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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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