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Anatomy > Exam 3 > Flashcards

Exam 3 Flashcards

1
Q

what are the three types of muscle?

A

skelatal, cardiac, and smooth

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2
Q

What characteristics classify a skeletal muscle?

A
  • striated
  • voluntary
  • require nervous system stimulation
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3
Q

What characteristics classify a cardiac muscle?

A
  • only in heart
  • striated
  • can contract without nervous system stimulation
  • involuntary
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4
Q

What characteristics classify a smooth muscle?

A
  • in walls of hollow organs
  • not striated
  • involuntary
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5
Q

what are the functions of muscle?

A
  • movement of bones/fluid
  • maintaining posture
  • heat generation
  • protects organs, forms valves
  • regulate elimination of materials
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6
Q

list the layers of skeletal muscle sheaths from external to internal

A
  • epimysium
  • perimysium
  • endomysium
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7
Q

what is the epimysium?

A

dense irregular ct surrounding entire muscle

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8
Q

what is the perimysium?

A

fibrous ct surrounding fascicles

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9
Q

what is the endomysium?

A

fine areolar ct surrounding each muscle fiber

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10
Q

What are the 2 attachment points for bone?

A
  • insertion (Moveable bone)
  • origin (immovable bone)
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11
Q

How does direct attachment occur?

A

epimysium fused to periosteum of bone

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12
Q

what is indirect attachment

A

connective tissue wrappings extend beyond muscle at tendon or aponeurosis

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13
Q

What is the sarcolemma?

A

plasma membrane of a skeletal muscle fiber

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14
Q

what is the sarcoplasm?

A

cytoplasm of a skeletal muscle fiber

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15
Q

what are myofibrils?

A
  • densely packed, rodlike parts of muscle fibers
  • contains sarcomeres
  • contains perfectly aligned repeating dark A band and light I bands
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16
Q

differentiate between H zone, M line, and Z disc

A

H zone: lighter region in midsection of A band where filaments don’t overlap

M line: line of protein myomesin bisects H zone

Z disc:coin shaped shet of proteins in midline of I band that anchors thin filaments and connects myofibrils

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17
Q

what is the smallest contractile unit of a muscle fiber?

A

sarcomere

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18
Q

what are sarcomeres composed of?

A

composed of thick and thin myofilaments made of contractile proteins

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19
Q

what is another name for thin filaments and what are their functions?

A

also called actin myofilaments, extend across I band and partway in A band, anchored to Z discs

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20
Q

what is another name for thick filaments and what are their functions?

A

also called myosin myofilaments, extend length of A band, connected at M line

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21
Q

what are thick filaments composed of?

A

the protein myosin, each composed of 2 heavy and 4 light polypeptide chains

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22
Q

What is the structure of a thin filament?

A

twisted double strand of fibrous protein F actin

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23
Q

What process does the sliding filament model of contraction describe

A

generation of force in muscles

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24
Q

According to the sliding filament model, where are the thick and thin filaments in a relaxed state?

A

overlap only at ends of A band

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25
Q

According to the sliding filament model, where are the thick and thin filaments during contraction?

A

the thin filaments slide past thick filaments, causing actin and myosin to overlap more

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26
Q

How do cross bridges form?

A

when myosin heads bind to actin

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27
Q

What must occur for a skeletal muscle to contract?

A
  • an action potential must be generated in sarcolemma
  • action potential must propagate along sarcolemma, briefly raising intracellular Ca2+ levels
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28
Q

what is a motor unit?

A

a motor neuron and all muscle fibers it supplies

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29
Q

What is the space between an axon ending and a single muscle fiber called?

A

neuromuscular junction

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30
Q

Where is the neuromuscular junction typically located on muscle fiber

A

situated midway along length of muscle fiber

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31
Q

what is the gel-filled space that separates the axon terminal and the muscle fiber

A

synaptic cleft

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32
Q

what neurotransmitter is found in synaptic vesicles?

A

acetylcholine (ACh)

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33
Q

Describe the events that occur at the neuromuscular junction

A
  1. nerve impulse arrives at axon terminal
  2. ACh released into synaptic cleft
  3. ACh diffuses across cleft and binds with receptors on sarcolemma
  4. action potential is generated
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34
Q

What are the three basic steps of action potential generation?

A
  1. end plate potential
  2. depolarization
  3. repolarization
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35
Q

What occurs during end plate potential (local depolarization)

A
  • ACh binding opens chemically (ligand) gated ion channels
  • simultaneous diffusion of Na+(in) and K+ (out)
  • more Na+ diffuses in, reducing neg charge in sarcolemma
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36
Q

What occurs during depolarization

A
  • end plate potential spreads to adjacent membrane areas
  • voltage-gated NA+ channels open
  • Na+ influx decreases membrane voltage toward critical voltage called threshold
  • once threshold is reached, AP is initiated
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37
Q

What occurs during repolarization

A
  • Na+ channels close and voltage-gated K+ channels open
  • K+ outflow rapidly restores resting polarity
  • muscle cannot be stimulated in refractory period until repolarization is complete
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38
Q

What is excitation-contraction coupling?

A

events that transmit AP along sarcolemma that lead to sliding of myofilaments

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39
Q

when does EC coupling occur?

A

during the latent period, the time between AP initiation and beginning of contraction

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40
Q

Describe the events of EC coupling

A
  • AP propagated along sarcomere to T tubules
  • voltage-sensitive proteins stimulate Ca2+ to release from SR
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41
Q

Describe what occurs at low intracellular Ca2+ concentration

A
  • tropomyosin blocks active sites on actin
  • myosin heads cannot attach to actin
  • muscle fiber is relaxed
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42
Q

Describe what occurs at higher intracellular Ca2+ concentration

A
  • Ca2+ binds to troponin
  • troponin changes chape and moves tropomyosin away from myosin binding sites
  • myosin heads bind to actin, causing sarcomere shortening and muscle contraction
  • when nervous stimulation ceases, Ca2+ is pumped back into SR and contraction ends
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43
Q

What is Rigor mortis

A
  • cross bridge detachment requires ATP
  • 3-4 hours after death muscles begin to stiffen with weak rigidity
  • at 12 hours post mortem, dying cells take in calcium forming cross bridges
  • no ATP can be generated to break cross bridges
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44
Q

True or false, muscle cells have extensive amounts of ATP in storage

A

false, stored ATP is spent after about 5 seconds of intense exertion

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45
Q

what are the three ways to generate ATP in skeletal muscle fiber?

A
  • immediate supply via phosphate transfer
  • short term supply via glycolysis
  • long term supply via aerobic cellular respiration
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46
Q

how is ATP generated in phosphate transfer?

A
  • myokinase transfers phosphate from one ADP to another
  • creatine kinase transfers phosphate from creatine phosphate to ADP
47
Q

how is ATP generated in glycolysis?

A
  • glucose is converted into 2 pyruvate molecules
  • 2 ATP released per glucose molecule
  • occurs in cytosol and does not require oxygen
48
Q

What criteria categorizes muscle fibers?

A

type of contraction generated and primary means used for supplying ATP

49
Q

What is the difference between oxidative and glycolytic fibers?

A
  • oxidative fibers are fatigue resistant, use aerobic respiration, has extensive capillaries, and many mitochondria
  • glycolytic fibers are fatigable, uses anaerobic respiration, and has less capillaries and mitochondria
50
Q

What are the 3 types of skeletal muscle fibers?

A
  1. slow oxidative fibers (type 1)
  2. fast oxidative fibers (type 2a, intermediate)
  3. fast glycolytic fibers (type 2b, fast anaerobic)
51
Q

What are the characteristics of slow oxidative fibers?

A
  • contractions are slower and less powerful
  • high endurance since ATP supplied aerobically
  • half the diameter of other fibers, red in color due to myoglobin
52
Q

What are the characteristics of fast oxidative fibers?

A
  • contractions are fast and powerful
  • primary aerobic respiration, but less delivery of oxygen
  • intermediate size, light red in color
53
Q

What are the characteristics of fast glycolytic fibers?

A
  • contractions are fast and powerful
  • contractions are brief (due to anaerobic ATP production)
  • largest in size, white in color due to lack of myoglobin
54
Q

True or false, a single muscle contains only one type of muscle fiber

A

false, a single muscle contains a mixture of fiber types

55
Q

What kind of muscle fiber might a long distance runner have a lot of?

A

higher proportion of slow oxidative fibers in legs

56
Q

Define Muscle Tension

A

the force generated when a muscle is stimulated to contract

57
Q

Define Muscle Twitch

A

a brief contraction to a single stimulus

58
Q

What are the three periods during a twitch?

A
  1. latent period
  2. contraction period
  3. relaxation period
59
Q

What is treppe?

A

an increases in twitch tension when stimuli occur 10-20 times per second

60
Q

What causes twitches to get stronger during treppe?

A

insufficient time to remove all ca2+ between twitches and increased heat improves efficiency

61
Q

What is muscle tone?

A

resting tension in a muscle generated by involuntary stimulation

62
Q

What is an isometric contraction?

A

increased tension while muscle length stays the same

63
Q

What is an isotonic contraction?

A

muscle tension overcomes resistance resulting in movement

64
Q

What is the length-tension relationship?

A

the tension a muscle produces depends on its length at the time of stimulation

65
Q

What are the functions of the nervous system?

A

collects information, processes, evaluates, and initiates a response to information

66
Q

What are the two factions of the afferent nervous system?

A
  1. somatic sensory system: detects stimuli we consciously perceive
  2. visceral sensory system: detects stimuli we typically don’t perceive
67
Q

What are the two factions of the efferent nervous system?

A
  1. somatic motor system: sends voluntary signals to skeletal muscles
  2. autonomic motor system: sends involuntary commands to heart, smooth muscle, and glands (divides into sympathetic and parasympathetic)
68
Q

List and define the general characteristics of neurons

A
  • excitability: responds to stimulus
  • conductivity: propagates electrical signal
  • secretion: release neurotransmitters
  • longevity: live throughout person’s lifetime
  • amitotic: lose mitotic ability after fetal development
69
Q

What part of the neuron is the nucleus found?

A

the cell body

70
Q

what are dendrites?

A

short, unmyelinated processes branching off cell body that receive input

71
Q

at what point does the axon attach to the cell body?

A

at the axon hillock

72
Q

What is anterograde transport?

A

axon moves newly synthesize material from cell body toward synaptic knobs

73
Q

what is retrograde transport?

A

axon moves used materials towards cell body for breakdown and recycling

74
Q

what are the three structural classifications of neurons?

A
  • multipolar (most common)
  • bipolar
  • uni polar
75
Q

What are the three functional classifications of neurons?

A
  • sensory neurons (mostly unipolar)
  • motor neurons (multipolar)
  • interneurons (multipolar)
76
Q

what is a nerve?

A

a bundle of parallel axons in the PNS

77
Q

what are the three connective tissue wrappings around a nerve?

A

epineurium, perineurium, endoneurium

78
Q

what is a synapse?

A

the place where a neuron connects to another neuron or an effector

79
Q

Describe characteristics of glial cells

A
  • non-excitable support cells
  • smaller than but far outnumber neurons
  • capable of mitosis
80
Q

What are the glial cells in the CNS?

A

astrocytes, ependymal cells, microglia, and oligodendrocytes

81
Q

What are astrocytes?

A
  • most abundant glial cell in CNS
  • help form blood-brain barrier by wrapping feet around brain capillaries
  • regulates tissue fluid composition
  • occupy space of dead neurons
82
Q

What are ependymal cells?

A
  • line internal cavities of CNS
  • helps produce CSF
  • ciliated simple cuboidal or simple columnar cells
83
Q

What are microglia?

A
  • small, rare cells that wander CNS and replicate in infection
  • phagocytic cells that engulf pathogens
84
Q

what are oligodendrocytes?

A

large cells with slender extensions that wrap around axons to form myelin sheath

85
Q

What types of glial cells are in the PNS?

A

satellite cells and neurolemmocytes (Schwann cells)

86
Q

What are satellite cells?

A
  • arranged around neuronal cell bodies in a ganglion
  • electrically insulate and regulate the exchange of nutrients and wastes
87
Q

what are schwann cells?

A
  • elongated flat cells that ensheath PNS axons with myelin
88
Q

what are gliomas

A

glial cell tumors

89
Q

Describe the process of myelination in the PNS

A
  • Schwann cell encircles neuron axon and wraps it in layers forming myelin sheath
  • Schwann cell’s cytoplasm and nucleus are pushed to periphery forming neurilemma
  • a Schwann cell can only myelinate 1 mm of axon so several are needed for one axon
90
Q

Describe the process of myelination in the CNS

A
  • one oligodendrocyte can only myelinate 1 mm of multiple axons each at multiple spots
  • no neurilemma formed
91
Q

How does multiple sclerosis impact the CNS

A

autoimmune disorder that causes oligodendrocytes to be attacked by immune cells

92
Q

What is needed for PNS axons to regenerate and what may improve the chance of success

A
  • regeneration possible if neuron cell body is still intact and enough neurilemma remains
  • success more likely if amount of damage is less extensive
93
Q

Name and describe the three types of channels

A
  • leak channels: always open for continuous diffusion
  • chemically gated channels: normally closed but open when neurotransmitter binds
  • voltage gated channels: normally closed but open when membrane charge changes
94
Q

Describe the characteristics of resting neurons

A
  • ions are unevenly distributed across the plasma membrane due to the actions of pumps
  • gated channels are closed in functional segments of cell
  • charge difference of -70 mV across membrane
95
Q

What is the most important factor in setting RMP

A
  • K+ diffusion is most important factor
  • diffuses out of cell due to concentration gradient
    -diffusion is limited by electrical gradient
96
Q

what role do sodium-potassium pumps play in maintaining RMP

A
  • by pushing 3 positive charges out and only 2 in, pump contributes about -3 mV
  • maintains concentration gradients for these ions
97
Q

what are excitatory postsynaptic potentials

A

depolarizations caused by cation entry

98
Q

what are inhibitory postsynaptic potentials

A

hyperpolarizations caused by cation exit or anion entry

99
Q

where do summation of EPSPs and IPSPs occur

A
  • occur at axon hillock
  • the sum may or may not reach threshold membrane
  • if threshold is reached at axon hillock, v-gated channels open and AP is generated
100
Q

what is the difference between spatial and temporal summation?

A
  • spatial summation occurs when multiple locations on a cell’s receptive regions receive neurotransmitters simultaneously
  • temporal summation occurs when a single presynaptic neuron repeatedly releases neurotransmitters and produces multiple EPSPS within a short period of time
101
Q

depolarization is a gain of positive charge as ____ enters the cell

A

Na+

102
Q

repolarization is return to negative potential as ____ exits

A

K+

103
Q

what is an absolute refractory period?

A
  • no stimulus can initiate another action potential
  • Na+ channels are open, then inactivated
104
Q

What is a relative refractory period

A
  • another action potential is possible (Na+ channels are reset)
  • minimum stimulus strength is greater
  • some K+ channels are still open so cell is slightly hyperpolarized
105
Q

Describe continuous conduction

A

occurs on unmylelinated axons, charge opens voltage gated channels which allows charge to enter, which spreads to adjacent region and opens more channels

106
Q

what is saltatory conduction

A
  • occurs on myelinated axons, action potential occurs only at neurofibril nodes which is where axon’s voltage gated channels are concentrated
  • after Na+ enters at a node it starts a rapid positive current down the inside of axon’s myelinated region
107
Q

what type of conduction is faster?

A

saltatory` is much faster and uses less ATP

108
Q

What is a graded potential?

A
  • occur in neuron’s receptive region due to ion flow through chemically gated channels
  • can be pos or neg changes in charge
  • local, can only travel a short distance
109
Q

what is an action potential

A
  • occur in axon due to ion flow through voltage gated channels
  • involved depolarization and repolarization
  • all or none once threshold is reached
  • propagate down entire axon to synaptic knob
110
Q

How do axon thickness and myelination contribute to conduction speed

A
  • thicker fibers conduct faster than thin ones
  • myelinated fibers move much faster than unmyelinated one
111
Q

what are the four chemical classes of neurotransmitters?

A
  1. acetylcholine
  2. biogenic amines
  3. amino acids
  4. neuropeptides
112
Q

How do neurotransmitters differ by effect?

A
  • excitatory transmitters cause EPSPs
  • inhibitory transmitters cause IPSPs
113
Q

What is the difference between direct and indirect neurotransmitters?

A
  • direct transmitters bind to receptors that are chemically gated channels
  • indirect transmitters bind to receptors that involve G-proteins and second messengers in order to cause postsynaptic potential

Anatomy (10 decks)

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