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anatomy and physiology > A&P Chp. 13: The Peripheral Nervous System and Reflex Activity > Flashcards

A&P Chp. 13: The Peripheral Nervous System and Reflex Activity Flashcards

1
Q

Modality

A

Mode
Each input is a specific type of sensation
Individual sensory neurons generally carry only one modality

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2
Q

Selectivity of Receptors

A

Sensory neurons respond strongly to one type of stimulus and weakly or not at all to other types
Some respond accidentally to other types of stimuli: rubbing your eye mechanically stimulates the eyes’ light receptors in the retina

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3
Q

Stimulation

A

1st Component of Sensation

Stimulus or change in the environment

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4
Q

Transduction

A

2nd Component of Sensation
Requires a sensory receptor cell or organd which responds to specific stimuli and converts them into receptor/generator potentials

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5
Q

Impulse generation and conduction

A

3rd Component of Sensation
If a receptor/generator potential (graded potential) reaches a threshold, then the neuron’s action potential will be send to the CNS

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6
Q

Integration

A

4th Component of Sensation
Some region of the CNS must receive and translate nerve impulses into sensations and perceptions
Generally occurs in the cerebral cortex

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7
Q

Mechanoreceptors

A

type of sensory receptor classification
classification by the type of stimulus
mechanical pressure or stretching
generate action potentials when deformed

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8
Q

Thermoreceptors

A

type of sensory receptor classification
classification by the type of stimulus
changes in temperature

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9
Q

Nociceptors

A

type of sensory receptor classification
classification by the type of stimulus
pain due to physical or chemical damage to nearby tissue

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10
Q

Photoreceptors

A

type of sensory receptor classification
classification by the type of stimulus
light strikes retinal receptor cells
generates action potentials in response to light energy

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11
Q

Chemoreceptors

A

type of sensory receptor classification
classification by the type of stimulus
certain specific chemical molecules are detected in the mucous fluids of the GI & respiratory tracts or in the blood or other body fluids

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12
Q

Exteroceptors

A

type of sensory receptor classification
classification by location
located at or near the body’s surface
provide information about the external environment

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13
Q

Interoceptors (visceroceptors)

A

type of sensory receptor classification
classification by location
found in blood vessels, connective tissues, and organs
provide information about the internal environment

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14
Q

Proprioceptors

A

type of sensory receptor classification
classification by location
located in muscles, tendons, joints and the internal ear
provide information about gravity, body and limb positions and skeletal muscle movements

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15
Q

Sensory Receptor Classification

A
  1. by the type of stimulus

2. by location

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16
Q

Adaptation by Sensory Receptors

A

A change in sensitivity to a long-lasting stimulus
Primarily by rapidly-adapting phasic receptors
1. pressure, touch, hearing, smell
2. adapt very quickly, respond less if the stimulus remains constant
3. allows us to shut out background “noise”
Little adaptation by slowly adapting tonic receptors
1. pain, body position, chemicals in the blood of CSF
2. adapt slowly, continue to respond even when the stimulus remains constant
3. continuous input is useful for some modalities because the body needs to make continuous responses to that kind of information

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17
Q

Anesthesia

A

Partial or complete loss of sensation

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18
Q

General Anesthesia

A

gas agents act in the CNS through poorly understood mechanisms

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19
Q

Local Anesthesia

A

drugs injected near peripheral nerves inhibit the opening of gated sodium channels, preventing local transmission of action potentials

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20
Q

Analgesia

A

reduced perception of pain without loss of other sensory information or loss of consciousness: biochemical interference with local stimulus (NSAIDs) or mimic endogenous endorphins in CNS (opiates)

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21
Q

Paresthesias

A 
abnormal sensations (burning, tingling, numbness) not related to normal stimulation
mechanical pressure on nerves in your legs puts your foot to sleep
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22
Q

Mixed Nerve

A

Functional Type of Nerve

contains both sensory and motor nerves

23
Q

Motor (efferent) nerves

A

Functional Type of Nerve
also carry proprioceptive sensory signals back to the CNS from the skeletal muscles, joints, and tendons being served by that nerve

24
Q

Sensory (afferent) nerves

A

Functional Types of Nerves

25
Q

Anatomy of Nerves

A

Bundles/fasicles of axons and dendrites
Endoneurium: around individual processes
Perineurium: around fasicles/ individual nerve fibers with their endoneurium
Epineurium: outermost covering around entire peripheral nerve

26
Q

Cranial Nerves

A

12 pairs of nerves which originate from the brain and exit through foramina of the skull
First 2 pairs originate from the forebrain (olefactory, optic)
Remainaing 10 pairs originate from the brain stem
OhOhOhToTouchAndFeelVeryGreenVegatablesAH

27
Q

Cranial Nerve I

A

Olfactory
Passes through the cribriform plate of the ethmoid bone
Purely sensory
Carries afferent impulses associated with sense of smell

28
Q

Cranial Nerve II

A

Optic
Arises from the retina of the eye and passes through the optic canals and converge at the optic chiasm
Purely sensory
Carries afferent impulses associated with vision

29
Q

Cranial Nerve III

A

Oculomotor
Fibers extedn from the ventral midbrain, pass through the superior orbital fissure, and go to the extrinsic eye muscles
Primarily motor
Somatic motor fibers to inferior oblique and superior, inferior, and medial rectus muscles, which direct eyeball, and to levator palpebrae muscles of the superior eyelid
Parasympathetic fibers to iris and smooth muscle controlling lens shape (reflex responses to varying light intensity and focusing of eye for near vision)

30
Q

Cranial Nerve IV

A

Trochlear
Fibers emerge from the dorsal midbrain and enter the orbits via the superior orbital fissures; innervate the superior oblique muscle
Primarily motor
Provides somatic motor fibers to superior oblique muscle that moves the eyeball

31
Q

Cranial Nerve V

A

Trigeminal
Composed of three divisions: ophthalmic, maxillary, and mandibular
Runs from face to pons via the superior orbital fissure, the foramen rotundum and the foramen ovale
Mixed: major sensory nerve of face; conducts sensory impulses from skin of face and anterior scalp, from mucosae of mouth and nose, and from surface of eyes; mandibular division also contains motor fibers that innervate muscles of mastication and muscles of floor of mouth

32
Q

Cranial Nerve VI

A

Abducens
Fibers leave the inferior pons and enter the orbit via the superior orbital fissure
Carries somatic motor fibers to lateral rectus muscle that moves the eyeball

33
Q

Cranial Nerve VII

A

Facial
Fibers leave the pons, travel through the internal acoustic meatus, and emerge through the stylomastoid foramen to the lateral aspect of the face
Mixed: supplies somatic motor fibers to muscles of facial expression and parasympathetic motor fibers to lacrimal and salivary glands; carries sensory fibers from taste of receptors of anterior portion of tongue

34
Q

Cranial Nerve VII

A

Vestibulocochlear
Two divisions: cochlear (hearing) and vestibular (balance)
Fibers arise from the hearing and equilibrium apparatus of the inner ear, pass through the internal acoustic meatus, and enter the brainstem at the pons-medulla border
Purely sensory: vestibular branch transmits impulses associated with sense of equilibrium from vestibular apparatus and semicircular canals; cochlear branch transmits impulses associated with hearing from cochlea

35
Q

Cranial Nerve IX

A

Glossopharyngeal
Fibers emerge from the medulla, leave the skull via the jugular foramen, and run to the throat
Mixed: somatic motor fibers serve pharyngeal muscles, and parasympathetic motor fibers serve salivary glands; sensory fibers carry impulses from pharynx, tonsils, posterior tongue (taste buds), and from chemoreceptors and pressure receptors of carotid artery

36
Q

Cranial Nerve X

A

Vagus
The only cranial nerve that extends beyond the head and neck
Fibers emerge from the medulla via the jugular foramen
Most important: only cranial nerve that extends down into the body to abdomen
Mixed: fibers carry somatic motor impulses to pharynx and larynx and sensory fibers from same structures; very large portion is composed of parasympathetic motor fibers, which supply heart and smooth muscles of abdominal visceral organs; transmits sensory impulses from viscera

37
Q

Cranial Nerve XI

A

Accessory
Formed from a cranial root emerging from the medulla and a spinal root arising from the superior region of the spinal cord
Mixed (but primarily motor in function)
Provides somatic motor fibers to sternocleidomastoid and trapezius muscles and to muscles of soft palate, pharynx, and larynx (spinal and medullary fibers respectively)

38
Q

Cranial Nerve XII

A

Hypoglossal
Fibers arise from the medulla and exit the skull via the hypoglossal canal
Mixed (but primarily motor in function)
Carries somatic motor fibers to muscles of tongue.

39
Q

Spinal Nerves

A

31 pairs of spinal nerves
originate in the spinal cord
all are mixed nerves
thousands of fibers per spinal nerve
Each pair serves a particular region of the body
Each pair also provides some service to the region supplied by the spinal nerve above it and the spinal nerve below it (redundancy)

40
Q

Dorsal Ramus

A

Spinal Nerve

Supplies posterior body trunk

41
Q

Ventral Ramus

A

Spinal Nerve

Supples the rest of the body trunk and the limbs

42
Q

Mningeal branch

A

spinal nerve

supplies the meninges and blood vessels within meninges

43
Q

Dermatones

A

Areas of the skin innervated by the cutaneous branches of each pair of spinal nerves
Each pair also provides some service to the region of the spinal nerve above and the spinal nerve below (redundancy)

44
Q

Reflex

A

rapid, predictable, automatic response to a stimulus

involved in homeostasis

45
Q

Inborn Reflex

A

unlearned, unpremeditated, and involuntary

46
Q

Two Fundamental Types of Reflexes

A
  1. Somatic Reflexes: produce contraction of skeletal muscle
    One is conscious of somatic reflexes only after they occur
    Politely informed you are touching a hot stove
  2. Autonomic (visceral) reflexes: generally they are not perceived consciously
    Produce responses by smooth muscle, cardiac muscle, glands to adjust conditions of the internal environment
47
Q

Components of a Reflex Arc

A
  1. Receptor: dendrites or other sensory structures respond to changes in the environment
  2. Sensory Neuron: conducts an impulse from a receptor to its axon terminals
  3. Integrating center (some region within the CNS)
    simple: monosynaptic (2 cells only: sensory and motor neurons)
    complex: polysynaptic (> 2 cells: interneurons involved)
  4. Motor Neuron: impulses from integrating center to an effector
  5. Effector: body part (muscle or gland) which responds to the motor nerve impulse
48
Q

Spinal Reflexes

A
  1. Receptors: muscle spindles and Golgi tendon organs
    Sensory mechanorecptors which respond to stretching
    Increased tension (stretching) stimulates the receptors
    Sends proprioceptive inputs to spinal cord
  2. Contraction of the skeletal muscle reduces tension on the muscle spindle
    Lowers the rate of action potential generation
    Decreases input to the spinal cord and higher centers: cortex and cerebellum
49
Q

Stretch Reflexes

A

If a muscle is being stretched, the strech is caused by the contraction of its antagonist
This sensory proprioception information contributes to maintaining proper muscle tone

50
Q

Patellar Reflex

A

Monosynaptic
Ipsilateral (same side)
Segmental (at one level of the spinal cord)
Polysynaptic component: for reciprocal inhibition of the antagonist

51
Q

Golgi (deep) tendon reflex

A

An increase in muscle tension activates receptors (Golgi tendon organ) in the tendon
The muscle relaxes and lengthens in response to its agonist’s contraction
D-T reflex inhibits the agonist
D-T reflex excites antagonist
Helps to regulate a smooth start and stop for a contraction
Input from the Golgi tendon organs are sent to the cerebellum and the cortex
Polysynaptic, ipsilateral, and segmental

52
Q

Flexor Reflex

A

A pull on the limb, extending it, will trigger the reflex
Also, a painful stimulus: a burn, pin, prick, toe stub, etc.
F-R causes an automatic withdrawal from the (dangerous) stimulus
Polysynaptic, ipsilateral, and segmental

53
Q

Crossed Extensor Reflex

A

Flexion of a body part is often balanced by extension of the same body part on the opposite side of the body
Polysynaptic, contralateral, segmental

anatomy and physiology (6 decks)

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