Lecture 12 - Musculoskeletal physiology Flashcards

1
Q

What are the four shared characteristics of muscles

A
  1. excitability
  2. contractability
  3. extensibility
  4. elasticity
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2
Q

What are the four important functions of muscle

A
  1. produce movement
  2. maintain posture and body position
  3. stabilize joints
  4. generate heat through contraction
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3
Q

What is the appearance and characteristics of:

skeletal muscle

A

striated, multi-nucleated peripherals

voluntary movement

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4
Q

Sarcolemma

A

muscle fiber plasma membrane that triggers action potentials

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5
Q

Sarcoplasm

A

muscle fiber cytoplasm

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6
Q

Myofibrils

A

Actin and myosin

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7
Q

Actin filaments

A

thin filaments containing troponin and tropomyosin

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8
Q

Myosin filaments

A

thick filaments

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9
Q

How are skeletal muscle fibers categorized

A

speed of contraction (slow or fast) and metabolic pathway (oxidative or glycolytic)

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10
Q

Myoglobin

A

protein within muscle that binds and stores oxygen; released and causes damage in rhabdomyolysis

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11
Q

What kind of job are slow oxidative fibers meant for? give an example

A

low-intensity endurance

distance walking

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12
Q

What kind of job are fast oxidative fibers meant for? give an example

A

medium intensity activities

sprinting

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13
Q

What kind of job are fast glycolytic fibers meant for? give an example

A

short term intense, powerful movements

hitting a grand slam

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14
Q

What is the appearance and characteristics of:

cardiac muscle

A

branched, uninucleated cells, connected by intercalated discs

involuntary movement

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15
Q

What cell junctions are in cardiac muscle

A

gap junctions (electrically couple cells) and desmosomes (hold together)

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16
Q

what muscle contains large numbers of mitochondria and why?

A

cardiac muscle; resistant to fatigue

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17
Q

What is the appearance and characteristics of:

Smooth Muscle

A

central nuclei in sheets, spindle-like cells

involuntary movement

18
Q

T/F: Smooth muscle typically contains two layers - longitudinal and circular

19
Q

What does the longitudinal layer of smooth muscle do

A

causes organ to shorten

20
Q

What does the circular layer of smooth muscle do

A

lumen of the organ constricts

21
Q

Varicosity

A

neuro-transmitter filled bulges that release neurotransmitters into the synaptic cleft in smooth muscles

22
Q

Pacesetter cell

A

can spontaneously trigger action potentials and contractions in the smooth muscle

23
Q

Summarize its role in contraction:

sarcolemma

A

site of action potential conduction that triggers contraction

24
Q

Summarize its role in contraction:

sarcoplasmic reticulum

A

regulates levels of ionic calcium - releases when the muscle is stimulated

25
Summarize its role in contraction: T Tubule
inward invagination of sarcolemma that allows for membrane potential to rapidly penetrate deep into the muscle fiber
26
Summarize its role in contraction: Myosin
forms cross bridge and acts as a motor to generate force
27
Summarize its role in contraction: ATP
prepares myosin for binding with actin by moving it to a higher-energy state and a "cocked" position
28
Where is the main storage site of glycogen
liver and muscle
29
Summarize its role in contraction: Actin
covered by regulatory proteins (tropomyosin and troponin) until released and then binds to myosin for contraction
30
Summarize its role in contraction: Troponin
3 subunits bind to tropomyosin, actin, and then calcium ions
31
Summarize its role in contraction: Tropomyosin
stiffens and stabilizes actin
32
Summarize its role in contraction: Calmodulin
SMOOTH MUSCLE calcium-binding site
33
What are the four steps needed for skeletal muscle to contract
1 - nerve stimulation 2 - action potential generated in the sarcolemma 3 - action potential propagated 4 - intracellular calcium rises briefly
34
What is excitation-contraction coupling
link electrical signals to contraction (steps 3 and 4)
35
Myosin ____ and Actin _____
pulls; slides
36
What are the 4 steps of the cross-bridge cycle
Formation - myosin attaches to actin Working (power) stroke - myosin pivots and pulls Detachment - ATP attaches to myosin and causes detachment Cocking - energy from hydrolysis of ATP puts myosin into a high-energy state
37
What is rigor mortis regarding contraction
absence of ATP that allows the release of cross-bridge
38
What are the 3 major differences in EC coupling between smooth and skeletal muscle
1 - calcium comes from the extracellular fluid 2 - calmodulin binds to calcium to active myosin 3 - slow contraction
39
T/F: Prior to successful cross bridge formation, calcium must bind to troponin in all muscle types.
False
40
Which of the following is NOT a characteristic of muscle: a. flexible b. excitable c. rigid
c. rigid
41