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BIOL155 > Nervous System - Overview > Flashcards

Nervous System - Overview Flashcards

1
Q

A patient reports that they are having trouble moving ONE hand. In which system is the problem most likely coming from?

A) Nervous system
B) Endocrine system
C) Reproductive system

A

A) Nervous system

There must be an issue in the nervous system so that no nerve can be fired to the muscle tissue/NMJ to contract the muscle

Because the problem is so localized (only ONE hand is affected), this is an indication that it is coming from the nervous system, because the nervous system is highly specific

Why isn’t it the other systems?

B) Endocrine system - hormone problems would affect both hands, and not just one hand

C) Reproductive system - does not have any correlation to moving one hand(?)

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2
Q

If someone is unable to move their hand, why would you get out a hammer and nail?

A

To gently tap the patient’s immobile hand with the hammer and nail to see if they react to it (SENSATION)

Or more specifically to see if they have REFLEX

Testing for SENSATION and REFLEX

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3
Q

What are the main function of the nervous system? Describe some characteristics of the nervous system

A
  1. Coordinate the rest of the body
  • specialized for rapid and specific information transfer
  • highly specific and localized
  • tells the body what to do
  • direct immediate and delayed responses to stimuli, usually by coordinating the activities of other organ systems

One of the two organ systems that tells the body what to do (nervous system and endocrine system)

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4
Q

Describe the gross anatomy of the nervous system

A

Hub & Spoke Organization

  • long peripheral nerves running to and from the brain and spinal cord to specific locations
  • central nervous system consists of the brain and spinal cord
  • branches out with nerve endings going in and out of the hub
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5
Q

Describe the histology of the nervous system

A

Neurons

  • interconnected cells with really long processes/projections make up all parts of the nervous system
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6
Q

There are two ways to divide the nervous system: What are they?

A

Anatomically and functionally

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7
Q

What are the three ANATOMICAL components of the nervous system?

A
  1. Central Nervous System (CNS)
  2. Peripheral Nervous System (PNS)
  3. Enteric Nervous System (ENS)
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8
Q

What is the Central Nervous System? (CNS)

A
  • found within the vertebrae and cranial bones = BRAIN AND SPINAL CORD
  • enclosed within bony shells
  • information processing, integrates, processes, and coordinates sensory input
    and motor commands
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9
Q

What is the Peripheral Nervous System? (PNS)

A
  • outside the skull and spine, but directly connected to the CNS
  • leaves the CNS, but every part of the PNS has a direction connection to the CNS
  • includes all the nervous tissue outside
    the CNS, except for that of the ENS
  • PNS carries motor commands from the
    CNS to peripheral tissues and systems
  • contains the somatic and autonomic nervous system
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10
Q

What is the Enteric Nervous System? (ENS)

A
  • neural cells within the DIGESTIVE SYSTEM which only indirectly connect to the CNS via the PNS
  • separate set of neurons that embedded in the walls of digestive organs that aren’t directly connected to the CNS
  • distinguished from the PNS nerves because they can operate independently
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11
Q

Differentiate the CNS from the PNS

A

CNS - BRAIN AND THE SPINAL CORD
- houses the vast majority of all neuronal cell bodies and their processes
- carries most of the weight of the nervous system

PNS - PERIPHERAL NERVES AND GANGLIA

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12
Q

Which parts of a neuron are in the CNS and which parts are in the PNS?

A
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13
Q

CNS: Brain

A

Contains more neurons than the spinal cord

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14
Q

CNS: Spinal cord

A

Contains most connections with the PNS

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15
Q

PNS: Nerves

A

Collections of long neuronal processes interacting with non-neuronal cells/organs
- go everywhere / long skinny projections

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16
Q

PNS: Ganglia

A

Groups of cell bodies outside the CNS
- bulges on nerves outside of the CNS
- group of cells

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17
Q

What are the three FUNCTIONAL classes of the nervous system?

A
  1. Sensory neurons (RECEPTORS) - afferent neurons
  2. Interneurons (INTEGRATORS) - spinal cord processing
  3. Motor neurons (EFFECTORS) - efferent neurons
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18
Q

What are sensory neurons?

A

Receptors
- passes information FROM OUTSIDE INTO the nervous system
- take info from outside the nervous system inside
- receives the information

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19
Q

What are receptors?

A

Receptors are sensory structures that detect changes in the internal or external environment

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20
Q

What are interneurons?

A

Integrators
- pass information between other neurons
- receives info from neurons and pass it to another neuron
- vast majority of neurons in the nervous system are interneurons
- only interact with other neurons

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21
Q

What are integrators?

A

Integrators are the brain and spinal cord

The brain functions in interpreting the messages from the nervous system

The spinal cord plays a role in relaying the information from the brain and different parts of the body

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22
Q

What are motor neurons?

A

Effectors
- pass information from neurons TO NON-NEURONAL CELLS
- receives info from interneurons and passes it to non-neuronal cells
- make other organs/tissues of the body do something

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23
Q

What are effectors?

A

Effectors are target organs and tissues that
respond to neural motor commands

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24
Q

Trace the path of a reflex arc

A
  1. Stimuli/receptor
  2. Sensory neuron
  3. Interneuron
  4. Motor neuron
  5. Effector/tissue/organ
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25
Q

How does the nervous system process and transfer information?

A

The nervous system uses electrical signals within excitable cells and chemical signals between cells

  • receiving and passing along information from non-neurotic cells to neurons, neurons to neurons, and from neurons to non-neurotic cells
  • modifies, filters, and integrates information
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26
Q

Match the following with the correct functional class of the nervous system:

  1. Receptor
  2. Effector
  3. Integrator
A
  1. Receptor
    - sensory neuron
  2. Effector
    - motor neuron
  3. Integrator
    - interneuron
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27
Q

Where are electrical signals used?

A

Within excitable cells

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28
Q

Where are chemical signals used?

A

Between excitable cells

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29
Q

What are electrical signals?

A
  • brief changes in the transmembrane potential of the plasma membrane
  • two types: graded potential and action potential
  • travels up and down the plasma membrane, passing information from one end of the cell to the other (WITHIN CELLS)
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30
Q

What are chemical signals?

A
  • release of neurotransmitters into synapses (gaps) between neurons
  • neuron communicating to another cell via sending neurotransmitters
  • BETWEEN CELLS !!

Ex: ACh is a neurotransmitter

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31
Q

How are action potentials different from graded potentials?

A

Action potential - short, sharp, spike
- a rapid sequence of changes in the voltage across a membrane
- associated with the ratios of ions inside/outside of the membrane
- occurs down the axon away from the cell body

Graded potential - changes in the membrane potential that vary in size
- different shapes, sizes, and directions
- involving dendrites and cell bodies

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32
Q

Where do action potentials take place? Where do graded potentials take place?

A

AP
- occur down the axon, away from the cell body

GP
- occur in dendrites, cell bodies, or axon terminals

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33
Q

Differentiate electrical signals from chemical signals

A

in a chemical synapse, the nerve impulse is transmitted chemically via neurotransmitters
- BETWEEN CELLS

in an electrical synapse, the nerve impulse is transmitted electrically via channel proteins
- WITHIN CELLS

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34
Q

True or False: The term CNS refers to the brain and the brainstem

A

FALSE

  • the brainstem is part of the brain
  • the CNS refers to the brain and the spinal cord
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35
Q

True or False: The PNS is one of three functional divisions of the NS

A

FALSE

  • the PNS is one of the ANATOMICAL divisions of the NS
  • the three FUNCTIONAL classes of the NS include sensory neurons, interneurons, and motor neurons
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36
Q

True or False: Skeletal muscles are the organ system in the body that can be directly controlled by neurons

A

FALSE

  • the nervous system can also control non-skeletal muscles such as the heart (cardiac muscle)
  • it can control all three types of muscle tissue (skeletal, cardiac, and smooth)
  • it can control any organ system
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37
Q

True or False: Interneurons are primarily found within the CNS

A

TRUE

  • most neurons are found in the CNS
  • enclosed in bony shells to protect the neurons
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38
Q

True or False: A nerve is not the same thing as an individual neuron

A

TRUE

  • a nerve is a bundle of neurons
  • made up of parts of neurons
  • but they are not neurons
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39
Q

True or False: Action potentials are electrical signals that pass information across the gaps between neurons

A

FALSE

  • electrical signals pass information within cells from one end to the other
  • in the neuron, specifically the axon
  • chemical signals pass information from cell to cell (between cells)
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40
Q

What are the two classes of cells in the nervous system?

A
  1. Neurons
  2. Neuroglia
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41
Q

What are neurons?

A
  • a type of nerve cell which transmits information
  • the principal cells of nervous tissue
  • longest cells of the body
  • made of 4 major structural components
  • neurons have neurites

Neurons are nerve cells that send messages all over your body to allow you to do everything from breathing to talking, eating, walking, and thinking

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42
Q

What are neuroglia?

A
  • play numerous supporting roles
  • also known as glial cells

The neuroglia are a diverse class of cells that provide developmental, physiological, and metabolic support for neurons

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43
Q

What are neurites?

A

elongated cell processes/projections found in neurons
- includes the dendrites and axon
- make up neurons

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44
Q

What are the 4 structural components/major regions of a neuron?

A
  1. Dendrites
  2. Cell body (soma containing nucleus)
  3. Axon
  4. Axon terminals
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45
Q

What are glial cells?

A
  • makes up half of all cells in nervous tissue
  • protect and maintain neurons
  • play supporting roles
  • also act as glue to glue neurons together
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46
Q

What is dendrite? (Characteristics)

A
  • receives inputs from other cells
  • typical dendrites are highly
    branched, with each branch bearing
    fine/short processes called dendritic spines
  • CNS neurons receive most of their information primarily at the dendritic spines
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47
Q

What is a cell body/soma? (Characteristics)

A
  • receives inputs and produces proteins
  • contains organelles that provide
    energy and synthesize the chemical
    neurotransmitters that are important
    in cell-to-cell communication
  • tends to also receive inputs from other cells
  • houses the nucleus and ribosomes
  • makes proteins and expresses genes
  • proteins made must be shipped
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48
Q

What is an axon? (Characteristics)

A
  • transmits action potentials to next cell
  • longest, only one that comes off the soma
  • made of four components
  • where the action potential is actually generated
  • long cytoplasmic process that extends away from the cell body
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49
Q

What is the longest neurite?

A

The longest neurite is almost always the AXON

  • axis neurite
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50
Q

Neurons are highly ________ cells with different cell compartments specialized for different functions

A

Neurons are highly POLARIZED cells with different cell compartments specialized for different functions

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51
Q

What is an axon terminal? (Characteristics)

A
  • converts action potentials to chemical signals
  • allows for the passage of info from one neuron to the next
  • takes AP to the axon terminals
  • specializations where chemical signaling happens
  • release of chemicals across the gaps to the next neuron
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52
Q

Differentiate dendrites, axons, and cell bodies

A

Dendrites - receive stimuli from the
environment or from other neurons

Cell bodies - contains the nucleus and
other organelles

Axons - carries information toward other cells

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53
Q

What are the four components of an axon?

A
  1. Axon hillock
    - origin of the axon from the cell body
  2. Axon initial segment
    - lies distally adjacent to the axon hillock
    - where an action potential is initiated.
  3. Axolemma
    - specialized portion of the plasma membrane that surrounds the cytoplasm (axoplasm) of the axon
  4. Axoplasm
    - cytoplasm for nerve cells
    - contains neurofibrils, neurotubules,
    small vesicles, lysosomes, mitochondria,
    and various enzymes.
54
Q

Information flow within a neuron is __________________ from dendrite to axon to axon terminal

A

UNIDIRECTIONAL

55
Q

What does it mean that information flow in a neuron is unidirectional?

A

dendrite -> axon -> axon terminal
1. sensory neuron
2. interneuron
3. motor neuron

  • information only travels in one direction
56
Q

What are the three ways to classify neurons?

A
  1. Classified anatomically based on neurite arrangement
  2. They could be classified with the type of neurotransmitter that they carry
  3. Classified functionally based on which organ system they are connected to
  • shape
  • location
  • type of chemical released
57
Q

What are the four classes of neuron types?

A
  1. Multipolar
  2. Bipolar
  3. Pseudo-unipolar
  4. Anaxonic
58
Q

What are multipolar neurons? (Characteristics)

A
  • many (2+) dendrites and only one axon
  • axons can branch later on but there is only one that comes off the soma
  • most common type in the CNS
  • axons of multipolar
    neurons can be as long as
    those of unipolar neurons

The longest carry motor commands
from the spinal cord to small
muscles that move the toes

59
Q

What are bipolar neurons? (Characteristics)

A
  • one dendrite and one axon
  • two distinct processes—one
    dendritic process that branches
    extensively at its distal tip, and one
    axon—with the cell body between
    the two
  • rare but occur in special sense organs,
    where they relay information about sight, smell, or hearing from receptor cells to other neurons
  • small
60
Q

What are pseudo-unipolar neurons? (Characteristics)

A
  • one axon connected to the soma but the dendrite connects to the axon
  • include sensory neurons in the PNS (most in the PNS are unipolar)
  • dendrites and axon are continuous—basically, fused—and the cell body lies off to one side
  • have very long axons

The longest are those carrying
sensations from the tips of the toes to the
spinal cord.

61
Q

What are anaxonic neurons? (Characteristics)

A
  • many neurites that act as both dendrite and axon terminals
  • VERY RARE
  • small and lack anatomical features that distinguish dendrites from axons; all the cell processes look alike
  • functions are poorly understood
62
Q

Give an example of a multipolar neuron

A

Most common type of neuron in the CNS

63
Q

Give an example of a bipolar neuron

A

Found in the retina of the eye, the roof of the nasal cavity, and the inner ear

64
Q

Give an example of a pseudo-unipolar neuron

A

Spinal and cranial nerve ganglia

65
Q

Give an example of an anaxonic neuron

A

Interneurons seen in the ganglia of the motor systems of various arthropods, including crayfish, locusts and cockroaches

66
Q

How many types of neurotransmitters can a neuron release?

A

Each neuron can only release one single type of neurotransmitter at its axon terminals

  • a neuron can be attached to multiple axon terminals, but they will all release the same type of neurotransmitter chemical
67
Q

Different neuronsnsmitter effects depend on the ____________present on the next cell.

A

Different neurons release DIFFERENT neurotransmitters.

Transmitter effects depend on the RECEPTORS present on the next cell

68
Q

What are the 8 most common/notorious neurotransmitters and what do they do?

A
  1. Noradrenaline/Norepinephrine - regulation of arousal, attention, cognitive function, and stress reactions; concentration
  2. Adrenaline/Epinephrine - “fight or flight” response, produced in stressful/dangerous situations
  3. Dopamine - chemical released in the brain that makes you feel good (temporary)
  4. Serotonin - controls your mood and is responsible for happiness (long-lasting)
  5. Gaba - calming effect, low levels cause anxiety, high levels improve focus
  6. Glutamate - memory neurotransmitter
  7. Acetylcholine - learning neurotransmitter, activates muscles in body
  8. Endorphins - euphoria neurotransmitter, reduces pain, sensation
69
Q

What are the two subdivision systems of the peripheral nervous system?

A
  1. Somatic nervous system
  2. Autonomic nervous system
70
Q

What is the somatic nervous system?

A
  • motor neurons innervating skeletal muscles
  • mostly about the motor system involving the skeletal muscle
  • motor neurons -> axon terminals -> skeletal muscles to make it contract
  • operates in circuits

Ex: sensory neurons in the skin, joints, muscles looking at the integument and skeletomuscular system

71
Q

What is the visceral/autonomic nervous system?

A
  • motor (effector) neurons innervating tissues OTHER THAN skeletal muscles
  • sensory neurons innervating visceral organs

Ex: heart, lungs, liver, pancreas, etc.
- affecting smooth muscle, cardiac muscle, glands, adipose / squishy organs

72
Q

Differentiate the somatic nervous system from the autonomic nervous system?

A

Somatic = skeletal muscles
Autonomic = smooth muscle, visceral organs, cardiac muscles, etc.

73
Q

What are the two subdivisions of the autonomic nervous system?

A
  1. Parasympathetic division
  2. Sympathetic division
74
Q

Which neurotransmitter is involved in the parasympathetic division? Sympathetic division?

A

Parasympathetic division?
- acetylcholine
- rest and digest

Sympathetic division?
- norepinephrine
- fight or flight

75
Q

True of False: The somatic nervous system is voluntary and the autonomic nervous system is involuntary.

A

FALSE

Autonomic nervous system IS INVOLUNTARY because you cannot control it and the actions are unconscious

BUT the somatic nervous system is not automatically assumed to be voluntary

76
Q

True or False - Explain why.

“The somatic nervous system creates voluntary movements and the autonomic nervous system creates involuntary movements.

A

The somatic nervous system can play a role in regulating voluntary movements, but it is also involved in involuntary movements such as reflexes.

When your muscles react and there is a reflex, this is an involuntary movement produced by the somatic system.

On the other hand, the autonomic
nervous system, we have no control over the ANS

77
Q

What are the four types of glial cells found within the nervous system?

A
  1. Ependymal cells
  2. Microglia
  3. Myelinating cells
  4. Astrocytes/satellite cells (metabolic-support cells)
78
Q

What are ependymal cells?

A
  • form a simple cuboidal columnar epithelium (ependyma)
  • lines fluid-filled passageways within the spinal cord and brain
  • cerebrospinal fluid (CSF) fills these cavities
  • assist in producing, monitoring, and circulating the CSF
79
Q

What are microglia?

A
  • developmentally related to monocytes and macrophages
  • migrate into the CNS as the nervous system forms
  • persist as mobile cells moving through the nervous tissue, removing cellular debris, wastes, and pathogens by phagocytosis
80
Q

What are myelinating (oligodendrocytes) cells?

A
  • provide a structural framework within the CNS by stabilizing the positions of axons
  • produce myelin and myelin sheaths
  • myelination allows electrical signals to travel rapidly and efficiently in axons

There are two distinct types of myelinating cells:
a) Schwann cells
b) Oligodendrocytes

81
Q

What are astrocytes?

A
  • maintain blood-brain barrier that isolates the CNS from the chemicals and hormones circulating in the blood
  • provide structural support within nervous tissue
  • regulate ion concentrations in ECF
  • regulate local blood flow (oxygen and nutrient supply)
  • regulate flow of CSF
  • absorb and recycle/buffer neurotransmitters that are not broken down or reabsorbed at synapses
  • form scar tissue after CNS injury
  • regulate the extracellular environment around neurons, and maintain/modify synaptic connections
82
Q

What is cerebrospinal fluid (CSF)?

A
  • cerebrospinal fluid becomes the extracellular fluid in the CNS
  • washes neurons free of toxicity because neurons generate a lot of waste and secrete weird stuff LMFAO
  • bathes and cushions the brain from banging into the cranium
  • fills the internal spaces and surrounds the brain and spinal cord
83
Q

What is the blood-brain barrier?

A

layer of cells that shields the brain from toxic substances in the brain

84
Q

What is myelin?

A

FAT AND PROTEIN

  • fat insulating sheath for the axons of the neuron
  • a membranous wrapping around axons that greatly increases the transmission speed of nerve impulses
  • when myelinating an axon, the tip of oligodendrocyte process expands to form a wide pad that gets wound around the axon, forming concentric layers of plasma membrane
  • layers create a myelin sheath
85
Q

Which two types of glial cells are found inside the CNS?

A
  1. Ependymal cells
  2. Microglial cells

ONLY FOUND IN THE CNS AND NOT THE PNS

86
Q

Describe the inside of the nervous system (canals/ventricles/etc)

A

There is a fluid-filled passageway within the spinal cord and the brain

The passageway narrows in the spinal cord and is called the CENTRAL CANAL

In the brain, the passageway forms cavities called ventricles -> ventricles run all the way through the CNS, are filled with fluid, and have cavities lined with ependymal cells

Cerebrospinal fluid (CSF) fills these internal spaces and also surrounds the brain and spinal cord

87
Q

Summarize ependymal cells, microglia, oligodendrocytes/myelinating cells, and astrocytes/satellite cells

A

Ependymal cells - line ventricles and secrete cerebrospinal fluid, which bathes and cushions CNS

Microglia - white blood cells which perform immune functions for the CNS and also help modify connections between neurons

Oligodendrocytes - wrap cellular processes containing myelin around the axon of neurons

Astrocytes/satellite cells -provide diverse forms of metabolic and physiological support

88
Q

True or False: All neurons are myelinated

A

FALSE

89
Q

Where are myelinating cells found?

A

Myelinating cells provide electrical insulation in BOTH THE CNS AND THE PNS

90
Q

What are the two distinct types of myelinating cells and where are they found?

A
  1. Schwann cells - PNS
  2. Oligodendrocytes - CNS
91
Q

Differentiate Schwann cells from Oligodendrocytes?

A

Schwann cells
- make myelin to wrap around axons
- same function as oligodendrocytes
- different location
- PNS

Oligodendrocytes
- make myelin to wrap around axons
- same function as schwann cells
- different location
- CNS

92
Q

What are satellite cells?

A
  • play a role in metabolic and physiological support
  • do most of the same things as astrocytes but in the PNS instead
93
Q

How do astrocytes differ from satellite cells?

A

satellite cells are NOT found in the CNS, and cannot produce CSF
- satellite cells are found in the PNS

astrocytes are found in the CNS

94
Q

True or False: There are about 9-10 glial cells for every neuron in the CNS

A

FALSE

There is only 1 glial cell for every neuron

95
Q

True of False: Astrocytes support dendrites, axon terminals and cell bodies, while satellite cells support axons

A

FALSE

Schwann cells support axons (producing myelin for myelinating axons)

Astrocytes and satellite cells support the dendrites and soma
(astrocytes in the CNS and satellite cells in the PNS)

96
Q

True or False: Myelin sheaths in the CNS are formed by oligodendrocytes while myelin sheaths in the PNS are formed by Schwann cells

A

TRUE

97
Q

True or False: Microglia are a brain-specific type of epithelial cell

A

FALSE

Microglia are blood cells (connective cells)

98
Q

True or False: Action potentials are shared between neurons and myelinating glia, but not other types of glia

A

FALSE

Only neurons can make action potentials, no glia can make action potentials

Other cells in the body, such as muscle cells are also capable of producing action potentials though

99
Q

Can a neuron be repaired or replaced if it is damaged? Can nervous tissue be repaired/replaced?

A

NO!!

New neurons CANNOT be born into adulthood
- if a neuron dies, IT WILL NOT BE REPLACED WAA WAA

100
Q

True or False: Nervous tissue CAN be repaired or replaced if it dies/is damaged

A

FALSE

New neurons cannot be born in adulthood

If a neuron dies, it will not be replaced

101
Q

What are the three ways that neurons die?

A
  1. Physical trauma to cell body
  2. Excitotoxicity (excessive excitatory synaptic activity) aka NEURON DEATH
  3. Severing an axon
102
Q

What happens during neuron death?

A

Neuron death happens during a stroke

If a neuron is too active electrically, it sends too many electric signals per unit time and it actually gets itself into a state where it commits apoptosis and it just chooses to die

(omg so relatable bestie)

103
Q

What happens when an axon is severed?

A
  • if you cut the axon from the neuron, it will die
  • if the axon is severed FAR AWAY from the cell body, it might not die
  • there is a chance that the axon will regrow if it was cut far from the cell body YIPPEE
104
Q

What does it mean for neurons to be post-mitotic?

A

It means that they CANNOT RETURN TO THE CELL CYCLE

  • they cannot replace themselves if they die
105
Q

What happens after a neuron dies? What cell comes to clean up the mess?

A

MICROGLIA (white blood cells) remove the remains of dead neurons (YUM)

106
Q

Differentiate neuron regeneration in the CNS and the PNS

A

CNS - neurons CANNOT spontaneously regenerate themselves

PNS - neurons/axons in the PNS can repair and regrow with the help of local glia

107
Q

Only axons in the _______ nervous system can repair and regrow with the help of local glia if damaged

A

PERIPHERAL NERVOUS SYSTEM

  • everything distal to the cut will die, but anything proximal to the cut may be able to repair/regrow
108
Q

What kind of glial cell helps with the regeneration/repair of axons in the PNS?

A

Schwann cells promote axon regrowth!!

Recall: Schwann cells are found in the PNS and oligodendrocytes are found in the CNS

109
Q

If an axon in the _________ nervous system is damaged, it typically CANNOT REPAIR OR REGROW

A

CENTRAL NERVOUS SYSTEM

110
Q

Describe what happens when an axon is damaged in the CNS

A
  1. An axonal injury occurs
  2. There is no macrophage to clear the debris
  3. Astrocytes secrete inhibitory molecules that stop axon sprouting / shuts it off / cannot repair an axon in the CNS
  4. If an axon is severed in the CNS, it will detect that change after a while and then the neuron will die
  5. Glial cells actively stop it from repairing itself

= NO AXON REGENERATION!!

111
Q

What are the CNS and PNS composed of?

A

Both the CNS and PNS are composed of nervous tissue (neurons and glia)

Everything in the CNS can be divided into white matter and grey matter

112
Q

What is grey matter?

A

Grey matter INTEGRATES SENSORY AND MOTOR FUNCTIONS

  • shows functional segregation
  • neighbouring cells/axons usually process/carry similar information
  • grey matter at different locations of the brain/spinal cord do different things
  • contain astro/micro-glia cells
  • contains neuron cell bodies / axon terminals
  • functional area with neurons passing info
  • synapses between neurons
113
Q

What is white matter?

A

White matter CARRIES INFORMATION

  • exclusively consists of myelinated axons (FAT) connecting one region to another
  • no cell bodies
  • no synapses
  • only axons which are the transmission lines take info from one to another
114
Q

Where is white and grey matter found?

A

in the CENTRAL NERVOUS SYSTEM (the brain and the spinal cord)

BRAIN
- outer cortex = grey matter
- closer to the centre of the brain = white matter

SPINAL CORD
- horn like shape in the centre = grey matter
- surrounding space = white matter

115
Q

Compare and contrast grey and white matter

A

GREY MATTER
- made of neuronal cell bodies
- place where the processing of sensation, perception, voluntary movement, learning, speech and cognition takes place

WHITE MATTER
- made up of large networks of nerve fibers (axons)
- allow for the exchange of info and communication between different areas of the brain (grey matter to grey matter)
- nerve fibers/axons are covered in myelin sheath

116
Q

Describe neural circuits throughout the nervous system:

Predictable or no?
Involuntary or voluntary?

A

The anatomy of neural circuits in the nervous system are HIGHLY PREDICTABLE

They support INVOLUNTARY REFLXES and CONSCIOUS/VOLUNTARY CONTROL

117
Q

What does white matter in the spinal cord do?

A

Spinal cord white matter relays sensory and motor information to and from the brain

118
Q

What does grey matter in the spinal cord do?

A

Circuits in the spinal cord grey matter are necessary and sufficient for simple reflexes, such as the withdrawal reflex

119
Q

What are the four types of white/grey matter in the spinal cord?

A
  1. Lateral white matter
    - descending projections from brain, voluntary motor control
  2. Dorsal white matter
    - projections to the brain, sensory awareness
  3. Dorsal grey matter
    - sensory processing
  4. Ventral grey matter
    - motor neuron somata
120
Q

What is a reflex arc?

A

A reflex arc is a neural pathway that controls a reflex

In vertebrates, most sensory neurons do not pass directly into the brain, but synapse in the spinal cord

This allows for faster reflex actions to occur by activating spinal motor neurons without the delay of routing signals through the brain

121
Q

Trace the pathway of a reflex arc

A
  1. Sensory neuron - afferent neuron (stimulus/receptor)
  2. Spinal reflex arc (rapid, involuntary)
  3. Motor neuron - efferent neuron (effector/response)
122
Q

What element of the spinal reflex arc/circuit might be damaged if:

The patient reports feeling the pin/hammer (and
flinches) but is unable to voluntarily move their hand.

A

Sensory neurons ✅
Reflex arc processing (reflex) ✅
Motor neurons ❌

It suggests a problem with the voluntary motor control component of the reflex arc.

The sensory neurons appear to be functioning because the patient perceives the stimulus, and the reflex arc is intact since the patient exhibits a reflexive response.

However, there may be an issue with the motor neurons or the muscles responsible for voluntary motor control.

123
Q

What element of the spinal reflex arc/circuit might be damaged if:

The patient reports feeling the pin/hammer, but
doesn’t flinch, and is unable to voluntarily move
their hand.

A

Sensory neurons ✅
Reflex arc processing (reflex) ❌
Motor neurons ❌

The sensory neurons appear to be functioning because the patient perceives the stimulus, but there may be an issue with the transmission of sensory information to motor neurons or with the motor neurons and muscles responsible for the motor response

The lack of a flinch/reflex indicates that there could be an issue in the spinal cord

It suggests a problem with the motor component of the reflex arc which is causing the inability to move their hand

124
Q

What element of the spinal reflex arc/circuit might be damaged if:

The patient doesn’t report feeling the
pin/hammer but can move the hand on command.

A

Sensory neurons ❌
Reflex arc processing (reflex) ❌
Motor neurons ✅

It suggests a problem with the sensory pathway, particularly the sensory neurons responsible for transmitting sensory information to the brain.

The lack of a reflex/flinch indicates that the spinal cord processing may be affected.

The ability to move the hand on command indicates that the motor component of the reflex arc, including motor neurons and muscles, is intact and functioning properly

125
Q

What element of the spinal reflex arc/circuit might be damaged if:

The patient’s hand still flinches at the pin/hammer but the patient does not report feeling it.

A

Sensory neurons ❌
Reflex arc processing (reflex) ✅
Motor neurons ✅ (unaffected)

It suggests that there may be an issue with the sensory pathway, such as damage to the sensory neurons or interneurons responsible for transmitting sensory information to the brain for conscious perception

The patient flinches so the spinal cord processing is unaffected–And there is no mention of their ability to move their hand upon command (so it is assumed to be unaffected)

126
Q

What is the function of the nervous system?

A

Coordinate the rest of the body - rapid and specific integration and transfer of information between different body systems and different regions using electrical and chemical signals

127
Q

What are the two classes of cells in nervous tissue?

A

Neurons
Neuroglia

Both of these classes are highly diverse and can be divided into many subtypes with different structures and functions

128
Q

What are the two divisions of the nervous system?

A

Nervous system can be divided into CENTRAL and PERIPHERAL divisions

129
Q

Capacity for repair is mostly restricted to which division of the nervous system?

A

Repair is mostly restricted to the PERIPHERAL NERVOUS SYSTEM

130
Q

Difference between sensory and motor and voluntary and involuntary/unconscious deficits

A

BIOL155 (34 decks)

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