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A&P 1 > Nervous system chapter videos > Flashcards

Nervous system chapter videos Flashcards

1
Q

What are the two structural divisions of the nervous system?

A
  • Central Nervous system
  • Peripheral nervous system
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2
Q

How are they functionally organized?

A

Sensory
Somatic sensory: skin, ears, etc,
Visceral blood: vessels or organs

Motor
Somatic Motor: going towards muscles
Autonomic: going to involuntary organs ex, heart

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3
Q

What are the two types of cells in the nervous tissue?

A

Nerouns
- A basic structural unit of the nervous system
- excitable cells that transmit electrical system

Glial cells
- Nonexcitable cells that primarily support and protect neurons

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4
Q

What are the special characteristics of the neuron?

A
  • Live long 100 years or more
  • Amitotic (don’t divide)
  • High metabolic rate (depends on a continuous supply of oxygen and glucose)
  • Plasma membrane
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5
Q

What is the function of the plasma membrane

A
  • Used for electrical signaling (excitable and conductivity)
  • Cell-to-cell interactions during the development
  • Secretion
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6
Q

Components of the neuron
(Cell body)

A
  • Enclosed by plasma membrane
  • Contains cytoplasm surrounding the nucleus
  • Neurons control center
  • Conducts electrical signal to axon
  • Perikaryon, cytoplasm within the cell
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6
Q

Components of the neuron
(Dendrites)

A
  • Short process branching off the cell body
  • May have one or many
  • Receive input and transfer it to the cell body
  • More dendrites = more input possible
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7
Q

Components of the neuron
(Axon)

A
  • longer process emanating from the cell body
  • makes contact with other neurons, muscle cells, or glands
  • first part, a triangular region, axon hillock
  • cytoplasm here termed axoplasm
  • plasma membrane here termed axolemma
  • gives rise to side branches, axon collaterals
  • at extreme tips, expanded regions, synaptic knobs
  • knobs containing numerous synaptic vesicles
  • contain neurotransmitter
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7
Q

What are the different types of neurons?

A

Multipolar Neuron - Multiple nerve processes extend directly from the cell body: typically many dendrites and one axon

Bipolar Neuron - Two nerve cell processes extend directly from the cell body; one dendrite and one axon

Unipolar Neuron - A single short cell process extends directly from the cell and looks like a T as a result of the fusion of two processes into one long axon

Anaxonic Neuron - Nerve cell processes are only dendrites; no axon present

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8
Q

What is Bidirectional axonal transport?

A
  • Bidirectional axonal transport
  • Axons dependent on cell body
  • for newly synthesized materials
  • for breakdown of used materials
  • Anterograde transport
  • movement of materials from cell body to synaptic knobs
  • Retrograde transport
  • movement of materials from synaptic knobs to cell body
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9
Q

Where do sensory neurons send signals to?

A

Spinal cord

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10
Q

Where do motor neurons send signals to?

A

Receive information and send it to the infector like a muscle.

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11
Q

What is the function of interneurons?

A

They do the integration

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12
Q

What is a nerve?

A
  • A bundle of axons
  • Epineurum surronds the nerve
  • Perinerium surrounds the facile
  • Endonerium surrounds bundles of axons
  • contains both motor or sensory neruns
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13
Q

What are the classifications of nerves?

A

Cranial Nerves
- extend from the brain

Spinal Nerves
- extend from the spinal cord

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14
Q

Sensory nerves

A
  • Contain only sensory nerves
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15
Q

Motor nerves

A
  • Contain only motor nerves
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16
Q

Mixed nerves

A
  • Contain both sensory and motor nerves
  • most named nerve in this category
  • individual neurons transmitting one type of information
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17
Q

What is a synapse?

A

A junction that mediates information transfer from one neuron:
- To another neuron, or
- To an effector cell

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18
Q

What is a Presynaptic neuron?

A

Presynaptic neuron-conducts impulses toward the synapse

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19
Q

What is a Postsynaptic neuron?

A

Postsynaptic neuron—transmits impulses away from the synapse.

20
Q

What is an Electrical synapse?

A
  • Much less common
  • Presynaptic and postsynaptic neuron physically bound together
  • Gap junctions present
  • No delay in passing electrical signal
  • In limited regions of brain and eyes
21
Q

What is Chemical synapse

A
  • Most common
  • Composed of presynaptic neuron, signal producer
  • Composed of postsynaptic neuron, signal receiver
  • Between axon and any portion of the postsynaptic neuron
  • most commonly with a dendrite
  • Knob almost touches the postsynaptic neuron
  • narrow fluid filled gap, the synaptic cleft
22
Q

Chemical synapses transmit signals from one neuron to another using neurotransmitters. Steps

A
  1. Action potential arrives at the axon terminal.
  2. Voltage-gated Ca2+ channels open and Ca2+ enters the axon terminal.
  3. ca2+ entry causes neurotransmitter - contains synaptic vesicles that release their contents through exocytosis.
  4. Neurotransmitter
    dilutes across the synaptic deft and binds to specific receptors on the
    postsynaptic membrane.
23
Q

What is Astrocytes?

A
  • Most abundant, versatile, and highly branched glial cells
  • Cling to neurons, synaptic endings, and capillaries
  • Support and brace neurons
  • Help determine capillary permeability
  • Guide migration of young neurons
  • Control the chemical environment
  • Participate in information processing in the brain
24
Q

Microglia

A
  • Small, ovoid cells with thorny processes
  • Migrate toward injured neurons
  • Phagocytize microorganisms and neuronal debris
25
Q

Ependymal Cells

A
  • Range in shape from squamous to columnar
  • May be ciliated
  • Line the central cavities of the brain and spinal column
    — Separate the CNS interstitial fluid from the cerebrospinal fluid in the cavities
26
Q

What two types of glial cells do the peripheral nervous system have?

A
  1. Satilite cells - wrap around the cell body
  2. Shwan cells - wrap around the axon
27
Q

What are Oligodendrocytes?

A
  • Branched cells
  • Processes wrap CNS nerve fibers, forming insulating myelin sheaths
28
Q

If a person suffers from meningitis (an inflammation of the coverings around the brain), which type of glial cell usually replicates in response to the infection?

A

Microglia are going to phagocytize the infection.

29
Q

Which specific type of glial cell ensheathes axons in the PNS?

A

Neurolemmocytes (Schwann cells)

30
Q

What is the function of myelin shealth

A

The segmented protein-lipoid sheath around most long or large-diameter axons
* It functions to:
- Protect and electrically insulate the axon
- Increase speed of nerve impulse transmission

31
Q

Process of the formation of myelin sheath

A

Schwann cells wraps many times around the axon
- Myelin sheath-concentric layers of Schwann cell membrane
Neurilemma-peripheral bulge of
Schwann cell cytoplasm
* Nodes of Ranvier
- Myelin sheath gaps between adjacent Schwann cells
- Sites where axon collaterals can emerge

32
Q

Unmyelinated axons

A
  • Associated with neurolemmocytes
  • No myelin sheath covers them
  • Axon in depressed portion of neurolemmocyte
  • Not wrapped in repeated layers
  • In CNS,
  • unmyelinated axons not associated with oligodendrocytes
33
Q

What is the function of the myelin sheath?

A

The myelin sheath provides a protective insulating covering around the axon. It prevents the passage of ions through the axonal membrane and allows for faster action potential propagation.

34
Q

Axon Regeneration process

A
  1. Trauma severs axon.
  2. The proximal portion of each severed axon seals off and swells. The distal portion of axon and myelin sheath disintegrate; the neurilemma survives.
  3. Neurilemma and endoneurium form a regeneration tube.
  4. Axon regenerates, and remyelination occurs.
  5. Innervation to effector is restored.
35
Q

Axon Regeneration

A

Factors influencing axon regeneration
- PNS axons
* vulnerable to cuts, trauma
- Regeneration possible if
* cell body intact
* enough neurilemma remains
- Regeneration success more likely if
* amount of damage less extensive
* smaller distance between site of damage and structure it innervates

36
Q

Role of Membrane lon Channels

A
  • Proteins serve as membrane ion channels
  • Two main types of ion channels
    1. Leakage (nongated) channels-always open
    2. Gated channels (three types):
  • Chemically gated (ligand-gated) channels open with the binding of a specific neurotransmitter
  • Voltage-gated channels—open and close in response to changes in membrane potential
  • Mechanically gated channels open and close in response to the physical deformation of receptors
37
Q

Pumps

A
  • Type of transport protein
  • Move substances against a concentration gradient
  • Require energy
  • e.g., sodium-potassium and calcium pumps in plasma membrane
38
Q

Channels

A

Move substances down a concentration gradient
- Leak channels
* always open for continuous diffusion
*, e.g., sodium ion and potassium ion channels

39
Q

What is the purpose of chemically gated channels

A

Chemically gated channels
* Only open when ligand binds to it.
* normally closed
* allow specific type of ion to diffuse when open
* e.g., chemically gated K* channels

40
Q

What are the Functions of voltage-gated channels?

A

Voltage-gated channels
* normally closed
* open in response to changes in electrical charge across membrane
* allow specific type of ion to diffuse
* e.g., voltage gated Nat channels

41
Q

Where are the channels located on neuron cells?

A

Chemically gated channels are located on dendrites or cell bodies

Voltage-gated channels are found on axons. Also, between myelin sheath.

Calcium channels found at the terminal

42
Q

What is the difference between a chemically gated channel and a voltage-gated channel in terms of how they function?

A

Chemically gated channels open in response to the binding of a neurotransmitter.

43
Q

Distribution of substances inside and outside neuron

A

Essential for neuron function
- More prevalent within cytosol
* negatively charged phosphate ions (e.g., in ATP)
* negatively charged proteins
* K+
- More prevalent in interstitial fluid
* Nat
* Cl

44
Q

Movement of substances and membrane potentials

A
  • Ions able to pass through membranes by transporting proteins
  • Phosphate-containing molecules and proteins
  • generally restricted from crossing
  • Net movement dependent on the electrochemical gradient
  • combination of the electrical and chemical gradient
45
Q

What is an electric gradient charge starting point?

A

Inside relatively negative
outside relatively positive

46
Q

Chemical concentration gradient

A

unequal distribution between two areas
* each substance with own chemical concentration gradient
* e.g., Kt with a higher concentration inside the neuron
* e.g., Nat with a higher concentration outside the neuron

47
Q

What is an electrical gradient? What is a chemical gradient?

A

An electrical gradient is a difference in electrical charge between two areas.
A chemical gradient is an unequal distribution of a substance between two areas.

48
Q

Neuron Function

A
  • Neurons are highly irritable
  • Respond to adequate stimulus by generating an action potential (nerve impulse)
  • Impulse is always the same regardless of stimulus

A&P 1 (25 decks)

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