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BIO 171 prof. Evans > Exam #3 > Flashcards

Exam #3 Flashcards

1
Q

What are two methods used to classify joints? What are the subclasses and descriptions?

A

Structural Classifications:

Fibrous = fibrous connective tissue
Cartilaginous = cartilage
Synovial = not joined directly

Functional Classifications:

Synarthrosis = immovable
Amphianthrosis = slightly movable
Diarthrosis = freely movable
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2
Q

What is the function of synovial fluid?

A

Synovial fluid is held in the cartilage, mechanically squeezed out, and lubricates the surface to reduce friction

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3
Q

What are the types of synovial joints? Axial? How do they move? Where are they found?

A

Plane joint = non-axial, slipping/gliding movement only (intracarpal joint)

Hinge joint = uniaxial, convex cylinder in one bone articulates with that of another (elbow joint)

Pivot joint = uniaxial, rotation on a single axis (proximal radiolnar joint)

Condyloid joint = biaxial, ovoid articulation (metacarpophangeal joint)

Saddle joint = biaxial, opposing surfaces are reciprocally concave-convex (carpometacarpal joint of thumb)

Ball & socket joint = multiaxial, one rounded bone fits into the cup-like depression of another bone (shoulder joint)

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4
Q

Muscle functions?

A

Movement of bones/blood

Maintaining posture and body position

Control of body openings and passages (vasodilation & vasoconstriction)

Heat generations (esp. in skeletal muscle) (vasoconstriction)

Glycemic control (reg. blood sugar levels)

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5
Q

What are the characteristics of muscle tissue?

A

Excitability (responsiveness or irritability): ability to receive and respond to stimuli

Contractility: ability to shorten when stimulated

Extensibility: ability to be stretched

Elasticity: ability to recoil to resting length

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6
Q

Organization of skeletal muscle?

A

Muscle tissue (cells / fibers)

Connective tissues

Nerves

Blood Vessels

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7
Q

Organization of connective tissue?

A

epimysium

perimysium

endomysium

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8
Q

What’s the role of the sarcomere?

A

… the functional unit of muscle contraction, separated by a dense material called Z lines.

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9
Q

What is the Z-line?

A

A dark thin protein band to which actin filaments are attached in myofibrils

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10
Q

What is the M-line?

A

runs through the exact center of the sarcomere

provide elasticity to the muscle

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11
Q

What are the binding sites on a myosin head? What do they do?

A

Binding site for actin to convert chemical energy, in the form of ATP, to mechanical energy.

Binding site for ATP (ATP hydrolysis, performs a power stroke associated with release of hydrolysis products, and detaches from actin upon binding with new ATP. )

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12
Q

What are the requirements for skeletal muscle contraction?

A

Activation: neural stimulation at a neuromuscular joint (NMJ)

Excitation-contraction coupling:
• Generation and propagation of an action potential along the sarcolemma

• Final trigger: a brief rise in intracellular Ca2+ levels

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13
Q

What are the steps of muscle relaxation?

A
  • Ach is broken down by AChE
  • SR recaptures Ca2+
  • Active sites covered, no cross-bridge formation
  • Contraction ends
  • Relaxation occurs, passive return to resting length
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14
Q

What are the steps in initiating muscle contraction?

A
  • Ach released, binding to receptors
  • Action potential reaches T-tubule
  • SR releases Ca2+
  • Active site exposure, cross-bridge formation
  • Contraction begins
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15
Q

Describe the sliding filament theory

A
  • In the relaxed state, thin and thick filaments overlap only slightly
  • During contraction, myosin heads bind to actin, detach, and bind again, to propel the thin filaments toward the M line
  • As H zones shorten and disappear, sarcomeres shorten, muscle cells shorten, and the whole muscle shortens
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16
Q

Define motor unit (diff. between small and large motor units)

A
  • Motor unit = a motor neuron and ALL (four to several hundred) muscle fibers it supplies
  • Small motor units in muscles that control fine movements (fingers, eyes) 1 neuron : 4-6 fibers
  • Large motor units in large weight-bearing muscles (thighs, hips) 1 neuron : 1000s fibers
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17
Q

Define muscle twitch. What are the phases?

A

… response of a fiber to a single stimulus

  • latent period = delay between activation of nerve and activation of muscle
  • contraction phase = cross-bridge formation, creates tension
  • relaxation phase = reabsorption of Ca into SR
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18
Q

What’s the difference between fused and unfused tetanus?

A

fused tetanus = force of contraction is smooth and constant because of very frequent APs (until fatigued)

unfused tetanus = force of contraction varies

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19
Q

Define tetanus

A

contraction of a muscle caused by stimuli (AP)

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20
Q

Define muscle tension

A

force of a muscle contraction

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21
Q

What is length-tension relationship?

A

amount of overlap between actin and myosin

too much overlap = not much force/tension

too little overlap = decreased froce/tension

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22
Q

How does the length of a sarcomere differ in the heart?

A

sarcomere length is shorter in the heart than in skeletal muscle, allowing heart to pump blood

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23
Q

What is motor unit recruitment?

A

same muscle to lift different masses (small mass = 5 fibers // large mass = 12 fibers)

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24
Q

What are the many differences between slow and fast twitch muscle fibers?

A 
large red slow twitch = 
(2 low glyco, 4 highs)
• low glycogen content
• low glycolytic capacity
• high fatigue resistance
• high capillary supply
• high mitochondria
• high myoglobin (carries oxygen)
• aerobic
• steady power

small white fast twitch =
(2 high glyco, 4 lows)
• high glycogen content
• high glycolytic capacity
• low fatigue resistance
• low capillary supply
• low mitochondria
• low myoglobin (carries oxygen)
• anaerobic
• explosive power

Most human muscles are mixed fibers, pink

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25
Know the types of muscle contractions
Isotonic: • concentric = muscle contracts, muscle opposes load (lifts) • eccentric = muscle elongates, muscle holds load Isometric = muscle contracts, cannot oppose load (cannot lift)
26
What is Myostatin?
inhibits muscle differential, muscles stay are normal size Myostatin deficiency, muscles get super toned without any regulation by Myostatin
27
What is muscle metabolism for? What are the types? Sources of energy? Time?
muscle metabolism is for the energy used in muscle contraction * Direct phosphorylation = coupled reaction of creatine phosphate and ADP. Anaerobic. 15s * Anaerobic respiration = glycolysis and lactic acid formation. Anaerobic (no O2 needed). 30-60s * Aerobic respitation = glucose, pyruvic acid, fatty acid. Aerobic (O2 required). Hours
28
Describe muscle fatigue
Physiological inability to contact Occurs when: • Ionic imbalances (K, Ca, Pi) interfere with E-C coupling • Prolonged exercise damages the SR and interferes with Ca regulation and release • Total lack of ATP occurs, during states of continuous contraction
29
Describe oxygen deficit/debt
Extra oxygen needed after exercise for: • oxygen reserves • glycogen stores • ATP and CP reserves Conversion of lactic acid to pyruvate acid, glucose, and glycolygen
30
Describe heat production
~40% of the energy released in muscle activity is useful as work remaining 60% given off as heat dangerous heat levels prevented by radiation of heat from skin and sweating
31
What does muscle performance depend on?
the distribution of muscle fibers
32
ID the structure that coordinates skeletal movement
golgi tendon organ = prevents overstretching and tearing of tendon muscle spindles (in muscle itself) un-stretched muscle: APs are generated at a constant rate stretched muscle: APs are generated at a high rate
33
What are the two types of muscle pathology?
Neurogenic diseases • Muscular Sclerosis = degeneration of myelin sheath • Spinal muscular atrophy = degeneration of spinal muscle Myopathic diseases: • Muscular dystrophy • Mitochondrea Myopathy
34
What is eburnation?
the rubbing/friction of bone-on-bone
35
What is atrophy?
shrinkage of muscle due to lack of use
36
What is hypertrophy?
enlargement of muscle due to overuse
37
What is Rigor Mortis?
no ATP to release myosin heads, muscles stay contracted as the cross-bridge formation remains
38
What's the difference between smooth and skeletal muscle contraction?
smooth = muscle contraction regulated by MLCK complex skeletal = muscle contraction regulated by TTC complex
39
Describe how mature muscle fiber becomes multinucleated
muscle fibers develop through the fusion of mesodermal cells called myoblasts
40
What forms the triad?
T-tubule & 2x terminal cisternae
41
What is transmembrane potential?
difference in electrical potential (voltage) across the membrane of a lining cell
42
What is action potential (AP)?
nerve impulses that allow for muscle contraction
43
Where are neurotransmitters found?
in vesicles in the motor neuron axon
44
What is a threshold stimulus?
minimum strength (mV) to initiate a contraction
45
What does "all-or-none response" mean?
the muscle fibers either contract or do not, there is no partial contraction
46
What does a partial but sustained contraction describe?
muscle tone
47
What attributes to the striated appearance of skeletal muscles?
repeating sarcomere units
48
What transmits muscle impulses into the cell interior?
T-tubules
49
What regulates Ca2+ levels? What is it called with Ca gates are opened/closed?
SR & T-tubules open Ca gate = depolarization closed Ca gate = repolarization
50
What happens to muscle when there is no Ca present? ... and with Ca present?
Without Ca, the muscle is relaxed because myosin heads cannot form cross-bridge With Ca, the binding of Ca to troponin causes a shift in the TTC allowing cross-bridge formation
51
What are the 7 steps of the NMJ?
1. ) AP travels the length of the axon of a motor neuron to the axon terminal 2. ) voltage gates Ca channels open, and Ca ions diffuse into the terminal 3. ) Ca entry causes synaptic vesicles to release ACh via exocytosis 4. ) ACh diffuses across synaptic cleft and binds to ACh receptors on ligand-gated cation channels 5. ) ligand-gated cation channels open 6. ) Na ions enter muscle fiber, K+ ions exit, causing AP to become less negative 7. ) once the membrane potential reaches threshold value, an AP propagates along sarcolemma
52
What are the 4 steps of the cross bridge cycle?
1. ) cross-bridge formation = ATP hydrolysis to ADP, cocks myosin head 2. ) cross bridge formation = myosin head attaches to actin in presence of Ca 3. ) power stroke = shortening of sarcomere, pulling actin towards center (M-line) 4. ) cross bridge detachment = ATP releases myosin from actin (Ca is then reabsorbed into SR) 4. ) reactivation of myosin head =
53
What is bronchoconstriction?
constriction of the airways in the lungs due to the tightening of surrounding smooth muscle
54
What is bronchodilation?
expansion of bronchial air passages
55
Describe smooth muscle contraction
slow, sustained contractions non-voluntary contain actin and myosin filaments no striations, no sarcomeres
56
What are the 4 steps in excitation-contraction coupling?
1. ) Ca comes in from the ECF & SR 2. ) Ca binds to calmodulin, making it active 3. ) Calmodulin activates MLCK, giving it energy 4. ) MLCK phosphorylates and cocks myosin head
57
Describe the force of muscle contraction
force is affected by the relative size of the fibers (fiber diameter) cell hypertrophy: increase of size and force of contraction) cell hyperplasia (more cells)
58
What are the 4 common muscle disorders?
Tetanus - permanent contraction Botulism - no AP Myasthenia gravis - low nerve stimulation Lou Gehrig's - ALS, degeneration of motor neurons
59
What are the 5 ligaments in the shoulder joint?
coracoacromial coracoclavicular coracohumeral glenohumeral acromioclavicular
60
What are the 5 ligaments in the knee joint?
fibular collateral tibial collateral posterior cruciate anterior cruciate patellar ligament
61
What are the three different layers of connective tissue in a muscle?
perimysium epimysium endomysium

BIO 171 prof. Evans (12 decks)

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