Muscular System Word Scramble

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Term	Definition
Tendons attach muscles to?	bones
Muscles do what?	contract or shorten
Circular layer	decreases diameter of tube or organ when contracted
Longitudinal layer	decreases length of tube or organ when contracted
Endomysium	surrounds each muscle fiber
Perimysium	surrounds each fascicle
Fascicle	a bundle of muscle fibers
Epimysium	surrounds each muscle
Tendons	epimysia blend into strong, cord-like tendons that attach muscle to bone
Origin	the muscle attachment to the immovable bone
Insertion	the muscle attachment to the movable bone (when the muscle contracts, the insertion moves towards the origin)
Sarcolemma	muscle cell membrane
Sarcoplasmic reticulum	stores calcium ions needed for contracton
Myofibrils	long, ribbon-like fibers of a muscle cell
Myofilaments	threadlike proteins in the myofibril (actin & myosin)
Sarcomeres	the functional unit of muscle fibers; contractile unit
Myosin	thich myofilament
Actin	thin myofilament
Irritability	the ability to receive and respond to a stimulus
Contractility	the ability to shorten
Producing Movement	locomotion, manipulation and facial expression are the primary functions of skeletal muscles
Maintaining Posture	holds body upright against gravity, stabilizes joints, maintains balance
Moving Substances	cardiac and smooth muscles are responsible for transporting substances like blood or food from one part of the body to another
Generating Heat	heat is a by-product of muscle activity, helps maintain body temperature
Muscles cross with how many joints?	At least one joint (with a few exceptions)
The bulk of the muscle is usually proximal to what?	the joint crossed
All muscles have at least what?	two attachments
Muscles can only pull but they can't?	push
During contraction, what does the muscle insertion do?	moves towards the origin
Define motor unit	One motor neuron and all the skeletal muscle cells it stimulates
Describe the neuromuscular junction	* The synapse where the neuron and muscle cell meet * The end of each motor neuron branches into axon terminals *Each axon terminal forms a junction with the sarcolemma of a muscle cell
Discuss the role of acetylcholine	it is the neurotransmitter responsible for muscle contraction stored in vesicles in the axon terminal released into the synapse when a nerve impulse reaches the axon terminal diffuses across the synaptic cleft to bind with receptors on sacrolemma
An ? is an electrical current generated by the "upset" or change in charge across the muscle cell membrane or sarcolemma	action potential
The result of this electrical impulse traveling from one end of the cell to the other is ? of the muscle cell	contraction
A single nerve impulse produces only ? contraction because ACh is broken down by ? to prevent continued contraction of the muscle cell	1 ; acetylcholinesterase
The ? pump helps the cell return back to its resting state	sodium-potassium
When muscle fibers are activated by the nervous system, the ? attach to binding sites on the thin filaments	myosin heads
Energy is provided by ? so that each crossbridge (myosin head link to actin) attaches and detaches several times during a ? pulling each thin filament toward the center of the ?	ATP ; contraction ; sacomere
This event occurs simultaneously in sarcomeres throughout the cell, causing the entire muscle cell to?	shorten
The attachment of myosin crossbridges to actin requires ? which is stored in and released by the?	calcium ions ; sarcoplasmic reticulum
When the action potential ends, calcium ions are immediately reabsorbed into the SR storage areas, and the muscle cell ? and return to its original ?	relaxes ; length
Defined fused tetanus	Successive contractions are added together to produce a smooth, sustained contraction
What does the "all-or-none" law state?	When stimulated adequately, the muscle cell will contract to its fullest extent; it never partially contracts
List the two ways in which graded muscle contractions can be produced	1. By changing the frequency of muscle stimulation 2. By changing the number of muscle cells being stimulated
What factor determines how forcefully a muscle contracts?	* The number of muscle cells that are stimulated * Fewer cells are stimulated when you are move a pen compared to when you swing a baseball bat
Describe muscle fatigue and its cause	* Occurs when the muscle becomes unable to contract * Caused by oxygen debt
Compare and contrast isotonic and isometric contractions	* Isotonic contractions occur when the muscle shortens and movement occurs * Isometric contractions occur when the muscles do not shorten; no movement occurs
How does regular exercise affect muscles?	Increases muscle size, strength, and endurance
Describe the results of aerobic exercise on muscles	Muscles become stronger, more flexible, and develop greater resistance to fatigue
Describe the results of resistance or isometric exercise on muscles	Muscles increase in size and strength; new filaments are made

Created by: DanariaW