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Skeletal Muscles

TermDefinition
Contractility The ability to shorten with force
Excitability Capacity to respond to a stimulus
Extensibility Ability to be stretched
Elasticity Recoil to their original resting length after they have been stretched
Skeletal muscle is surrounded by a connective tissue sheath called what? Epimysium
Fascia Another connective tissue that surrounds and separates muscles
Fasciculi Numerous visible bundles
Fasciculi are surrounded by loose connective tissue called what? Perimysium
Fasciculi are composed of single muscle cells called what? Fibers
Each fiber is surrounded by a connective tissue sheath called what? Endomysium
A threadlike structure that extends from one end of the fiber to the other? Myofibrils
Myofibrils consist of 2 major kinds of protein fibers. What are they? Actin & Myosin
Define actin. Thin myofilaments. They resemble 2 minute strands od pearls twisted together.
Define myosin. Thick myofilaments. They resemble bundles of minute golf clubs
Actin an myosin myofilaments form highly ordered units called what? Sarcomeres
Basic structural and functional unity of the muscle Sarcomere.
.... joined end to end to form the myofibril. Sarcomeres.
Muscles help to produce what? Heat essential for maintenance of normal body temperature.
Each side of the Z line is a light area called what and consists of what? I Band, and consists of actin.
The A band extends the what of the myosin? The length.
In the center of each sarcomere is another light area called what and consists of what? H band zone, and consists of only myosin.
Myosin myofilaments are anchored in the center of the sarcomere at a dark staining band called what? The M line
The charge difference across the membrane is called what? Resting Membrane Potential
An attachment site for actin? Z line
The brief reversal back of the charge is called what? Action potential
Nerve cells that carry action potentials to skeletal muscle fibers? Motor Neurons
Each branch that connects to the muscle forms a what near the center of the cell? Neuromuscular junction, or synapse
A single motor neuron and all the skeletal muscle fibers it innervates are called what? Motor Unit
How is a neuromuscular junction formed? By an enlarged nerve terminal resting in an indentation of the muscle cell membrane.
The enlarged terminal is called what? Presynaptic terminal
Synaptic Cleft Space between the presynaptic terminal and the muscle cell
Postsynaptic Terminal Muscle Fiber
Each presynaptic terminal contains synaptic vesicles that secrete a neurotransmitter called what? Acetylcholine
The acetylcholine released into the synaptic cleft between the neuron and muscle cell is rapidly broken down by an enzymes Acetylcholinesterase
Muscle contractions Occurs as actin and myosin myofilaments slide past one another causing the sarcomeres to shorten
Sliding Filament Mechanism The sliding of actin myofilaments past myosin myofilaments during contraction
A contraction of an entire muscle in response to a stimulus that causes the action potential in one or more muscle fibers. Muscle twitch
A muscle fiber will not respond to stimulus until that stimulus reaches a level called what? Threshold
The phenomenon All-or-none response
Lag phase The time between application of a stimulus to a motor neuron and the beginning of a contraction
Time of contraction Contraction phase
The time during which the muscle relaxes Relaxation phase
Tetany Where the muscle remains contracted without relaxing
The increase in number of motor units being activated Recruitment
Name 3 things about ATP 1.) It's needed for energy for muscle contraction 2.) It's produced in the mitochondria 3.) It's short-lived and unstable
High-energy molecule Creatine Phosphate
Anaerobic Respiration Without Oxygen
Aerobic Respiration With Oxygen
Oxygen Debt The amount of oxygen needed in chemical reactions to convert lactic acid to glucose and to replenish the depleted stores of creatine phosphate stores in muscle cells
Results when ATP is used during muscle contraction faster than it can be produced in the muscle cells Muscle Fatigue
2 types of muscle contractions? 1.) Isometric 2.) Isotonic
Isometric The length of the muscle does not change, but the amount of tension increases during the contraction process
Isotonic The amount of tension produced by the muscle is constant during contraction, but the length of the muscle changes
Muscle tone refers to constant tension produced by muscles of the body for long periods of time Muscle tone
Contracts quickly and fatigue quickly; well adapted to perform anaerobic metabolism Fast-twitch fibers
Contract more slowly and are more resistant to fatigue; they are better suited for aerobic metabolism Slow-twitch fibers
The most stationary end of the muscle Origin (head)
The end of the muscle undergoing the greatest movement Insertion
The portion of the muscle between the origin and the insertion Belly
Synergists Muscles that work together to accomplish specific movements
Antagonists Muscles that work in opposition to one another
Among a group of synergists, if one muscle plays the major role in accomplishing the desired movement, it is the what? Prime Mover
Occipitofrontalis Raises Eyebrows
Orbicularis Oculi Closes Eyelid (Crows Feet)
Orbicularis Oris Puckers the Lips
Buccinator Flattens the Cheeks
Zygomaticus Smiling
Levator Labii Superioris Sneering
Depressor Anguli Oris Frowning
Mastication Chewing
2 tongue muscles 1.) Extrinsic 2.) Intrinsic
Extrinsic Moves the tongue
Intrinsic Changes the shape of the tongue
2 Mastication muscles Masseter and Temporalis
2 Kissing Muscles Buccinator and Orbicularis Oris
Created by: hannahxoxo