Anatomy & Physiology: Muscle Physiology
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- Where do the thick and thin filaments overlap?
- A Band
- What is the functional contractile unit of a myofibril?
- sacromere
- Where are only thin filaments found?
- I Band
- What is the end of the sarcoplasmic reticulum, a t-tubule and the end of the other sarcoplasmic reticulum?
- triad
- What hydrolyzes ATP to relase energy?
- ATPase
- Where are only thick filaments found?
- H Zone
- After the calcium moves the TTC away from the binding sites on actin, what happens?
- myosin heads attach to form the cross-bridge
- What is the thick filament made of?
- myosin
- What happens when calcium is released?
- binding site is open
- What are the rod-like protein molecules that run parallel within the myofibril?
- myofiliments
- when atp binds to myosin head and cross bridge releases
- cross-bridge detachment
- What is the modified endoplasmic reticulum?
- sarcoplasmic reticulum
- What contains ATPase?
- myosin
- What releases calcium and takes it back up?
- sarcoplasmic reticulum
- What happens when the myosin head is cocked?
- atp is hydrolyzed to release energy (to reposition head to create a new cross bridge)
- Actin is actually the what site?
- binding
- Myosin has a natural and unnatural -.
- sitting position
- What is the repeated series of light and dark bands created by the myofiliments?
- striations
- What is required to move the TTC away from the binding sites on actin?
- calcium
- What is a muscle's ability to receive/respond to stimuli?
- excitability/irritability
- When the thin filaments are pulled toward the center of the sacromere by the thick filaments
- power stroke
- What are the four functional characteristics of muscles?
-
excitability
contractility
extensibility
elasticity - What happens when CA is taken up by the SR?
- muscle relaxes
- What is the electrical signal called which stimulates cells in the muscle to contract?
- response
- A high level of CA, muscle is.....
- contracted
- What are three stimuli that are associated with muscle excitablility/irritability?
-
chemical (neurotransmitter)
hormone
change in pH - Four effects of contraction/ca release on sarcomeres?
-
-shorten, muscle shortens
-z lines slide toward each other
-I bands shorten
-h zone disappears - What is a muscle's ability to shorten?
- contractility
- What is a nerve and all the fibers it serves?
- motor unit
- What are the two types of myofiliments?
- thick and thin
- When the myofibril contracts, what comes closer together?
- the Z lines
- What is a muscle's ability to be stretched?
- extensibility
- If the stimulus is constant, time between contractions short and Ca levels increase or decrease?
- increase
- What is a muscle's ability to resume resting length after being stretched?
- elasticity
- Why can't tetanus occur indefinitely?
- run out of atp, causing muscle fatigue
- What is the boundary line between sacromeres?
- Z Line
- How do you get a muscle to send more force?
- send more stimuli
- What are thin filaments made of?
- actin, tropomyosin and troponin
- Stronger stimuli causes what?
- mulitple unit summation
- What attaches to the tropomyosin to form a complex?
- troponin
- What is sustained contraction?
- tetanus
- Skeletal attachment, movable bone?
- insertion
- "cramps" due to the lack of atp
- contractures
- What covers the binding sites on the filament for the myosin heads?
- tropomyosin
- Increasing stimuli causes more muscle fibers- motor units to act, called what?
- recruitment
- When the TTC moves out of the way and the myosin heads attach to the actin, what is this called?
- cross-bridge
- What helps to produce smooth and controlled contractions?
- stronger stimuli
- The normal function of skeletal muscle depends on what?
- nerves and rich blood supply
- What is recruitment?
- letting some cells work, some rest
- What are three characteristics of skeletal muscle?
-
highly innervated
lots of blood supply
branch of at least one nerve - What is treppe?
- when repeated stimuli cause 2nd contraction to be stronger than 1st
- Skeletal attachment, less movable bone?
- origin
- What helps with muscle fatigue (some cells at tetanus, some at resst)?
- stronger stimuli
-
Sacro-
Myo- - muscle
- Treppe: limit based on what?
- filaments running out of room to slide within sarcomere
- Skeletal muscle attachment must have what two things?
- a tendon and aponeuroses
- type of muscle fiber recruited depends on what?
- need
- What are associated with myofibrils?
- t-tubules
- What is when muslces change length and move something?
- isotonic contraction
- What element is extremely important in contraction?
- calcium
- What is an ex of isotonic contraction?
- lifting weights
- What attaches the muscle to the bone?
- tendon
- What is when muscles contract but there is no shortening/lengthening?
- isometric contraction
- What are tendons made of?
- connective tissue
- What is an ex of isometric contraction?
- pushing on a wall
- What controls contraction?
- the sarcoplasmic reticulum
- how many types of muscle fiber is a motor unit comprised of?
- one
- What occurs because the muscle hasn't fully relaxed before the onset of the second stimulus?
- rapid stimulation
- Stimuli in rapid succession will produce what?
- a second twitch stronger than the first ("summation")
- What causes wave summation and tetanus?
- rapid stimulation
- physical inability to conract
- muscle fatigue
- Can tetanus occur indefinitely?
- no
- muscles are made up of how many types?
- three