Sensory Pathways

Question 1

general senses

Answer 1

are temperature, pain, touch, pressure, vibration,

and proprioception

Question 2

Special senses

Answer 2

are olfaction, vision, gustation, equilibrium, hearing

Question 3

transduction

Answer 3

translation of stimulus to action potential; not all

stimuli are transduced

Question 4

receptor specificity

Answer 4

receptor responds to

some things but not others

Question 5

tonic receptors

Answer 5

tonic receptors are always on; information conveyed by

changing frequency of action potentials

Question 6

phasic receptors

Answer 6

phasic receptors are off except when conditions change

Question 7

adaption

Answer 7

reduction in sensitivity in presence of constant

stimulus

Question 8

Slow adapting receptors

Answer 8

slow-adapting receptors –show little or no adaptation; typical
of tonic receptors (pain)

Question 9

Fast adapting receptors

Answer 9

fast-adapting receptors –strong initial response then gradual
decline in sensitivity; typical of phasic receptors (temperature)

Question 10

nociceptors

Answer 10

pain receptors; large receptive fields (often

hard to determine exact source of pain); common in skin, joints, bone, blood vessel walls

Question 11

nociceptors are sensitive to … and are…. (frequency)

Answer 11

sensitive to temperature extremes, mechanical damage, dissolved chemicals (such as those released from injured cells) •

tonic receptors & slow adapting (pain is long-lasting)

Question 12

types of axons on nociceptors

Answer 12

type A for fast pain to reflex centers & primary sensory cortex
(myelinated) –

type C for slow pain; aching sensation (nonmyelinated)

Question 13

thermoreceptors

Answer 13

temperature receptors; free nerve endings in skin,
muscle, liver, hypothalamus; ~4x more cold receptors than warm

phasic receptors & fast-adapting (very active when temperature
changes)

Question 14

mechanoreceptors

Answer 14

stimuli that distort the cell membrane activate
mechanically-gated channels

•

Question 15

types of mechanoreceptors

Answer 15

3 types - tactile receptors, baroreceptors, proprioreceptors

Question 16

tactile receptors

Answer 16

sense touch, pressure, vibration: - free nerve endings sensitive to touch & pressure

Question 17

location of tactile (mechanoreceptors)

Answer 17

• hair root plexus with nerve ending around hair follicle; monitor
  movements across body surface
• merkel’s discs (tactile discs) for fine touch & pressure; very sensitive
  with very small receptive fields
• meissner’s corpuscles for fine touch & pressure & low frequency
  vibration
• pacinian (lamellated) corpuscles for deep pressure - ruffini corpuscles for pressure & distortion of skin

Question 18

baroreceptors

Answer 18

baroreceptors –
free nerve endings in walls of distensible
organs (for exampls, blood vessels) monitor pressure changes - **baroreceptors monitor blood pressure & regulate cardiac
function

Question 19

proprioceptors

Answer 19

monitor positions of joints, tension in
tendons & ligaments, state of muscle contraction

• tonic & slow-adapt = continuously sending information to the
  CNS about relative position of body

Question 20

chemoreceptors

Answer 20

respond to water or lipid soluble chemicals;
monitor pH, oxygen & carbon dioxide levels in blood

• send information to brainstem regions involved with autonomic
  control of respiration and cardiovascular function

Question 21

labeled lines

Answer 21

link between peripheral receptor and cortical neuron

each labeled line carries information about one sensory modality (one type of sensory stimulus)

Question 22

modality

Answer 22

different sensory types (modality) take different pathways through spinal cord and brain to cerebral cortex (route that the neurons drive)

Question 23

First order neuron

Answer 23

Located in periphery

afferent neuron carries info to the CNS

Question 24

Second order neuron

Answer 24

located in spinal cord or brainstem

will send stimulus to third order if meant to be aware of stimulus

Question 25

third order neuron

Answer 25

located in thalamus; projects to the primary sensory cortex if stimulus is supposed to be perceived

Question 26

3 main ascending somatic sensory pathways

Answer 26

posterior columns; spinothalamic; spinocerebellar

Question 27

Two tracts in the posterior column

Answer 27

fasciculus gracilis - carries fine sensory stimuli from inferior body to CNS Fasciculus cuneatus - carries fine sensory stimulus from superior body to CNS

Question 28

Posterior Column: First order neurons synapse on second order neurons in the

Answer 28

medulla oblongata

Question 29

decussate

Answer 29

to cross

Question 30

Decussation occurs on the... in the posterior columns and ascend along the

Answer 30

synapse of the second order neuron in the medulla oblongata and ascend along the lemniscus

Question 31

Third order neuron always synapses on the

Answer 31

neurons of the primary sensory cortex

Question 32

functional map of primary sensory cortex

Answer 32

homunculus

Question 33

Thalamus sorts information based on

Answer 33

sensory modality and body region

Question 34

Anterior Spinothalamic Tract carries info about

Answer 34

fine touch and pressure/vibrations

Question 35

decussation in the anterior Spinothalamic tract occurs in the

Answer 35

spinal cord

Question 36

Main differences between spinothalamic tract and posterior column

Answer 36

level of decussation; spinothalamic goes through the anterior white matter (axons in front of the spinal cord); location of the 2nd order neuron

Question 37

Similarities between spinothalamic tract and posterior columns

Answer 37

similarities: ends in the thalamus and begin in the dorsal root ganglion

Question 38

lateral spinothalamic tract

Answer 38

carries info to the CNS about pain and temperature

Question 39

Third neuron synapses in the..... in the anterior and lateral spinothalamic tracts

Answer 39

thalamus

Question 40

difference between anterior and lateral spinothalamic tract

Answer 40

location of ascending axon (2nd order neuron)

Question 41

spinocerebellar pathway

Answer 41

carries proprioceptive information

Question 42

There is no.... in the spinocerebellar pathway

Answer 42

3rd order neuron

Question 43

spinocerebellar is all about

Answer 43

coordinated movements NOT awareness

Question 44

somatic motor nervous system

Answer 44

efferent division that controls skeletal muscle

Question 45

somatic motor pathways are

Answer 45

descending

Question 46

corticospinal pathway

Answer 46

Motor pathway provides voluntary control of skeletal muscle; originates at primary motor cortex

Question 47

medial and lateral pathways (motor)

Answer 47

provides subconscious motor control (for example turning away from a bright light or turning toward a loud sound) originate in midbrain

Question 48

Function of ANS

Answer 48

subconscious homeostatic adjustments

Question 49

hypothalamus

Answer 49

hypothalamus is integrative center for all autonomic activity

Question 50

divisions of ANS

Answer 50

sympathetic and parasympathetic

Question 51

sympathetic

Answer 51

fight or flight

Question 52

parasympathetic

Answer 52

rest and digest

Question 53

Dual innervation

Answer 53

an organ receives both sympathetic and | parasympathetic innervation; most organs are dually innervated

Question 54

autonomic tone

Answer 54

autonomic neurons show a resting level of | spontaneous activity; allows them to increase or decrease their activity, providing a range of control options

Question 55

ANS general pathway

Answer 55

Hypothalamus ->Preganglionic neurons in brainstem (parasympathetic) or thoracic and lumbar segments of the spinal cord (sympathetic) ->ganglionic neurons in in PNS ->effector

Question 56

ANS pathway difference between sympathetic and parasympathetic

Answer 56

Stimulus travels through preganglionic neurons in the brain stem in the parasympathetic vs travel through segments of spinal cord (lumbar and thoracic) in the sympathetic

Question 57

hebian learning rule

Answer 57

When neuron A repeatedly participates in firing neuron B, the strength of the action of A onto B increases” ("Neurons that fire together wire together.")

Question 58

NMDA receptor is

Answer 58

the molecular basis for learning

Question 59

What neurotransmitter is released in a learning synapse?

Answer 59

glutamate

Question 60

Glutamate receptors responsible for learning and memory

Answer 60

AMPA receptor binds glutamate and opens sodium channels = depolarization NMDA binds receptor and will only open if the cell is depolarized allowing calcium to enter the post synaptic cell.

Question 61

Calcium is important in the post synaptic cell because

Answer 61

it allows for alteration of genes, which creates stronger synapses

Question 62

Which ion is initially blocking the glutamate receptor NMDA if the post synaptic neuron is not depolarized?

Answer 62

Magnesium

Question 63

calcium turns on post synaptic neuron cell genes to create more ____. These, in turn, create more receptors and channels, allowing for a stronger ____.

Answer 63

proteins / synapse

Question 64

LTP

Answer 64

long term potential - shows an increase in synaptic strength over time. Bigger EPSP present

Question 65

How does the pre synaptic cell know to make more neurotransmitters? aka... retrograde message?

Answer 65

Calcium turns on genes in post synaptic cell; post synaptic cell releases nitrous oxide, which is re absorbed by the pre-synaptic cell and tells it to make more neurotransmitter

Question 66

Describe the process of LTP

Answer 66

presynaptic cell stimulates repeatedly --> NMDA channels open on postsynaptic cell --> Ca++ enters postsynaptic cell --> turns on genes --> increase # of receptors on postsynaptic membrane = stronger synapse

Question 67

NMDA receptors are called co(incident) receptors because

Answer 67

They require two things to simultaneous events to occur before opening chemical gated channels: 1. glutamate & 2. depolarization (to relieve Mg++ block)

Question 68

Ca++ will only enter postsynaptic cell (and activate genes) if...

Answer 68

the presynaptic cell causes a strong depolarization;