Unit 7.1: Muscle Tissue

Functions of the Muscles

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* Produce movement
* Maintain posture and balance
* Stabilize joints
* Generate heat

Excitability/responsiveness

the ability to receive and respond to an electrical signal

Contractility

the ability to shorten forcibly when stimulated

Extensibility

the ability to extend or stretch when relaxed

Elasticity

the ability of a muscle cell to recoil and resume resting length after stretching

Skeletal Muscle

voluntary, muscles that connect to your bones and allow you to perform a wide range of movements and functions

Cardiac muscle

involuntary, makes up the thick middle layer of the heart

Smooth Muscle

involuntary, found inside the walls of hollow organs

Epimysium

surrounds the whole muscle

Perimysium

surrounds fascicles

fascicles

groups of muscle fiber cells

Endomysium

surrounds each individual muscle fiber cell

Tendons

pull together with muscle fiber cells to move the skeleton

Sarcolemma

cell/plasma membrane of a muscle fiber cell

Sarcoplasm

cytoplasm of a muscle cell

Sarcoplasmic Reticulum

specialized endoplasmic reticulum (ER)

* Stores, releases, and reuptakes calcium which is important for the contraction cycle

T-Tubules

infoldings of the sarcolemma

* Carries electrical impulses throughout the sarcoplasmic reticulum very quickly

Myofibrils

Makes up majority of the cell volume

* protein bundles within the muscle fiber cells

Myofilaments

protein fibers that make up the myofibrils

* Contain actin and myosin

actin

thin fibers found in myofilaments

myosin

thick fibers found in myofilaments

Sarcomere

the contractile unit of a muscle fiber

* Overlaps the actin and myosin filaments
* Z-line boundaries on each side
* Contract in unison to shorten the entire muscle