Chapter 2: what is the nervous system's functional anatomy? (P2) Flashcards

1
Q

what is the somatic Nervous system: transmitting information?

A

SNS
- monitored & controlled by the CNS
- in the PNS realm
- in charge of everything (needs to go to the spinal nerves = which is the SNS)

  1. has cranial nerves by the brain (movement and sensation)
  2. spinal nerves by the spinal cord segments

Cranial Nerves
- includes 12 nerve pairs – that control sensory/motor functions of the (head, neck, and internal organs)

functions
1. afferent functions
- incoming into the CNS
- sensory information & goes into the spinal cord to the brain

  1. efferent functions
  2. both functions **some might be in charge of both sensory aspects
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2
Q

what are cranial nerves?

A
  • these are nerves coming out of the brainstem
    **we can also take a look at all the nerves coming out of it
  1. olfactory
    function = smell
    –> sensory
  2. optic
    function = vision
    **we can check the eye pressure, which can constrict the optic nerve
    **if there’s a problem with the optic nerve we won’t be able to see
    –> sensory
  3. oculomotor
    function = eye movement
    - this can constrict the pupils
    - the pupils splinter –> modulated by the oculomotor
    –> motor
  4. trochlear
    function = eye movement
    **these are the up and down movements of our eyes
    –> motor
  5. trigeminal
    function =masticatory movements & facial sensations
    **this is chewing & facial sensation
    –> both (sensory + motor)
  6. abducens
    function = eye movement
    –> motor
  7. facial
    function = facial movement & some taste sensation
    **this is smiling and moving the eyebrows / taste sensation
    –> both
  8. auditory vestibular
    function = hearing & balance
    **hearing infection or vertigo
    - the nerve is in charge of our balance
    –> sensory
  9. glossopharyngeal
    function = tongue & pharynx movement & sensation
    **mucus going down our throat = pharynx
    –> both
  10. vagus
    function = heart, blood vessels, viscera, movement of larynx & pharynx
    **cranial nerve important for the ANS
    **In charge of heart rate, blood vessels
    –> both
  11. Spinal accessory
    function = neck movement
    –> motor
  12. hypoglossal
    function = tongue movement
    –> motor
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3
Q

What are spinal nerves?

A

spinal cord
- inside bony spinal column made of small bones called = vertebrae

**this is part of our CNS

Vertebrae
- categorized into 5 anatomical regions
1. cervical = neck
2. Thoracic = upper mid back
3. lumbar = lower back
4. sacral = bottom of the spine
5. coccygeal = at the very bottom of the spine

body segments
- body segments corresponding to spinal cord segments = dermatomes (w sensory and motor nerves)

: sends info to the skin

: Dermatomes - if you have spinal cord damage (C7) –> you are likely not to move from the spinal cord down
**quadrapalegic –> can’t have sensation from the neck down (C7-C8)

  • above the C7 can be dangerous (might not be able to breath without a ventilator)
  • lumbar = motor commands will stop there
  • anything from L2 down –> we can’t move and it’s not sensed by the brain

Ways which people find out they have dermatomes:
- shingles
- this is a type of herpes that makes people have lots of rashes (lots of connections between our nerves and skin)
- when our spinal cord is infected by shingles (will show up as a rash in the shape of a dermatome)

spinal cord segment
- interconnected so adjacent segments can operate together to direct complex coordinated movements

  • motor movement/pertaining to the part of the body its sensing
  • also have connections from one side to the other one
  • complex motor movement that can happen due to the spinal cord
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4
Q

What are the SNS connections?

A
  • the SNS = bilateral (2-sided)

nerve fibers
1. posterior
- dorsal in 4-legged animals
- fibers are afferent = they carry info from the body’s sensory receptors
**dorsal = sensory receptors & afferent

  1. Anterior root
    - ventral in animals
    - fibers are efferent = they carry info from the spinal cord to the muscles
    **anterior (ventral) = motor commands
  2. Law of bell and Magendie
    - doesn’t change form person to person
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5
Q

describe the spinal nerve connections

A

1(a)
- fibers entering posterior root = bring sensory info from sensory receptors
**sensory neuron
**made of neurons

2(b)
- fibers leaving anterior root = carry motor info to the nucleus
**motor neuron
**sometimes sends directly to the motor neurons

  1. (c)
    - collateral branches of sensory neurons may cross to other side/influence motor neurons there
  2. (d)
    - white-matter fiber tracts carry info to / from the brain
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6
Q

What is Bell Palsy?

A
  • diagnosed by exclusion
  • caused by inflammation of facial (7th) nerve
    **probably by infection w virus or some other inflammatory agent

: one side will be successful, the other one will not bc of the inflammation in the 7th nerve

  • 7th nerve travels through fallopian canal / becomes inflamed, swells, and stops nerve functioning
  • 1 in 65 ppl = afflicted some time in their life
    **most people fully recover –> few are profoundly affected
  • can completely damage the nerve itself and be paralyzed

EX: those who have TBI can impact the nerves
**usually the nerves are affected

EX2: whip-lash

**usually something not that serious (justin bieber had this)

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7
Q

what are the Autonomic and Enteric Nervous Systems: Visceral Relations?

A
  1. control of the viscera (internal organs) including:
    - heart
    - gut
    - liver
    - lungs
    (all require complex neural systems)
  2. ANS & ENS = hidden partners
    - functioning in the background as CNS controls perceptions / behaviors
  3. ANS & ENS interact w the CNS
    **however, each has distinctive anatomy and functions

ANS
- in charge of a lot of things
- things that we usually can’t control (heart beat)

**both of the nervous systems can work together but also can work independently

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8
Q

What is the ANS: regulating internal functions?

A

ANS
- regulating internal functions (without conscious awareness)

  1. sympathetic division
    - forms ipsilateral connections
  • arouses the body for action
    EX: increases heart rate & blood pressure)
  • mediates the fight or flight response
  • in charge of arousing
  1. Parasympathetic division
    - opposite of the sympathetic –> prepares the body to rest and digest
  • reverses the fight or flight response

**both can be active at the same time
- can be separate but also on –> at the same time
- we can see if one’s more than the other (increase in heart rate)

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9
Q

Describe the ANS diagram figure

A

sympathetic ganglion
- groups of nerves together that serves a function

  • the 2 ANS pathways exert opposing effects
  • all fibers connect at “stops” –> this is formed by the ganglia from the CNS to target ANS organs

Left
- arousing sympathetic fibers that connect to chain of ganglia near the spinal cord

Right
- calming parasympathetic fibers that connect individual ganglia near target organs

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10
Q

What is the Enteric Nervous system: Controlling the Gut?

A

ENS
- network of neurons embedded in the lining of the gastrointestinal tract

What it controls:
1. bowel motility
2. secretion
3. blood flow to permit fluid & nutrient absorption
4. support waste elimination

**functions largely independently of the ANS

  • brain & ENS connect through the ANS **especially through the vagus nerve
    EX: helps out with the digestion aspect

**the ENS is sometimes called the “second brain”
- very complex
- lots of sensations by the microbiota

EX: people who have anxiety and depression
- they don’t have the same bacteria and organisms that are living in normal individuals **essentially the gut doesn’t work the same

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11
Q

Describe the Enteric Nervous System (ENS) *need to know this

A

ENS
- formed by network of neurons embedded in the lining of the gastrointestinal tract

  • congregation of neurons form = ganglia
    –> the ganglia then sends projections to the ANS and CNS (in part through the vagus nerve) = also known as cranial nerve 10 to control the gut
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12
Q

What is Microbiome?

A

ENS
- interacts with gut bacteria known collectively as = microbiome

: 3.9 x 10^13 microbiota populate the adult gut **that outnumbers the host cells by a factor of 1:3

: microbiota influences the nutrient absorption

ex: IBS
- we can take bacteria from someone whose healthy and put it into their own intestines
**the microbiota can be helpful for the intestines

: is the source of neurochemicals that regulate array of physiological/psychological processes

  • this relationship inspired development of class of compounds known as psychobiotics
    **live microorganisms used to treat behavioral disorders)

: micro can influence both CNS and ENS = leading to changes in behavior

EX: its important to know what we eat
–> we tend to eat things that have prebiotic (such as yogurt or fermented foods)

–> these microbiotas are in charge of keeping us healthy and our minds healthy and normal

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13
Q

What are the Ten Principles of Nervous system Function? (1)

A

neural circuits = series of neurons interconnected by synapses that subserve a function when activated

Sherrington & Adrian
- neuron = excitable cell

Monosynaptic cell
EX: Patellar
–> this goes directly to the dorsal root
(most of the things we do is monosynaptic)

Polysynaptic cell

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14
Q

What are the 10 principles of the Nervous system function? (2)

A
  • sensory & motor division pervade the Nervous system

: segregation of sensory & motor functions exists throughout the nervous system
**described by the law of Bell and magendie that exists throughout the nervous system

  1. intrafusal muscle system
    - groups of fibers that are really deep within the muscle

Main function
- sensory of the muscle functions and tendons

  1. Extrafusal muscle system
    **does most of the work
  • sensory & motor functions = divided in cortex in 2 ways
  1. separate sensory & motor cortical regions process particular set of sensory inputs
  2. entire cortex = organized around sensory & motor distinction
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15
Q

What are the 10 principles of nervous system function? (3)

A
  • CNS functions on multiple levels
  • is organized hierarchically and in parallel

: nature of the neural connectivity –> suggest the brain has both serial (or hierarchical) & parallel
circuitry

: unconnected regions **must have widely differing functions
–> this is bc not all cortical regions are connected to one another

  • hierarchical circuit hooks up linear series of all regions concerned w a particular function

EX: vision
– in serial system: the info from the eyes goes to regions that detect simplest properties (such as color or brightness)

  • this info is passed along to another region that determines shape –> then to another that measures movement
    **and so on until at the most complex level the information is understood

**essentially, information flows sequentially from regions that make simpler discrimination –> to regions that make more complex discrimination in the hierarchy

Figure 2-34: Modules of Neural information Processing

A) simple hierarchical model of serial cortical processing
1. primary
2. secondary
3. tertiary

B) in distributed hierarchical processing model
–> each of several processing streams have multiple levels **areas at each level interconnect

Additional Notes
- although the brain has many serial connections –> many expected connections are missing

EX: visual system
- not all cortical regions are connected to one another

figure 2-34B
- shows the information flow in a distributed hierarchy

  • although these multiple parallel pathways are connected to one another
    –> those connections are more selective than connection in a purely serial circuit
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16
Q

What are the 10 principles of nervous system function? (4)

A

many brain circuits = crossed

  • each hemisphere receives sensory stimulation from the opposite (contralateral) side of the body
    **also controls muscles on the contralateral side

EX: most hemisphere will receive info from the opposite side of the body
**when we’re smelling from one nostril –> it will go into a separate region

**motor commands are contralateral

  • A crossed nervous system have to join both sides of the perceptual world together
    –> in order to do so: innumerable neural connections **links brain’s left & right sides

–> connecting cable = corpus callosum (200mill) nerve fibers join left/right cerebral hemispheres
**allowing them to interact

: 4 important exceptions to crossed-circuit principle:

  1. olfactory sensation & somatic
  2. autonomic
  3. enteric PNS connections

crossed organization
- explains why people who have a stroke or other damage to the left cerebral hemisphere –> have difficulty sensing stimulation to the right side of the body **or moving body parts on the right side

**also true for people whose stroke occurs in the right cerebral hemisphere

17
Q

what are the 10 principles of the nervous system function? (5)

A

brain functions = localized & distributed
- Broca, wernicke/others demonstrated particular functions are = localized

EX: Broca
when damage occurs to ventroposterior region of the frontal lobes –> people are unable to produce spoken language

EX 2: Wernicke
- found that damage occurs to a different region
–> left posterior superior temporal gyrus pronounced deficits in language comprehension result

Result
- Broca/Wernicke showed that particular functions are localized

  • some brain regions are prime importance to adults

**function is still being distributed, although its localized

  • within a brain region –> function is among neurons that do the information processing
    **if some neurons are destroyed –> remaining neurons can continue carrying out the function
  • only when majority of neurons within specific functional region = destroyed we see catastrophic failure of the associated function to occur
18
Q

what is the 10 principles of the nervous system function? (6)

A

the brain is symmetrical/asymmetrical

  • hemispheres look like mirror images –> some dissimilar features exist

: cortical asymmetry = essential for integrative tasks
(including language and body control)

EX: language
- if language zone existed in both hemispheres –> each connected to one side of the mouth (we would be able to talk out of both sides of our mouth at once)
**that would make talking awkward

solution
- locate language control of the mouth on one side of the brain –> orgaining the brain allows us to speak w a single voice

  • language = typically situated on left side
    –> spatial functions = right side
  • hemispheres have different functions although they look similar

EX: logic vs creative (this is the reason why the brain is asymmetrical

19
Q

what are the 10 principles of the nervous system function? (7)

A
  • the NS works by juxtaposing excitation & inhibition

: in addition to making movements
–> the brain also prevents
1. movements

  1. excitation (increased neural activity)
    –> to produce some action
  2. inhibition (decreased neural activity)
    - to prevent other actions

EX: tourettes & Parkinsonism

: a brain injury in a region that initiates speech may render a person unable to talk (a loss of behavior)

Tourettes
- a person w an abnormality in a region that inhibits inappropriate language (swearing) **may be unable to inhibit this form of speech
**inhibition isn’t working properly

Parkinsons
- can have uncontrollable shaking of hands
**bc neural system that inhibits movements has failed

  • often have difficulty initiating movements/ appear frozen bc they can’t generate excitation needed to produce deliberate movements
  • juxtaposition of excitation & inhibition = central to the way the brain produces behavior **can also be seen at level of individual neurons
  • All neurons evince a spontaneous activity rate –> can either increase (excitation) or decrease (inhibition)
20
Q

what are the 10 principles of nervous system function? (8)

A
  • the brain divides sensory input for object recognition & motor control

: sensory systems
- evolve 1st for influencing movement **before thing recognition
**2 separate processes

  • visual information (in cortical circuit)
    –> travels from eyes to thalamus to visual regions of the occipital lobe

–> from the occipital cortex (info then diverges along 2 separate pathways)

  1. ventral stream
    - leads to temporal lobe for object identification

ventral stream injuries
- blind for object recognition
**cannot distinguish a cup from a spoon

**however, they can shape their hands correctly when being asked to reach for an object they can’t identify

  1. dorsal stream
    - which goes to the parietal love to guide movements relative to objects

dorsal stream injuries
- can recognize objects –> but can be clumsy in reaching movements bc they don’t know the correct form for hand postures until they contact objects

  • important implications for understanding brain organization

3 important implications
1. dorsal/ventral visual systems = exemplify parallel information processing in the brain

  1. we might think we’re aware of our entire sensory world **sensory analysis required for some movements = not conscious
  2. unconscious/conscious brain processing underlies important difference in our cognitive functions

**unconscious movement system
- always acting in present
- in response to ongoing sensory input

**conscious object recognition system
- allows us to escape present / bring to bear info from the past (forming neural basis of enduring memory)

21
Q

what are the 10 principles of the nervous system function? (9)

A
  • the NS produces movement in perceptual world the brain constructs

EX; relation to sensations, memories, and myriad other forces/factors

: individual realities –> both between/ within species = are mere approximations of what is actually present

EX: we only have 3 primary colours that make up our perception vs the rainbow shrimp that has many color receptors than us

: the brain of individuals develops in a particular set of environmental circumstances on a plan common to that species

**the behavior the brain produces is directly related to the world that the brain has constructed

22
Q

what are the 10 principles of the nervous system function? (10)

A

neuroplasticity = hallmark of nervous system functioning

  1. experience alters the brain’s organization –> neuroplasticity = required for memory & learning
  2. neural connection changes = required for information storage
    **forgetting = due to loss of memory connections
  3. plasticity can be beneficial
    - recovery from brain injuries/diseases
    - normal aging