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Anatomy and Physiology I > Ch.11 > Flashcards

Ch.11 Flashcards

1
Q

The Nervous System

A
  • Works in conjunction with endocrine system to control homeostasis and regulate body activities
  • Nervous: uses electrical signal, fast
  • Endocrine: uses hormones, slower
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2
Q

Integration

Basic Function

A

control centers in brain/cord process/interpret sensory input coordinate appropriate response to stimuli

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3
Q

Sensory

Basic Function

A

receptors detect stimulus and sensory neurons convey message to control centers

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4
Q

Motor

Basic function

A

motor neurons send messages from control center to effectors to bring about response

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5
Q

Neuroglia

A

(Cells that support the neuron)

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6
Q

Total Neuroglia

A

2 in PNS + 4 in CNS = 6 total
- Most have cell body with projections, each has specific function

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7
Q

Types of CNS neuroglia

A
  1. Astrocytes
  2. Microglia
  3. Oligodendrocytes
  4. Ependymal cells
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8
Q

Astrocytes

CNS neuroglia

A
  • Most abundant
  • Act as scaffolding for neurons
  • Anchor neurons to capillaries
  • Help maintain composition of the interstitial fluid
  • In embryos secrete chemicals that help neurons make connections
  • Recycle neurotransmitters
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9
Q

Microglia

CNS neuroglia

A
  • Small cells
  • Macrophages
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10
Q

Oligodendrocytes

CNS neuroglia

A
  • Fewer projections
  • Projections form
    myelin sheath in CNS
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11
Q

Ependymal cells

CNS neuroglia

A
  • Epithelium-like
  • Simple cubodial w/cilia
  • Line the ventricles and central canal
  • Forms part of the choroid plexus (which produces cerebrospinal fluid)
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12
Q

Types of PNS supporting cells

A
  1. Satellite cells
  2. Schwann cells
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13
Q

Satellite cells

PNS supporting cells

A
  • Cling to surface of neuron
    cell bodies in ganglia
  • Provides nutrients
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14
Q

Schwann cells

PNS supporting cells

A
  • Form myelin in PNS
  • Insulate neuron axons
  • nodes of ranvier (1mm)
  • Neurolemma (PM)
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15
Q

Myelnated

A

faster conduction

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16
Q

Unmyelnated

A

Slower conduction

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17
Q

Neurons

A

= nerve cells
Characteristics:
1. Conduct electrical impulses
2. Extreme longevity
3. Amitotic
4. Fast rate of metabolism

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18
Q

Cell body

Neuron

A
  • ganglia: collections of nerve cell bodies found in the PNS
  • nuclei: collections of nerve cell bodies found in the CNS
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19
Q

Processes

Neuron

A
  • tracts: bundles of nerve cell processes found in the CNS
  • nerves: bundles of nerve cell processes found in the PNS
    – dendrites
    – axons
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20
Q

Structural classification of neurons

A

Based on number of processes

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21
Q

Multipolar neuron

A
  • 99% of neurons
  • Major neuron type in the CNS
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22
Q

Bipolar Neuron

A
  • Rare
  • Found in the special sense organs (eye, olfactory mucosa
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23
Q

Unipolar Neuron

A
  • Found mainly in the PNS
  • Most are sensory neurons
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24
Q

Sensory (Afferent)

Functional classification of neurons

A
  • Message TO CNS
  • Most unipolar, bipolar
25
Q

Interneurons/Integration (Association neurons)

Functional classification of neurons

A
  • connect afferent and efferent neurons
  • Mostly multipolar
26
Q

Motor (Efferent)

Functional classification of neurons

A
  • Message FROM CNS
  • Most multipolar
27
Q

How do neurons communicate?

A

via electrical impulses & neurotransmitters

28
Q

Ion Channels

A

Allow ions to diffuse across the cell membrane

29
Q

Leakage Channels

Ion Channel

A
  • Never really completely close, allows slow diffusion of specific ion
  • there are more K+ leakage channels, than there are Na+ leakage channels
30
Q

Gated Channels

Ion Channel

A
  • These open and close, and when closed do not allow any diffusion of ions
  • 3 types:
    1. Voltage-Gated Channels
    2. Ligand-Gated Channels
    3. Mechanically-Gated Channels
31
Q

Voltage-Gated Channels

Type of gated channel

A

open when membrane potential changes

32
Q

Ligand-Gated Channels

Type of gated channel

A

open when chemicals (like hormones or neurotransmitters) attach to them

33
Q

Mechanically-Gated Channels

Type of gated channel

A

open & close in response to mechanical forces (like vibrations and pressure)

34
Q

Na+/K+ pumps

A
  • Are active transport membrane proteins that pump 3 Na+ out of the cell, while pumping 2 K+ into the cell
  • they maintain an electrical and chemical gradient across the membrane
  • Positive outside, negative inside
35
Q
A
36
Q

Resting Membrane potential

A
  • Polarized membrane = voltage gradient across the membrane
  • Average potential is -70 mV
  • Leakage channels create the potential and Na+/K+ pumps maintain it.
37
Q

1) Resting state

A

All gated Na+ and K+ channels are closed

38
Q

2) Depolarization

A

When cation (like Na+) channels open, cations diffuse into the cell and brings the voltage difference closer to 0

39
Q

3) Repolarization

A

Na+ channels are inactivating, and K + channels open

40
Q

4) Hyperpolarization

A

When anion channels open, or K+ channels open, ions diffuse across the membrane and bring the voltage difference further from 0

41
Q

Graded potential

A
  • Localized, short lived change in membrane potential occurs on dendrites and cell bodies
  • Only initial stimulus opens ion channel
  • Becomes less effective as it moves away from contact point (like rock in a pond)
  • Big stimulus causes more channels to open, bigger waves
  • If this change in potential reaches the axon hillock at enough strength, it may cause an action potential
42
Q

Graded potential process

A
  1. Stimulus (like heat, pressure, neurotransmitter binding, etc) detected on the cell body or
    dendrites
  2. causes ligand-gated or mechanically gated channels to open
  3. depolarization or hyperpolarization of the membrane at that point
  4. change in potential ripples out from the contact point.
43
Q

Action potential

A
  • Nerve Impulse on axon
    1. Graded potential reaches hillock voltage-gated channels open
    2. Na+ rushes into cells
    3. Membrane depolarizes at that location
    4. At threshold of -55 mV potential propagates (Na+ channels on adjacent membrane open)
    5. Na+ channel opening is immediately followed by Na+ channel closing and K+ channel opening
    6. K+ rushes out of cells
    7. Membrane repolarizes
    8. Propagation of repolarization (potassium channels on adjacent membrane open)
44
Q

Graded potential vs action potential

A

Graded potential:
- Produced by gated channels on dendrites and soma
- May be a positive (depolarizing) or negative (hyperpolarizing) voltage change
- Graded: proportional to stimulus strength
- Reversible; returns to RMP if stimulation ceases before threshold is reached
- Local; has effects for only a short distance from point of origin
- Decremental; signal grows weaker with distance
Action Potential:
- Produced by voltage regulated gates on the trigger zone and axon
- Always begins with depolarization
- All or none; either does not occur at all or exhibits peak voltage regardless of stimulus strength
- Irreversible; goes to completion once it begins
- Self propagating; has effects a great distance from point of origin
- Nondecremental; signal maintains same strength regardless of distance

45
Q

speed of transmission depends on

A
  1. Axon diameter
    - Bigger diameter = faster transmission
    - A fibers = large diameter (300 mi/hr)
    – go to skin, skeletal muscles, joints
    - B fibers = smaller diameter (40 mi/hr)
    – Autonomic nervous system fibers
    - C fibers = smallest diameter (2 mi/hr)
    – Autonomic nervous system fibers
  2. Myelin sheath
    - A & B myelinated
    - C is unmyelinated
46
Q

Multiple Sclerosis

A
  • Autoimmune disease
  • Immune system attacks myelin sheaths
  • Messages sent much slower
  • Symptoms: weakness, clumsiness, blurred vision, speech impairment, poor skeletal muscle control, poor balance
47
Q

Synapses

A

Where neurons communicate with each other (usually thousands per neuron)

48
Q

Presynaptic neuron

A

sends message TO synapse

49
Q

Postsynaptic neuron

A

carries message
away FROM synapse

50
Q

Electrical synapse

A
  • Neurons connected via gap junctions
  • Found in developing embryos and limited areas of adult brains
51
Q

Chemical Synapse

A

contains:
1. Presynaptic Neuron: Axon terminal w/vesicles containing neurotransmitters
2. Synaptic Cleft
3. Postsynaptic Neuron: Receptor region

52
Q

Excitatory Synapse

A
  1. Na+ and K+ channels open
  2. Since there is higher gradient for Na+ than K+/ Na+ diffuses in faster
  3. membrane depolarizes
  4. graded potential
53
Q

Inhibitory Synapse

A
  1. K+ channels open and K+ diffuses out OR
    Cl- channels open and Cl- diffuses in
  2. hyperpolarization
54
Q
A
55
Q

Neurotransmitters

A

Chemicals released by a presynaptic neuron into the synaptic cleft and attaches to postsynaptic neuron where it causes some effect

56
Q

Acetycholine

A
  • used at skeletal neuromotor junctions and by
    autonomic and interneurons neurons
  • binds briefly to the postsynaptic neuron and then quickly degraded by enzyme into acetic acid and choline, which are then recaptured by the presynaptic neuron
57
Q

Dopamine (a catecholamine)

A
  • Important in integrating emotions and skeletal muscle tone
  • Too little = Parkinson’s
  • Too much = schizophrenia
58
Q

Serotonin = (an indolamine)

A
  • Involved in sensory reception, mood, appetite, sleep
  • Loss of receptor is a hallmark of Alzheimer’s Disease
  • Prozac (and other selective serotonin reuptake inhibitor - SSRI’s) block its uptake to relieve
    anxiety & depression
58
Q
A

Anatomy and Physiology I (14 decks)

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