Flashcards in Muscular System Deck (69)
Types of Muscle
Narrow cylindrical fibers, non-striated, uninucleate; occurs in walls of internal organs; is involuntary;
Has striated, branched, generally uninucleated fibers; occurs in walls of heart; is involuntary;
Has striated, tubular, multinucleated fibers; is usually attached to skeleton; is voluntary.
Functions of the Muscular System
Support the body
Allow for movement of bones and other structures
Help maintain constant body temperature
Assist in movement of fluids in cardiovascular and lymphatic vessels
Fluid filled sacs that provide cushioning between tendons and bones
The connective tissue that connects muscle to bone
Attachment of a muscle to a stationary bone
Attachment of a muscle on a bone that moves
Does most of the work when moving
Assists the prime mover
Works against the prime mover - purpose is to undo what was done by the prime mover
Muscles are named based on what seven characteristics?
Direction of fibers
Number of attachments
Do muscles pull or push?
Portion of sarcolemma that penetrates muscle cells.
Smooth endoplasmic reticulum that stores Ca+
One contracting unit of the muscle cell; made of the proteins actin and myosin
Thick filaments shaped like a golf club
Region on a sarcomere where actin but no myosin is
Region where myosin is but no actin
Length of the myosin fiber
How do filaments go over one another during muscle contraction?
Filaments slide over one another - do NOT crunch up!
First step of ATP in cellular work of motion...
ATP is split when myosin head is unattached (so becomes ADP)
Second step of ATP in cellular work of motion
ADP + P are bound to myosin as myosin head attaches to actin
Third step of ATP in cellular work of motion
Upon ADP+P release, power stroke occurs; head bends and pulls actin
Fourth step of ATP in cellular work of motion
Binding of fresh ATP causes myosin head to return to resting position
Movement of myosin head to pull actin
Calcium complex that modifies the position of tropomyosin
First step of Muscle Fiber Contraction
Nerve impulses (action potential) travels down motor neurons to a neuromuscular junction
Where a motor neuron connects to skeletal muscle
A nerve fiber and all of the muscle fibers that it innervates
Second Step of Muscle Fiber Contraction
Acetylcholine (ACh) is released from the neurons and bind to the muscle fibers. (Synaptic vesicles of the neuron contain ACh, a neurotransmitter, where it binds with receptor on the sarcolemma)
Third Step of Muscle Fiber Contraction
Binding of ACh stimulates impulses down the T-tibules causing calcium to be released from the sarcoplasmic reticulum
Fourth Step of Muscle Fiber Contraction
Calcium complex (troponin) modifies tropomyosin, exposing binding site
Fifth Step of Muscle Fiber Contraction
Myosin head binds with actin (thanks to ADP + P)
Sixth Step of Muscle Fiber Contraction
ADP + P are released, resulting in a power stroke
Seventh Step of Muscle Fiber Contraction
Additional ATP allows for myosin head to return to resting position and calcium to be pumped back into sarcoplasmic reticulum
Method of detecting changes in ions associated with muscle contraction
Difference in charge from place to place - can be detected on surface of skin
A nerve fiber and all of the muscle fibers it stimulates - "all or none"
Motor Unit Recruitment
Increases the strength of contraction by increasing the number of motor units in use
Fatigue sets in when...
...you have recruited same motor units for a while and depleted energy (ATP)
Muscle twitch is...
A single motor unit contraction, caused by infrequent electrical impulses, and lasts a fraction of a second.
Increase in muscle contraction until maximum sustained contraction (tetanus) is reached, and lasts until fatigue (muscle relaxes despite stimulation due to depletion of energy reserves).
Maximal sustained contraction
Decrease in a muscle's ability to generate force, when the muscle relaxes despite stimulation due to depletion of energy reserves.
Four sources of ATP for muscle contraction...
Stored in muscle fibers
Fastest way to acquire ATP but only sustains cell for seconds; builds up when a muscle is resting (anaerobic).
Fast-acting but results in lactate build-up (anaerobic)
Not an immediate source of ATP, but best long term source (aerobic)
Protein that transports oxygen directly to mitochondria of muscle cells
Fast Twitch Fiber Characteristics
Creatine-Phosphate pathway and fermentation for ATP
Fewer blood vessels
Slow Twitch Fiber Characteristics
Cellular Respiration for ATP
More blood vessels
Fast Twitch Muscle Characteristics
Slow Twitch Muscle Characteristics
Sudden, involuntary muscle contractions that are usually painful
Multiple spasms of skeletal muscles
Strong, painful spasms often of the leg and foot
Stretching or tearing of a muscle
Twisting of a joint involving muscle, ligaments, and joints
Chronic achy muscles; not well understood
Group of genetic disorders in which muscles progressively degenerate and weaken
Autoimmune disorder that attacks ACh receptors and weakens muscles of the face, neck, and extremities
Cancers originating in support tissues (bone, muscle) are called sarcoma
Amyotrophic Lateral Sclerosis (ALS)
Lou Gehrig's Disease; genetic disorder in which motor neurons degenerate leading to loss of voluntary muscle contractions