Learning Objectives 4

Epithelial,connective, and nerverous.

• Excitability (when a muscle is stimulated by the nervous system
• Conteractibility (stimulation of muscle cells generates tensions within the cell which cause the cell to shorten.)
• Elasticity(must be capable of extending in length in response to the contration of the opposing muscle cells.)

membrane plasma of a muscle fibers

cytoplasma of a muscle fiber

a cyndrical structure that makes up the sacoplasma of the skeletal muscle fibers containing thousands of long cyindrical structure.

are deep investigations of the sarcolemma that extends into the sarcoplasm of the skeletal muscle fibers as a network of narrow membranous tubules. Muscle impulses generated when a nerve impulse reaches the sarcolemma travel rapidly along the sarcolemma and then spread internally along the sarcolemma and then spread internally along the membranes of the t-tubule network.

similar to the smooth endoplasmic reticulim of other cells. The sarcoplasmic reticulum stores calcium ions needed to initiate muscle contractions, it runs parallel to the muscle fibers.

They are primarily composed of 2 strands of the protien actin twisted around each other to form a helical shape. each spherical molecule is called G actin and each filament composed of a strand of G-actin molecules is called F actin.

• Assembled from bundles of the protien myosin. Each myosine molecule in a thick filament consists of 2 strands eacg strand has a free globular head and an attached, elongated tail.
• Components: Are assembled from bundles of the protien myosin. Each myosin molecule in a thick filament consists of 2 strands, each strand has a free gobular head and an attached, enlongated head.

is the functional contractile unit of a skeletal muscle fiber. There are numerous sacromeres in each myofibril. Each shortens as the muscle fiber contracts.A contractile unit of a muscle fiber.

It attaches the muscle to bone, skin or other muscle.

Are connected from bone to bone.

A relulatory protien that attaches to actin to anchor itself in place, attaches to tropomysin to hold it in place. provides a binding site for calcium ions.

is short twisted taht covers sections of the actin strand.

When a muscle contracts, thick and thin filaments slide past each other and the sacromere shortens.

the point where a motor neuron meets a skeletal muscle fiber.

is a expanded tip of an axon. When is nears the sarcolemma of a muscle fiber, it expands further to cover a relatively large surface area of the sarcolemma.

is numerously found in the snynaptic knob, its filled with molecules of the neurotransmitter acetylcholine (ACh)

Specialized region of the sarcolemma, it has folds and indentions to increase the membrane surface area covered by the synaptic knob.

a narrow space seperating the synaptic knob and motor end plate.

in the motor end plate act like doors that normally are closed. ACh is the only key to open these receptor doors.

An enzyme that resides in the synaptic cleft and rapidly breaks down molecules of ACh that are released into the synaptic cleft. Thus ACHE is needed so that ACH will not continually stimulate the muscle.

composed of a single motor neuron and all of the muscle fibers it controls. Typically controls only some of the muscle fibers in an entire muscle. Most muscles have many motor units, which means that many motor neurons are needed to innervate an entire muscle. Thus, a largemuscle has numerous motor units. The smaller the motor units, the finer the control, like fine motor movement like the eyes. All or nothing princible.

Contract slowly , have endurance, lots of vascular supply, called red fibers due to the red pigment myoglobin (a oxygen binding, reddish apppearing protien that is structurally related to hemoglobin.) Needs lots of ATP so lots of mitochondria.

contain large glycongen reserves densely packed myofibrils and few mitochondria. Called white fibers due to their lack of myoglobin. Anaerobic, majority in body are fast fibers.

the less mobile attachment of a muscle.

the more mobile attachement of the muscle.

a musclethat produces a particular movement, such as extending the forearm.

is a muscule whoses actions oppose those of hte antagonist. They are invertly related.

a muscle that assits the agnoist in preforming its action.

arranged around a opening also calld a sphincter Ex. Orbivularis oris the mouth

run parallel to its long akis. Have a central body called belly. Have high endurance not as strong.

widespread muscles that converge on a common attachment sit (pectoralis major)

all muscle fibers are on the same side of the tendon (extensor digitorum finers)

most common type. muscle on both side of the tendon.

has branches of the tendon within the muscle (the deltoid)

a enlongated rigid object that rotates around a fixed point called the fulcrum (like a Seesaw).

occurs when an effort applied to 1 point on the level exceeds the resistance located at some other point. The part of a lever from the fulcrum to the point of effort is called the effort arm and the part from the fulcrum to the point of resistance arm.

has a fulcrum in the middle between the effort and the resistance (pair of scissors)

between the fulcrum in the middle between the applied effort (lifting the wheelbarrow rare standing on your tipy toes)

an effort is applied between resistance and the fulcrum, as when picking with forceps (mandible chewing food)