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KIN 173 2.1
Terms in this set (56)
Involuntary muscle; controlled by the autonomic nervous system. (no striations)
Controlled by the autonomic nervous and endocrine systems.
Voluntary muscle; controlled consciously by the somatic nervous system.
Skeletal muscle functions
-Conversion of electrical signals to mechanical movement.
-Creates force production for locomotion.
-Creates force production for postural support.
-Creates force production for breathing.
-Creates heat production during cold stress (shivering).
Mechanical movement of the muscles strain the _________ tissues, which transfers force to the _________ which moves the bone.
On top of surrounding the entire muscle
"Around" surrounds fascicles (bundles of muscle fibers)
"Internal" surrounds individual muscle fibers
Each muscle fiber is a single muscle cell or _________.
Cell membrane of a myocyte
Cytoplasm of a myocyte.
Releases calcium during muscle contraction. Absorbs calcium ions during relaxation.
Run perpendicular to the myofibril. Major site for the coupling of excitation and contraction. Open to extracellular fluid.
Contain contractile proteins. The basic unit of a muscle.
The smallest functional units of myofibril. Have a specialized arrangement of actin and myosin filaments which run in parallel to each other along the length of the muscle fiber.
The thin filament that provides binding sites for myosin.
The thick filament that is long with a fibrous tail and globular heads, which binds to actin.
Sliding Filament Theory
In its simplest form states that muscle fibers shorten when myosin protein filament pull together actin protein filaments.
I, H, A
During contraction, the ___ band and ___ zone get smaller, while the ___ band stays the same length.
the greatest amount of force can be generated with the actin and myosin overlapping ______ of their filaments.
Too ________ overlap means little force can be generated.
Too _______ overlap and there is nowhere for the myosin to move the actin
comprised of a single alpha motor neuron and the muscle fiber it innervates.
Alpha motor neurons
Have large-caliber, heavily myelinated fibers to rapidly conduct action potentials.
Once the action potential reaches the motor end plate, ______________ is released at the neuromuscular junction.
The action potential triggers calcium channels in the __________ which allow calcium to flow into the cell, and activates calcium release channels in the sarcoplasmic reticulum.
Type IIa (fast fiber)
Better suited for anaerobic activity. These fibers play major role in high intensity exercise.
Type IIx (fast fiber)
Better suited for anaerobic activity. These fibers are activated when the force demanded of a muscle is high.
Type I (slow fibers)
These fibers are needed in higher aerobic endurance.
Calcium dependent binding
Occurs when the sarcoplasmic reticulum releases calcium into sarcoplasm.
The calcium binds to __________, which "unlocks" tropomyosin from blocking the binding sites on actin.
ATP dependent release
Once the myosin is able to form a "cross-bridge" with the actin, it will begin a "power stroke"
Full cycle, calcium, troponin, myosin, power, ATP
___________ is pumped into the sarcoplasm. Calcium binds to _________, which stops tropomyosin from blocking binding sites. The _________ head forms a cross-bridge with the actin. The myosin completes a ________ stroke. ______ binds to the myosin head, releasing the cross-bridge. Calcium ions are sucked back into the sarcoplasmic reticulum. ATP is hydrolyzed to provide energy for the next power stroke.
Connection between actin filaments in different sarcomeres
Gap b/t actin filaments within a sarcomere.
Gap b/t myosin filaments across two sarcomeres.
Length of the myosin filament.
Type II muscle fibers also have: _______ alpha motor neurons, _______ nerve conduction velocity, and more outputting of calcium b/c of a more developed sarcoplasmic reticulum.
Maximum velocity is always achieved at the __________ resistance.
Motor units recruited in order of size of neuron.
50, 25, 25
Most individuals muscles are made up of: ___% slow twitch type 1 fibers, ____% type IIa fibers, ____% type IIx fibers
Athletes in speed and strength events generally have an increased percentage of __________ fibers
Athletes in endurance events generally have an increased percentage of ________ fibers.
Static, muscle exerts force without changing length, pulling against immovable object, ex. postural muscles.
Isotonic, concentric, eccentric
___________ - muscle shortens during force production
___________ - muscle produces force but length increases
A sensory receptor that receives stimuli from within the body.
Integration of information from enteroceptors regarding the position of one's body in space.
length, change in length
Muscle spindles provide information to the CNS regarding the _________, and rate of _________ ____ ________ of individual muscles
Stretch and tension
Golgi tendon organs provide info to the CNS regarding the amount of muscle __________ and ___________
Located deep within the muscle mass, scattered widely through the muscle body, and attached to the tendon, the endomysium or the perimysium.
There are several of these muscle fibers in a muscle spindle. They have contractile proteins at either end, with a central region that is wrapped by sensory dendrites.
The intrafusal fibers are innervated by an efferent neuron known as the _______ motor neuron. It's role is to maintain muscle spindle ____________.
When the muscle is stimulated to contract by the alpha motor neuron, the gamma motor neuron is simultaneously stimulated.
Discharge of muscle spindle afferents evokes the _______ _________
Allows muscle tone to be regulated quickly and efficiently without direct intervention by higher brain centers.
Golgi tendon organs, force generation
This is in a series with muscle fibers, located in the tendons that attach muscle to bone. Provides information about the muscle tension.
-Prevents muscle damage during excessive ________ ____________.
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