(Lab quiz) Exercise 12: Microscopic Anatomy and Organization of Skeletal Muscle

Because the cells of skeletal muscle are relatively large and cylindrical in shape, they are also known as

fibers

Each muscle fiber is surrounded by thin connective tissue called the

endomysium

A cordlike structure that connects a muscle to another muscle or bone is

a tendon

The junction between an axon and a muscle fiber is called a

nueromuscular junction

The contractile unit of muscle is the

sarcomere

connective tissue covering a bundle of muscle fibers

perimysium

bundle of muscle fibers

fascicle

contractile unit of muscle

sarcomere

superficial sheath that covers the entire muscle

epimysium

thin areolar connective tissue surrounding each muscle fiber

endomysium

plasma membrane of the muscle fiber

sarcolemma

a long organelle with a banded appearance found within muscle fibers

myofibril

actin- or myosin-containing structure

myofilament

cord of collagen fibers that attaches a muscle to a bone

tendon

List three reasons why the connective tissue sheaths of skeletal muscle are important.

The connective tissue wrappings...

-bundle the muscle fibers together, increasing coordination of their activity

-add strength to the muscle

-provide a route for entry and exit of blood vessels and nerves to the muscle fibers

Why are there more indirect—that is, tendinous—muscle attachments to bone than there are direct attachments?

They conserve space (less bulky than fleshy muscle attachments) and are more durable than muscle tissue where bony prominences must be spawned

How does an aponeurosis differ from a tendon structurally?

an aponeurosis is a sheet of white fibrous connective tissue; a tendon is a band or chord of the same tissue

How is an aponeurosis functionally similar to a tendon?

both serve to attach muscles to bones or to other muscles

The junction between a motor neuron's axon and the muscle fiber plasma membrane is called

neuromuscular

The actual gap between the axon terminal and the muscle fiber is called a

motor units

Within the axon terminal are many small vesicles containing a neurotransmitter substance called

synaptic cleft

stimulating muscle contraction (both voluntary and involuntary), and acting as a neuromodulator in the brain to regulate attention, learning, and memory

acetylcholine

the change in electrical potential associated with the passage of an impulse along the membrane of a muscle cell or nerve cell

Action potential