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A&P I - Grace College > Exam 3 - Muscular/Nervous System > Flashcards

Exam 3 - Muscular/Nervous System Flashcards

1
Q

Components of the Central Nervous System

A

Brain and Spinal Cord

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2
Q

Components of the Peripheral Nervous System

A

Cranial nerves, spinal nerves, ganglia, and plexuses

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3
Q

Gray Matter

A

Areas in the CNS that contain neuron cell bodies, dendrites, and unmyelinated axons; they have a dusky gray color

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4
Q

White Matter

A

Regions in the CNS that are dominated by myelinated axons.

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5
Q

Divisions of the Peripheral Nervous System

A

Somatic and Autonomic

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6
Q

Somatic Nervous System

A

Controls skeletal and muscle contractions

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7
Q

Autonomic Nervous System

A

Automatically regulates smooth muscle, cardiac muscle, glandular secretions and adipose tissue at the subconscious level

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8
Q

Neuron

A

Basic functional unit of the nervous system; perform all the communication, information processing, and control functions of the nervous system.

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9
Q

Neuroglia

A

Supporting cell of the neuron; have functions essential to the survival and functionality of neurons and to preserving the physical and biochemical structure of the neural tissue.

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10
Q

Cell Body

A

Contains a large, round nucleus with a prominent nucleolus

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11
Q

Perikaryon

A

The cytoplasm surrounding the nucleus in the cell body

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12
Q

Dendrites

A

A variable number of slender, sensitive processes which extend out from the cell body.

Play key roles in intercellular communication

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13
Q

Axon

A

Long cytoplasmic process capable of propagating an electrical impulse known as an action potential

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14
Q

Axoplasm

A

The cytoplasm of the axon

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15
Q

Axolemma

A

A specialized portion of the plasma membrane that surrounds the axoplasm.

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16
Q

Classification of Neurons by Structure

A

Anaxonal, Bipolar, Unipolar, Multipolar

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17
Q

Classification of Neurons by Function

A

Sensory, Motor, Interneurons

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18
Q

Anaxonal Neurons

A

Small and have numerous dendrites, but no axon.

Located in the brain and in special sense organs.

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19
Q

Bipolar Neurons

A

Have two distinct processes - one dendrite that branches extensively into dendritic branches at its distal tip, and one axon-with the cell body between the two.

Rare; they occur in special sense organs, where they relay information about sign, smell, or hearing from receptor cells to other neurons.

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20
Q

Unipolar Neurons

A

The dendrites and axon are continuous-basically fused- and the cell body lies off to one side.

The initial segment lies where the dendrites converge. The rest of the process, which carries action potentials, is usually considered an axon.

Most sensory neurons of the peripheral nervous system are unipolar.

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21
Q

Multipolar Neurons

A

Have two or more dendrites and a single axon.

They are the most common neurons in the CNS. All the motor neurons that control skeletal muscles are multipolar neuron.

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22
Q

Sensory Neurons

A

Afferent; Deliver information from sensory receptors to the CNS

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23
Q

Types of Sensory Neurons

A

Interoceptors, Exteroceptors, Proprioceptors

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24
Q

Interoceptors

A

Monitor the digestive, respiratory, cardiovascular, urinary, and reproductive system and provide sensations of distention (stretch), deep pressure, and pain.

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25
Q

Exteroceptors

A

Provide information about the external environment in the form of touch, temperature, or pressure sensations and the more complex senses of taste, smell, sight, equilibrium (balance), and hearing.

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26
Q

Proprioceptors

A

Monitor the position and movement of skeletal muscles and joints.

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27
Q

Motor Neurons

A

Carry instructions from the CNS to the peripheral effectors in a peripheral tissue, organ, or organ system.

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28
Q

Interneurons

A

Located between sensory and motor neurons; distribute sensory information and coordinate motor activity.

The more complex the response to a given stimulus, the more interneurons involved.

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29
Q

Four Types of Neuroglia in the CNS

A
  1. Ependymal Cells
  2. Astrocytes
  3. Oligodendrocytes
  4. Microglia
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30
Q

Ependymal Cells

A

Line the central canal and ventricles of the CNS, where they form a simple cuboidal to columnar epithelium (known as ependyma)

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31
Q

Astrocytes

A

Largest and most numerous neuroglia in the CNS

Functions:

  • Maintaining the blood-brain barrier
  • Repairing damaged neural tissue
  • Guiding neuron development
  • Controlling the Interstitial Environment
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32
Q

Oligodendrocytes

A

Have slender cytoplasmic extensions but the cell bodies are smaller with fewer processes than astrocytes

Processes generally are in contact with the exposed surfaces of neurons.

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33
Q

Microglia

A

The least numerous and smallest neuroglia in the CNS are phagocytic cells

Their slender processes have many fine branches; these cells can migrate through neural tissue

Migrate into the CNS as the nervous system forms. There they remain, acting a wandering janitorial service and police force by engulfing cellular debris, waste products, and pathogens.

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34
Q

Schwann Cells

A

Either form a thick, myelin sheath or indented folds of plasma membrane around peripheral axons

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35
Q

Satellite Cells

A

Surround neuron cell bodies in ganglia

They regulate the environment around the neurons.

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36
Q

Types of Membrane Potentials

A

Resting membrane potential, graded potential, action potential, synaptic activity, information porocessing

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37
Q

Factors Contributing to Membrane Potentials

A
  1. Extracellular Fluid (ECF) and Intracellular Fluid (Cytosol) differ greatly in ionic composition - The ECF contains high concentrations of Sodium and Chlorine ions whereas the cytosol contains high concentration of potasium ions and negatively charged proteins.
  2. Cells have selectively permeable membrane - Ions cannot freely cross the lipid portions of the plasma membrane, they can entor or leave the cell only through the membrane channels.
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38
Q

Electrochemical Gradient

A

For a specific ion, the sum of the chemical and electrical forces acting on that ion across the plasma membrane

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39
Q

The Na/K Pump

A

Maintains the concentration of sodium and potassium ions across the plasma membrane.

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40
Q

Leak Channels

A

Always open; Their permeability can vary from moment to moment as the protein that make up the channel change shape in response to local conditions.

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41
Q

Gated Channels

A

Open or close in response to specific stimuli. Each gated channel can be in one of three states:

  1. Closed but capable of opening
  2. Open
  3. Closed and incapable of opening
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42
Q

Types of Gated Channels

A
  1. Chemically Gated Channels
  2. Voltage-gated Channels
  3. Mechanically Gated Channels
43
Q

Chemically Gated Channels

A

Open or close when they bind specific chemicals.

44
Q

Voltage-gated Channels

A

Open or close in response to changes in the membrane potential. They are characteristic of areas of excitable membranes, which are capable of generating and propagating an action potential.

45
Q

Mechanically Gated Channels

A

Open or close in response to physical distortion of the membrane surface.

46
Q

Graded Potentials

A

Changes in the membrane potential that cannot spread far from the site of stimulation.

Any stimulus that opens a gated channel produces a graded potential.

47
Q

What happens during a graded potential?

A

Resting State - Resting membrane with closed chemically gated sodium ion channels

Stimulation- Membrane exposed to chemical that opens the sodium ion channels

Graded Potential - Spread of sodium ions inside plasma membrane produces a local current that depolarizes adjacent portions of the plasma membrane.

48
Q

Resting Membrane Potential

A

The membrane potential of an unstimulated, resting cell.

All neural activities begin with a change in the resting membrane potential of a neuron.

49
Q

Depolarization

A

Any shift from the resting membrane potential towards a more positive potential

50
Q

Repolarization

A

The process of restoring the normal resting membrane potential after depolarization

51
Q

Hyperpolarization

A

An increase in the negativity of the resting membrane potential

52
Q

Maintenance of the Resting Membrane Potential

A
  1. Na/K Pump
  2. Leak Channels
  3. Large negative ions that cannot cross the membrane
53
Q

Action Potential

A

Propagated changes in the membrane potential that, once initiated, affect an entire excitable membrane.

54
Q

Action Potential Mechanism

A
  1. Stimulus causes sodium channels to open allowing the sodium ions that were outside the membrane to rush into the cell. This causes the cell’s electrical potential to become more positive.
  2. If the signal is strong enough and the voltage reaches a threshold, it triggers the action potential. More gated ion channels open, allowing more sodium ions inside the cell, and the cell depolarizes so that the charges across the membrane completely reverse. The inside of the cell becomes positively charged and the outside becomes negative.
  3. The peak voltage of the action potential causes the gated sodium channels to close and potassium channels to open. Potassium ions move outside the membrane and sodium ions stay inside the membrane repolarizing the cell. The result is a polarization that’s opposite of the initial polarization that had Na+ ions on the outside and K+ ions on the inside.
  4. The neuron becomes hyperpolarized when more potassium ions are on the outside than sodium ions are on the inside. When the potassium ion gates finally close, the neuron has slightly more potassium ions on the outside than it has sodium ions on the inside. The causes the cell’s potential to drop slightly lower than the resting potential.
  5. The neuron enters refractory period, which returns potassium to the inside of the cell and sodium to the outside of the cell. The sodium potassium pump goes back to work, moving sodium ions to the outside of the cell and potassium ions to the inside, returning the neuron to its normal polarized state.
55
Q

Continuous Propagation

A

Occurs in unmyelinated axons

Step by step depolarization and repolarization of each adjacent segment of axolemma

56
Q

Saltatory Propagation

A

Occurs in myelinated axons

More rapid; Voltage gated channels present primarily at nodes of Ranvier

Action potential appears to leap from node to node

Less overall movement of sodium and potassium ions during propagation so less ATP energy used by sodium potassium pumps maintaining membrane potential

57
Q

Refractory Period

A

Period when the plasma membrane does not respond normally to additional depolarizing stimuli from the time an action potential begins until the normal resting membrane potential has been stabilized

58
Q

Absolute Refractory Period

A

This is the time during another stimulus given to the neuron (no matter how strong) will not lead to a second action potential

59
Q

Relative Refractory Period

A

A period when a greater than normal stimulus can stimulate a second response

60
Q

Type A fibers

A

Largest, myelinated axons, with diameters ranging from 4 to 20 picometers.

These fibers carry action potentials at speeds of up to 120 meters per second, or 268 mph.

Carry sensory information about position, balance, and delicate touch and pressure sensations from the skin surface to the CNS. The motor neurons that control skeletal muscles also send their commands over large, myelinated Type A axons.

61
Q

Type B fibers

A

Smaller, myelinated axons, with diameters ranging from 2-4 picometers.

Their propagation speeds average around 18 meters per second or roughly 40 mph.

Type B fibers and carry information to and from the CNS. They deliver temperature, pain, and general touch and pressure sensations. They also carry instructions to smooth muscle, cardiac muscle, glands, and other peripheral effectors.

62
Q

Type C fibers

A

Unmyelinated and less than 2 picometers in diameter.

These axon propagate action potentials at the leisurely pace of 1 meter per second, or a mere 2 mph.

Type C fibers carry information to and from the CNS. They deliver temperature, pain, and general touch and pressure sensations. They also carry instructions to smooth muscle, cardiac muscle, glands, and other peripheral effectors.

63
Q

Afferent

A

Coming to CNS

64
Q

Efferent

A

Going away from CNS

65
Q

Neurilemma

A

The outer surface of a Schwann cell that encircles an axon in the PNS

66
Q

Neurofibrils

A

Microfibrils in the cytoplasm of a neuron

67
Q

Ganglion

A

A collection of neuron cell bodies in the PNS

68
Q

Myelin

A

An insulating sheath around an axon; consists of multiple layers of neuroglial membrane; significanly increases the nerve impulse propagation rate along the axon

69
Q

The All or None Principle

A

A stimulus of threshold intensity that could elicit maximum contraction

70
Q

Twitch

A

Single, isolated skeletal muscle contraction

71
Q

Stages of Twitch

A
  1. Latent Period - Period from when stimulus arrives at the muscle until the actual shortening of the ends or until contraction begins (Impulse going in, calcium going out of the sarcoplasmic reticulum)
  2. Contraction - The cross bridge cycle is taking place, the myosin is pulling over itself. The myosin and actin are interacting together. The fibers are going back to the initial length.
  3. Resolution - The muscle is returning to its initial length because the calcium is coming back in.
  4. Refractory Period - Period of time after the stimulus during which the muscle cannot respond to another stimulus
72
Q

Tetanus

A

Fused twitches - Continually twitches without relaxation

73
Q

Incomplete Tetanus

A

There is some relaxation between the twitches

74
Q

Complete Tetanus

A

Tetanus in which stimuli to a particular muscle are repeated so rapidly that decrease of tension between stimuli cannot be detected.

75
Q

Tone

A

State of partial contraction of the entire muscle

Does not defy the all or none law

Not all cells are working at the same time in the muscle

76
Q

Factors that Determine Tension of Skeletal Muscle

A 
Metabolic Conditions
Initial Length of Fiber
Frequency of Stimulus
Strength of Stimulus
Temperature
77
Q

Mechanism of Tone

A
  1. Some motor neurons are firing, some are not.

2. When all are firing, it causes fatigue

78
Q

Isometric vs. Isotonic

A

Isometric - The tone changes but the length stays the same

Isotonic - The length changes but the tone stays the same

79
Q

Types of Skeletal Muscle Fibers

A

Slow Oxidative Type I - Split ATP more slowly

Fast Oxidative Type II A - Split ATP more quickly but still oxidate

Fast Glycolytic Type II B - Split extremely fast

80
Q

Characteristics of Smooth Muscle

A

Non-striated, uninucleated, involuntary

Gets some calcium from the outside of the cell

Sarcoplasmic reticulum is not well developed (when action potential comes to the cell, calcium comes out)

Short, spindle-like fibers

No T Tubules

81
Q

Physiology of Smooth Muscle Contraction

A

The trigger for smooth muscle contraction is the appearance of free calcium ions in the cytoplasm. This produces an overall rise in calcium ion concentration in the cell.

Once in the sarcoplasm, the calcium ions interact with calmodulin, a calcium-binding protein. Calmodulin then activates the enzyme myosin light chain kinase which in turn enables myosin heads to attach to actin.

Slower onset of contraction

Maintenance of muscle tone

Stretch-relaxation response of smooth muscle

82
Q

Multiunit Smooth Muscle Cells

A

Innervated in motor units comparable to those of skeletal muscles, but each smooth muscle cell may be connected to more than one motor neuron.

83
Q

Visceral Smooth Muscle Cells

A

Lack direct contact with any motor neuron

84
Q

Structural Characteristics of Cardiac Muscle Tissue

A

Relatively small; has a single, centrally placed nucleus; typically branched

The T tubules are short and broad and there are no triads; they encircle the sarcomeres at the Z lines rather than at the zones of overlap.

An action potential makes the sarcolemma more permeable to extracellular calcium ions.

Contain intercalated discs; involuntary; striated

85
Q

Intercalated Discs in Cardiac Muscle Tissue

A

At an intercalated disc, the sarcolemmas of two adjacent cardiac muscle cells are extensively intertwined and bound together by gap junctions and desmosomes. These connections help stabilize the position of adjacent cells and maintain the 3-D structure of the tissue.

The gap junction allows ions and small molecules to move from one cell to another. These junctions create a direct electrical connection between two muscle cells.

86
Q

Functional Characteristics of Cardiac Muscle Tissue

A
  1. Nervous stimulus is not required (automaticity). Specialized cardiac muscle cells called pacemaker cells normally determine the timing of the contractions.
  2. The nervous system can alter the pace or rate set by the pacemaker cells and adjust the amount of tension produced during a contration.
  3. Cardiac muscle cell contractions last about 10 times as long as they do those of skeletal muscle fibers. They also have longer refractory periods and do not readily fatigue.
  4. The properties of cardiac muscle sarcolemmas differ from those of skeletal muscle fibers. As a result, individual twitches cannot undergo wave summation, and cardiac muscle tissue cannot produce tetanic contractions. This different is important because a heart in a sustained tetanic contraction could not pump blood.
87
Q

Physiology of Cardiac Muscle Tissue

A
  1. Nervous stimulus not required
  2. Prolonged contraction period
    2a. Plateau in action potential due to voltage gated calcium channels
    2b. Longer refractory period prevents tetanus
  3. Dependence upon aerobic metabolism for ATP
  4. Contracts as unit
88
Q

Epimysium

A

Connective tissue covering the entire muscle body

89
Q

Fascia

A

Layers of connective tissue that surround muscle and nerves

90
Q

Fasicle

A

Bundle of muscle cells

91
Q

Perimysium

A

Connective tissue that surrounding a bundle of muscle fibers

92
Q

Endomysium

A

Connective tissue that surrounds each individual muscle fiber

93
Q

Tendon

A

Cylindrical band that binds muscle to bone

94
Q

Aponeurosis

A

Broader sheet type of connective tissue that is connecting muscle to muscle or muscle to bone

95
Q

Origin

A

Point of fixed attachment that does not change position when the muscle contracts

96
Q

Insertion

A

Point of attachment of a muscle; the end that is easily moveable

97
Q

Agonist

A

Primary mover; muscle responsible for a specific movement

98
Q

Antagonist

A

Opposes the movement of the agonist

99
Q

Synergist

A

Muscle that assists a prime mover in performing its primary action

100
Q

Fixator

A

Muscle that acts as a stabilizer of one part of the body during movement of another part

101
Q

Compartment Muscle Groups

A

Consist of the muscles in this region along with the nerves and vessels thta come to this region

102
Q

How Muscles are Named

A
  1. Size - Gluteus maximus
  2. Shape - Deltoid
  3. Direction of Fibers - Rectus femoris
  4. Action - Levator scapulae
  5. Origin and Insertion - Sternocleidomastoid
  6. Number of Origins - Triceps brachii
  7. Location - Biceps brachii
103
Q

Threshold

A

The membrane potential at which an action potential begins

A&P I - Grace College (5 decks)

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