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From Wikipedia

Muscular system

The muscular system is the anatomical system of a species that allows it to move. The muscular system in vertebrates is controlled through the nervous system, although some muscles (such as the cardiac muscle) can be completely autonomous.


There are three distinct types of muscles: skeletal muscles, cardiac or heart muscles, and smooth (non-striated) muscles. Muscles provide strength, balance, posture, movement and heat for the body to keep warm.

Upon stimulation by an action potential, skeletal muscles perform a coordinated contraction by shortening each sarcomere. The best proposed model for understanding contraction is the sliding filament model of muscle contraction. Actin and myosin fibers overlap in a contractile motion towards each other. Myosin filaments have club-shaped heads that project toward the actin filaments.

Larger structures along the myosin filament called myosin heads are used to provide attachment points on binding sites for the actin filaments. The myosin heads move in a coordinated style, they swivel toward the center of the sarcomere, detach and then reattach to the nearest active site of the actin filament. This is called a rachet type drive system. This process consumes large amounts of adenosine triphosphate (ATP).

Energy for this comes from ATP, the energy source of the cell. ATP binds to the cross bridges between myosin heads and actin filaments. The release of energy powers the swiveling of the myosin head. Muscles store little ATP and so must continuously recycle the discharged adenosine diphosphate molecule (ADP) into ATP rapidly. Muscle tissue also contains a stored supply of a fast acting recharge chemical, creatine phosphate which can assist initially producing the rapid regeneration of ADP into ATP.

Calcium ions are required for each cycle of the sarcomere. Calcium is released from the sarcoplasmic reticulum into the sarcomere when a muscle is stimulated to contract. This calcium uncovers the actin binding sites. When the muscle no longer needs to contract, the calcium ions are pumped from the sarcomere and back into storage in the sarcoplasmic reticulum.


There are approximately 639 skeletal muscles in the human body.

The following are some major muscles and their basic features:

Aerobic and anaerobic muscle activity

At rest, the body produces the majority of its ATP aerobically in the mitochondria without producing lactic acid or other fatiguing byproducts. During exercise, the method of ATP production varies depending on the fitness of the individual as well as the duration, and intensity of exercise. At lower activity levels, when exercise continues for a long duration (several minutes or longer), energy is produced aerobically by combining oxygen with carbohydrates and fats stored in the body. Activity that is higher in intensity, with possible duration decreasing as intensity increases, ATP production can switch to anaerobic pathways, such as the use of the creatine phosphate and the phosphagen system or anaerobic glycolysis. Aerobic ATP production is biochemically much slower and can only be used for long-duration, low intensity exercise, but produces no fatiguing waste products that can not be removed immediately from sarcomere and body and results in a much greater number of ATP molecules per fat or carbohydrate molecule. Aerobic training allows the oxygen delivery system to be more efficient, allowing aerobic metabolism to begin quicker. Anaerobic ATP production produces ATP much faster and allows near-maximal intensity exercise, but also produces significant amounts of lactic acid which render high intensity exercise unsustainable for greater than several minutes. The phosphagen system is also anaerobic, allows for the highest levels of exercise intensity, but intramuscular stores of phosphocreatine are very limited and can only provide energy for exercises lasting up to ten seconds. Recovery is very quick, with full creatine stores regenerated within five minutes.

Cardiac muscle

Heart muscles are distinct from skeletal muscles because the muscle fibers are laterally connected to each other. Furthermore, just as with smooth muscles, they are not controlling themselves. Heart muscles are controlled by the sinus node influenced by the autonomic nervous system.

Smooth muscle

Smooth muscles are controlled directly by the autonomic nervous system and are involuntary, meaning that they are incapable of being moved by conscious thought. Functions such as heart beat and lungs (which are capable of being willingly controlled, be it to a limited extent) are involuntary muscles but are not smooth muscles.

Control of muscle contraction

Neuromuscular junctions are the focal point where a motor neuron attaches to a muscle. Acetylcholine, (a neurotransmitter used in skeletal muscle contraction) is released from the axon terminal of the nerve cell when an action potential reaches the microscopic junction, called a synapse. A group of chemical messengers cross the synapse and stimulate the formation of electrical changes, which are produced in the muscle cell when the acetylcholine binds to receptors on its surface. Calcium is released from its storage area in the cell's sarcoplasmic reticulum. An impulse from a nerve cell causes calcium release and brings about a single, short muscle contraction c

From Yahoo Answers

Question:Which of the following does NOT play a role in maintenance of systemic acid/base homeostasis? a. Bicarbonate buffering system. b. Respiratory system. c. Integument system. d. Renel system.

Answers:C integumentary system is your skin.

Question:I have to do a report on the muscular system for school, and I find all this confusing stuff, please make it short and simple about 4 to 5 sentences... THANX

Answers:nerve impulse travels to muscle impulse is conducted to sarcomeres in the muscle through the t tubule impulse depolarises muscle, calcium floods in more calcium is released from the sarcoplasmic reticulum. (calcium induced calcium release) calcium binds to troponin, which moves tropomyosin. cross bridges form and actin fillaments are pulled. muscle contracts don't worry too much about the actin and myosin - just remember impulse, t tubule, sarcomre, calcium, contraction

Question:1. Skeletal muscle is made of elongated cells called ______________ 2 . The types of muscles that have the same function, or work together to perform a particular function are called _____________ 3. Thin actin filaments are anchored at their midpoints to a structure called the _______________ 4.The more stationary bone that a muscle connects to is called the _________________ 5.The more movable bone that a muscle connects to is called the _________________ 6. The _________________________ is the functional unit of muscle contractions. 7. An example of a semi-moveable joint is a a. pivot joint b. fixed joint c. hinge joint d. none of the above. 8. Which of the following occurs when skeleton muscles contracts? a. the myosin heads remain attached to actin filaments b. the myosin filaments overlap c. the myosin heads bend outward d. the sarcomeres shorten 9.Explain how muscles pairs work together to move a limb? Thanks very much :D

Answers:2. antagonistic muscles 7. c (may b)

Question:Hello :) Okay so I have this worksheet that I have to put in order I believe. And It says it is for Blood Glucose Regulation. So could anyone please help me put these in order ? Thank You :) These are not in order, I need to put them in order. 1) Pancreas detects increase in blood glucose (after a meal) 2) Increase in insulin secretion because of increase in blood sugar and parasympathetic stimulation. 3) Increased uptake of glucose due to insulin excess converted to glycogen ( stored in muscle liver) or fat (stored in adipose tissue) which causes decrease in glucose in blood. 4) Pancreas detects decrease in glucose.Physical activity causes increased sympathetic stimulation of pancreas in epinephrine from adrenal medulla. 5) Decreased blood sugar causes decreased secretion of insulin, sympathetic stimulation and epinephrine. 6) Decreased uptake of glucose in tissue provides more glucose for brain, glycogen broken down to glucose, glucose synthesized, fat is broken down which increases glucose in blood and release from liver. Could you please help me put all six of these sentences in order please. Thanks a ton

Answers:I think it would be better for you to figure it out on your own, sorry, but I do have something that I think might help you. Please refer to the source section of my answer. I hope it's helpful. I think it'd be better for you to figure it out from the picture, you'll learn it better.

From Youtube

Homeostasis :Betty is concerned about her husband, Bob, and his homeostasis. Bob does not like wearing a helmet while he rides his motorcycle. After warning Bob about one of the risks of disrupting homeostasis from a head-impact, she has a long discussion with her friend Meredith about homeostasis, she learns about Bob's accident. After the funeral, Betty has a chat with Natalie explaining what happened to Bob and how his homeostasis failed. Homeostasis is your body's physiological way of maintaining balance through its many complex systems. Extreme injurys such as head injuries can distrupt homeostasis.

Muscular System :A Flash animation for the childrens Kid's Health website...completed for 360Kid productions in Boston MA