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Muscular system Cheat Sheet by

Test Review


acet­ylc­hol­ine- neurot­ran­smitter released from the synaptic vesicles that initiate action in the muscle fiber.
actin- a cellular protein that contains two other proteins
anta­gon­ist- counte­racts with agonist
apon­eur­oses- a broad flat tendon
Aden­osine tripho­sphate (ATP)* is the bioche­mical way to store and use energy. For your muscles -- in fact, for every cell in your body -- the source of energy that keeps everything going is called ATP.
axon­-the long threadlike part of a nerve cell along which impulses are conducted from the cell body to other cells.
cont­rac­tion- shortening of the muscles
cross bridges- the
head of a myosin molecule that projects from a myosin filament in muscle and in the sliding filament of muscle contra­ction is held to attach tempor­arily to an adjacent actin filament and draw it into the A band of a sarcomere between the myosin filaments.
elas­tic­ity- ability of a muscle tissue to elongate or stretch
fasc­ia- layers of dense. fibrous, connective tissue which compar­tme­ntalize muscle adding to structure.
hype­rtr­ophy- to increase in bullk
inse­rti­on- : the part of a muscle by which it is attached to the part to be moved, usually distally located, and has a small surface area.
musc­le- body tissue made of long cells that contract when stimulated and produce motion
myof­ibr­il- contra­ctile unit composed of myosin and actin
myos­in- fibrous protein that forms (together with actin) the contra­ctile filaments of muscle cells and is also involved in motion in other types of cells.
orig­in* body segment with the most mass, usually proximally located, large surface area of attachment
spasm an involu­ntary and abnormal contra­ction of muscle or muscle fibers or of a hollow organ that consists largely of involu­ntary muscle fibers

Cellular Struct­ure­& Function

A membrane is perm­eable when materials can pass through it.
Diff­usion is the movement form an area of high concen­tration to an area of low concen­tra­tion.
Mole­cules, gas ions, nutrients, and waste are able to pass through the cell membrane
Muscle cells provide movement
Nerve cell provide commun­ica­tion
Red blood cells provide oxygen transport
Movement can occur up or down a cell membrane
A cell membrane is a boundary wall surrou­nding cytoplasm of a cell
Muscle tissue has the property of contra­cti­lity.
coll­agen is a protein which comprises bundles of flexible but strong white fibers.
Adip­ose is known as fat tissue (pro­tec­tion, energy storage, and insula­tion
Fibr­ous connective tissue is found in the ligaments and tendons


- Skeletal Muscle is an organ of the muscular system
-Ske­letal Muscle is composed of skeletal muscle tissue, nervous tissue, blood, and connective tissue**
- Tend­ons Connect a muscle to bone it consist of dense connective tissue.
-Deep Fascia is fascia that surrounds or penetrates the muscle
-Sub­cut­aneous fascia is fascia beneath the skin
-Sub­serous fascia is a connective tissue layer of the serous membranes covering organs in various body cavities.
-Myo­fib­ril­sare threadlike structures and are located in the sarcop­lasm.
-Thick Myofil­ame­nts are composed of myosin
-Thins Myofil­ame­nts are composed of actin
-Tro­ponin and tropom­yosin associate with actin filaments
-Tra­nsverse tubules are membranous channels that extend into the sarcoplasm as invagi­nations continuous with the sarcolemma and contains extrac­ellular fluid

Skeletal Muscle Structure

EPEN- (EP)im­ysium- a strong connective tissue that covers all muscle fibers to form a bundle called fasciculi.
(PE)ri­mysium- connective tissue that binds groups of muscle fibers together
(EN)do­mysium- connective tissue that covers the muscle fiber.
Muscle Belly to hold all muscle fibers together also to shorten when contra­cted.
Skeletal Muscles are named in relation to their attachment
A sarc­ole­mma is a membrane that lays beneath the (EN­)d­omysium
Sacr­opl­asmic reticulm surrounds the myofibrils
TTS (Trans­verse Tubule System)- storage for calcium

Muscle Contra­ction

Tension within the muscle but no change in length isot­onic
Tension and the muscle changes in length isom­etric
conc­ent­ric is when the muscle shortens
Ecce­ntric is when the muscle lengthens

Motor neuron- a nerve that carries impulses from the brain and stimulates muscle contra­ction
neur­omu­scular juncti­on- the end of the axon terminal where it attaches to the muscle fiber
motor end plate- the location on the muscle fiber at the end of the axon terminal
motor unit- a motor neuron and the muscle fibers it innervates

Muscle Tissue

A single twitch is a simple muscle cont­rac­tion
A kymo­graph is a machine used to record muscle activity
A myog­ram is a machine that traces the muscle twitch
Latent period before contra­ction starts
cont­raction phase during muscle shortening
rela­xation phase after the contra­ction phase
Recovery Period is a short interval where the muscles are supplied with oxyg­en. It last about 60 sec.
all or none princi­ple- the principle that under given conditions the response of a nerve or muscle fiber to a stimulus at any strength above the threshold is the same: the muscle or nerve responds completely or not at all.
Prin­ciple source of heat in the body is muscle contra­ction example: shiv­ering

Energy Sources

- ALL energy is from the sun
- Imme­diate energy in humans is from ATP
- ATP is made by energy released from the breakdown of foods and other compounds of food

3 Processes for producing ATP

1.. Phos­phagen System- During short-­term, intense activi­ties, a large amount of power needs to be produced by the muscles, creating a high demand for ATP. The phosphagen system (ATP-CP system) is the quickest way to resynt­hesize ATP). Creatine phosphate (CP), which is stored in skeletal muscles, donates a phosphate to ADP to produce ATP: ADP + CP — ATP + C. Since this process does not need oxygen to resynt­hesize ATP, it is anaerobic, or oxygen­-in­dep­endent. As the fastest way to resynt­hesize ATP, the phosphagen system is the predom­inant energy system used for all-out exercise lasting up to about 5- 10 seconds. However, since there is a limited amount of stored CP and ATP in skeletal muscles, fatigue occurs rapidly.

2. Glyc­oly­sis- Glycolysis is the predom­inant energy system used for all-out exercise lasting from 30 seconds to about 2 minutes and is the seco­nd-­fas­test way to resynt­hesize ATP. During glycol­ysis, carb­ohy­dra­te—in the form of either blood glucose (sugar) or muscle glycogen (the stored form of glucos­e)—is broken down through a series of chemical reactions to form pyruvate (glycogen is first broken down into glucose through a process called glycog­eno­lysis). Conversion to lactate occurs when the demand for oxygen is greater than the supply (i.e., during anaerobic exercise). Conver­sely, when there is enough oxygen available to meet the muscles’ needs (i.e., during aerobic exercise), pyruvate (via acetyl­-CoA) enters the mitoch­ondria and goes through aero­bic metabo­lism.

3. Aerobic System- The oxidation of carb­ohy­rates or fats. Unlimited source of Energy ATP produced by aerobic glycol­ysis, from Kerb's cycle and a huge source from fat metabolism

Sliding Filament Theory of Muscle Contra­ction

During muscle contra­ction, the globular heads of the myosin attach to the active site of the actin myofil­ament and “ratchet” or swivel pulling the actin toward the center of the sarcomere (unit of contra­ction). This causes the actin myofil­aments to slide past one another resulting in a shortening of a sarcomere. The sarcomere shortens and the muscle contracts.

Charac­ter­istics of Fiber Types

Fast Twitch- The speed of contra­ction is high. The force­(p­ower) is high. It takes a short time for the fast twitch muscles to become tired. Carb­ohy­dra­tes­(gl­ycogen) fuel the fast twitch fibers. Fast twitch muscles are anae­robic which means they don't need oxygen. Lactic acid and heat** is the waste that fast twitch muscles produce.

Slow Twitch- The speed of contra­ction is low. The force­(p­ower) is low. It takes a long time for the slow twitch muscles to become tired. Carb­ohy­drates and fats fuel the slow twitch fibers. Slow twitch muscles are aero­bic which means they need oxygen. carbon dioxide, water, and heat is the waste that slow twitch muscles produce.

Energy Continuum- Energy Pathways Diagram

Digaram of muscle contra­ction

Sliding filament theory proposes that the a-band contain flexible cross bridges that come in contact with energy sites on more numerous I-band and with the availa­bility of energy, the cross-­bridges pull the active filament a short distance and release it and attach to another site, resulting in a shortening of the H-zone between the I-ba­nds


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