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Anatomy

muscles eastham

QuestionAnswer
The ability of skeletal muscle to shorten with force is Contractility
The capacity of skeletal muscle to respond a stimulus is Excitability
The ability to be stretched is Extensibility
Ability to recoil to their original resting length after they have been stretched is Elasticity
Muscles help produce heat essential for maintenance of normal Body temperature
Epimysium Each skeletal muscle is surrounded by a connective tissue sheath
Fascia Is another connective tissue located outside the epimysium, it surrounded and sperates muscles
Muscle is composed of numerous visible bundles called Muscle fasciculi
Fascicle are surrounded by loose connective tissue called Perimysium
The fasciculi are composed of single muscle cells called Fibers
Each fiber is surrounded by a connective tissue sheath called Endomysium
The cytoplasm of each fiber is filled with Myofibrils
Myofibrils Threadlike structure that extends from one end of the fiber to the other
Myofibrils consist of two major kinds of protein fiber Actin myofilaments Myosin myofilaments
Action myofilaments Thin myofilaments, resemble two minute strands of pearls twisted together
Mysoin myofilaments Thick myofilaments, resemble bundlesbof minute golf clubs
Action and myosin myofilaments form highly ordered units called Sarcomeres
Sarcomeres are joined end to end to form the Myofibril
The sarcomere is the basic structural and functional unity of the Muscle
The arrangement of actin and mysoin give a Banded appearance
Each side of the Z line is a light area called the I band, consists of actin
A band extends the length of Mysoin
In the center of each sarcomere is a light area called the H zone
H zone only consists of Mysoin
Mysoin myofilaments are anchored in the center of the sarcomere at a dark staining band called M line
The charge difference across the membrane is called Resting membrane potential
Motor neurons Nerve cells that carry action potentials to skeletal muscle fibers
Axons enter the muscle and Branch
Each branch that connects to the muscle forms Neuromuscular junction or synapse
A single motor neuron and all the skeletal muscle fibers it innervates are Motor unit
Many motor units form a Single muscle
Neuromuscular junction Formed by an enlarged nerve terminal resting in an indentation of the muscle cell membrane
The enlarged nerve terminal is Presynaptic terminal
The space between the presynaptic terminal and the muscle cells is Synaptic cleft
The space between the presynaptic terminal and muscle fiber Is Postsynaptic terminal
Each presynaptic terminal contains Synaptic vesicles
Each presynaptic terminal contains synaptic vesicles that secreate a synaptic clet called Acetylcholine
When an actin potential reaches the nerve terminal it causes the synaptic vesicles to Realese acetylcholine into the synaptic cleft by exocytosis
The acetylcholine diffuses across the synaptic cleft binds to receptor molecules in the Muscle cell membrane
The combination of acetylcholine with its receptor causes an influx of sodium ions into the Muscle fiber
The acetylcholine released into the synaptic cleft between neuron and muscle cell is Rapidly broken down by an enzymes
Occurs as actin and mysoin myofilaments slide past one another causing sarcomeres To shorten
When sarcomeres shorten it causes the Muscle to shorten
The sliding of action myofilaments past mysoin myofilaments during contraction is called Sliding filament mechanism of muscle contraction
Muscle twitch A contraction of an entire muscle in response to as stimulus that causes the sctin potential in one or more muscle fibers
A muscle fiber will not respond to stimulus until the stimulus reaches a level called Threshold
Once the stimulus reaches the threshold level Muscle fibers will contract maximally
Phenomenon is called All or none response
Time between application of a stimulus to a motor neuron and the beginning of a contraction is the Lag phase
Time of contraction is the Contraction phase
Time during the which the muscle relaxes is the Relaxation phase
Tetany Where the muscle remains contracted without relaxing
The increase in number of motor units being actiaved is called Recruitment
ATP (adenosine triphosphate) Needed for energy for muscle contraction
ATP is prodeced in The mitochondria
Shot lived and unstable ATP
Degenerates to the more stable ADP (adenosine diphosphate)
When at rest they can't stockpile ATP but they can store another high energy molecule called Creating 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 creating phosphate stores in muscle cells
Muscle fatigue Results when ATP is used during muscle contraction faster than it can be produced in the muscle cells
Two types of muscle contraction Isometric Istonic
Isometric (Equal distance) length of the muscle does not change, but amount of tension increases during contraction process
Isotonic (Equal tension) 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
Fast-twitch fibers Contract quickly and fatigue quickly, well adpated to perform anaerobic metabolism. Ex. White meat of chicken breast
Slow-twitch fibers Contract more slowly and are more resistant to fatigue, they are better suited for aerobic metabolism. Ex.dark meat legs of chicken
Attatcmen points of the muscle is connected to the bone by A tendon
Origin(head) The most stationary end of the muscle
Insertion The end of the muscle undergoing the greatest movement
The portion of the muscle between the orgin and the insertion is The belly
Muscles that work together to accomplish specific movements are Synergists
Muscles that work in opposition to one another are Antagonists
Amount a group of synergits, if onemuscke plays the major role in accomplishing the desired movement It is the prime mover
Created by: dealove