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Phys 1412 > Topic 6: Nervous System IV > Flashcards

Topic 6: Nervous System IV Flashcards

1
Q

Efferent (Motor) Nervous Systems

A

-Autonomic and Somatic Nervous systems

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2
Q

Autonomic Nervous System

A

CNS ⇒ smooth + cardiac muscle, glands

-2 neurons to effector (preganglionic + postganglionic)

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3
Q

ANS neurons can be distinguished by the type of nt released:

A
  • cholinergic = Ach

- adrenergic = norepinephrine (NE)

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4
Q

Autonomic Divisions

A
  • Sympathetic

- Parasympathetic

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5
Q

Sympathetic Nervous System

A
  • function = prepares body for activity
  • fight or flight response
  • activated during exercise
  • nt at ganglion=Ach
  • nt at E=NE (except in sweat glands)
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6
Q

To stop chemical stimulation need to remove nt (SNS)

A
  • ACh broken down by acetylcholinesterase (AChE) – on postsynaptic membrane (cell body/dendrites of postsynaptic cell)
  • NE broken down by MAO (monoamine oxidase) ) - in synaptic end bulb of the neuron that released it
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7
Q

b) Parasympathetic Nervous System

A
  • function = rest + digest
  • “housekeeping”
  • most organs innervated by ANS have both SNS + PSNS – usually have opposite actions
  • ANS regulates internal processes continuously and automatically
    e. g. heart rate ⇒ SNS excites, PSNS inhibits
  • nt=Ach
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8
Q

Effects of ANS

A

Organ(s): SNS (fight or flight)/PSNS (rest + digest)

  1. Pupils of Eyes (iris muscles): dilate/constrict
  2. Heart: increase heart rate (HR) & force of contraction/lower HR
  3. Gastrointestinal Tract: lower motility/increase motility
  4. Blood Vessels (smooth muscle): vasoconstriction/*no innervation of blood vessels (except penis + clitoris)
  5. Sweat Glands: increase secretion (cold sweat)/no innervation
  6. Digestive Glands: decrease secretion (except saliva)/increase secretion (all of them)
  7. Genitals: ejaculation (♂)/erection, lubrication (♂ + ♀)
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9
Q

Higher Control of ANS

A

Cerebrum to hypothalamus to medulla oblongata to ANS to SNS/PSNS

  • hypothal. does not need cerebral input for its ANS functions, but emotions can cause autonomic effects
    e. g. blushing, fainting, cold sweat, ⇑ HR etc.
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10
Q

Somatic Nervous System

A

CNS ⇒ Skeletal muscles

  • 2 neurons to effector (upper motor neuron + lower motor neuron)
  • 3 types of movement:
    • Reflexes, voluntary, rhythmic
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11
Q

Reflexes

A
  • spinal - least complex - require sensory input from e.g. proprioceptors (e.g. muscle spindles)
  • postural - for balance, posture
    • require sensory input from e.g. proprioceptors (e.g. muscle spindles), eyes, inner ear
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12
Q

Voluntary

A
  • most complex

- no external stimuli required (act of will)

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13
Q

Rhythmic

A
  • walking, running etc.

- combination of reflex + voluntary

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14
Q

Levels of motor control

A

-Level 1: Planning
-Level 2:
-Level 3:
-Level 4: Spinal Cord
-Cerebellum
-Basal Nuclei
Corticospinal (Direct) Pathway

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15
Q

Level 1: Planning

A
  • do you want to want move? – If yes, what movement needed? Which muscles need to contract?
  • plans sequence of muscle contractions
  • signals primary motor cortex
  • works with input from cerebellum
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16
Q

Level 2

A

signals directly to lower motor neurons (via corticospinal tract) – for fine skilled movements

17
Q

Level 3

A
  • brain stem nuclei ⇒ descending motor tracts ⇒ lower motor neurons (= indirect tracts)
  • receive input from cortex, basal nuclei, cerebellum
  • involved in co-ordination of large muscle groups for:
    • maintenance of posture
    • locomotion
18
Q

Level 4: Spinal Cord

A
  • contains cell bodies of lower motor neurons
  • networks of neurons (central pattern generators; CPGs) which set rhythmic, repeated movements (e.g. walking, running)
  • require cortical signals to begin or stop movement
19
Q

Cerebellum

A
  • role in planning + initiating movement ⇒ sends input to cortical areas
  • stores planned movement + compares actual to plan, using sensory input from e.g. proprioceptors - corrects if necessary
  • maintains balance, controls eye movements, and has a role in maintaining muscle tone (=low level of contraction)
  • coordinates skilled voluntary muscle movements and timing of contractions involving more than 1 joint
20
Q

Basal Nuclei

A
  • aid in planning movement
  • suppress unwanted motions e.g. at rest
  • role in maintaining muscle tone
21
Q

Corticospinal (Direct) Pathway

A 
-cortex to skeletal muscle 
Parts: 
-Upper motor neurons
   -cell bodies in primary motor cortex
   -axons into spinal cord
-Lower motor neurons 
   -cell bodies in ventral horn of spinal cord
   -axons exit via spinal nerves
22
Q

Clinical Applications

A
  • Destruction of Upper Motor Neurons

- Destruction of Lower Motor Neurons

23
Q

Destruction of Upper Motor Neurons

A

-reflex arcs still present
Get:
-Spastic Paralysis - ⇑ muscle tone (no muscle atrophy)
-Exaggerated reflexes e.g. patellar, Achilles, Babinski sign
e.g. Plantar reflex – scratch sole of foot
-normal response = planar flexion (toes curl under)
-Babinski sign = extend big toe - indicates damage to upper motor neurons (except in babies where it’s normal – corticospinal tract not yet fully myelinated)

24
Q

Destruction of Lower Motor Neurons

A

Get:

  • loss of reflex arc (no reflex)
  • flaccid paralysis - ⇓ tone, marked muscle atrophy
    e. g. Polio (poliomyelitis) = virus destroys cell bodies in ventral horn of sp. cord.
25
Q

Language

A

areas in left cortex of most people (equivalent areas on right side provide emotional components of language – e.g. tone of voice, gestures)

26
Q

Important brain regions for language

A
  • Cortex – for concepts and ideas
  • Wernicke’s area, Broca’s area, basal nuclei
  • Areas of the visual and auditory cortex
27
Q

Brain damage to:

A
  • Wernicke’s - can’t understand spoken or written words ⇒ can speak but words are meaningless or mixed up
  • Broca’s – understand words but difficult to speak or write sensibly
28
Q

Wernicke’s area, Broca’s area, basal nuclei

A
  • make up the language implementation system

- analyzes the incoming and produces outgoing word sounds and grammatical structures

29
Q

Areas of the visual and auditory cortex

A

-signals pass from language areas to premotor cortex to plan muscle contraction ⇒ primary motor cortex initiates planned contractions

Phys 1412 (12 decks)

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