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

http://www.blackwellpublishing.com/matthews/myosin.html

Neuromuscular JunctionWhere a muscle is innervated

-OR-Place where a nerve meets a muscle

NeuronNerve Cell

Motor NeuronThe nerve that stimulates a muscle to contract

Motor End PlateAxon of a motor neuron that attaches to the sarcolemma of the muscle fiber

Muscle

Neuron

Motor End Plate

Motor UnitThe combination of the motor neuron and the muscle it innervates

                               

Physiology of ContractionAn action potential causes the release of Ca+2 ions stimulating the myosin to move the actin filament

http://www.brookscole.com/chemistry_d/templates/student_resources/shared_resources/animations/muscles/muscles.html(labeling picture)

Muscle Contraction Summary

http://bcs.whfreeman.com/thelifewire/content/chp47/4702001.html

Narrated Summary with tabs

Energy for ContractionThe body uses ATP for energyThis ATP can be produced by the body in 3 ways

Phosphagen SystemADP + P + Energy ATP

FastNot a lot of energy

Anaerobic System1C6H12O6 2C3H6O3 + ATP

Glucose is broken down into Pyruvic AcidNeeds no oxygenNot a lot of ATP

Aerobic System1C3H6O3 + O2 CO2 + H2O + ATP

Starts with Pyruvic Acid from AnaerobicNeeds Oxygen to take placeMakes a lot of energyMany Steps - longest

What Happens When You ExerciseThe 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 PrincipleWhen 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 contractSub-Threshold Stimulus – a stimulus that is too weak to cause a contraction

MyogramA record of the electrical activity of a muscle to determine the type of contraction

TwitchA rapid, jerky response to a single stimulus

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

LatentPeriod

ContractionPeriod

RelaxationPeriod

RefractoryPeriod

TetanusA sustained contration

TreppeA muscle contracts more forcefullu after contracting several times

IsotonicTension remains constant but the muscle shortensLifting

IsometricTension increases but muscle does not shorten

Muscle TensionThe force of a muscle contraction

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

Muscular AtrophyWasting away of muscle

Muscular HypertrophyIncrease in the size of muscle fibers