Chapter 8. The Muscular System

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Musculoskeletal system

The bones, muscles, and joints together form an integrated system called the _____.

Myology

The scientific study of muscles.

my/o

Muscle CF.

-logy

Study of suffix.

Orthopedics

The branch of medical science concerned with the prevention or correction of disorders of the musculoskeletal system.

Orth/o

Correct (straight) CF

Ped/i

Child (foot) CF

40% - 50%

(Skeletal) Muscle tissue constitutes about _____ of the total body weight.

Skeletal , cardiac , smooth

Three types of muscular tissue.

Skeletal muscle tissue

Is attached to bones and moves parts of the skeleton.

Striations

Alternating dark and light protein bands visible under a microscope.

Voluntary

Muscle that can be made to contract and relax by conscious control.

Cardiac muscle tissue

Found only in the heart, forms the bulk of the heart wall.

Involuntary

Muscles contractions are not under conscious control.

Smooth muscle tissue

Is located in the walls of hollow internal structures, such as blood vessels, airways, the stomach, and the intestines.

Skeletal muscle tissue

Striated & Voluntary.

Skeletal muscle tissue

Function includes stabilizing body positions.

Cardiac muscle tissue

Striated & Involuntary.

Cardiac muscle tissue

Develops pressure for arterial blood flow.

Smooth muscle tissue

Nonstriated & Involuntary.

Smooth muscle tissue

Maintains diameter of tubes.

Smooth muscle tissue

Moves material in GI tract and reproductive organs.

Sphincters

Ring-like muscles that close body openings.

Producing body movements
Stabilizing body positions
Storing and moving substances
Producing heat

Functions of muscular tissue.

Smooth muscle tissue

Sphincters regulate flow in tubes.

Muscle fibers
Connective tissue
Nerves
Blood vessels

Muscles consist of.

Epimysium

Layer of connective tissue that wraps the entire muscle.

Epi-

Above, upon (prefix).

Perimysium

Layer of connective tissue that surrounds the fascicle.

Fascicle

Bundle of muscle fibres.

Peri-

Around (prefix).

Endomysium

Layer of connective tissue that surrounds each individual muscle fibre.

Endo-

In, within (prefix).

Tendon

Three layers of connective tissue that extend beyond the muscle as a _____.

Skeletal muscle tissue

Well-supplied with blood vessels and nerves.

Skeletal muscle tissue

Terminal of a neuron on each muscle fibre.

Muscle fiber

Elongated cylindrical cells.

Sarcolemma

Plasma membrane covering each muscle fibre.

Transverse (T) tubule

Tunnel in from the surface to center of each muscle fibre.

Multiple nuclei

Lie near the surface of cell (muscle fibre) under the sarcolemma.

Sarcoplasm

The muscle fiber's cytoplasm.

Sarcoplasmic reticulum

A network of fluid filled membrane enclosed tubules.

Sarcoplasm

Contains many mitochondria that produce large amounts of ATP during muscle contraction.

Sarcoplasmic reticulum

Stores calcium ions required for muscle contraction.

Sarcoplasm

Contains myoglobin.

Myoglobin

Red pigmented protein related to Hemoglobin that carries oxygen.

Myofibrils

Cylindrical structures extending along the entire length of the muscle fibre.

Thin filaments , Thick filaments

Myofibrils consist of two types of protein filaments called _____ and _____.

Sarcomere

Filaments overlap in repeating patterns.

Z discs

Sarcomeres are separated from one another by.

A band

Dark area that extends the entire length of the thick filaments.

H zone

At the centre of each A band is a narrow zone which contains only the thick filaments.

I band

A lighter coloured area to either side of the A band that contains thin filaments no thick filaments.

Myosin

Thick filaments are composed of the protein _____ which is shaped like two golf clubs twisted together.

Myosin tails

Golf club handles are arranged parallel to each other, forming the shaft of the thick filament.

Myosin heads

The heads of the golf clubs project outward from the surface of the shaft.

Actin

Thin filaments are anchored to Z disks, and are composed of the protein _____.

Tropomyosin

In a relaxed muscle, myosin is blocked from binding to actin because strands of the protein _____ cover the myosin binding sites on actin.

Myosin binding site

Each actin molecule contains a _____ where a myosin head can attach.

Troponin

The tropomyosin strands are held in place my the protein _____.

Motor unit

Neuron plus triggered fibers.

Neuromuscular Junction (NMJ)

Neuronal ending to muscle fibre.

Synaptic end bulb

At neuron terminal.

Synaptic end bulb

Release neurotransmitters.

Motor end plate

Muscular area.

Synaptic cleft

Gap between synaptic end bulb and motor end plate.

1. Release of acetylcholine (ACh)
Diffuses across cleft
3. Activation of ACh receptors
5. Generation of Muscle Action Potential
Repeats with each neuronal action potential
7. Breakdown of ACh

Action at NMJ.

1. Muscle action potential causes Ca2+ to release from Sacroplasmic Reticulum (SR).
2. Ca2+ binds to troponin.
3. Moves tropomyosin off actin sites.
4. Myosin binds & starts cycle.

Contraction Trigger.

1. Breakdown of ACh to stop muscle action potentials.
2. Ca2+ ions transported back into SR lowering concentration, This takes ATP.
3. Tropomyosin covers actin binding sites.

Relaxation.

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