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Physiology 209 > CNS Cognitive and Motor > Flashcards

CNS Cognitive and Motor Flashcards

1
Q

What is the type of receptor class for the auditory system?

A

Mechanoreceptors

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2
Q

What is the stimulus energy for the auditory system?

A

Sound

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3
Q

True/False: Auditory system picks up changes in pressure waves around the head

A

True

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4
Q

T/F: As the frequency of the sound goes up, your sensitivity to the sound decreases?

A

False

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5
Q

Presbycusis?

A

Natural reduction in hearing sensitivity(higher frequencies) as you age

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6
Q

Why does the human ear have specific folds compared to dogs?

A

Because humans are trying to capture certain frequencies of sounds (lowest sensitivity 4kHz) whereas dogs want to capture other frequencies

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7
Q

What is the tympanic membrane and what does it do?

A

It is known as the ear drum
-It vibrates as pressure waves change around the head and pulls/pushes back and forth

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8
Q

What is in the cochlea and what occurs there?

A

-The cochlea contains neurons
-This is where transduction occurs

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9
Q

What is in the inner ear?

A

The cochlea

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10
Q

What is the middle ear?

A

Air filled cavity attached to the back of the throat via the eustacian tube

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11
Q

What is the roles of smallest bones in the body (Malleus, incus & stapes) ?

A

Connect the tympanic membrane to the inner ear

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12
Q

What happens to your ears when you fly? and when you pop them ?

A

Pressure changes in the middle ear making it less able to vibrate (harder to hear). When you pop your ears you normalize the pressure by letting air come in/out of the eustacian tube

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13
Q

Where is the inner ear?

A

Embedded in the skull bone

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14
Q

T/F: the cochlea is wound up?

A

True

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15
Q

How does sound flow through the ear?

A
  1. Tympanic membrane moves back and forth in response to pressure waves.
  2. The tympanic membrane is coupled with the oval window causing it to also move back and forth.
  3. This causes the pressure wave to fly to the end of the cochlea and around the tip and come back to the front where it pushes/pulls the round window
  4. As the round window pulls ou the oval window pushes in (and vice versa)
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16
Q

What happens when you speak?

A

Your voice can be loud, so the malleus, incus and stapes bones are attached to skeletal muscles that contract before you speak to reduce movement of the tympanic membrane and oval window

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17
Q

What is the basilar membrane?

A

It is the membrane that lines the cochlear duct and contains the neurons for transduction

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18
Q

What causes the basilar membrane to move up/down?

A

THe pressure waves produced by the oval window

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19
Q

WHat affects the location of the local vibrations on the basilar membrane?

A

The frequency of the sound

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20
Q

Where does low frequnecy sound cause vibrations on the basilar membrane?

A

Near the tip

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21
Q

Where does high frequency sound cause vibrations on the basilar membrane?

A

Closer to the oval and round windows

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22
Q

Where do complex sounds (consisting of multiple frequencies) cause vibrations on the basilar membrane?

A

Multiple locations depending on their different frequencies

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23
Q

What are the three fluid-filled compartments of the cochlea?

A
  1. Scala vestibuli
  2. Scala media
  3. Scala tympani
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24
Q

What occurs at the organ of corti?

A

Basilar membrane motion is converted into neuronal activity
(it contains neurons for transduction)

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25
Q

What does the basilar membrane do to the organ of corti?

A

When the basilar membrane moves it causes the sterocilia attached to the tectorial membrane of the organ of corti to move which causes ion channels to open/close

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26
Q

What are inner/outer hair cells?

A

They are the cells in the organ of corti with the sterocillia attached to them

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27
Q

Differences between inner/outer hair cells?

A

Inner:
- Have lots of afferents

Outer:
- Less afferents
-Recieve efferent from brain to tell them to contract
- Less involved in transduction
Shape the motion of the basilar memmbrane

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28
Q

WHat happens as the basilar membrane moves upward?

A

Sterocillia move to the right

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29
Q

What happens as the basilar membrane move down?

A

Stereocillia move to the left

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30
Q

WHere are the mechanoreceptors located in the ear?

A

In the hair cells of the organ of corti

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31
Q

How are the sterocillia organized?

A

From shortest to tallest

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32
Q

Where are the ion channels located on the stereocillia?

A

On their tips

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33
Q

What are tip links ?

A

-Tiny strings that connect shorter cillia to the taller cillia
-They gate the ion channels

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34
Q

What happens when stereocilia are close together(pushed toward the small cilia)?

A

-There is less force on the tip links
- Ion channels will be close

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35
Q

What happens when stereocillia are far apart(pushed toward the tall cillia)?

A

-More force on the tip links
- Ion channels will be pulled open

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36
Q

Do hair cells fire action potentials?

A

NO

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37
Q

What happens after ions channels are opened?

A
  1. Potassium enters the ion channel
  2. Potassium depolarizes the hair cell
  3. Depolarization cause Ca2+ to enter the cell
  4. Ca2+ triggers the release of neurotransmitters onto afferents
  5. Afferents fire action potentials which are sent to the brain
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38
Q

What happens when ion channels are closed?

A

-Neurotransmitter stops being released
-No action potentials

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39
Q

Why does potassium depolarize the cell instead of hyperpolarize it and stop neurotransmitter release?

A

Cochlear duct has different ionic composition than anywhere else in the body

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40
Q

What is the central auditory pathway?

A
  1. Eighth cranial nerve
  2. Medulla
  3. Midbrain
  4. Thalamus
  5. Primary auditory cortex
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41
Q

How is auditory info in the brain different than visual/ somatosensory?

A

It is bilaterally represented in the brain (goes to both sides instead of just one)

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42
Q

What does the brain do with auditory information ?

A

Recieves info from each cohclea and uses it to compares the sounds and orient them in space

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43
Q

What receptor mediates the vestibular system?

A

Mechanoreceptors

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44
Q

What is the energy source for vestibular system?

A

-Gravity
-Acceleration

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45
Q

What is the role of the vestibular system ?

A

Helps with balance

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46
Q

What are vestibular organs?

A

-Semicircular canals(part of the inner ear)
-Utricle
-Saccule

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47
Q

What are the semicircular canals responsible for?

A

Angular acceleration (rotation)

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48
Q

What is the utricle responsible for?

A

Horizontal movement

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49
Q

What is the Saccule responsible for?

A

Vertical movement

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50
Q

What is the vestibular occular reflex ?

A

When the vestibular organs control your vision and move your eyes as your heads moves
-This is done to stabalize your vision
-You head rotates and eyes rotate in the opposite direction so that gaze remains constant

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51
Q

Do vestibular organs have sterocilia with tip links?

A

Yes

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52
Q

What happens when you rotate your head?

A

1.Stereocillia move with you head because they are sttached to the bone.
2. THe fluid inside the semicircular canals has inertia (doesn’t move right away)
3. The fluid will then push the capula (flexible membrane) and bends it
4. Since the stereocillia are in the capula they bend as well
5. When the stereocilia bend the tip links open/close ion channels

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53
Q

Why do you get dizzy from spinning?

A

The fluid in the semicircular canals spins with you but when you stop the hair cells stop but the fluid wants to keep moving and pushes on the capula bending the stereocilia.

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54
Q

Why do you feel sick from being dizzy?

A

Due to the conflict between sensory systems (ex. visual system is not moving but vestibular is)

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55
Q

Is there fluid in the semicircular canal?

A

Yes and it has inertia

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56
Q

What happens during linear acceleration?

A

Otoliths have mass and tend to have inertia and lag behind this causes the stereocillia inserted into the otolith complex to bend (opening ion channels (transduction))

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57
Q

What type of receptors are involved in the gustatory sytstem?

A

Chemoreceptors

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58
Q

What are the different types of taste?

A

Sweet, sour, salt, bitter, umami

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59
Q

What are papillae?

A

Tiny bumps on tongue that have taste buds

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60
Q

What is the taste pore?

A

Attached to the taste bud it is lined by cells that express chemoreceptors when food cells bind to the receptors they cause an action potential via the taste afferent

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61
Q

How does salty transduction occur?

A

Sodium ions from food flow through the ion channels causing the transduction process

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62
Q

What is the sour taste ?

A

Perception of how acidic the substance is

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63
Q

How does sour transduction occur(2 ways) ?

A

Low pH(acidic) have more protons, these protons interact with the ion channels
-The protons either block or flow through the ion channel

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64
Q

Why did the bitter taste evolve ?

A

To avoid eating things that are harmful

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65
Q

How does bitter transduction occur?

A

Some bitter molecules block ions channels
Some bitter molecules trigger G-protein cascade

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66
Q

How does the sweet transduction occur?

A

Glucose binds to receptors activating a G-protein cascade, which either opens/closes ion channels

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67
Q

What is umami?

A

Flavour enhancing taste

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68
Q

How does umami transduction occur?

A

Has receptors for glutamate that activate a G-protein cascade when glutamate is bound

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69
Q

Central taste pathway ?

A
  1. Tongue
    2.Cranial Nerves
  2. Medulla
  3. Thalamus
  4. Ipsilateral gustatory cortex
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70
Q

How is the taste pathway differne tfrom other pathways?

A

Does not cross the midline

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71
Q

What is olfactory?

A

Sense of smell

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72
Q

What are the olfactroy receptors? What does this mean?

A

Chemoreceptors (molecules must enter the nose)

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73
Q

What happens after molecules enter the nasal cavity?

A

They dissolve into the olfactory epithelium and then bind to receptors on the cilia. The olfactory receptor cells then send axons up across the bone to the olfactory bulb which then the axons leave the bulb via the olfactory tract and which projects to the brain

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74
Q

Transduction in the olfactory system?

A
  1. Odorant binds to the chemoreceptor on the cilia
  2. Chemoreceptor activates a G-protein cascade
  3. G-protein cascade results in the opening of ion channels
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75
Q

T/F: Each olfactory receptor cell has a unqiue odorant receptor and binds a different odorant

A

T

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76
Q

How can we distinguish 10000 different odours with only 1000 different oderant receptors?

A

One type of oderant will bind really well to one type of oderant receptor and may bind not as well to others.
The net result is a population of oderant receptors that are activated for a specific molecule
- The brain uses the population code to distinguish which of the 10 000 odours it is

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77
Q

True/False :The central olfactory pathway goes through the thalamus ?

A

False

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78
Q

Why do certain odours make us think certain memories?

A

Because the olfactory system project largely on the limbic system which is responsible for emotions and memories

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79
Q

What is the state of consciousness?

A

Level of arousal whether you are awake or sleeping

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80
Q

How is the state of consciousness measured?

A

By behaviour (ex. moving, talking) and brain activity

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81
Q

What is the conscious experience?

A

Thoughts, feelings, desires, ideas (everything about the mental life)
-Capacity to experience your existence instead of just recording and responding to stimuli

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82
Q

What does an EEG measure?

A

Activity of neurons located near the scalp in the gray matter of the cortex (cerebral cortex)

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83
Q

What does the frequency on an EEG represent?

A

Levels of responsiveness

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84
Q

What does the amplitude on an EEG represent?

A

Synchronous neural activity

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85
Q

What happens if there is too much synchronous activity?

A

Seizure

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86
Q

Typically high frequency results in ? and low frequency results in?

A

Low amplitude
High amplitude

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87
Q

If an EEG shows slow frequencies and large amplitudes the person is probably….

A

Relaxed with eyes closed

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88
Q

If an EEG shows fast frequencies and small amplitude the person is probably…

A

Alert

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89
Q

What are the two stages of sleep?

A
  1. NREM
  2. REM
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90
Q

Stage 1 of sleep vs stage 4?

A

Stage 1:
- Lower amplitudes / faster frequencies
-Less synchrony

Stage 4:
-Higher amplitudes/ slower frequencies
-More synchrony

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91
Q

How long does it change to go from stage 1 to stage 4?

A

30-45 minutes

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92
Q

What happens after about 1 hour of NREM?

A

You enter REM sleep

93
Q

WHat does the EEG of REM sleep look like?

A

Very similar to the EEG when awake
- Low amplitude/ Fast frequencies

94
Q

T/F: when you are younger you get more REM sleep?

A

True

95
Q

T/F : once you are in REM you stay there for the night?

A

False, throughout the night you continuously cycle through all the sleep stages

96
Q

What pysiological changes occur during REM sleep?

A
  • Increase eye movement
  • Increased inhibition of skeletal muscle (low muscle tone) (but twitching can occur)
    -Increased heart rate
  • Increased respiration
    -Dreaming
97
Q

What is sleep apnea?

A

Sudden reduction is respiration when sleeping

98
Q

What causes sleep apnea?

A

When skeletal muscles are relaxed during REM some ppl snore(acute sleep apnea) but for some people the muscles aroudntheir throat become too relaxed that the tongue falls back and blocks the airway. THis causes you to wake up to breathe and robs you of REM sleep

99
Q

What is the circadian rythm ?

A

-Sleep wake cycke
-Regulates 24 hour sleep/wake cycle

100
Q

What two areas of the brain mediate the circadian rhythm?

A
  1. Hypothalamus
  2. Reticular activating system
101
Q

What neurons are activated when awake?

A

Aminergic neurons

102
Q

What neurons are activated when asleep?

A

Cholinergic neurons

103
Q

When awake what increases/decreases?

A

Increases:
- Norepinephrine/Serotonin (from brain stem)
-Histamine(Hypothalamus)
Decreases:
-Acetylcholine(brain stem)
-GABA(hypothalamus)

104
Q

When asleep what increases/decreases?

A

Increases:
-Acetylcholoin(Brain stem)
-GAGA (hyp)
Decreases:
-Norepinephrine/Serotonin (from brain stem)
-Histamine(Hypothalamus)

105
Q

What is motivation?

A

Tendency to seek out rewards

106
Q

What are emotions?

A

-Accompany our conscious experience
-Help remember memories
-How we rate different experiences

107
Q

What is the mesolimbic pathway?

A

The reward pathway (tells your brain to do something because it is rewarding)

108
Q

What is the primary neurotransmitter in the mesolimbic pathway ?

A

Dopamine

109
Q

WHat areas of the brain are involved in the mesolimbic pathway?

A

-Prefrontal cortex
-Midbrain
-Locus ceruleus (brain stem)

110
Q

What is the limbic system responsible for ?

A

Emotions(how you rate sensory experiences)

111
Q

What parts of the brain are involved in the limbic system?

A
  • Hippocampus(memory)
    -Amygdala(emotional response)
    -Olfactory bulb
112
Q

What are the two memory systems?

A
  1. Declaritive memory
  2. Procedural memory
113
Q

What is the declarative memory responsible for?

A

Conscious experiences that can be put into words (names, facts, places)

114
Q

What is the procedural memory responsible for?

A

Skilled behaviour (how to ride a bike)

115
Q

Where does the short-term declarative memory occur?

A

In the hippocampus and other parts of the temporal lobe

116
Q

Where does the long-term declarative memory occur?

A

Many areas of the cortex

117
Q

Where do short-term procedural memories occur?

A

Everywhere(widely distributed)

118
Q

Where do long-term procedural memories occur?

A

Basal nuclei, cerebellum, premotor cortex( slowly put into motor areas)

119
Q

What is consolidation ?

A

The transfer of a memory from short-term to long-term
-Can take a day or more

120
Q

What helps with consolidation?

A

Sleep

121
Q

Where is language in the brain?

A

Left Hemisphere

122
Q

What are the two areas of the brain responsible for language?

A
  1. Broca’s Area
  2. Wernicke’s Area
123
Q

What is the Broca’s Area responsible for?

A

The production of speech

124
Q

What is the Wernicke’s area responsible for?

A

Written and spoken comprehension

125
Q

What is aphasia?

A

A language deficit, can be due to damage at the broca’s area or wernicke’s area or caused by parietal damage

126
Q

What does damage at the broca’s area cause?

A

Individuals are not able to produce speech but can comprehend language

127
Q

Why is the broca’s area close to the primary motor cortex ?

A

Speech requires a lot of coordinated movement by the tongue and mouth.
By having it close it helps produce highly regulated muscle contractions

128
Q

What is sensory neglect and what can cause it?

A

Sensory neglect: Neglact on the contralateral side of the world (this side of the world does not exist)
-Can be caused by parietal damage

129
Q

What are two types of motor behaviour?

A
  1. Voluntary (walking around, writing)
  2. Reflexive (every second thousands of motor contractions occur to keep you upright, make it so you don’t flop over)
130
Q

What make up most of our motor activity?

A

Reflexive

131
Q

What happens when a muscle extends?

A

Extensor muscle contracts (agonist)
Flexor muscle relaxes (antagonist)
-Increased angle around the joint

132
Q

What happens when a muscle flexion occurs?

A

Extensor mucle relaxes (antagonist)
Flexor muscle contracts (agonist)
-Decreased angle around the joint

133
Q

How does a muscle become activated/relaxed?

A

Activation:
-Motor neurons become active
Relaxed:
-Motor neurons inhibited

134
Q

How is limb position maintained when there is no movement?

A

There is a balance of the flexor and extensor muscle tension

135
Q

Where are the motor neurons located?

A

In the CNS

136
Q

True/False: Motor neurons are only excitatory?

A

True: they only cause muscles to contract because they release acetylcholine

137
Q

What are the two types of motor neurons and what do they innervate?

A

Alpha: innervate skeletal (extrafusal) muscle
Gamma: innervate muscle spindle (intrafusal)

138
Q

Where are the cell bodies of motor neurons?

A

Ventral Horn of spinal nerves or brain stem of cranial nerves

139
Q

Who do motor neurons recieve most of their input from?

A

Interneurons, in the gray matter of the spinal cord

140
Q

What information do spinal interneurons integrate and send to motor neurons?

A
  • Pain
    -Tension monitoring
    -Voluntary movements
    -Coordinates complex movements (walking)
    -Length monitoring
    -Proprioceptive feedback
141
Q

What are three types of spinal reflexes?

A
  1. Withdrawl Reflex
  2. Stretch Reflex
  3. Inverse stretch reflex
142
Q

What are spinal reflexes?

A

Occur automatically not mediated by the brain/CNS mediated by the spinal cord

143
Q

Most imporant spinal reflex?

A

Stretch reflex

144
Q

True/False: Spinal reflexes can be overridden?

A

True

145
Q

When do withdrawl reflexes occur?

A

When you encounter an unexpected paiful stimulus

146
Q

How does the withdrawl reflex work?

A
  1. Nociceptors activated, send action potentials
  2. Synapse 2nd order neurons then to brain
  3. Some nociceptors synapse onto interneurons that activate motor neurons for the ipsilateral flexor muscles the muscle contracts and limb withdraws
  4. Extensor muscle is relaxed
147
Q

When is a whithdrawl reflex overidden ?

A

When you pick up your hot dinner and don’t want to drop it

148
Q

What is the cross extensor reflex?

A

When the limb that is not withdrawn must change things to compensate for the withdrawn limb
ex. If you withdraw a leg the other limb must take the weight

149
Q

Why i the withdrawl reflex polysynaptic?

A

Because there are multiple synapses between the afferent and the motor neuron

150
Q

What happens in the cross extensor reflex?

A

The opposite thing that happened in the ipsilateral side

151
Q

When do you withdraw your limb more ?

A

When the stimulus is more painful the magnitude that the limb is withdrawn is way more

152
Q

What happens when the stimulus is less painful?

A

-Less interneurons are activated
-Smaller withdrawl
- Less afterdischrage

153
Q

What is irradiation?

A

Increase in rate and magnitude of withdrawl response with increase stimulus strength

154
Q

What is afterdischarge?

A

When the limb remains withdrawn after removed from the stimulus

155
Q

What maintains afterdischarge?

A

Feedback loops in the spinal cord

156
Q

When is the afterdischarge smaller?

A

Less painful stimuli

157
Q

What does the stretch reflex control?

A

Controls muscle length

158
Q

What occurs during the stretch reflex?

A
  1. Stretching of muscle activates stretch receptors embedded in the muscle
  2. Receptors synapse to dorsal column to brain and onto motor neurons/interneurons
  3. Synapse onto motor neurons activates the muscle being stretched and inhibits muscle not being stretched
159
Q

What are the extrafusal muscle fibres?

A

Big muscles that cause you to move
Innervated by alpha neurons

160
Q

What composes the muscle spindle?

A

-Contains the muscle stretch receptor
-Intrafusal muscles on either side of the receptors (activated by gamma)
-In parallel with extrafusal muscle fibres

161
Q

Does the muscle spindle feel force by extrafusal muscles ?

A

No, since the muscle spindle is parallel with the extrafusal muscles it does not feel force

162
Q

Do intrafusal muscle fibers create force for us to move?

A

No, only extrafusal muscles produce force causing us to move

163
Q

What is the function of the muscle spindle?

A

To report the length of the muscle to the CNS
-The muscle spindle is always the same length as the extrafusal muscle fibers

164
Q

What is the golgi tendons function ?

A

To report the tension of muscles to the CNS

165
Q

What two afferents come from the stretch receptors in the muscle spindle?

A
  1. Ia
  2. II
166
Q

What do the Ia primary afferents report and why?

A

The Ia afferent is rapidly adapting and reports changes in muscle length

167
Q

What do the II secondary afferents report and why?

A

The II afferent is non-adapting and reports static positions in muscle length

168
Q

Which type of afferent will mediate the stretch reflex?

A

The Ia afferent mediates the stretch reflex because it is a rapid change in muscle length . It is not even recognized by the II afferents

169
Q

Muscle spindle when the muscle is extended?

A
  1. Muscle stretches
  2. Extrafusal muscle fibres lengthens, so muscle spindle lengthens
  3. Increase in muscle spindle afferent activity tells CNS that the muscle lengthened
170
Q

Muscle spindle when the muscle is flex?

A
  1. Muscle shortens
  2. Extrafusal muscle fibres shorten, so muscle spindle shortens
  3. Stretch receptor in the middle of the muscle spindle stops working and muscle spindle collapses and sensitivity is reduced
171
Q

What is the role of gamma neurons?

A

While alpha neurons shorten muscles, gamma neurons cause the intrafusal muscles fibers to contract on each side of the stretch receptors and pull the middle tight (of the muscle spindle)

172
Q

What is alpha-gamma coactivation?

A

When alpha neurons are shortening extrafusal muscles and gamma are contracting intrafusal

173
Q

Why do gamma motor neurons contract intrafusal muscle fibres of the muscle spindle?

A

To prevent the spindle from getting to stretched out and floppy
-Helps maintain the muscle spindles sensitivity as it becomes shorter

174
Q

What are the three properties of the stretch reflex?

A
  1. Resists change in muscle length (as muscle get longer it tends to pull back (sets muscle tone))
  2. Mono- and polysynaptic components
  3. Feedback from muscle spindles
175
Q

What activates the golgi tendon organ?

A

Increased tension/force

176
Q

Will a relaxed muscle activate the golgi tendon organ?

A

NO

177
Q

Will a passively stretch muscle (like tendon tap) activate the golgi tendon organ?

A

NO

178
Q

Will a contracted muscle activate the golgi tendon organ?

A

YES

179
Q

What happens when the golgi tendon organ feels a lot of tension?

A

The golgi tension organ is pulled causing the collagen fibres wrapped around nerve endings to pinch off the free nerve endings. This activates mechanically gated ion channels in the Ib afferent

180
Q

How is the inverse stretch reflex different from the stretch reflex and withdrawl reflex?

A

Inhibits the muscle that is contracting

181
Q

Is the inverse stretch reflex polysynaptic?

A

YES

182
Q

What do higher centers control?

A

They initiate movement consciously

183
Q

What is the role of the middle level of motor control?

A

Does things you don’t think about as you are moving
- Executes individual muscle contractions
-Makes corrections based on sensory info

184
Q

What are the two major descending pathways of motor control down the spinal cord?

A
  1. Corticospinal
  2. Extrapyramidal
185
Q

What is the corticospinal pathway responsible for?

A

Skilled movements
- Innervates both alpha and gamma neurons
-Comes from sensorimotor cortex and goes to brainstem/spinal cord

186
Q

What is the extrapyramidal pathway responsible for?

A

Trunk & Posture (helps you stand/sit upright)
- Originates from neurons in the brain stem

187
Q

T/F: Voluntary movements have an “involuntary” component?

A

True

188
Q

What is the final common pathway?

A

When motor neurons innervate muscles

189
Q

Voluntary control pathway ?

A
  1. Pre-frontal cortex
  2. Premotor cortex
  3. Primary motor cortex/somatosensory cortex
190
Q

Is the primary motor cortex somatotopic map the same as the somatosensory one?

A

YEs

191
Q

Why are their more regions of the somatotopic map of the primary motor cortex dedicated to the hands/face?

A

Because the hands and face require more neurons for more highly skilled movements

192
Q

What are three characteristics of the somatotopic motor representation?

A
  1. It is laid out nicely along the cortex with fingers on the same hand together on the cortex
  2. Size of the body structures is proportional to the number of neurons dedicted to their motron control
  3. Size of the body structure is proportional to the degree of skill required to operate the area of the body
193
Q

What part of the brain is involved in consciously initiating movement?

A

Higher Centers

194
Q

Where does the corticospinal descending pathway begin and end?

A

Begins at the primary motor cortex(precentral gyrus)
and ends on the brainstem and spinal cord

195
Q

Where does the extrapyramidal descending pathway begin and end?

A

Begins at the brainstem and ends at the spinal cord

196
Q

What descending pathway is involved in skilled movements of the hands, feets and fingers?

A

The corticospinal

197
Q

What descending pathway is involved in trunk & posture?

A

The extrapyramidal

198
Q

Does the corticospinal pathway cross the medulla and what does this mean?

A

Yes, this means that the corticospinal controls contralateral muscles

199
Q

What do the axons of the extrapyramidal pathways innervate?

A

Interneuron in the spinal cord

200
Q

What do the axons of the corticospinal pathways innervate?

A
  1. Spinal interneurons
  2. Regulates alpha/gamma motor neurons activity
201
Q

What descending pathway has several descending tracts ?

A

Extrapyramidal

202
Q

Do the extrapyramidal pathways cross the medulla?

A

Yes some cross the medulla and other do not

203
Q

What do the extrapyramidal pathways control?

A

-Upright posture
-Balance
-Walking
-Control trunk and postural muscles

204
Q

What is muscle tone?

A

The resistance of a skeletal muscle to stretch

205
Q

What is normal muscle tone?

A

Resitance of skeletal muscle to stretch is slight and uniform (tested by tendon tap reflex)

206
Q

What happens when you have damage to your descending pathways?

A
  1. Hypertonia: Abnormally high muscle tone
  2. Spasticity: Overactive motor reflexes
  3. Rigidity: Constant muscle contraction
207
Q

Why does damage to descending pathways lead to overactive motor neurons?

A

Descending pathways inhibit interneurons. When the spinal cord in damaged it will not recieve these descending pathways and thus its interneurons will not be inhibited

208
Q

Why happens when your motor neurons are damaged?

A
  1. Hypotonia: Abnormally low muscle tone
  2. Atrophy: Loss of muscle mass
  3. Decreased or missing reflexes
209
Q

What part of the brain is the basal nuclei in for motor control pathway?

A

Middle level

210
Q

What does the basal nuclei do?

A

Determines the specific sequence of movements needed to accomplish a desired action

211
Q

What is the basal nuclei?

A

A collection of cell bodies in the cerebral cortex

212
Q

What diseases affect the basal nuclei ?

A
  1. Parkinson’s
  2. Huntington Disease
213
Q

What is Parkinson disease?

A

Reduced dopamine input to the basal nuclei

214
Q

What is Huntington Disease?

A

Widespread loss of neurons in the brain
-Neurons in the basal nuclei are preferentially lost

215
Q

What are four symptoms of parkinson’s?

A
  1. Akinesia: Reduced movements
  2. Bradykinesia: Slow movements
  3. Muscular Rigidity
  4. Resting Tremor (tremor stops when movement starts)
216
Q

Treatments for Parkinson’s

A

Increasing dopamine concentrations in the brain

217
Q

What are the two symptoms of Huntington’s ?

A
  1. Hyperkinetic disorder: excessive motor movements
  2. Choreiform movements: jerky, random involuntary movements of limbs and face
218
Q

What level of the motor control pathway is the cerebellum in?

A

Middle Level

219
Q

What does the cerebellum do for motor control?

A

Controls movement timing, planning and error correction
-Involved in learning new motor skills

220
Q

What part of the brain recieves all somatosensory, auditory, visual and descending pathways?

A

Cerebellum

221
Q

How many neurons are in the cerebellum?

A

Half of all of the brains neurons are in the cerebellum

222
Q

What is Asynergia?

A

A cerebellar deficit where smooth movement are subdivided into their separate components
- Have to think of every individual contraction that must occur

223
Q

What is Dysmetria?

A

A cerebellar deficit where you are unable to target movements correctly “Past pointing”
-ex. you miss your coffee cup when you try to grab it

224
Q

What is Ataxia?

A

A cerebellar deficit where you have an incoordination of muscle groups
-Individuals will have an awkward walk where they can’t walk smoothly or easily

225
Q

What is intention tremor?

A

A cerebellar deficit where you have a tremor during voluntary movements but not at rest

226
Q

Are cerebellar deficits characterized by paralysis and weakness?

A

No neither of these are seen in cerebellar deficits

227
Q

Can a person with cerebellar deficit learn highly skilled movements?

A

No it is unlikely that they will be able to learn highly skilled motor movements but they will still be able to move

228
Q

What does the middle level of the motor control pathway control and what two parts of the brain doe sit include?

A
  1. Executes individual muscle contractions
  2. Makes corrections based on sensory information
    -involves the Basal nuclei and the Cerebellum
229
Q
A

Physiology 209 (6 decks)

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