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BIOL155 > Nervous System Organization > Flashcards

Nervous System Organization Flashcards

1
Q

Describe the relationship between sensory neuron/interneuron and excitatory/inhibitory

A

If the sensory neuron is excitatory then the interneuron must be inhibitory

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2
Q

Can neural tissue be repaired or replaced if it is damaged? (in the PNS/CNS)

A

If you cut a neuron’s axon, it will usually regrow if it is in the PNS (if the Schwann cells are still there), but will not regrow if it is in the CNS

If you cut the axon far enough from its cell body, there is a chance that it will regrow!

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3
Q

What makes up the CNS and the PNS?

A

CNS and PNS make up most of the nervous system

CNS - mostly interneurons and synapses (white and gray matter / neurons and glial cells)

PNS - mostly sensory and motor neurons (neurons and glial cells)

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4
Q

Describe the organization of the CNS

A

The CNS has the MAJORITY of the neurons and synapses

Contains majority of neuron cell bodies

Also contains layers of extra protection for its tissues inside the skull and vertebral column

White matter in the CNS acts as a highway connecting/sending information from one place to another

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5
Q

What is cerebrospinal fluid (CSF)

A

Different from extracellular fluid - specialized for the central nervous system

Fluid that continually flows in the cavities of the brain’s ventricles and around the brain/spinal cord

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6
Q

What are the four characteristics of CSF?

A
  1. CSF is produced by the ependymal cells in the brain’s ventricles (get the fluid from blood supply)
  2. CSF drains wastes from CNS tissue through glymphatic pumping
    - assisted by astrocytes
    - pumped through every bit of brain tissue
    - takes away toxins that are harmful for the brain (happens when sleeping)
  3. CSF cushions impact between CNS and skull
    - fills space between the spinal cord and vertebra / brain and skull
    - contained in layers of membrane called meninges
  4. Returns CSF to bloodstream
    - constantly being produced, so it needs to be drained or else pressure will build up
    - valves coming out of the second/third layers of meninges where fluid can be drained out
    - fluid is circulated, taking away wastes and returning to the bloodstream
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7
Q

What is the blood brain barrier (BBB)?

A

A barrier that restricts the transport of water and molecules between the blood and CNS

There is a tight epithelium/endothelium lining blood vessels that only allows lipophilic molecules or hydrophilic molecules with specific transport proteins to reach the CNS

Materials can only pass from brain to blood if they can pass through the walls of the epithelium

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8
Q

Endothelial cells in the CNS express high numbers of what kind of transporters?

A

Endothelial cells in the CNS express high numbers of glucose transporters and co-transporters

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9
Q

What kind of glial cell controls blood vessel diameter?

A

Astrocytes!

Astrocytic processes control blood vessel diameter, and thus can rapidly adjust local blood flow

Determines how much oxygen can get to a particular section

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10
Q

What do functional MRI (fMRI) scans do?

A

Estimate activity in different CNS locations based on the amount of blood flow under different conditions

Whether the astrocytes are dilating the blood vessels for increased blood flow

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11
Q

What are the two main components of the central nervous system?

A
  1. Spinal cord
  2. Brain
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12
Q

What is the function of the PNS?

A
  • collect and relay sensory/afferent info
  • relay motor/efferent commands
  • contains the sensory and motor nerves
  • path for nerves to go to and from the spinal cord
  • nerves carrying commands to efferent organs coming from CNS
  • system of wireless relaying
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13
Q

What is the function of the CNS (brain/spinal cord)?

A

BRAIN
- contains the majority of the (inter)neurons and synapses
- comparing all sorts of sensory info coming through
- complex processing/remembering/etc
- conscious awareness
- source of voluntary control (movements)

SPINAL CORD
- initial processing of sensory/afferent info
- executes motor/efferent commands to skeletal muscles
- in charge of reflexes (action potentials in skeletal muscles that do not pass through the brain)
- most motor neurons making NMJ can be found here
- generating streams of action potentials

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14
Q

The destination or source of the most efferent(motor) and afferent(sensory) axons of the PNS are located at the _____________

A

Spinal cord

And it is topographically organized by regions

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15
Q

What are the four regions of the spinal cord?

A
  1. Cervical
  2. Thoracic
  3. Lumbar
  4. Sacrum
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16
Q

Each spinal cord segment shows the same organization of afferent and efferent nerve roots: Describe the two types of roots

Note: Roots enter and leave the spinal cord

A
  1. Dorsal root = ENTERING
    - contains afferent axons
    - has a bulge (ganglia)
    - sensory axons entering the spinal cord
  2. Ventral root = LEAVING
    - contains efferent axons
    - handles motor information
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17
Q

What would happen if your dorsal root was damaged?

A

Since the dorsal root is in charge of handling sensory information (afferent neurons)

If it was damaged, then that would result in sensation deficit = numbness

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18
Q

What would happen if your ventral root was damaged?

A

Since the ventral root is in charge of handling motor information (efferent neurons)

If it was damaged, then that would result in movement deficit = paralysis
(You would not be able to move your skeletal muscles)

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19
Q

What region does the cervical spinal cord segment process information to and from?

A

Upper limbs

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20
Q

What region does the lumbar spinal cord segment process information to and from?

A

Lower limbs

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20
Q

What region does the thoracic spinal cord segment process information to and from?

A

Trunk

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21
Q

What region does the sacral spinal cord segment process information to and from?

A

Lower limbs / ano-genital region

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22
Q

Describe the ratio of white matter to grey matter as you get closer to the brain up the spinal cord

A

Amount of white matter increases as you get closer to the brain

Ex: Sacral segment has the least white matter: grey matter, where the cervical segment has the most white matter: grey matter

White matter thickness increases steadily as you go from inferior to superior segments, but there are enlargements of gray matter in the cervical and lumbar regions

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23
Q

What symptom would be experienced if:

There was a squeezing of VENTRAL ROOT from the bulging CERVICAL intervertebral disc

A

Motor neuron damage = Paralysis in the upper limbs

Weakness/paralysis of upper limbs or hand

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24
Q

What symptom would be experienced if:

There was DORSAL ROOT avulsion (detachment) in SUPERIOR SACRAL segments

A

Sensory neuron damage = Numbness in the lower limbs/ano-genital region

Numbness of posterior surface of lower limb

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25
Q

What symptom would be experienced if:

There was a rupture of the L1 or L2 spinal nerve

A

The spinal nerve connects to both the dorsal and ventral root

Would result in both motor and sensory neuron damage = weakness, paralysis, and numbness

Numbness of proximal thigh AND lower limb weakness or paralysis

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26
Q

What are the two regions of gray matter?

A

Dorsal horn
Ventral horn

27
Q

What is the dorsal horn? Characteristics and functions

A

Sensory processing
- affects sensation

28
Q

What is the ventral horn? Characteristics and functions

A

Contains motor neurons, dendrites, and somata (cell bodies)

29
Q

Dorsal regions of the spinal cord refer to the front / back

A

back / upperside

30
Q

Ventral regions of the spinal cord refer to the front / back

A

front / underside

31
Q

Does the withdrawal reflex arc take place in white or gray matter?

A

Simple spinal reflexes such as the withdrawal reflex are contained within circuits in the spinal segment’s GRAY MATTER

32
Q

Trace the path of a spinal withdrawal reflex

A

Sensory neuron -> dorsal root

Interneuron

Motor neuron -> ventral root

33
Q

What kind of information does the dorsal column (white matter) of the spinal cord segment carry?

A

GOING UP!

Ascending sensory relay to brain

  • carrying sensory information
  • affecting arms and legs
  • only way info can go from lower limbs to the brain
34
Q

What kind of information does the lateral column (white matter) of the spinal cord segment carry?

A

GOING DOWN!

Descending motor commands from brain to motor neurons

  • affecting everything in the lower limbs
35
Q

White matter columns are largest in the ______ levels of the spinal cord

They are smallest in the ________________________

A

Largest in superior levels of the spinal cord
- axons relaying between the brain & all spinal levels

Smallest in the sacral spinal cord
- only containing axons communicating with sacral nerves/sacral motor neurons

36
Q

What is the function of white matter in spinal cord segments?

A

To act as highways communicating what is coming in and going out of the spinal cord

37
Q

What symptoms would be experienced if there was:

Damage in dorsal column

A

Dorsal column = ascending white matter
- sensory information relay to brain affecting arms and legs

Numbness in arms, legs, and torso
(anything ascending up the spinal cord)

38
Q

What symptoms would be experienced if there was:

Damage in dorsal horn

A

Dorsal horn = gray matter
- in charge of spinal reflexes
- sensation

Impaired withdrawal reflexes (sensory)

39
Q

What symptoms would be experienced if there was:

Damage in lateral column

A

Lateral column = white matter
- descending motor commands
- affects lower limbs

Paralysis in lower limbs

40
Q

What symptoms would be experienced if there was:

Damage in ventral horn

A

Ventral horn = gray matter
- in charge of motor neurons, dendrites, and cell bodies

Impaired withdrawal reflexes (motor)

41
Q

What are the anatomical regions of the brain?

A
  1. Forebrain
  2. Midbrain
  3. Hindbrain
42
Q

What are the physiological regions of the brain?

A
  1. Cerebrum
  2. Diencephalon
  3. Cerebellum
  4. Brainstem
43
Q

What is the telencephalon of the brain?

A

Commonly known as the cerebral hemispheres

There are three main components to the telencephalon:

  1. Limbic system
  2. Basal ganglia
  3. Cerebral cortex
44
Q

Where are the neuron cell bodies in the human brain found?

A

Most neuron cell bodies in the human brain are found within the CEREBRAL CORTEX of the telencephalon

45
Q

What are the 5 lobes of the cerebral cortex

A
  1. parietal lobe
  2. occipital lobe
  3. frontal lobe
  4. temporal lobe
  5. insula
46
Q

What are the 6 primary cortical areas of the cerebral cortex?

A

M1: primary motor cortex
G1: gustatory cortex
O1: olfactory cortex
A1: primary auditory cortex
V1: primary visual cortex
S1: primary somato-sensory cortex

47
Q

What are the functions of the frontal lobe?

A
  • executive lobe
  • actions
  • motor control
  • problem-solving
  • speech production
48
Q

What are the functions of the parietal lobe?

A
  • taste
  • touch perception
  • temperature
49
Q

What are the functions of the temporal lobe?

A
  • hearing / auditory perception
  • memory / information retrieval
  • language comprehension
50
Q

What are the functions of the occipital lobe?

A
  • vision
51
Q

What are the functions of the primary motor cortex?

A

to generate signals to direct the movement of the body

52
Q

What are the functions of the gustatory cortex?

A

perception of taste and flavour

53
Q

What are the functions of the olfactory cortex?

A

processing and perception of odour

54
Q

What are the functions of the primary auditory cortex?

A

bring about the conscious perception of sound

provide a basis for the comprehension and production of meaningful utterances

55
Q

What are the functions of the primary visual cortex?

A

to receive, segment, and integrate visual information

56
Q

What are the functions of the primary somato-sensory cortex?

A

to detect sensory information from the body regarding temperature, proprioception, touch, texture, and pain

57
Q

What are the functions of the brainstem?

A

involuntary responses

58
Q

What are the functions of the cerebellum?

A

balance and coordination

59
Q

Where do most spinal descending and ascending pathways originate from or lead to?

A

PRIMARY CEREBRAL CORTICAL AREAS

Most spinal descending and ascending pathways terminate at or originate from the primary cerebral cortical areas

60
Q

In ascending projections, what two areas relay synapses?

A
  1. thalamus
  2. hindbrain
61
Q

Do primary cortical areas connect to spinal nerves on the same side of the body?

A

NO!

Primary cortical areas are directly connected to spinal nerves on opposite sides of the body

In other words, they process info coming from or going to the other side of the spinal body

62
Q

What does decussation mean?

A

Decussation means crossing the midline

It describes how the primary cortical areas are connected to spinal nerves on the opposite sides of the body

63
Q

The brain is lateralized: What does this mean?

A

The brain is separated so that different sides dominant certain functions

This works hand in hand with the decussation of the hindbrain, in that info coming from the left side is processed by the right hemisphere whereas info coming from the right side is processed by the left hemisphere

64
Q

What is an electroencephalography (EEG) and what is its purpose?

A

A machine that measures electrical fields generated by the activity of neurons in the brain that can be detected from electrodes on the scalp -> used to help map the origin of epileptic seizures

65
Q

How do EEGs help map out the origin of epileptic seizures?

A

The electrodes nearest the abnormal brain tissue that initiates the seizure will show abnormal activity before other electrodes

By surgically removing this abnormal brain tissue, some forms of epilepsy can be cured!

66
Q

How does mild electrical stimulation of the cortex probe for seizure foci and map precise sub-regions within primary cortices?

A

Lightly stimulating the motor strip (M1) triggers twitch movements of different muscles/parts of the body, depending on exactly where you stimulate

Stimulating in a primary sensory cortex creates phantom sensations for that sensory modality

BIOL155 (34 decks)

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