus leads to a graded potential

Question 18

graded potential

Answer 18

variable-strength signals that can transmitted in short distances

may lose strength when they are transported through nueron

graded pot is proportional to stimulus strength — when ss becomes stronger so does gp

Question 19

action potential

Answer 19

large depolarizations can be transmitted over longer distances

do not lose their strength when in transmission

Question 20

depolarizations

Answer 20

rapid rise in potential

initiated by the opening of sodium ion channels within the plasma membrane.

Question 21

stimulus intensity is encoded by:

Answer 21

1. action potential frequency

2. number of receptors activated. A)single sensory unit stimulated. B)multiple “ “ ‘

Question 22

pt1
receptor potentials
-occur
-stimulus

Answer 22

• in separate receptor cells

- opens ion channels receptor causing graded membrane potential

Question 23

pt2
receptors potential
ect.

Answer 23

• receptor cell releases chemical messenger
• chemical messenger open ion channels in afferent neuron AP generating region
• If threshold reached, AP is generated

Question 24

pt1
Generator potentials
occur
stimulus

Answer 24

• specialized nerve endings

- ‘’ ‘’ ‘ ‘ ‘ local current flow

Question 25

pt 2
generated potential
ect

Answer 25

Local current flow opens ion channels in
afferent neuron AP generating region

• If threshold reached, AP is generated

Question 26

The receptive field of a sensory neuron

Answer 26

region of space where presence of stimulus alters the firing of that neuron

Question 27

Transduction defintion

Answer 27

converting energy forms in electrical signals via receptor/generator potential which triggers an action potential if large enough to reach threshold

Question 28

membrane potential

Answer 28

is the difference in electrical charge between the inside and the outside of the neuron

Question 29

receptors :adaption

Answer 29

a change in receptor cell to a long lasting stimulus

Question 30

two types of adaption

Answer 30

1. peripheral - occurs in receptor cell

2. habituation- occurs in brain

Question 31

adaptation:

two different of receptors based on their ability to adapt or not

Answer 31

rapidly adapting receptors-phasic receptors

slow adapting receptors- tonic receptors

Question 32

PHASIC
responds to
adapt
function

Answer 32

-pressure , touch, hearing , smell

v quickly-responds less if stimulus is constant

avoid background noise

Question 33

TONIC
responds
adapts
function

Answer 33

pain, propioception , chemical changes in blood of CSF

v slowly response even if stimulusnis constant

allows stimulus to be continous evaluated

Question 34

Adaptation mechanisms:

mechanical

Answer 34

physical mechanical mechanism that brings out the decrease in response in a receptor neuron.

Question 35

Adaptation mechanisms:

chemical

Answer 35

membrane enzyme or intercellular signalling mechanisms induces response termination (common in olfactory responses)

Question 36

all or none law

Answer 36

if a single nerve fibre is stimulated , it will always give a maximal response and will always produce an electrical impulse of a single amplitude

as long as the stimulus reaches the threshold , the full response will be given