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Chapter 12 Muscle Physiology
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46
Physiology
Undergraduate 2
11/18/2013

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Term
Skeletal Muscle
Definition
Muscle that is connected to at least two bones
Term
Tendons
Definition
Cords of elastic connective tissue that connect muscle to bone
Term
What are the four main functions of muscles?
Definition
1. Produce movement
2. Maintain posture
3. Stabilize joints
4. Generate heat
Term
Fascicles
Definition
Numerous bundles of individual muscle cells.
Term
Muscle Fibers
Definition
Muscle cells
Term
Sarcolemma
Definition
The plasma membrane of a muscle fiber
Term
Myofibril
Definition
Rod-like structures found in the sarcoplasm of a muscle fiber which contain the fiber's contractile machinery.
Term
What proteins make up the filaments in a myofibril?
Definition
Myosin and actin
Term
Sarcoplasmic Reticulum
Definition
A saclike membranous network that surrounds each myofibril. Stores calcium.
Term
Transverse Tubules (T-Tubules)
Definition
Structures that transmit action potentials from the sarcolemma into the cell's interior, triggering the release of calcium from the sarcoplasmic reticulum.
Term
Lateral Sacs (Terminal Cisternae)
Definition
Located near the t-tubules and store caclium
Term
Triad
Definition
A t-tubule and the two lateral sacs it is associated with.
Term
Thick and Thin Filaments
Definition
Protein fibers in the myofibril
Term
Sarcomere
Definition
Fundamental repeating unit that creates a myofibril
Term
Z Lines
Definition
Border the sarcomere on either side and run perpendicular to the long axis. They also anchor the thin filaments at one end
Term
M Lines
Definition
Run perpendicular to the long axis and connect the thick filaments.
Term
A Band
Definition
Thick filaments of the sarcomere
Term
H Zone
Definition
A light region in the center of the A bands in which only thick filaments are present.
Term
I Band
Definition
Light region in which only the thin filaments are present.
Term
Actin and Myosin
Definition
Compose the thick and thin filaments of the sarcomere. Referred to as contractile proteins.
Term
G Actin
Definition
Actin monomers that are the basic components of each thin filament. Contains a myosin binding site.
Term
F Actin
Definition
Polymer made up of G actins that are bound together. Makes up actin strands found in thin filaments.
Term
Regulatory Protein
Definition
Protein that enable muscle fibers to start or stop contracting.
Term
What are the two regulatory proteins present in thin filaments of the sarcomere?
Definition
Tropomyosin and Troponin
Term
Tropomyosin
Definition
Long fibrous molecule that extends and blocks the myosin binding sites in muscles at rest.
Term
Troponin
Definition
Complex of three proteins that are responsible for the actions produced by calcium ions which bind to it and trigger muscle contraction.
Term
Thick filaments are composed of what type of molecule?
Definition
Myosin
Term
Crossbridges
Definition
The heads of myosin molecules that bridge the gap between thick and thin filaments
Term
Bare zone
Definition
The middle of the thick filament in which no crossbridges are present.
Term
What two sites do myosin heads possess?
Definition
Actin-binding site that can bind to actin molecules and ATPase site that controls enzymatic activity and hydrolyzes ATP.
Term
During muscle contractions what happens to each region of the sarcomere?
Definition
The A band doesn't change. I band and H zone shorten. Z lines move closer to each other.
Term
Sliding-Filament Model
Definition
Muscles contract because the thick and thin filaments of the myofibril slide past one another.
Term
Crossbridge Cycle
Definition
The mechanism that drives the sliding of thick and thin filaments past one another during muscle contraction.
Term
Excitation-Contraction Coupling
Definition
The sequence of events that links the action potential to the contraction
Term
Neuromuscular Junction
Definition
Receive end-plate potentials, resulting in depolarization
Term
Creatine Phosphate
Definition
A compound that donates its phosphate to ADP to form ATP which muscles rely on for immediate use during contraction. (Use while preparing to use the energy produced by oxidative phosphorylation)
Term
Creatine phosphate + ADP in the presence of creatine kinase yields...
Definition
Creatine + ATP
Term
Creatine is broken down into...
Definition
Creatinine which is excreted from the body in the urine
Term
Creatinine can be measured in what bodily fluids?
Definition
Serum or urine
Term
Creatinine measurements are performed in order to evaluate what?
Definition
Renal function
Term
Normal Creatinine values
Definition
0.7-1.3 mg/dL for men and 06.-1.1 mg/dL for women
Term
Increased levels of creatinine can result from what?
Definition
Dehydration, renal failure, tubular necrosis, glomerulonephritis, diabetic nephropathy and rhabdomyolysis
Term
Decreased levels of Creatinine can result from what?
Definition
Muscular dystrophy and myasthenia gravis
Term
Creatinine phosphokinase
Definition
Normal values 10-120 micrograms per liter. An increase in serum indicates injury or stress to muscle tissue, the hear or the brain.
Term
Smooth muscle
Definition
Lacks striations
Is under involuntary control by the autonomic nervous system
Contains actin and myosin
Does not contain sarcomeres
Term
Are actin and myosin larger in skeletal muscle or smooth muscle?
Definition
Smooth muscle.
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