Anatomy

Alternating contraction and relaxation of cell
Chemical energy changed into mechanical energ

Attaches to bone, skin or fascia
Striated (light & dark bands visible with scope)
Voluntary control of contraction & relaxation

Striated in appearance
Involuntary control
Autorhythmic because of built in pacemaker

Anatomy:
Striated, branching fibers
Single centrally located nucleus

Anatomy:
Cells connected by intercalated discs with gap junctions
Same arrangement of thick & thin filaments as skeletal

What are the 3 types of muscle tissue?

Attached to hair follicles in skin
In walls of hollow organs -- blood vessels & GI

Nonstriated in appearance (looks smooth)
Involuntary

Smooth muscle: Thick & thin myofilaments not orderly arranged so lacks __________.

Sliding of thick & thin filaments generates _________

Transferred to intermediate filaments & dense bodies attached to sarcolemm

Muscle fiber contracts and twists into a ______ as it shortens -- relaxes by untwisting

When do skeletal muscles stop dividing?

Growth is enlargement of existing cells

Satellite cells & bone marrow produce some new cells
If not enough numbers---fibrosis occurs most often

All healing is done by fibrosis (scar formation)

Cells can grow in size (hypertrophy)
Some cells (uterus) can divide (hyperplasia)
New fibers can form from stem cells in BV walls

What are the functions of Muscle Tissue? (4)

Properties of Muscle Tissue:
Respond to chemicals released from nerve cells

Properties of Muscle Tissue:
Ability to shorten and generate force

Properties of Muscle Tissue:
Ability to be stretched without damaging the tissue

Properties of Muscle Tissue:
Ability to return to original shape after being stretched

What is the Superficial Fascia of Skeletal Muscle composed of?

Dense irregular connective tissue around muscle

Connective tissue components of the muscle include:

Surrounds the whole muscle

Surrounds bundles (fascicles) of 10-100 muscle cells

Separates individual muscle cells

Long, cylindrical & multinucleated

Muscle cell membrane

What is the sarcoplasm filled with?

Red-colored, oxygen-binding protein

Muscle fibers are filled with threads called _______

What are myofibrils separated by?

The contractile proteins of muscle

SR: System of tubular sacs similar to _________ _____ in nonmuscle cells

Stores Ca+2 in a relaxed muscl

Triggers muscle contraction in SR

Invaginations of the sarcolemma into the center of the cell

Filled with extracellular fluid
Carry muscle action potentials down into cell

Where do you find mitochondria in muscle cells?

Every mature muscle cell developed from ______ myoblasts that fuse together in the _____. (multinucleated)

Can mature muscle cells divide?

What is muscle growth the result of?

Retain the ability to regenerate new cells

Thick filament

Thin filaments

How are striations created?

Filaments are arranged in compartments called _______

Sacromeres are separated by _______

Myosin cross bridges pull thin actin filaments toward the centre of the sarcomere resulting in __________________________

This event requires release of calcium ions from the SR into the cytosol and energy (ATP) from the mitochondria

Sliding Filament Mechanism of Contraction:

Do thick and thin filaments change in length during contraction?

What nerve is supplied by a nerve, artery and veins

What does each motor neuron supply?

Where are nerve fibers and capillaries found?

Swellings of axon terminals

Contain synaptic vesicles filled with acetylcholine (ACh)

Contains 30 million ACh receptors.

Variations in Skeletal Muscle FIbers (3)

More myoglobin, an oxygen-storing reddish pigment
More capillaries and mitochondria

Less myoglobin and less capillaries give fibers their pale color

How do contraction and relaxation speeds vary?

How is there variance in skeletal muscle fibers in terms of resistance to fatigue?

Red in color (lots of mitochondria, myoglobin & blood vessels)
Small muscle fibers and least powerful muscle type
Prolonged, sustained contractions for maintaining posture
Use ATP at a slow rat

White in color (few mitochondria & BV, low myoglobin)
Large muscle fibers, most powerful contractions
Contractions last for short duration; used for weight-lifting
Split ATP fast but fatigue quickly

Muscle fibers are intermediate in thickness:gives strength of contraction
Red in color and contain moderate amounts of myoglobin & blood vessels
Both good source of energy and ability to split ATP at a fast rate; used for walking and sprinting

wasting away of muscles
caused by disuse (disuse atrophy) or severing of the nerve supply (denervation atrophy)

Increase in the diameter of muscle fibers
Resulting from very forceful, repetitive muscular activity and an increase in myofibrils, SR & mitochondria

A state of muscular rigidity that begins 3-4 hours after death and lasts about 24 hours

After death, Ca+2 ions leak out of the SR and allow ______ heads to bind to _______

Why: crossbridges cannot detach from actin until proteolytic enzymes begin to digest the decomposing cells.

Similar to testosterone
Increases muscle size, strength, and endurance
Many very serious side effects

What are some side effects of Anabolic Steroids?

Inherited, muscle-destroying diseases
Sarcolemma tears during muscle contraction
Mutated gene is on X chromosome so problem is with males almost exclusively

Appears by age 5 in males and by 12 may be unable to walk
Degeneration of individual muscle fibers produces atrophy of the skeletal muscle

Gene therapy is hoped for with the most common form = Duchenne muscular dystrophy