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BIO 235 Midterm 2 > Chapter 16: Sensory, Motor, and Integrative Systems > Flashcards

Chapter 16: Sensory, Motor, and Integrative Systems Flashcards

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1
Q

Differentiate between sensation and perception

A

Sensation is the conscious or subconscious awareness of changes in the external or internal environment

Perception is the conscious interpretation of sensations and is primarily a function of the cortex

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2
Q

Describe the two groups of sensory modalities

A

Sensory modality is a unique type of sensation (touch, pain, etc.

  1. General senses refers to both somatic senses and visceral senses
  2. Special senses refers to smell, taste, vision, hearing, and equilbrium
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3
Q

Define somatic senses

A

Tactile sensations, thermal sensations, pain sensations, and proprioceptive sensations

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4
Q

Define visceral sensations

A

Provide info about the conditions within internal organs

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5
Q

A sensory receptor responds only weakly or not at all to other stimuli. What is this characteristic called?

A

selectivity

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6
Q

List the 3 ways sensory receptors can be grouped into called

A
  1. microscopic structure
  2. location of receptors and origin of stimuli that activate them
  3. type of stimulus detected
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7
Q

On a microscopic level, sensory receptors may be one of which types? (3)

A
  1. Free nerve endings of first-order sensory neurons
  2. Encapsulated nerve endings of first-order sensory neurons
  3. Separate cells that synapse with first-order sensory neurons
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8
Q

Define free nerve endings

A

Bare dendrites; they lack any structural specialization that can be seen under a light microscope

Ex. receptors for pain, temp, tickle, itch, and some touch sensations

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9
Q

Define encapsulated nerve endings

A

Dendrites are enclosed in a connective tissue capsule that has a distinctive microscopic structure

the different type of capsules enhance the sensitivity or specificity of the receptor

Ex. pressure, vibration, and some touch sensations

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10
Q

Define separate cells

A

Sensory receptors for some special senses are separate cells that synapse with sensory neurons

Ex. hair cells in inner ear, gustatory cells in taste buds, photoreceptors in retina

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11
Q

Define generator potential

A

Stimulated free or encapsulated endings generate a potential and when large enough to reach threshold, it triggers one or more nerve impulse in the axon of a first-order sensory neuron that propagates to CNS

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12
Q

Define receptor potential

A

Sensory receptors that are separate cells produce graded potential that triggers release of NT through exocytosis which then produce a PSP int he first0order neuron that may trigger one more more impulses to CNS

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13
Q

Describe the 3 ways sensory receptors are classified based on their receptor location and activating stimuli

A

Exoreceptors - located at or near body surface; sensitive to stimuli originating outside the body provide info about external environment

Interoceptors - located in blood vessels, visceral organs, and nervous system; provide info about internal environment; impsules usually not consciously perceived

Proprioceptors - located in muscles, tendons, joint, and inner ear; provide info about body positions, muscle length and tension, position and motion of joints, and equilibrium

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14
Q

Describe the 6 way sensory receptors are classified based on the type of stimulus detected

A

Mechanoreceptors - detect mechanical stimuli (touch, pressure, vibration, proprioception, hearing, equilibrium, and stretching of internal organs)
Thermoreceptors - detect changes in temp
Nocioceptors - respond to painful stimuli resulting from physical or chemical damage
Photoreceptors - detect light that stringed the retina
Chemoreceptors - detect chemicals in the mouth, nose, and body fluids
Osmoreceptors - detect osmotic pressure of the body

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15
Q

Describe adaptation characteristic in sensory receptors

A

Generator or receptor potential decreases in amplitude during a maintaining, constant stimulus causning frequency of impulses to decrease

Ex. A hot shower sensation decreases as you become comfortable with the warmth even though the temp has not changes

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16
Q

What is the difference between rapidly adapting and slowly adapting receptors?

A

Rapidly adapting receptors adapt quickly - they are specialized for signalling changes in a stimulus (pressure, touch, smell)

Slowly adapting receptors adapt slowly and continue to trigger nerve impulses as long as the stimulus persist (pain, body position, chemical composition of the blood)

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17
Q

What is the difference between somatic sensations and cutaneous sensations?

A

Somatic sensations arise from stimulation of sensory receptors embedded ni the skin of subQ layer; in mucous membranes; in muscles, tendons, joints; and inner ear

Somatic sensations that arise from stimulating the skin surface are cutaneous sensations

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18
Q

List the 4 modalities of somatic sensation?

A

tactile
thermal
pain
proprocepttive

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19
Q

Describe Corpuscles of touch (meissner corpuscles)

A

A tactile receptor (touch)

Capsule surrounds mass of dendrites in dermal papillae of hairless skin

Sensations: touch, pressure, slow vibrations

Adaptation rate: rapid

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20
Q

Describe hair root plexuses

A

A tactile receptor (touch)

Free nerve endings wrapped around hair follicles in skin

Sensations: touch

Adaptation rate: rapid

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21
Q

Describe Type I cutaneous mechoreceptors (Merkel discs)

A

A tactile receptor (touch)

Saucer-shaped free nerve endings make contact with tactile epithelial cells in epidermis

Sensations: touch, pressure

Adaptation rate: slow

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22
Q

Describe type II cutaneous mechoreceptors (Ruffini corpuscles)

A

A tactile receptor (touch)

Elongated capsule surrounds dendrites deep in dermis and in ligaments and tendons

Sensations: touch, stretching of the skin

Adaptation rate: slow

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23
Q

Describe lamellate for Pacinian corpuscle

A

A tactile receptor (pressure)

Oval, layered capsule surrounded dendrites; present in dermis and subQ layer, submucosal tissues, joints, periosteum, and some viscera

Sensations: pressure and fast vibrations

Adaptation rate: rapid

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24
Q

Describe itch and tickle receptors

A

A tactile receptor

Free nerve endings in skin and mucous membrane

Sensations: itching and tickling

Adaptation rate: rapid and slow

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25
Q

Describe vibration sensations

A

Receptors for vibrations are corpuscles of touch (low freq vibrations) and lamellate corpuscles (high freq vibrations)

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26
Q

Describe phantom limb sensation

A

After amputation, person may still experience sensations as if the limb were still there

Severed endings of sensory axons are still present in the remaining stump and if activated the cortex interpret the sensation

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27
Q

Describe theroreceptors and the two distinct thermal sensations - coldness and warmth

A

Thermoreceptors are free nerve endings that have receptive fields on the surface of the skin

Cold receptors are located in the stratum basal of the epidermis and are attached to myelinated A fibers and a few unmyelinated C fibers (10-40C)

Warm receptors are not as abundant and are located in the dermis and are attached to unmyelinated C fibers (32-48C)

Temperatures below 10C primarily stimulate pain receptors rather than thermorecepotrs

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28
Q

Describe nocioceptors

A

Pain receptors

Free nerve endings in every body tissue except the brain

Adaption: slow

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29
Q

Differentiate between fast and slow pain

A

Fast pain occurs rapidly (~0.1s) because the nerve impsulses propagate along myelinated A fibers - sharp, acute pain

Slow pain begins +1 sec after and gradually increases in intensity as impulses are conducted along unmyelinated C fibers - chronic, burning, aching

30
Q

Describe superficial and deep somatic pain

A

Superficial - pain that arises from stimulation of receptors in the skin

Deep - stimulation of receptors in skeletal muscles, joints, tendons, and fascia

31
Q

Describe visceral pain

A

Results from stimulation of nociceptors in visceral organs

32
Q

Define referred pain

A

In instances of visceral pain, the pain is often felt in or just deep to the skin that overlies the stimulated organ or in a surface area far from the stimlated organ

33
Q

Define kinestheisa

A

The perception of body movements

34
Q

Define proprioceptors

A

Embedded in muscles (especially postural muskies) and teens andimform us of the degree to which muscles are contracted, the amount of tension, and the position of joints

35
Q

Describe muscle spindles

A

Receptor type: proprioceptor

Sensory nerve endings wrap around central area of encapsulated intramural muscle fibers within most skeletal muscles

Sensations: muscle length

Adaptation: slow

36
Q

Describe tendon organs

A

Receptor type: proprioceptor

Capsule encloses collagen fibers and sensory nerve ending at junction of tendon and muscle

Sensations: muscle tension

Adaptation: slow

When a muscle contracts, it exerts a force that pulls the point s of attachment at either end toward each other to protect from excessive tension

37
Q

Describe joint kinaesthetic receptor

A

Several types are present within and around the articular capsules of joins

Free nerve endings and type II cretinous mechanoreceptors respond to pressure

Small lamellated corpuscles in connective tissue respond to acceleration/deceleration of joints during movement

38
Q

Define intrafusal fibers

A

Each muscle spindle consists of several slowly adapting sensory nerve endings that wrap around 3-10 specialized muscle fibers, called intrafusal fibers

Connective tissue incomes this and anchors the spindle to the endomysium and perimysium

39
Q

Define gamma motor neurons

A

These terminate near both ends of the intrafusal fibers and adjust the tension in a muscle spindle to variations in the length of the muscle

This maintains sensitivity of the muscle spindle to stretching

40
Q

Define extrafusal muscle fibers and alpha motor neurons

A

Extrafusal muscle fibers are ordinary skeletal muscle fibers that surround muscle sponges

They are supplied by large diameter A fibers called alpha motor neurons

During a stretch reflex alpha motor neurons are activates that connect to extrafusal muscle fibers int he same muscle, causing contraction which receives the stretching

41
Q

How is a muscle spindle activated?

A

When the central areas of the intrafusal fibers are stretched

42
Q

Describe the sets of of 3 neurons (1st, 2nd, 3rd) in a somatic sensory pathway

A

First-order neuron - conduct impulses from somatic receptors into the brainstem or spinal cord

Second-order neuron - conduct impulses form the brainstem and spinal cord to thalamus; axons decussate in the brainstem or spinal cord before ascending to thalamus

Third order neuron - conduct impulses from thalamus to primary somatosensory area of the cortex on same side

43
Q

Define relay stations

A

Regions within the CNS where neurons synapse with other neurons that are part of a particular sensory or motor pathway

Names as such because neuronal signal are being relayed from one region to another

44
Q

Describe the posterior column-medial lemniscus pathway

A

Consists of 2 tracts:

  • cuneate fasiculus: conveys impulses for touch, pressure, vibration and conscious proprioception from limbs, trunk, neck, and posterior head ascend along this pathway
  • Gracile fasiculus: covers nerve impulses for touch, pressure, and vibration for lower limbs and lower trunk

Axons of first-order neurons from one side of body form posterior column on same side and end in medulla, where they synapse with dendrites and cell bodies of second-order neurons.

Axons of second-order neurons decussate, enter medial lemniscus on opposite side, and extend to thalamus

Third-order neurons transmit nerve impulses from thalamus to primary somatosensory cortex on side opposite the site of stimulation.

45
Q

Describe the anterolateral (spintothalamic) pathway

A

Conveys nerve impulses for pain, cold, warmth, itch, and tickle from limbs, trunk, neck, and posterior head.

Axons of first-order neurons from one side of body synapse with dendrites and cell bodies of second-order neurons in posterior gray horn on same side of body.

Axons of second-order neurons decussate, enter spinothalamic tract on opposite side, and extend to thalamus.

Third-order neurons transmit nerve impulses from thalamus to primary somatosensory cortex on side opposite the site of stimulation.

46
Q

Describe the trigenimothalamic pathway

A

Conveys nerve impulses for touch, pressure, vibration, pain, cold, warmth, itch, and tickle from face, nasal cavity, oral cavity, and teeth.

Axons of first-order neurons from one side of head synapse with dendrites and cell bodies of second-order neurons in pons and medulla on same side of head.

Axons of second-order neurons decussate, enter trigeminothalamic tract on opposite side, and extend to thalamus.

Third-order neurons transmit nerve impulses from thalamus to primary somatosensory cortex on side opposite the site of stimulation.

47
Q

Where is the primary somatosensory area located?

A

The postcentral gyri of the parietal lobes of the cerebral cortex

Each region receives sensory input from a different part of the body

Some parts of the body (lips, face, tongue, hand) provide input to large regions in the somatosensory area

48
Q

How do the somatosensory and motor representations compare for the hand, and what does this difference imply?

A

Hand has a larger representation in the motor area which implies greater precision in the hands movement control than fine ability in its sensation

49
Q

Describe the posterior and anterior spinocerebellar tract

A

Convey nerve impulses from proprioceptors in trunk and lower limb of one side of body to same side of cerebellum.

Proprioceptive input informs cerebellum of actual movements, allowing it to coordinate, smooth, and refine skilled movements and maintain posture and balance.

50
Q

Define lower motor neurons

A

Have their cell bodies in the brainstem and spinal cord and extend through cranial nerves to innervate skeletal muscles of the face and head and extend through spinal nerves to innervate muscles of the limbs and trunk

51
Q

Describe local circuit nuerons

A

Interneurons which receive their input from sensory receptors and innervate lower motor neurons

Located in the brainstem and spinal cord

They help coordinate rhymes activity in specific muscle groups (ex. flexion and extension during walking)

52
Q

Describe upper motor neurons

A

Innervate local circuit neurons and lower motor neurons - mostly synapse with local circuit neurons

UMNs from cortex are essential for execution of voluntary movements and other UMNs originate in motor center of the brain stem which help regulate muscle tone, control posture, and help balance the head and body

53
Q

Describe the function of basal nuclei neurones - how are they connected to the somatic motor pathway?

A

Assist movement by providing input to UMNs

They are interconnected with the motor areas of the cortex via the thalamus and the brainstem and thus help initiate and terminate movements and establish muscle tone

54
Q

Where is the primary motor area located?

A

The precentral gyrus of the frontal lobe

55
Q

Compare the locations and functions of the direct and indirect motor pathways

A

Direct - provide input to LMNs from motor neurons via axons that extend directly from the cerebral cortex; consist of axons that descend from pyramidal cells which are UMNs with pyramidal shaped cell bodies located in the primary motor area and premotor area

Indirect - provide input to LMNs from motor centres in the basal ganglia, cerebellum and cerebral cortex

Both govern generation of impulses in LMNs which stimulate contraction of skeletal muscles

56
Q

What is the final common pathway?

A

LMNS as they provide all output to skeletal muscles

57
Q

Explain how the basal ganglia contributes to movement

A

Initiation and termination of movement - receives input from sensory, association, and motor areas of the cortex and from substania nigra and sends feedback to UMNs via thalamus

Suppression of unwanted movements - inhibitory effects on thalamus and superior colliculus

Muscle tone - globus pallidus sends input to reticular formation that reduces muscle tone

58
Q

Explain how the cerebellum contributes to movement

A

Monitoring intentions for movement - receives input from cortex and basal nuclei regarding planned movements

Monitoring actual movement - receives input from propricentors in joints/muscles that reveals what is happening

Compares command & sensory signals

Sends corrective feedback - if there is a discrepancy it sends signal to UMNs via thalamus

59
Q

What structure is responsible for the circadian rhythm?

A

Established by the suprachiasmatic nucleus of the hypothalamus

60
Q

How does the reticular activating system (RAS) influence awakening?

A

When the RAS is activated many impulses are transmitted to widespread areas of the cortex, both directly and via the thalamus increasing cortical activity

For arousal to occur RAS must be stimulated which can be from many somatic stimuli - the result of arousal is the state of consciousness

Certain senses such as olfactory are hard to activate RAS

61
Q

Define neural plasticity

A

The capability for change - associated with learning and injury repair

62
Q

Define the following types of memory:

Immediate
Short term
Long term

A

Immediate - ability to recall ongoing experineces for a few seconds; provides perspective to the present time that allows us to know where we are and what were doing

Short term - temporary ability to recall a few pieces of information for second to minutes

Long term - information that is remembered fro days to years that can be retrieved when needed

63
Q

Define memory consolidation

A

Reinforcement that results from the frequent retrial of a piece of information

64
Q

Define long term potentiation (LTP)

A

Transmission at some synapses within the hippocampus is enhanced (potentiated) for horus or weeks after a brief period of high-frequency stimulation

Glutamate is released that acts of NMDA receptors on postsynaptic neurons

65
Q

Describe the staages of sleep

A

NREM consists of 4 stages that people go through ~1hr

  • stage 1: transition between wakefulness and sleep
  • stage 2: light sleep, the first stage of true sleep, fragments of dreams, eyes roll slowly
  • stage 3: moderate sleep; body temp and BP decrease
  • stage 4: deep sleep brain metabolism and body temp decreases; sleep walking

REM (usually 3-5 episodes per night) - eyes move rapidly back and forth under closed eyelids

  • stages gradually lengthen as the night progresses
  • total REM decreases as a person ages
  • neuronal activity is high and oxygen use and brain flow is higher than during intensive mental or physical activity
  • when most dreaming occurs
66
Q

Describe narcolepsy

A

condition in which REM sleep cannot be inhibited during waking periods and thus involuntary periods of sleep that last ~15 min occur throughout the day

  • deficiency of orexin which has a role in prompting wakefulness
67
Q

Describe Parkinson’s disease

A

A progressive disorder of the CNS characterized by degeneration of DA in the substania nigra which causes involuntary skeletal muscle contractions

68
Q

Describe cerebral palsy

A

A motor disorder the results in the loss of muscle control and coordination; caused by damage to the motor areas of the brain during fetal life, birth, or infancy

69
Q

Describe a coma

A

State of unconsciousness in which a persons responses to stimuli are reduced or absent

Caused by brain trauma

70
Q

Describe pain threshold

A

The smallest intensity of a painful stimulus at which a person perceives pain

All individuals have the same pain threshold, however they differ in their pain tolerance

BIO 235 Midterm 2 (8 decks)

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