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54 Cards in this Set

  • Front
  • Back
What is a muscle fiber?
Highly specialized skeletal muscle cells
Characteristics of Skeletal Muscles
Voluntary Control, Has Striations, Many Nucleus near Sarcolemma, Narrow T tubules that form triads with SR, Extensive SR that stores and releases Ca ions, Rapid Twitch Contractions stimulated by a neuron
Characteristics of Cardiac Muscles
Involuntary Control, Has Striations, Single Nucleus, Large T tubules that form diads with SR and regulate the Ca ion entry into sarcoplasm, less extensive SR than skeletal muscles, slow separate contractions
Characteristics of Smooth Muscles
Involuntary Control, No Striations, Single nucleus near the center of cell, No T tubules, Poorly Developed SR, Visceral contractions are electrically coupled sheets of contract autorhythmically, multiunit contractions are individual fibers contract when stimulated by neuron
functions of skeletal muscles
movement, posture, heat production
3 characteristics of skeletal muscle
excitability or irritability, contractility, and extensibility
excitability
ability to be stimulated
contractility
ability to contract or shorten
extensibility
ability to extend or stretch
What type of neuron innervates skeletal muscle?
sommatic motor neuron
Sarcoplasm
cytoplasm of a muscle fiber
sarcolemma
plasma membrane of a muscle fiber
myofibrils
bundles of very fine muscles in cytoplasm of fiber with thick and thin filaments running parallel and the T tubules running perpendicular
thin filaments
made of actin, tropomyosin, and troponin
actin looks like beads and the tropomyosin looks like thick string with the troponin spaced along the tropomyosin
What zone is in the middle of the a band
H zone
H zone
he middle region of the thick filaments where they do not overlap the thin filaments
Glucose is stored in muscles as
glycogen
Z line
dense plate or disk to which the thin filaments directly anchor and is a usefull landmark for separating one sarcomere from the next
A band
the segment that runs the entire length of the thick filaments
I band
the segment that includes the Z line and the ends of the thing filaments where they do not overlap the thick filaments
sarcomere
a segment of the myofibril between two successive Z lines
Thick filaments
made up of myosin molecules which are shaped like golf clubs with their long shafts bundled together to form a thick filament and their "heads" sticking out from the bundle
What protein molecules form cross bridges?
myosin heads which form with actin
what structures make up a triad?
a T tubule sandwiched between sacs of the SR
What does troponin bind to?
Ca ion
What is the function of the protein tropomyosin?
blocks the active sites on the actin molecule
What is the major rold of the SR?
pumps Ca ions from the Sarcoplasm and stores them within its sacs
What is the function of T tubules?
allow electrical signals, or impluses, traveling along the sarcolemma to move deeper into the cell
When a muscle contracts, what structures are pulled toward the center of the sarcomere?
thin filaments
In the sliding filament theory, what slides past what?
thin filaments slide past the thick filaments, heading toward center of the sarcomere
What is acetylcholine?
neurotransmitters that contacts the sarcolemma of the adjacent muscle fiber
Ca ions attach to what protein of the thin filament
Troponin
Events of Muscle Contraction in order
1)energized myosin heads of the thick filaments bind to actin molecules in the nearby thin filaments 2)The myosin heads bend with great force, literally pulling the thin filaments past them 3)Each head then releases itself, binds to the next active site, and pulls again
Where does calcium go after muscle contraction?
back into the sacs of the SR
What is the neuromuscular junction?
type of connection called a synapse, characterized by a narrow gap, of synaptic cleft, across which neurotransmitter molecules transmit signals.
hypertrophy
increased size of an organ or part caused by an increase in the size of its cell
atrophy
wasting away of tissue, decreased in size of a part
In excitation-contraction coupling, where is Ca ions released? What does Ca ions bind to? What blocks the myosin heads?
Ca ions are released into the SR where it binds to the troponin molecules, the tropomyosin blocks the myosin heads
myoglobin
large protein molecule containing iron groupd that attract oxygen molecules and hold them temporarily
What is a motor unit?
motor neuron plus the muscle fibers to which is attaches
White fibers
fast muscle fibers iwht little myoglobin
red fibers
slow muscle fibers with high levels of myoglobin
tetanus
smooth, sustained contractions caused by high frequency stimulation
isotonic contractions
tone or tension within a muscle remains the same as the length of the muscle changes, the muscle gets shorter
isometric contractions
muscle length remains the same while the muscle tension increases
treppe
gradual steplike increase in the srength of contraction that can be observed in a series of twitch contractions that occur about 1 second apart
cramps
painful muscle spasms when a muscle organ is mildly inflamed, but they can be symptom of any irritation or ion and water imbalance
Endurance training
aerobic training
aerrobic respiration
catabolic process in the stage of cellular respiration requiring oxygen taking place in the sarcoplasm and the mitochondria
anaerobic respiration
catabolic process in the stage of cellular respiration not requiring oxygen, byproduct of lactic acid, liver changes the acid back into glucose
muscle fatigue
muscle does not respond to the strongest stimuli, repeated stimulation of muscle in time lessens its excitability and contractillity, lack of ATP
Three phases of twitch contraction
latent period, contraction phase, relaxaion phase
Graded strength principle
skeletal muscles contract with varying degrees of strength at different times
metabolic condition of individual fibers with high ATP influences their capacity to generate force, amount of load place on muscle, length tension relationship, number of fibers contracting simultaneously
muscle sructures
myofilament, myofibril, muscle fiber, fascle muscle