Unit 2_Intro to Sensory Systems Flashcards

1
Q

Where does perception begin?

A

At the receptor level

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2
Q

What triggers an electrical signal in a sensory receptor?

A

A stimulus

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3
Q

Once a stimulus triggers an electrical signal in a sensory receptor, information is then relayed/processed from cell to cell with the ultimate goal of reaching the cortex for what?

A

conscious perceptions

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4
Q

It is important to note sensations are needed to trigger responses like what?

A

reflexes, movements, and alertness

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5
Q

Almost all sensory information is sent to the cerebral cortex for perception via what?

A

The thalamus (Smell is the exception)

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6
Q

This large ovoid mass is the largest of the four components and each half of the brain contains one. In many individuals there is a short inter-thalamic adhesion that connects the two thalami across the third ventricle that lies between them. Contains nuclei that may be divided into 5 functional nuclear groups.

A

Thalamus

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7
Q

What comprises the nuclei of Group 1 - Sensory Group?

A
  1. lateral geniculate (LG) – Eye
  2. medial geniculate (MG) – Ears
  3. ventral posterolateral (VPL) – Body
  4. ventral posteromedial (VPM) - Face
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8
Q

These nuclei have connections with the basal ganglia and the cerebellum and are involved in motor control?

A

GROUP 2 – Motor Group

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9
Q

These nuclei have important connections with limbic system structures and are involved in emotions such as anxiety and also in memory?

A

GROUP 3 – Limbic Group

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10
Q

These nuclei are likely involved in the complex processing of sensory information?

A

GROUP 4 – Multimodal Group

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11
Q

Recent evidence suggests that these nuclei are involved in the regulation of consciousness along with roles in movement control and pain?

A

GROUP 5 – Intralaminar Group

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12
Q

What kind of neurons are sensory nerves?

A

Pseudounipolar

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13
Q

Sensation is transmitted via what type of nerves?

A

Peripheral nerves

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14
Q

The morphological distinction between _______ and _______ is blurred.

A

Axons
Dendrites

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15
Q

Where are cell bodies residing in the peripheral nervous system for sensory neurons?

A

Ganglions in the spinal cord

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16
Q

Having myelin on the peripheral nerve will do what?

A

Decrease capacitance and allow EPSP or IPSP to have same magnitude when it reaches cell body

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17
Q

What is a specialized cell or group of cells that transform a type of physical energy into an electrical signal?

A

Somatosensory Receptors

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18
Q

What are two structure types of Somatosensory Receptors?

A

Free nerve ending

Special receptor cell

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19
Q

A sensory neuron in a sensory ganglion whose peripheral process is specialized for reception?

A

Free nerve ending

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20
Q

A sensory neuron in a sensory ganglion whose peripheral process is connected to what?

A

Special receptor cell

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21
Q

Axons (fibers) with the largest diameter and most myelin have the greatest what?

A

conduction velocities

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22
Q

Axons (fibers) with the smallest diameter and little or no myelin have the slowest what?

A

conduction velocities

23
Q

Axonal conduction velocity is inversely related to what?

A

Axonal resistance (Ra) and Axonal Capacitance (Cm)

24
Q

Small diameter axons have what?

A

high resistance

25
Q

Unmyelinated axons have what?

A

high capacitance

26
Q

Large diameter axons have what?

A

low resistance

27
Q

Myelinated axons have what?

A

low capacitance

28
Q

Peripheral nerves contain what?

A

Both myelinated and unmyelinated axons

29
Q

Axons associated with skin are named differently than what?

A

Those associated with muscle

30
Q

The amount of stimulus relate to what?

A

Types of fibers being triggered

31
Q

How are receptors classified?

A

based on the form of energy or chemical to which they respond

32
Q

What receptors respond to mechanical deformation, detect vibration, tapping, pressure, stretch, etc., connected to
Group I (a and b)
Group II (A beta), and
Group III (A delta) nerve fibers?

A

Mechanoreceptors

33
Q

What receptors respond to the presence of certain molecules, detect chemical changes such as glucose, oxygen and carbon dioxide changes in blood, connected to Group IV (C) nerve fibers?

A

Chemoreceptors

34
Q

What receptors respond to non-painful temperature changes, warm receptors, cold receptors, connected to
Group III (A delta) and
Group IV (C) nerve fibers?

A

Thermoreceptors

35
Q

What receptors are not necessarily responsive to one type of energy, but respond when the magnitude is sufficient to begin to cause tissue damage, connected to
Group III (A delta) and
Group IV (C) nerve fibers?

A

Nociceptors

36
Q

What respond to light energy and are not connected to the Group 1-IV (A-C) nerve fibers but to specialized retinal ganglion axons?

A

Photoreceptors (rods and cones)

37
Q

What convert physical and chemical energy into electrical signals through a process called transduction?

A

Receptors

38
Q

What process is the following:

  1. local event (stimulus) at a receptor leads to a change in membrane conductance for specific ions (Na+, K+). The result is a net movement of + charge into the cell leading to a decrease in membrane potential or depolarization.
  2. depolarizes the receptor membrane and produces a RECEPTOR or GENERATOR POTENTIAL (these will be summed for action potentials).
A

Transduction

39
Q

What are a local graded potential which are dependent on the stimulus intensity and may be subthreshold, threshold, or suprathreshold?

The amplitude of this potential is proportional to the stimulus intensity.

A

Receptor potentials

40
Q

The potential will be transmitted around the receptor membrane until it reaches the beginning of what?

This area contains the voltage gated channels where, if the receptor potential is large enough and reaches threshold, it will generate an action potential which propagates down the peripheral nerve towards the CNS.

A

The distal end of axon or first node of Ranvier (if axon is myelinated).

41
Q

CNS identification of a stimulus intensity is done by what?

A

frequency coding and population coding

42
Q

What occurs with stimulus intensity; amplitude of receptor potential; frequency of action potentials to CNS all increase linearly?

A

Frequency (rate) coding

43
Q

What occurs when stronger stimuli activate more receptors which activate more axons (fibers) which tells CNS that the intensity has increased?

A

Population coding

44
Q

What occurs when each type of receptor usually only responds (easily; i.e. there is best stimulus) to one stimulus type?

A

Receptor specificity

45
Q

What is the organization of central nervous system pathways that describes a relationship between a particular part of the body and a particular area of the brain (SENSORY MAP)?

A

Somatotopy

46
Q

What are the basis of topography?

A

Receptive fields

47
Q

What is the spatial domain (e.g., where on skin) of a sensory neuron in the sense organ where stimulation excites or inhibits the neuron?

A

The receptive field

48
Q

What are small in areas such as the fingers and face, and huge in areas that don’t require much precision such as the back and thigh?

A

Receptive fields

49
Q

What refers to the organization of central nervous system pathways that describes a relationship between a particular part of the body and a particular area of the brain (really CNS since spinal cord has this kind of organization)?

A

Somatotophy

50
Q

What is a precise mapping of the projections at each station on each sensory pathway that enables our cortex to localize a sensory experience? It allows the CNS to encode for the localization and quality of the stimulus.

A

The sensory map - homunculus

51
Q

What suggests that no matter how you stimulate a pathway you will have the same perception?

A

Labelled line theory

52
Q

What occurs when receptor potential decreases in amplitude in response to constant maintained stimuli?

A

Adaptation

  • slowly adapting receptors and rapidly adapting
  • rapidly adapting receptors = better detection of changes in environmental stimuli
53
Q

What is the lowest stimulus intensity that a subject can detect?

A

Absolute Sensory Threshold

Thresholds are NOT FIXED (can be raised or lowered)

54
Q

What help shape more complex receptive fields within CNS?

A

Interneurons