Lab 9 (EXAM 3)

terminal cisternae

dilated end-sacs of SR which cross the muscle fiber from one side to the other enlarged areas of the sarcoplasmic reticulum surrounding the transverse tubules.

Endomysium

extension of perimysium that penetrates each fascicle and surrounds each individual muscle cell

Perimysium

extensions of epimysium that divide the muscle into bundles of muscle cells called fascicles

Triad

group of three

Aponeurosis

"the white areas basically"

In order for muscles to pull on bones to produce movement, they must be attached to bone. Skeletal muscles are attached to bones in three ways:

(1) directly to the periosteum (2) by means of a tendon (3) with an aponeurosis.

skeletal muscle coverings

-Epimysium -Perimysium -Endomysium

Recall that skeletal muscle contraction is initiated when nerve cells called motor neurons excite the individual muscle fibers.

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Skeletal muscle cells or muscle fibers are long and cylindrical.

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Tendon (attachment)

A tendon is a strong, white cord that attaches muscle to bone. An example of a tendon is the insertion of the triceps brachii. -Tendons are composed of dense regular connective tissue containing rows of fibroblasts separated by bundles of collagen fibers. This was the same type of connective tissue present in ligaments (the bands connecting connect bone to bone).

Muscle Excitation At The Neuromuscular Junction: Synapse or junction between a motor neuron and skeletal muscle fiber.

Action Potential: A long distance depolarization event, that is conducted along the membrane of a muscle cell or a nerve fiber. Voltage-gated ion channel: Ion channel that is stimulated to open or close by changes in voltage across the plasma membrane.

Aponeurosis (attachment)

An aponeurosis is a broad sheet of dense connective tissue that connects a muscle to another muscle or to bone. An example of an aponeurosis is the galea aponeurotica, the origin of the frontalis.

Directly to the periosteum (attachment)

An example of a muscle that is directly attached to the periosteum is the origin of the brachialis.

Sarcomere

Contractile unit of muscle

Know "Cross Bridge Cycling" steps!

GREAT video/activity explanation in PAL

Know "Excitation-Contraction Coupling" steps!

GREAT video/activity explanation in PAL

Know "The Neuromuscular Junction" steps!

GREAT video/activity explanation in PAL

Myofibrils

Microscopic protein filaments that make up muscle cells/fibers

Excitation-Contraction Coupling: The sequence of events linking a muscle fiber action potential to muscle fiber contraction through the release of calcium ions.

Muscle Excitation At The Neuromuscular Junction: Synapse or junction between a motor neuron and skeletal muscle fiber.

Action potential: A long-distance electrical signal transmitted along an axon. Also called a nerve impulse. Ion channels: Integral membrane proteins through which ions diffuse across the cell membrane. Voltage-gated ion channel: Ion channel that is stimulated to open or close by changes in voltage across the plasma membrane. Chemically-gated ion channel: Ion channel stimulated to open by binding with a chemical ligand.

Neuron: Cell of the nervous system specialized to generate and transmit electrical signals or action potentials. Neurotransmitter: Chemical messengers usually released from synaptic vesicles in neuron axon terminals that communicate with target cells Muscle fiber: Muscle cell

Mitochondria

Powerhouse of the cell, organelle that is the site of ATP (energy) production

H zone

The H zone gets shorter (and may disappear) during muscle contraction. Thick filaments only

Skeletal muscles are covered by three continuous layers of connective tissue.

These connective tissue components protect and support the muscle and provide passageways for nerves and blood vessels. All three layers of connective tissue extend beyond the muscle to form the tendons, which attach the muscle to bone.

thin filaments

actin, troponin, tropomyosin

Sarcoplasm

cytoplasm of a muscle cell/fiber

A band

dark area; whole thick filament length; thick+thin ** "A" for dArk

Epimysium

layer of dense connective tissue that surrounds the entire muscle; also known as deep fascia

I band

light band; thin filaments only ** "I" for lIght"

thick filaments

myosin

Sarcolemma

plasma membrane of muscle cell/fiber

nuclei sarcoplasm

skeletal muscles cells are multi-nucleate; the nuclei typically lie close to the sarcolemma and appear like bumps

sarcoplasmic reticulum (SR)

specialized smooth endoplasmic reticulum, which stores, releases, and retrieves Ca++

Z line

the line formed by the attachment of actin filaments between two sarcomeres of a muscle fiber in striated muscle cells; end of sarcomere

T tubules

tubular infoldings of the sarcolemma which penetrate through the cell and emerge on the other side these are deep invaginations of the plasma membrane found in skeletal and cardiac muscle cells. These invaginations allow depolarization of the membrane to quickly penetrate to the interior of the cell.