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1st Year > KIN 103 (Chp: 10 - Neurons) > Flashcards

KIN 103 (Chp: 10 - Neurons) Flashcards

1
Q

What are the three types of neurons? (Simple neuron)

A
  • may or may not have myelinated axons
  • free nerve endings
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2
Q

What are the three types of neurons? (Complex neuron)

A
  • enclosed nerve endings
  • connective layers of tissue around them (Pacinian corpuscle)
  • myelinated axons
  • usually for sensing touch
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3
Q

What are the three types of neurons? (Special neurons)

A
  • Specialized receptor hair end
  • Synaptic vessicles
  • synapses
  • myelinated axons
  • usually for the senses of the body
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4
Q

Adequate stimulus:

A

Adequate stimulus: each type of receptor responds preferentially to a particular type of stimulus or form of energy.

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5
Q

Chemoreceptors

A

stimulated by: oxygen, pH, organic molecules

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6
Q

Mechanoreceptors

A

Stimulated by: pressure, cell stretch, vibrations

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7
Q

Photoreceptors

A

Stimulated by: Photons of light

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8
Q

Thermoreceptors

A

Stimulated by: Varying degrees of heat

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9
Q

Transduction

A

Transduction: stimulus energy converted into information processed by CNS, ion channels or second messengers initiate membrane potential change in sensory receptor (graded potentials)

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10
Q

Receptor potential:

A

Receptor potential: change in membrane potential of sensory receptor (graded potential), can initiate action potentials or release neurotransmitter

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11
Q

Threshold

A

Threshold: minimum stimulus required to generate large enough receptor potential to initiate action potentials (or release neurotransmitter)

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12
Q

Receptive field

A

Receptive field: neurons are activated when stimuli fall within a specific physical area (i.e. region on the skin or on the retina)

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13
Q

Primary and secondary sensory neurons (which have larger sensory fields?)

A

Primary and secondary sensory neurons have primary (smaller) and secondary (larger) receptive fields, respectively.

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14
Q

Do secondary receptive fields overlap?

A

Yes they do, in fact secondary receptive fields are a combination of primary receptive fields in a said area

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15
Q

Two point discrimination

A

Essentially the principle that when we touch two places on someone’s skin it may trigger a feeling of only one place since the neurons go through convergence

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16
Q

Modalities (what are they?)

A

Different types of information (modalities) are processed in different regions of the brain

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17
Q

Does all sensory information reach the brain?

A

Some information does not reach the brain, eg: Visceral reflexes are integrated in brain stem or spinal cord and usually do not reach conscious perception (eg. control of blood pressure)

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18
Q

What type of pathways does sensory information travel through?

A

Most sensory information travels from the body to the brain along ascending pathways in the spinal cord or from the head to the brain via cranial nerves

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19
Q

Four properties of all stimuli: (What are they?)

A

Modality, location, intensity, duration

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20
Q

Modality (Definition)

A

Modality: What kind of stimulus is it (touch, sound, light)?
- indicated by which sensory neurons are activated and where those neurons terminate in brain
- specific to receptor type (adequate stimulus)

21
Q

labeled line coding (what is it?)

A

labeled line coding
- 1:1 association of receptor with sensation
- Each type of receptor projects to a specific part of the brain.

22
Q

Lateral inhibition (what is it?)

A

Lateral inhibition: increases contrast between active receptive fields and inactive neighbors (slide 13)

23
Q

Population coding (what is it?)

A

Population coding: the CNS evaluates input from multiple receptors to obtain more information than can be provided by a single receptor (slides 7, 12, 13)

24
Q

Intensity

A

Intensity = frequency of APs (frequency coding) and number of receptors activated (population coding)

25
Q

Duration

A

Duration = duration of AP discharge “train” and resulting neurotransmitter release.

26
Q

Tonic receptors

A

Tonic receptors: are slowly adapting receptors that responds for the duration of the receptor
- Provides continuous feedback as long as the stimulus is applied
(eg. Baroreceptors, proprioceptors)

27
Q

Phasic receptors

A

Phasic receptors: rapidly adapt to a constant stimulus and turn off, they fire once more when stimulus turns off
- Signals and on and an off
- “event detectors”

28
Q

Modality (its 4 types)

A
  • Touch
    • Proprioception
    • Temperature
    • Nociception
      • Pain
      • Itch
29
Q

Where do fine touch and proprioception synapse in the CNS?

A
  • They synapse in the medulla
  • once more in the thalamus
30
Q

Where do nociceptors and course touch senses synapse in the CNS?

A
  • They synapse in the dorsal root of the spinal cord
  • once more in the thalamus
31
Q

What is important to note about sensory pathways?

A
  • they all enter from one side (either left or right) and contact the opposite side of the brain
32
Q

Tertiary sensory neurons (where do they terminate?)

A
  • They terminate in the somatosensory cortex
33
Q

Somatosensory cortex

A
  • Within it the body is mapped
  • The maps created are “plastic” and can change over time and with use
  • The amount of space each part has in the somatosensory cortex is proportional to the sensitivity of the part
34
Q

The axons of Somatosensory neurons differ for each their purposes (what are these differences? - A(beta)

A

A(beta)
- Large, myelinated
- Fast conduction
- Mechanical stimuli

35
Q

The axons of Somatosensory neurons differ for each their purposes (what are these differences? - A(delta)

A

A(delta)
- Small, myelinated
- Medium speed
- Cold, fast pain, mechanical stimuli

36
Q

The axons of Somatosensory neurons differ for each their purposes (what are these differences? - C)

A

C
- Small, unmyelinated
- Slow speed
- Slow pain, heat, cold, mechanical stimuli

37
Q

Merkel receptors (What are they?)

A

Merkel receptors: sense steady pressure and texture

38
Q

Meissner’s corpuscle

A

Meissner’s corpuscle: responds to flutter and stroking movements

39
Q

Pacinian corpuscle

A

Pacinian corpuscle: sense vibration

40
Q

Ruffini corpuscle

A

Ruffini corpuscle: responds to skin stretch

41
Q

Temperature Receptors

A
  • Located throughout the body
  • Play a role in homeostasis
  • In the skin they are free nerve endings
    located in subcutaneous layers
  • Cold receptors
    - Activated at temperatures below body
    temperature
  • Warm receptors
    - Activated above body temperature to
    about 45°C
    - Pain receptors activated above 45°C
42
Q

Nociceptors (Definition)

A

Nociceptors are free nerve endings that respond to strong chemical, mechanical, thermal stimuli that may damage tissue (Fig 10.10)

43
Q

Pain (Definition)

A

Pain is our subjective perception of the activation of nociceptors.
- Fast pain, sharp and localized (Adelta fibers)
- Slow pain, more diffuse (C fibers) (see Table 10.3)

44
Q

Itch (Definition)

A

Itch is our subjective perception of the activation of nociceptors in the skin

45
Q

How can Nociceptor discharge be altered?

A
  • Nociceptor discharge can be altered by local chemicals
    ○ Chemicals that mediate inflammatory response (histamine, serotonin) increase nociceptor discharge by activating the receptor or decreasing their threshold
    ○ Leads to inflammatory pain, increases sensitivity to pain at inflammation site
46
Q

Nociceptor pathways (Reflex pathway)

A

Reflex pathways through the spinal cord produce an integrated “withdrawal” response…

47
Q

Nociceptor pathways (Ascending pathway)

A

Ascending pathways to the brain (Fig. 10.8) mediate conscious sensation (pain or itch) and can initiate autonomic responses (nausea, sweating).

48
Q

Referred pain (What is it?)

A

Referred pain: pain from a heart attack is often felt in the neck, shoulder and left arm
- Because they share a common secondary field receptor
- (THIS HAS A LOT TO DO WITH THE TWO POINT DISCRIMINATION)

49
Q

Pain control (gate modulation theory)

A

Essentially the theory that there are C neurons connected to an inhibitory gate that opens when a signal is fired but close when there is no signal firing
(NEURONS CAN TURN ON AND OFF INHIBITORY NEURONS)

1st Year (37 decks)

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