Ascending Pathways

Question 1

why are receptors good at sensing external stimuli

Answer 1

they have different structures
transducing elements that allow a specific type of stimulus to produce action potentials.
each receptor type specialises in one or more sensations

Question 2

why are nerve receptors for pain different

Answer 2

they are just bare nerve endings and are triggered by a variety of stimuli (chem and physica, pressure, temp)
multimodal

Question 3

Hair follicle receptors

Answer 3

touch

Question 4

merkel endings

Answer 4

pressure, low freq vibration

Question 5

Meissner corpuscles

Answer 5

light touch

Question 6

Pacinian corpuscles

Answer 6

vibration
joint pressure sense

Question 7

Ruffini endings

Answer 7

skin stretch
pressure
jps

Question 8

nociceptors

Answer 8

pain

Question 9

muscle spindle

Answer 9

muscle length
proprioception

Question 10

golgi tendon organs

Answer 10

jps

Question 11

what are dermatomes

Answer 11

A dermatome is an area of skin in which sensory nerves derive from a single spinal nerve root

Question 12

how can you measure messages from individual sensory neurons

Answer 12

electrophysioloically

Question 13

what is a receptive field

Answer 13

The receptive field encompasses the sensory receptors that feed into sensory neurons and thus includes specific receptors on a neuron as well as collectives of receptors that are capable of activating a neuron via synaptic connections.

Question 14

does a small receptive field give a higher degree of differentiation than large receptive field

Answer 14

yes

Question 15

what kind of receptive field does the back have

Answer 15

large

Question 16

what kind of receptive field do pacinian corpuscles have

Answer 16

generally large, each with a smaller more sensitive area

Question 17

what kind of receptive field do meissner’s corpuscles have

Answer 17

smaller receptive fields on tips over palms of hands

Question 18

do receptive fields overlap

Answer 18

yes

Question 19

describe lateral inhibition

Answer 19

it is to refine sensory input and sharpens discrimination
dendrites are dense at the centre
stimuli in the centre activate more dendrites and cause faster firing and faster AP (even if same stimulus at the periphery)
therefore can differentiate where the stimulation is in the receptive field
if receptive fields are overlapping, different intensity of signals are being fired (eg, closer to centre of A field and B, and none at C)
the train of action potentials can be inhibited via inhibitory interneuron.
As well as normal axon firing there are collateral branches that come off axon A (where stimulus is closes to) which has an excitatory neurotransmitter in it, this excited the inhibitory interneuron which gives off an inhibitory neurotransmitter onto axon B.
A firing fast inhibits firing of B axon–» enhancing of discrimination

Question 20

list the sensory receptors and their different speeds

Answer 20

A alpha –proprioceptors of skeletal muscle- 270mph
A beta –mechanoreceptors of skin- 167mph
A delta–pain, temperature 67mph
C–temperature, pain, itch 5mph (no saltatory conduction)

Question 21

what are white matter tracts of the spinal cord

Answer 21

Fasciculus gracilis
Fasciculus cuneatus
Dorsal spinocerebellar tract
ventral spinocerebellar tract
spinothalamic

Question 22

what makes up the dorsal columns

Answer 22

fasciculus gracilis and cuneatus

Question 23

what info does fasciculus gracilis

Answer 23

lower part of body

Question 24

what info does fasciculus cuneatus carry

Answer 24

T5 upwards

Question 25

where do spinocerebellar tracts carry info

Answer 25

carry proprioceptive info from muscle spinsles (dorsal) and golgi organs (ventral)
spine to cerebellum

Question 26

what makes up the anterolateral system

Answer 26

anterior and lateral spinothalamic tracts
they carry pain and temperatue

Question 27

where on a topographical arrangement of the body can you find the area which needs the most detail

Answer 27

lateral side
hands, face, lips, upper lip, eyes