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Physiology > Week 4 > Flashcards

Week 4 Flashcards

1
Q

What is sensory system?

A

Part of the nervous system that consists of sensory receptors that receive stimuli from the external and internal environment.

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2
Q

What is sensory transduction?

A

The process by which a stimulus is transforemd into an electrical response

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3
Q

What is hyperaglesia?

A

An increased senstitivity to a painful stimuli. It can last for hours after the initial stimulus has gone.

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4
Q

Describe dorsal column pathway:

A

Sensory neuron don’t cross over immediately, instead they ascend on the same side of the spinal cord and make the first synapse in the brainstem.

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5
Q

Why does referred pain occurs?

A

Because viscerl and somatic afferent often converge on the same neuron in the spinal cord.

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6
Q

What is referred pain?

A

Sensation of pain is experienced at a site different from the injured area.

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7
Q

What is the pattern of response to stimulus based on the location in the receptor field?

A

Afferent neurons respond more vigorously to stimuli applied in the center of the receptor field because of a greatest receptor density.

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8
Q

What is adaptation?

A

A decrease in receptor sensitivity that results in a decrease in action potential frequency.

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9
Q

What does acuity depend on?

A
  • Convergence of neuronal input in the specific ascending pathways (greater convergence results in less acuity).
  • Size of receptive field
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10
Q

Where is the visual cortex located?

A

In the occipital lobe

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11
Q

Where do olfaction pathways project?

A

In the limbic system and olfactory cortex located in the undersurface of frontal and temporal lobes.

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12
Q

Describe Pacinian receptors:

A

Rapidly adapating mechanoreceptor for virbation and deep pressure.

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13
Q

Describe what happen if the receptor is the afferent neuron itself:

A

Afferent neurons with speialized receptor tips don’t generate the action potential. Instead, local current flows a short distance along the axon to the first node of Ranvier and there an action potential is generated.

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14
Q

What does an increase in the graded potential generates?

A

It generate an increase in action potential frequency and an increase in neurotransmitters release at the axon terminal of the afferent neuron.

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15
Q

What are specific ascending pathways?

A

Afferent sensory pathways that convey information of a single type of sensory information. These pass to the brainstem and the thalamus and from there go to specific areas of the cerebral cortex.

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16
Q

How does stimulation produced analgesia work?

A

Electrical stimulation of specific areas of the CNS can reduce pain by inhibiting pain pathways. The descending axon end at lower brainstem and spinal level of the interneurons and inhibit transmission between the nociceptor neuron and the secondary ascending pathways.

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17
Q

What are the two types of rapidly adapting receptors?

A

On response and on off response.

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18
Q

Describe lateral inhibition:

A

Information from an afferent neurons with receptor at the edge of a stimulus is strongly inhibited compared to information from afferent neuron at the center of it.

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19
Q

Describe Ruffini receptor:

A

They are slowly adapting mechanoreceptors for skin stretch.

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20
Q

What are the two types of sensory receptors?

A

1) Specialized ends of primary afferent neurons

2) Separated receptor cells that signal the primary afferent neurons by releasing neurotransmitters.

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21
Q

What is a stimulus?

A

The energy or chemical that impinges upon and activates a sensory receptor.

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22
Q

What do Messner’s corpuscle sense?

A

Rapidly adapting mechanoreceptor for pressure and touch.

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23
Q

What is analgesia?

A

Selective suppresion of pain without effect on consciousness or other sensations.

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24
Q

How is temperature sensed?

A

The sensors are ion channles in the plasma membrane of free neuron endings called transient receptor potential proteins and they are transmitted along small-diameter afferent neurons with little or no myelination.

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25
Q

Where is the somatosensory cortex located?

A

A strip of cortex that lie in the parietal lobe (just posterior to the central sulcus)

26
Q

How do touch and pressure sensation arise?

A

From stimulation of mechanoreceptors

27
Q

What are the two mechanisms of reticular formation and cerebral cortex control over afferent information?

A
  • Directly by synapses on the axon terminal

- Indirectly via interneurons that affect other sensory pathways.

28
Q

Describe rapidly adapting (phasic) receptors:

A

Generate a receptor and an action potential at the onset of a stimulus but very quicly cease responding.

29
Q

Where is the gustatory cortex located?

A

Adjacent to the region of somatosensory cortex where infromation from the face are processed.

30
Q

What are the two ways of coding the stimulus location?

A
  • Site of stimulated receptor
  • The fact that each Action Potential travel an unique pathways to specific regions of CNS associated with that region of the body and that modality?
31
Q

What are somatic receptors?

A

Receptors that carry information from the skin

32
Q

What are the three factors that control the magnitued of the receptor potential?

A

1) Stimulus strength
2) Temporal summation of successive receptor potential
3) Adaptation

33
Q

What are sensory receptors?

A

Peripheral ends of the afferent neurons change information coming from the exterior environment into a graded potential that can initiate an action potential.

34
Q

What is a second way of coding stimulus intensity?

A

As stimulus strength increase receptor on adjacent branches of an afferent neuron are activated resulting in a summation of their local current.

35
Q

What are the two major receptors for posture and movement?

A
  • Muscle spindle stretch

- Golgi tendons organs

36
Q

What is a sensation?

A

A sensory finromation that reaches consciousness

37
Q

What is a receptor potential?

A

A graded response to different stimulus intesities.

38
Q

What is coding?

A

The conversion of stimulus energy into a signla that conveys informations to CNS.

39
Q

Describe Anterolateral Pathway:

A

The first synapste betwenn sensory receptors neuron and a second neuron is located in the gray matter of the spinal cord. This second neuron immediately crosses on the opposite side of the spinal cord and then ascend through the anterolateral column to the thalamus where it synapse with cortically projecting neurons.

40
Q

What are the 5 different classes of sensory receptors?

A

1) Mechanoreceptor
2) Thermoreceptor
3) Photoreceptor
4) Chemoreceptor
5) Nociceptor

41
Q

What is a perception’

A

A person’s awareness of the sensation.

42
Q

Where is the auditory cortex located?

A

In the temporal lobe.

43
Q

What do muscle-spindle stretch respond to?

A

Absolute magnitude of the spindle stretch and the rate of the stretch.

44
Q

What is acuity?

A

Precision with which we can locate and discern one stimulus from an adjacent one.

45
Q

What is a receptive field?

A

Area of the body that leads to the activity of a particular afferent neuron

46
Q

What do Golgi tendons monitor?

A

They monitor muscle tension.

47
Q

Desribe Merkel’s corpuscle?

A

Slowly adapting mechanoreceptors for pressure and touch.

48
Q

What are nonspecific pathways?

A

Are activated by sensory units of several different types of signal information called polymodal neurons. They end in the brainstem reticular formation and regions of thalamus and cerebral cortex that are not highly discriminative.

49
Q

What is the first step in the generation of a sensation?

A

The transduction of stimulus energy first into graded potential and then into action potential.

50
Q

Where does coding begins?

A

At receptive neurons in the PNS.

51
Q

What is recruitment?

A

Stronger stimuli activate receptor on the endings of adjacent neuron, this calling of receptor on additional afferent neurons is called recruitment.

52
Q

Describe slowly adaptin (tonic) receptors:

A

Maintain a persistent or slowly decaying receptor potential during a constant stimulus.

53
Q

How is pain sensed?

A

Nociceptors respond to intense mechancal deformation, extreme temperature or many chemical. The primary efferent nociceptors enter the CNS directly and synapse with ascending neurons.

54
Q

Why is a particular receptor sensitive to a kind of modality?

A

Because of the signal transduction mechanism and ion channels incorporated in the receptor plasma membrane.

55
Q

What are the two neural pathways of somatosensory system?

A

1) Anterolateral pathways.

2) Dorsal column pathway.

56
Q

What are the 5 factors that affect perception?

A

1) Sensory receptors mechanisms and processing of information along different pathways
2) Emotion, personality and experience
3) Not all information entering the CNS give rise to conscious experience.
4) We lack suitable receptors for many types of potential stimuli
5) Damaged neural networks
6) Drugs
7) Mental Illness

57
Q

How are endings from axons of specific somatic pathways grouped in different regions in the somatosensory cortex?

A

According to peripheral location of the receptor and the most innervated parts of the body corresponds to the largest areas.

58
Q

What is modality?

A

The type of stimulus

59
Q

Describe what happen if the recepto is on a separate cell:

A

Receptor potential on the cell alters the release of neurotransmitters from that cell that diffuse across the extracellular cleft and bind to receptor proteins on the afferent neurons that generate a graded potential.

60
Q

Why is laterla inhibition important?

A

It enhances the contrast between center and periperhy of a stimulated region.

61
Q

What is a sensory unit?

A

A single afferent neuron with all its receptor endings

Physiology (7 decks)

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