Side ASide B
Skeletal muscles are organs composed of
Skeletal muscle tissue, connective tissue, nerves and blood vessels.
Skeletal muscle 6 functions
1. Produce skeletal movement - pull on tendons.
2. Maintain posture and body posture.
Three layers of connective tissue that are part of each muscle:
1. Epimysium - surrounds the entire muscle
2. Perimysium - divides the muscle into departments
Surrounds the entire muscle. Separates the muscle from surrounding tissues and organs.
Divide the skeletal muscle into a series of compartments called fascicle. Contains blood vessels...
Within fascicle, surrounds the individual skeletal muscle cells, or muscle fibers. Contains...
Embryonic stem cells that function in the repair of damaged muscle tissue
Bundle of collagen fibers from epimysium, perimysium and endomysium at each end of the...
Characteristics of skeletal muscle fiber.
Sarcolemma, what does it surround?
Plasma membrane of a muscle fiber. It surrounds the sarcoplasm.
Through what is signal to contract?
Through Transvers tubules.
Responsible for skletal muscle fiber contraction. Consist of bundles of protein filaments called...
The sarcoplasmic reticulum
Related to smooth endoplasmic reticulum. Forms a tubulat network around each individual myofibril....
Pair of terminal cisternae an transverse tubule.
What causes muscle contration to begin?
When stored calcium ions are released into the sarcoplasm. These ions then diffuse into sarcomeres.
The smallers functional units of the muscle. Contains: thick and thin filaments, proteins that...
The A band
Located in the center of the sarcomere and contain thick and thin filaments, M-line, H-band...
The M line
Central portion of the sarcomere. Help stabilize the positions of the thick filaments.
Contains only thick filaments. Is bigger at reast and gets shorter when contracted.
Zone of overlap
Thin filaments are in between the thick elements. Each thin filaments is surrounded by 3...
The I band
Contains thin filaments and no thick filaments.
The Z line
Consist of proteins called actinins, which interconnect thin filaments. Mark the boundaries...
Helps keep the thick and thin filaments in proper alignment and aids in restoring resting sarcomere...
Thin filaments contains
Actin, trompomyosin (blocks the myosin binding site - prevents cross bridge cycling until it...
Made of myosin molecules. Has a core of titin. Does the pulling. Has binding sites for actin...
The globular head of the myosin protein that composes the thick filament. Has the ability to...
What happens when a skeletal muscle fiber contracts? 4
1. The H bands and I bands get smaller
2. The zones of overlap get larger
3. The z lines...
Sliding filament theory
The thin filaments are slighting toward the center of each sarcomere, alongside the thick filaments....
Where does the communication between the nervous system and skeletal muscle occur?
At neuromuscular junction (NMJ)
A single contraction produced by single stimulation.
1. the latent period - begins at stimulation
Skeletal muscle is stimulates a second time immediately after the relaxiation phase has ended,...
Summation of twitches.
Second stimulus arrives before the relaxiation phase has ended and the second contraction is...
Stimulus continues and the muscle is never allowed to relax.
Higher stimulation frequency eliminates the relaxiation phase. Action potentials arrive so...
Size of motor unit is an indication of how fine the control of movement is. The fewer the #...
1) ACh released, binding to receptors
2) Action potential reaches T tubule
What is motor end plate?
Place where tips of a motor neuron axon contact a muscle cell to stimulate muscle contraction....
What is Rogor mortis and what causes it?
A fixed muscular contraction after death. When calcium builds up in the cytoplasm because it...
What are the 2 types of muscle contractions?
Isotonic ( concentric and eccentric) and isometric
What is a Isotonic contraction?
Tension rises and the skeletal muscles's lenth changes. muscle...
The muscle does not change length and the tension produced never exceeds the load.
How do cells generate ATP? 2 ways
1. Through aerobic metabolism in mitochondria
2. Glycolysis in the cytoplasm
What is muscle fatigue?
When muscles can no longer perform a required activity
What are the 3 characteristics of muscle fatigue?
Exhaustion of metabolic reserves,High acidity from presence of lactic acid, and Damage to cell...
What are the 3 types of Skeletal muscle fibers?
Fast, Slow, and Intermediate Fibers
What is Muscle Hypertrophy
growth from heavy training, increased diameter of muscle fibers, increased number of myofibrils,increased...
What is Muscle Atrophy?
muscle shrinkage due to lack of activity
What does aerobic endurance involve?
Prolonged, aerobic activities (e.g., aerobic exercise), slow twitch fibers
Made by nerve cell at motor endplate
changes permeability of sarcolemma and triggers the...
Breaks down Ach
found in synaptic cleft and ssarcolemma
takes place in mitochondria
glucose + O2 yields CO2 +H2O...
Glucose (no oxygen)yields CO2 +lactic acid
incomplete breakdown of glucose, also...
When muscles run out of oxygen
rising lactic levels lower tissue pH levels then muscles can...
by-product of anaerobic respiration, build up lowers pH and interferes with contraction until...
What causes the myocin head to release from actin?
ATP binding to myocin
Resting tension in a skeletal muscle.
Breakdown of glucose to pyruvic acid in the cytoplasm, provides 2 ATP molecules and generates...
When becomes glycolysis important?
It provides substrates for aerobic metabolism.
Whenenergy demands are at a maximum and the...
Fast fibers - white muscle fiber, fast-twitch, type II fibers
Large glycogen reserves, few mitochondria. Produce powerful contractions, fatigue rapidly....
Slow fibers - red muscle fibers, slow-twitch, type I fibers.
Surrounded by extensive network of capillaries, higher supply to support mitochondrial activity....
Intermediate fibers - Type II A fibers
Between fast and slow fibers, in appearance, resemble more fast fibers.
Lenght of time a muscle can continue to contract while supported by mitochondrial activity....
Length of time muscular contraction can continue to be supported by glycolysis ad by the existing...
Only found in heart. Cells contain organized myofibrils, striated appearance, single, centrally...
The plasma membranes of two adjacent cardiac muscle cells are extensively intertwined and bound...
Forms sheets, bundles or sheaths around almost every organ. Has single, centrally located nucleus....
The membranous network that surrounds each myofibril is the
The binding of calcium ions causes ACh to be released from what structure?
For tropomyosin to be shifted off its position covering the active sites of G actin molecules,...
The binding of ACh to the motor end plate causes a change in membrane permeability to
What event in a muscle contraction marks the beginning of the relaxation of the muscle...
Detachment of crossbridges
Sequence of events in a contraction cycle?
Active-site exposure, crossbridge attachment, pivoting, crossbridge detachment, myosin reactivation...
A feature found in cardiac muscle cells that is lacking in skeletal and smooth muscle cells...
In which part of the sarcomere are myosin heads able to form crossbridges with actin?
Zones of overlap
At rest, active sites on the actin are bloced by
Inreractions between actin and myosin filaments of the sacromere are
Responsible for muscle contraction.
A broad tendinous sheet that ma serve as the origin or isertion of a skeletal muscle
What are the three types of muscle? Which are striated?
1. skeletal, cardiac, smooth2. skeletal and cardiac
Sliding Filament Theory
Amount of tension is proportionate to the overlap lenght of the thick and thin filaments
Ca regulation of contraction:
1. which muscles are controlled by thin filament regulation?
1. cardiac and skeletal (striated)
Describe muscle regeneration of:
1. regeneration is possible: satellite cells become myoblasts which become myotubes which...
What is plasticity?
Atrophy is caused by?
hypertrophy is caused by?
what kind of...
plasticity - muscle adaptation
atrophy - disuse such as bed rest, immobilization, denervation
Primary function of ATP
Trnsfer of energy from one location to another rather than long-term storage of energy.
Why would ATP transfer its energy to creatine?
ATP can't be stored but at rest, a skeletal muscle fiber produces more ATP than it needs. So...
Small molecule that muscle cells assemble from fragments of amino acids.
What happens if after heavy exercise, energy reserves in a muscle are depleted?
An oxygen dept occurs.
What happens during anaerobic glycolysis?
ATP is produces, oxygen is not consumed and pyruvic acid is produced.
In response to action potentials arriving along the transverse tubules, the sarcoplasmic reiculum...
Acts as an energy reserve in muscle tissue.
Where is each skeletal muscle fiber controlled by a motor neuron?
At a single neuromuscular junction.
What is the function of T-tubules?
Extension of the sarcolemma, provides a pathway for the conduction of electrical signals deep...
What is the terminal cisternae?
Part of the SR which store and release calcium
What happens when calcium ion binds to troponin?
Tropomyosi moves into the groove between the helical actin strands.
When do active sites on the actin become available for binding?
After calcium binds to troponin.
Tissues of the body characterized by widel spaced cells with large amounts of intracellular...
Organizational levels of skeletal muscle - biggest to smallest
Whole muscl is surrounded by epimysium (connective tissue).
Fascicl is surrounded my perimysium...
The neuromusclular junction
The place where a motor neuron stimulates a muscle cell. Skeletal muscle cells contract as...
Structures distributed throughout the sarcoplasm in a network of intermediate filaments composed...
What happens when action potential arrives at the axon terminal?
When the action potential arrives at the axon terminal, the voltage change of the membrane...
What structure contains ACh - acetylcholine?
Synaptic vesicles in the synaptic terminal.
Sequence of events at the neuromusclar junction.
1. Action potential arrives at axon terminal.
2. Calcium ions enter axon terminal.
Six steps of cross bridge cycling
1. The influx of calcium, triggering the exposure of binding sites on actin.
2. The binding...
A chemical process in which an enzyme uses water to split one molecul into smaller parts.
Thick and thin filaments - picture
Thick and thin filaments - picture