Hypertrophy of rat extensor digitorum longus muscle injected with ...
Muscular System Day 2. Muscle Development Hypertrophy – The growth and increase of the size of...
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Transcript of Muscular System Day 2. Muscle Development Hypertrophy – The growth and increase of the size of...
Muscle Development
• Hypertrophy – The
growth and increase of the size of muscle cells
• Example? Bodybuilding
Atrophy – The decrease in the size of skeletal muscle cells. When a muscle atrophies, it necessarily becomes weakerExample? Inactivity, when a cast is put on a limb.
Myostatin
• Myostatin is a protein that limits muscle tissue growth by slowing down the development of muscle cells,
• i.e. higher concentrations of myostatin in the body may cause the individual to have less developed muscles
• What would myostatin inhibitors do?
Muscular Physiology
• Each muscle is made up of many Muscle Fibers
• Each muscle fibre is made up of Myofibrils• Each myofibril is made up of a series of
Sarcomeres• The Sarcomere is made of 2 types of proteins, a
thin filament (Actin) and a thick filament (Myosin)
Messages from the nervous system travel via nerves into the muscle telling it to contract. A motor nerve connects to a muscle and branches out into nerve endings. It is these endings which stimulate the muscle fibres.
How Does a Muscle Know When to Contract?
Muscle FatigueA muscle requires fuel and oxygen for energy. Muscles that are repeatedly contracted require a high amount oxygen and energy.
If a person continues to exercise without rest, then the muscles in the body run out of oxygen. As a result, there is a
build up of lactic acid which causes a burning sensation in the muscles.
This causes the muscles to stop working properly. A consequence of working the muscle hard like this is that you may feel stiffness and soreness in the muscles for a time afterwards.
Why Some Athletes Use Drugs
• Athletes may have several reasons for using performance-enhancing drugs. An athlete may want to:
• Build mass and strength of muscles and/or bones • Increase delivery of oxygen to exercising tissues • Mask pain • Stimulate the body • Relax • Reduce weight • Hide use of other drugs
Anabolic steroids are mostly testosterone (male sex hormone)
and its derivatives. Examples of anabolic steroids include:
• Anabolic steroids are mostly testosterone (male sex hormone) and its derivatives. Examples of anabolic steroids include:
• Testosterone • Dihydrotestosterone • Androstenedione (Andro) • Dehydroepiandrosterone (DHEA) • Clostebol • Nandrolone • These substances can be injected or taken as
pills.
Anabolic steroids have a number of possible and well-known side effects, including:
• Jaundice and liver damage because these substances are normally broken down in the liver
• Mood swings, depression and aggression because they act on various centers of the brain
Males
• The excessive concentrations interfere with normal sexual function and cause:
• Baldness
• Infertility
• Breast development
Females
• The excessive concentrations cause male characteristics to develop and interfere with normal female functions. The drugs can:
• Stimulate hair growth on the face and body • Suppress or interfere with menstrual cycle,
possibly leading to infertility • Thicken the vocal cords, which causes the
voice to deepen, possibly permanently • If pregnant, interfere with the developing
fetus