Muscle Tissue 2 Muscle Contrations

The Sliding Filament Theory The thin filaments (actin) slide over the thick causing the sarcomere to shorten. This process requires ATP

Mechanism of Filament Sliding Animation tthews/myosin.html

Neuromuscular Junction Where a muscle is innervated -OR- Place where a nerve meets a muscle

Neuron Nerve Cell

Motor Neuron The nerve that stimulates a muscle to contract

Motor End Plate Axon of a motor neuron that attaches to the sarcolemma of the muscle fiber Muscle   Neuron  Motor End Plate

Motor Unit The combination of the motor neuron and the muscle it innervates

Physiology of Contraction An action potential causes the release of Ca+2 ions stimulating the myosin to move the actin filament imations/muscles/muscles.html (labeling picture)

Muscle Contraction Summary ontent/chp47/ html Narrated Summary with tabs

Energy for Contraction The body uses ATP for energy This ATP can be produced by the body in 3 ways

Phosphagen System ADP + P + Energy  ATP Fast Not a lot of energy

Anaerobic System 1C 6 H 12 O 6  2C 3 H 6 O 3 + ATP Glucose is broken down into Pyruvic Acid Needs no oxygen Not a lot of ATP

Aerobic System 1C 3 H 6 O 3 + O 2  CO 2 + H 2 O + ATP Starts with Pyruvic Acid from Anaerobic Needs Oxygen to take place Makes a lot of energy Many Steps - longest

What Happens When You Exercise The muscle cells burn off the ATP they have floating around in about 3 seconds. The phosphagen system kicks in and supplies energy for 8 to 10 seconds. This would be the major energy system used by the muscles of a 100-meter sprinter or weight lifter, where rapid acceleration, short-duration exercise occurs. If exercise continues longer, then the glycogen-lactic acid system kicks in. This would be true for short-distance exercises such as a 200- or 400-meter dash or 100-meter swim. Finally, if exercise continues, then aerobic respiration takes over. This would occur in endurance events such as an 800- meter dash, marathon run, rowing, cross-country skiing and distance skating.

All or None Principle When a muscle fiber is stimulates it either completely contracts or does not contract at all

Threshold Stimulus – the weakest stimulus that can cause a muscle to contract Sub-Threshold Stimulus – a stimulus that is too weak to cause a contraction

Myogram A record of the electrical activity of a muscle to determine the type of contraction

Twitch A rapid, jerky response to a single stimulus

Latent Period – time between the application of the stimulus and the muscle contraction Contraction Period – time when filament are sliding over each other, causing a contraction Relaxation Period – Time during which filaments are sliding back into place Refractory Period – Time following a contraction during which a muscle is unable to respond to a stimulus

Latent Period Contraction Period Relaxation Period Refractory Period

Tetanus A sustained contration

Treppe A muscle contracts more forcefullu after contracting several times

Isotonic Tension remains constant but the muscle shortens Lifting

Isometric Tension increases but muscle does not shorten

Muscle Tension The force of a muscle contraction

Muscle Tone State of partial contraction – muscle is tight but not causing movement

Muscular Atrophy Wasting away of muscle

Muscular Hypertrophy Increase in the size of muscle fibers