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Chapter 6 - Muscles


Contractility The ability of skeletal muscle to shorten with force
Excitability the capacity of skeletal muscle to respond to a stimulus
Extensibility the ability to be stretched
Elastic ability to recoil to their original resting length after they have been stretched
Epimysium the connective tissue sheath surrounding the skeletal muscle
Fascia another connective tissue located outside the epimysium
Muscle Fasciculi (Fascicle) numerous visible bundles the compose muscles
Perimysium surrounds the muscle fasciculi
Fibers the single muscle cells the compose the fasciculi
Endomysium a connective tissue sheath that surrounds each muscles fiber
Myofibrils a threadlike structure that extends from one end of the fiber to the other
Myofibers consist of 2 major kinds of protein fibers
Actin Myofilaments thin myofilaments. they resemble 2 minute strands of pearls twisted together
Myosin Myofilaments thick myofilaments. they resemble bundles of minute golf clubs
Sarcomere joined end to end to form the myofibril
Sarcomere is... the basic structural and functional unity of the muscle
Each sarcomere extends... from one Z line (disc) to another Z line
Each Z line is... an attachment site for actin
The banded appearance is... because of the arrangement of actin and myosin
What is on each side of the Z line? a light area called an I band, it consist of actin.
Resting Membrane Potential the charge difference across the membrane
Action Potential the brief reversal back of the charge
Motor Neurons are nerve cells that carry action potentials to skeletal muscle fibers
Neuromuscular Junctions or Synapse each branch that connects to the muscle near the center of the cell
Motor Unit a single motor neuron and all the skeletal muscle fibers it innervates
Presynaptic Terminal the enlarged nerve terminal
Synaptic Cleft the space between the presynaptic terminal and the muscle cell
Postsynaptic Terminal the muscle fiber
Synaptic Vesicles each presynaptic terminal contains this
Acetylcholine a neurotransmitter that secretes from the synaptic vesicles
Acetylcholinesterase the acetylcholine released into the synaptic cleft between the neuron and muscle cell rapidly broken down by enzymes
Sliding Filament Mechanism the sliding of actin myofilaments past myosin myofilaments during contraction
Muscle Twitch is a contraction of an entire muscle in response to a stimulus that causes the action potential in one or more muscle fibers
Threshold a muscle fiber will not respond to stimulus until that stimulus reaches this level, at which point the muscle fiber will contract maximally
All-or-none Response either it is going to contract to its maximum, or it wont at all.
Lag Phase the time between application of a stimulus to a motor neuron and the beginning of a contraction
Contraction Phase time of contraction
Relaxation Phase time during which the muscle relaxes
Tetany where the muscle remains contracted without relaxing
Recruitment the increase in number of motor units being activated
ATP (adenosine triphosphate) is needed for energy for muscle contraction
ATP is produced... in the mitochondria
The three types of muscle skeletal, cardiac, smooth
Anaerobic Respiration without oxygen
Aerobic Respiration with oxygen
Oxygen Debt is 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.
Muscles Fatigue results when ATP is used during muscle contraction faster than it can be produced in the muscle cells
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 does not change, but the length does in the contraction process
Muscle Tone refers to the constant tension produced by muscle of the body for long periods of time.
Fast-Twitch Fibers contract quickly and fatigue quickly
Slow-Twitch Fibers contract slowly and are more resistant to fatigue
Origin (head) is the most stationary end of the muscle
Insertion is the end of the muscle undergoing the greatest movement
Belly between the origin and the insertion
Synergists muscles that work together to accomplish specific movements
Antagonists muscles that work in opposition to one another
Prime Mover a muscle that plays the major role in accomplishing the desired movement
Muscles are name according to... location, size, orientation of fibers, shape, origin, insertion, and function.
Facial Muscles occipitofrontalis, orbicularis oculi, orbicularis oris, buccinators, zygomaticus, levator labii superioris, depressor anguli oris
Mastication chewing
4 pairs of mastication 2 pair of pterygoids, temporalis, and masseter
Tongue Muscles intrinsic and extrinsic
Neck Muscle sternocleidomastoid
Occipitofrontalis raises the eyebrows
Orbicularis Oculi closes the eyelids and causes "crowfeet" wrinkles in the skin at the lateral corners of the eye
Orbicularis Oris puckers the lips
Buccinator flattens the cheeks. Trumpets muscle
Zygomaticus smiling muscle
Levator Labii Superioris sneering
DePressor Anguli Oris frowning
Instinsic Tongue Muscle change shape of the tongue
Extrinsic Muscle moves the tongue
Sternocleidomastoid lateral neck muscle and prime mover. Rotates and abducts the head.
Hamstring Muscles posterior thigh muscles; flexes the leg and extends the thigh
Created by: telliott803