Alexander Graham Bell invention of the telephone is the culmination of work done by many individuals, the history of which involves a collection of claims and counterclaims. The development of the modern electrical telephone involved an array of lawsuits founded upon the patent claims of several individuals and numerous companies.

This article covers the early years from 1844 to 1898, from conception of the idea of an electric voice-transmission device, to failed attempts to use "make-and-break" current, to successful experiments with electromagnetic telephones by Antonio Meucci, Alexander Graham Bell and Thomas Watson, and finally to commercially successful telephones in the late 19th century.

Telephone
A telephone, or phone, is a telecommunications device that permits two or more users to conduct a conversation when they are too far apart to be heard directly.

The muscular system is an organ system consisting of skeletal, smooth and cardiac muscles. It permits movement of the body, maintains posture, and circulates blood throughout the body. The muscular system in vertebrates is controlled through the nervous system, although some muscles (such as the cardiac muscle) can be completely autonomous. Together with the skeletal system it forms the musculoskeletal system, which is responsible for movement of the human body.

Muscles

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 ofadenosine 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 sarcomerewhen 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.

Aerobic and anaerobic muscle activity

At rest, the body produces the majority of its ATP aerobically in the mitochondria^[1] without producing lactic acid or other fatiguing byproducts.^[2] 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.^[2] 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.^[2] 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.^[2]

Cardiac muscle

Main article: Heart 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

Main article: 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.

Skeletal muscle

Main article: Skeletal muscle

See also: List of muscles of the human body

There are approximately 639 skeletal muscles in the human body.

The DepEd Vision

We dream of Filipinos
who passionately love their country
and whose values and competencies
enable them to realize their full potential
and contribute meaningfully to building the nation.

As a learner-centered public institution,
the Department of Education
continuously improves itself
to better serve its stakeholders. 

---

The DepEd Mission

To protect and promote the right of every Filipino to quality, equitable, culture-based, and complete basic education where:

Students learn in a child-friendly, gender-sensitive, safe, and motivating environment.
Teachers facilitate learning and constantly nurture every learner.
Administrators and staff, as stewards of the institution, ensure an enabling and supportive environment for effective learning to happen.
Family, community, and other stakeholders are actively engaged and share responsibility for developing life-long learners.

The DepEd Vision

We dream of Filipinos
who passionately love their country
and whose values and competencies
enable them to realize their full potential
and contribute meaningfully to building the nation.

As a learner-centered public institution,
the Department of Education
continuously improves itself
to better serve its stakeholders. 

---

The DepEd Mission

To protect and promote the right of every Filipino to quality, equitable, culture-based, and complete basic education where:

Students learn in a child-friendly, gender-sensitive, safe, and motivating environment.
Teachers facilitate learning and constantly nurture every learner.
Administrators and staff, as stewards of the institution, ensure an enabling and supportive environment for effective learning to happen.
Family, community, and other stakeholders are actively engaged and share responsibility for developing life-long learners.

The DepEd Vision

We dream of Filipinos
who passionately love their country
and whose values and competencies
enable them to realize their full potential
and contribute meaningfully to building the nation.

As a learner-centered public institution,
the Department of Education
continuously improves itself
to better serve its stakeholders. 

---

The DepEd Mission

To protect and promote the right of every Filipino to quality, equitable, culture-based, and complete basic education where:

Students learn in a child-friendly, gender-sensitive, safe, and motivating environment.
Teachers facilitate learning and constantly nurture every learner.
Administrators and staff, as stewards of the institution, ensure an enabling and supportive environment for effective learning to happen.
Family, community, and other stakeholders are actively engaged and share responsibility for developing life-long learners.