ANS Flashcards
(149 cards)
1
Q
What structures plan and refine complex/volitional movement, and what kind of skills does this include?
A
- Motor cortex
- Basal ganglia
- Cerebellum
- Plan and refine highly evolved skills like writing and playing piano
2
Q
Does complex/volitional movement include postural support or movements against gravity, and which limbs are primarily involved?
A
- Does not include postural or anti-gravity movements
- Primarily involves distal limbs
3
Q
Where is the motor cortex located and how is it organized?
A
- Precentral gyrus
- Somatotopically organized with the body mapped upside down
4
Q
Do cortical areas correspond to physical body size, and which body parts have larger representations?
A
- No
- They correspond to motor function complexity
- Hands and lips have larger cortical areas due to more motor innervation and processing
5
Q
What is the distorted neurological body map called, and does it represent sensory or motor functions?
A
- The Cortical Homunculus
- Represents motor functions
6
Q
Are speech muscles represented by a large or small area?
A
Larger
7
Q
Where do most descending axons from the motor cortex go, and do any synapse directly on motoneurons?
A
- Most go to interneurons
- About 20% of corticospinal axons synapse directly on motoneurons
8
Q
Which motor nuclei receive direct corticospinal synapses?
A
Primarily distal limb and speech motor nuclei
9
Q
Why does the motor cortex replace some functions of the red nucleus, and how does the complexity of movements compare?
A
- To provide more space to organize complex movements
- The motor cortex organizes more complex movements than the red nucleus
10
Q
Where is the red nucleus found and what is it responsible for?
A
- Located in the midbrain
- It is considered the first region for programming sophisticated distal limb movements
11
Q
What kinds of movements does the red nucleus program, and are cyclical movements like walking or breathing included?
A
- Sophisticated distal limb movements
- Gripping a cup
- Not cyclical movements like walking or breathing
12
Q
How advanced are red nucleus movements compared to playing the piano, and can you give an example of a primitive movement it controls?
A
- More primitive than piano playing
- An example is gripping all the fingers together
13
Q
What is the rubrospinal tract, and what kind of synergies do its cells activate?
A
- A tract from the red nucleus to the spinal cord that activates localized synergies
- Especially in distal limbs and the face
14
Q
How precise is the red nucleus connection to distal motor nuclei, and which limbs does it control?
A
- Very precise
- It controls distal limbs like fingers
15
Q
Where does the rubrospinal tract cross and descend, and where does it terminate?
A
- Crosses the midline and descends contralaterally
- Terminating mostly in the intermediate zone (not directly on motoneurons)
16
Q
Where does the rubrospinal tract descend in spinal white matter, and what other tract is found alongside it?
A
- Descends in the lateral white matter alongside the corticospinal tract
17
Q
Why are the lateral white matter and corticospinal tract found together, and where in the ventral horn are they located?
A
- Both are concerned with distal motor nuclei
- They tend to be located laterally in the ventral horn
18
Q
What do the reticulospinal and vestibulospinal tracts organize, and how widespread are they?
A
- Organize widespread postural and locomotory synergies
- Very widespread
19
Q
Do the reticulospinal and vestibulospinal tracts deal with precise hand movements? Why is their widespread nature useful?
A
- No, they control posture
- The widespread nature is useful because many muscles must work together to keep the body upright
20
Q
Can the reticulospinal and vestibulospinal tracts activate muscles at multiple spinal levels and do they have large terminal fields?
A
- Yes, they can activate muscles at multiple spinal levels (e.g., cervical and lumbar)
- Large terminal fields
21
Q
What is a synergy, and what are muscle groups used in synergy called?
A
- A group of muscles contracting together for a specific purpose
- Muscle groups used in synergy are called functional groups of muscles
22
Q
How localized are rubrospinal synergies, and what is an example?
A
- Highly localized
- Especially in distal limbs and the face
- An example is gripping or holding a ball with all five fingers
23
Q
How widespread are synergies from the reticulospinal tract, and what is their primary purpose?
A
- Very widespread
- Typically covering half the body
- Primary purpose is generating support postures
24
Q
Where are postural synergies located and how extensive are they?
A
- Postural centers
- Cover large body territories
- Require many muscles
25
Where do axons from the motor cortex project first, and what happens in the brainstem?
- To the brainstem
- Where they cross the midline
26
Where do these axons end up after crossing, and what is the name of this tract?
- End up in the spinal cord
- Forming the corticospinal tract
27
Do corticospinal pathways cross to the ipsilateral or contralateral side, and where?
- They cross to the contralateral side at the bottom of the brainstem (medulla oblongata)
28
Where do corticospinal axons travel in the spinal cord, and how do they activate motor neurons?
- Travel in the lateral white matter
- Activate motor neurons either directly or via interneurons
29
Is there a small branch of corticospinal axons that might stay on the same side?
Yes, sometimes, but it's variable
30
What other tract is located near the corticospinal tract in the lateral white matter?
The rubrospinal tract
31
How are single motor nuclei represented in the motor cortex, and what does each cortical locus represent?
- Represented in columns at many loci
- With each locus representing a different synergy
32
What happens when a muscle is represented at multiple cortical loci, and what do different combinations of muscles result in?
- The muscle is combined with different neighbors to form different synergies
- Resulting in different movements
33
Are different muscle combinations represented multiple times in the motor cortex, and are all daily synergies mapped there?
- They are represented many times
- All synergies used in daily activities are mapped in the motor cortex
34
Which body parts have muscles involved in many synergies, and what kind of representation do rarely used muscles have?
- Fingers
- Toes
- Facial muscles
- Speech muscles
- Rarely used muscles have sparse representation
35
Can individual motor maps differ between people, and what is the motor cortex mapping based on?
Yes, maps differ based on personal experience
36
How is representation of synergies particularly obvious, and when is the motor map primarily laid out?
- It is obvious with languages
- Primarily laid out during development and early stages
37
Why might learning pronunciation in a new language be harder later in life, and what needs to be recreated?
- Those synergies haven’t been laid down
- Synergies for certain words/sounds need to be recreated with greater effort
38
Can the motor map be changed significantly in adulthood?
No, it mostly remains as laid out early in life
39
What kind of connection does a specific motor cortex neuron have with thumb motor neurons, and what type of grip activates it?
- A direct synaptic connection
- Highly active during precision grip
40
What does the thumb EMG measure, and can you give examples of precision and power grips?
- It measures thumb contraction
- Precision grip example: holding a pencil
- Power grip example: squeezing a ball
41
Is the thumb contracting during both grips, and is the cortical neuron equally active during both?
- Yes, the thumb contracts during both grips
- The neuron is only highly active during precision grip and not active during power grip
42
Does this imply a simple one-to-one mapping between the neuron and the thumb muscle?
No
43
What drives a particular activity in a given motor neuron, and can the same muscle be activated by different cortical areas?
- A specific part of the motor cortex drives activity
- Yes, the same muscle can be activated by different cortical areas for different tasks
44
What is a motor field, how many spinal segments does one corticospinal axon usually synapse with, and are all synaptic contacts operational?
- The set of synaptic contacts a single corticospinal axon makes with motor nuclei in multiple spinal segments
- One axon usually synapses with more than one segment
- Many synapses are 'silent' and not always active
45
What potential does the motor field offer, and can one corticospinal axon connect with many motor neurons?
- Offers plasticity
- The ability to rewire connections
- Yes, one axon can connect with many motor neurons
46
Is the motor field typically small or extensive, and why is plasticity important after injury?
- It can be extensive
- Plasticity helps prevent cortical motor neurons from becoming useless if a muscle is lost
47
What does the extent of plasticity depend on, and does the motor field allow adults to learn new skills?
- Depends on the extent of the motor field
- Yes, it allows adults to learn new skills by rewiring connections
48
What type of sensory input has direct access to the motor cortex, and where does it come from?
- Proprioceptive input
- Coming directly from the thalamus and somatic association cortex
49
Where does cutaneous input come from, and what kind of information does it provide?
- From somatosensory association areas
- Providing postural and motion information
50
Does cutaneous input go directly to the motor cortex, and why or why not?
- No, it goes through the somatosensory cortex first
- Because it requires more processing
51
Where does most sensory information go through before reaching the cortex, and what sensory input bypasses this?
- Most go through the thalamus
- Olfactory information bypasses the thalamus
52
Can directly stimulating a nerve cause muscle contraction, and what is summation?
- Yes, it can cause contraction
- Summation is stimulating the nerve multiple times to generate tension
53
What can summation lead to in terms of muscle tension?
- Generating maximum tension
- Almost tetanus
54
Where are the premotor areas located, and how are they connected to the motor cortex and motor nuclei?
- In front of the motor area
- They project into the motor cortex
- Have parallel routes to motor nuclei
55
What is a key function of premotor areas, and what role do they play in movement sequencing?
- Select specific motor cortical synergies
- Organize them into the proper sequence for a given movement
56
What type of movements do premotor areas help generate, and how are they organized?
- Patterns for learned, highly evolved movements
- By sequencing synergies
57
Do all premotor areas share any general property, and can they be considered programming centers?
- All project into the motor cortex
- Can be considered programming centers at the cortical level
58
What types of sensory input does the premotor cortex receive, and for what purpose?
- Visual
- Auditory
- Somatosensory
- For cueing movement phases
59
How do environmental cues relate to movement, and where are the object-action associations made?
- Thousands of environmental cues (e.g., a door knob or button) trigger motor reactions
- These cues are recognized by sensory association areas
- And forwarded to the premotor cortex
- Where specific motor actions are selected
60
Where is the association between objects and their movement made, and where is the movement selected?
- Made in the premotor areas
- The movement is selected at the premotor cortex
61
What initiates synergies in a visuomotor response, and how is the hand prepared?
- Coordinated activities and cues initiate synergies
- The hand is both shaped and oriented in advance to match the target object’s shape and orientation
62
What is the primary role of premotor neurons, and when are they active?
- Set up the motor cortex by selecting synergies
- Active during the preparatory phase of movement
- Usually silent during execution
63
What roles do cues play in visuomotor responses, and are these responses simple movements?
- Cues are essential
- Visuomotor responses involve coordinated sets of activities
- Not random movements
64
What happens to premotor neuron activity between a warning cue and a go cue?
- Remain very active
- Maintaining activity until the go cue is given
- They become silent once the go cue arrives because their job is done
65
Which visual streams target the dorsal and ventral halves of the premotor cortex, and what information do they process?
- The dorsal visual stream goes to the dorsal half and processes spatial location
- The ventral stream goes to the ventral half and deals with object form, such as shaping the hand
66
What is Broca’s area, what is its function, and where does it receive input from?
- Premotor zone involved in sequencing language elements for speech, writing, or typing
- Receives input from Wernicke’s area
67
Where is the SMA located, and what type of representation does it have?
- The medial wall of the hemisphere
- Has a complete somatotopic representation
- Though less detailed than the motor cortex
68
What are the key functions of the SMA?
- Processes internal volitional signals
- Coordinates bilateral limb movements
- Assists in postural stabilization
69
Is it easy to learn bimanual tasks as an adult, and what is an example SMA action?
- No, it's difficult (e.g., learning piano as an adult)
- An example is lifting a bottle while using the other arm for support
70
Where is the CMA located, and what kind of drive does it process?
- The cingulate sulcus
- Processes emotional and motivational drives to movement
71
What kind of behavior and function is the CMA associated with?
- Emotional behavior
- Mediates emotional movements
- Plays a role in autonomic function
72
What areas drive voluntary versus genuine smiles, and is the CMA part of the limbic system?
- The SMA can drive voluntary smiles
- The CMA drives genuine emotional smiles
- The CMA is part of the limbic system
73
Can different premotor areas generate the same movement, and how do they differ?
- Yes
- But they differ in the drives they originate from
- Cognitive (SMA) vs emotional (CMA)
74
What is the ANS responsible for, and what functions does it regulate besides emergencies?
- Controls involuntary bodily functions
- Like internal organs and blood flow
- Besides emergencies, it also regulates:
1. Exercise
2. Emotion
3. The effect of gravity
4. Eating
75
What systems does the ANS work with, and how fast are its responses?
- Works with the endocrine and behavioral state systems to maintain homeostasis
- Its actions are quick to help preserve internal stability
76
Can you consciously control functions like pupil dilation?
No
77
What are the two subdivisions of the ANS, their nicknames, and how do they usually interact?
- The Sympathetic Nervous System (SNS): "fight or flight"
- The Parasympathetic Nervous System (PNS): "rest and digest"
- Tend to oppose each other
78
How is the ANS pathway structured, and what does this arrangement allow?
- Divided into preganglionic and postganglionic components
- Allows for more divergence
- One preganglionic neuron can synapse with several postganglionic neurons
79
Where are preganglionic neurons located, and where do they project?
- Cell bodies are in the CNS (brainstem or spinal cord)
- Their axons project to autonomic ganglia
80
Where are postganglionic neurons found, and where do their axons go?
- Found in autonomic ganglia between the CNS and target tissue
- Their axons extend to the target tissues
81
What key communication happens in autonomic ganglia?
Synaptic transmission from preganglionic to postganglionic neurons
82
What neurotransmitter do both sympathetic and parasympathetic preganglionic neurons release, and what receptor do they target?
- Acetylcholine (ACh)
- Which acts on nicotinic receptors
83
What neurotransmitters and receptors are used by most postganglionic neurons in the SNS and PNS?
- Most sympathetic postganglionic neurons secrete norepinephrine (NE)
- Which acts on adrenergic receptors
- Most parasympathetic postganglionic neurons secrete ACh
- Which acts on muscarinic receptors
84
Is there an exception in sympathetic postganglionic neurotransmitter usage?
- Yes
- At sweat glands
- ACh is released instead of NE
85
Where do sympathetic preganglionic neurons originate, and where do they synapse?
- Originate in the thoracolumbar spinal cord
- Specifically in the intermediolateral horn
- Synapse in the sympathetic chain ganglia
86
How are sympathetic ganglia arranged, and where are they located?
- Linked together in a chain parallel to the spinal cord
- Sit close to the spinal cord
87
How long are the pre- and postganglionic neurons in the SNS?
- Preganglionic neurons: short
- Postganglionic neurons: long
88
What is the main physiological response associated with sympathetic activation, and what changes occur?
- The fight-or-flight response
- Heart rate and blood pressure increase
- Pupils dilate
- Gastrointestinal and urinary functions decrease
- Energy stores are mobilized
89
Why does the sympathetic system have a diffuse effect?
Due to widespread and interconnected innervations
90
What happens to blood flow in muscles during sympathetic activation?
Blood is diverted to the muscles
91
Where do parasympathetic preganglionic neurons originate and synapse?
- Originate in the brainstem or sacral spinal cord
- Synapse in ganglia near the target tissue
92
How long are the pre- and postganglionic neurons in the PNS?
- Preganglionic neurons: long
- Postganglionic neurons: short
93
Where are parasympathetic ganglia located?
Near or on the effector (target) organ
94
When is parasympathetic activity most dominant, and what does it cause?
- During relaxed states, like resting or digesting food
- It decreases heart rate and blood pressure
- Stimulates bladder contraction and urination
95
What is the adrenal medulla, and how is it related to the sympathetic system?
- A specialized neuroendocrine tissue considered a modified sympathetic ganglion
- Acts with the SNS
96
What stimulates the adrenal medulla, and what does it release?
- Stimulated by preganglionic sympathetic neurons
- It releases epinephrine (adrenaline) directly into the bloodstream
97
What are the effects of epinephrine release, and what are chromaffin cells?
- Epinephrine causes prolonged, widespread effects
- Chromaffin cells are axonless secretory cells in the adrenal medulla
- That release large amounts of epinephrine
98
Are most organs innervated by both sympathetic and parasympathetic systems?
Yes
99
What is the term for both autonomic branches being active at rest, and which one typically dominates?
- Tonic activity
- The parasympathetic nervous system typically dominates
100
Do the sympathetic and parasympathetic systems have opposing effects on effector organs, and are they antagonistic or complementary?
- Yes, they usually have opposing effects
- They are considered complementary
101
What is the primary function of dual innervation?
To regulate organs and maintain homeostasis
102
How do sympathetic and parasympathetic systems affect cardiac output and gastrointestinal function?
- Sympathetic activity increases cardiac output and decreases gastrointestinal activity
- Parasympathetic activity reduces cardiac output and increases gastrointestinal activities
103
What happens to blood flow to the gut and skin during sympathetic activation?
- Blood is diverted from the gut and skin to the muscles
104
What is piloerection?
When your hair stands up
105
What are the main targets of autonomic neurons, and do they target skeletal muscle?
- Smooth muscle
- Cardiac muscle
- Glands
- No, they do not target skeletal muscle
106
What is the synapse between postganglionic autonomic neurons and their target cells called, and what do these neurons have instead of discrete axon terminals?
- The neuroeffector junction
- They have varicosities instead of discrete axon terminals
107
What are varicosities and what do they contain?
Axon swellings containing vesicles filled with neurotransmitters
108
Where are neurotransmitters stored in postganglionic neurons, and what triggers their release?
- In varicosities
- Release is triggered by an action potential
109
What ion enters the varicosity to trigger exocytosis?
Calcium (Ca²⁺)
110
What happens after neurotransmitter binds to receptors on target tissues?
It results in a response from the target tissue
111
How is norepinephrine removed from the synapse and what does MAO stand for?
- Reuptaken or metabolized by monoamine oxidase (MAO)
112
Why might MAO inhibitor antidepressants cause constipation?
- Increase sympathetic activity, which decreases gastrointestinal activity
113
What are autonomic reflexes also known as, and what do they often involve?
- Visceral reflexes
- They often involve internal organs
114
Can some visceral reflexes occur without brain input, and what is an example?
- Yes
- Urination is one such spinal reflex
115
Can autonomic reflexes be modulated and how?
- Yes
- Often by descending signals from the brain
116
What are autonomic efferent networks used to produce, and why are they important?
- Functional reflexes
- They form negative feedback loops for homeostasis
117
What system works with the autonomic nervous system to produce these reflexes, and what is the overall goal?
- The sensory system
- The goal is to maintain homeostasis
118
What is an example of a learned reflex that modulates a simple spinal reflex?
Toilet training
119
Where is the pupillary light reflex organized, and what afferents does it use?
- The pretectal area of the midbrain
- It uses ON and OFF afferents
120
What system and cranial nerve are involved when there is too much light, and what muscle contracts?
- Parasympathetic system
- Cranial nerve III (oculomotor)
- Circular iris muscles contract
121
What system and spinal region are involved when it’s dark, and what muscle contracts?
- Sympathetic system
- Thoracic spinal cord
- Radial muscles contract
122
What pigment is found in retinal ganglion cells involved in this reflex?
Melanopsin
123
What can an absent pupillary light reflex indicate?
Head injury or damage to the parasympathetic pathway
124
Can the pupillary light reflex be triggered by an illusion of brightness, and what does this suggest?
- Yes
- It suggests cortical influence on the reflex
125
What happens to pupils when you glance at a brighter image illusion, and how do they readjust?
- Pupils rapidly constrict
- Then slowly readjust to true light intensity
126
Where is the cardiovascular center located and what does NTS stand for?
- In the ventrolateral medulla (VLM)
- Beside the respiratory center
- NTS = Nucleus of the Solitary Tract
127
What are baroreceptors and what reflex helps adjust blood pressure based on posture?
- Sensors that detect blood vessel pressure
- The baroreflex
128
What is orthostatic hypotension also known as, and what happens to BP during it?
- Postural hypotension, head rush, or dizzy spell
- BP falls suddenly when standing quickly
129
Why do you feel dizzy when standing up quickly, and what helps prevent this?
- Blood pools at the bottom, reducing blood flow to the brain
- The cardiovascular center adjusts BP to prevent fainting
130
What is the baroreflex pathway from stimulus to response, and how is it regulated?
1. Baroreceptors detect blood pressure changes and send input to the Nucleus of the Solitary Tract (NTS)
2. The NTS sends this information to the ventrolateral medulla (VLM)
3. The caudal half of the VLM inhibits the rostral half, which normally excites sympathetic efferents
4. This inhibition reduces sympathetic output and lowers blood pressure
5. When blood pressure is low, there is less inhibition from the caudal VLM, allowing the rostral VLM to increase sympathetic output, raising BP and HR.
131
What does the rostral VLM excite, and what is the outcome?
- Excites sympathetic efferents
- Which increases blood pressure and heart rate
132
What is a major sympathetic influence on muscle vasculature, and why is it important?
- Noradrenergic vasoconstriction
- Which is tonically active and crucial for maintaining blood pressure
- It is part of the baroreflex
133
How does sympathetic vasoconstriction help when standing quickly, and what assists pilots similarly?
- Prevents blood pressure from dropping by keeping blood in the upper body
- Pilots wear G-suits to constrict blood vessels in limbs, keeping blood in the chest and brain
134
What is fainting when standing up too quickly considered, and what does it achieve?
A safety mechanism that diverts blood to the head to prevent oxygen deprivation
135
Which systems work with the ANS to maintain homeostasis, and what sensory info does it use?
- Works with the endocrine and behavioral state systems
- Receives both somatosensory and visceral information
136
What are the main autonomic control centers and their functions?
- The hypothalamus
- Pons
- Medulla
- Regulate blood pressure, body temperature, and other essential functions
137
Where are autonomic reflexes integrated, and what brainstem centers are involved?
- Integrated in the brain
- Particularly in the cardiovascular and respiratory centers of the lateral medulla and pons
138
What does the brainstem do with sensory input, and where does it send output?
- Receives sensory input and relays output to peripheral muscles and glands
139
What is the PAG, where is it found, and what does it coordinate?
- A midbrain premotor center that coordinates autonomic behaviors like fight, fear, feeding, vocalization, sex, and breathing
140
How is the PAG organized and what determines its columns?
- Organized into longitudinal columns based on behavioral patterns
141
How does the PAG interact with other brain areas, and what systems does it use?
- Interacts with the hypothalamus
- Via the reticular formation and hypothalamus
142
Where does the fight (rage) column project, and what are its effects?
- Projects to the cardiovascular center and the raphé nuclei
- Releasing serotonin in the spinal cord
- This serotonin depolarizes motoneurons and inhibits pain transmission in the dorsal horn
143
What does the reticular activating system do, and through what system does this occur?
- Causes a global shift in CNS activity through the diffuse modulatory system
- Which mainly uses metabotropic mechanisms
144
What are the neurotransmitter systems in the diffuse modulatory system?
1. Cholinergic (ACh)
2. Serotonergic (Serotonin)
3. Noradrenergic (Norepinephrine)
4. Dopaminergic (Dopamine)
5. Histaminergic (Histamine)
145
Where do cholinergic neurons originate, where do they terminate, and what are they involved in?
- Originate: Base of cerebrum, pons, midbrain
- Terminate: Cerebrum, hippocampus, thalamus
- Involved in: sleep-wake cycle, arousal, attention, and sensory processing (via thalamus)
146
Where do Serotonergic neurons originate, where do they terminate, and what are they involved in?
- From raphé nuclei; lower nuclei project to the spinal cord, upper to the brain
- Involved in mood, emotion, aggression, depression, pain modulation, locomotion, and sleep-wake cycle
147
Where do Noradrenergic neurons originate, where do they terminate, and what are they involved in?
- Origintaes: locus coeruleus
- Terminates: cortex, thalamus, hypothalamus, olfactory bulb, cerebellum, midbrain, spinal cord
- Affects attention, learning, memory, anxiety, mood, and sleep-wake cycles
148
Where do Dopaminergic neurons originate, where do they terminate, and what are they involved in?
- From substantia nigra and ventral tegmentum
- Projects to cortex and limbic system
- Controls motor function and reward/addiction
149
Where do Histaminergic neurons originate, where do they terminate, and what are they involved in?
- From posterior hypothalamus
- Projects through forebrain
- Involved in wakefulness and sleep-wake control
- Antihistamines inhibit CNS wakefulness, causing drowsiness
