INTRODUCTION TO MUSCULAR SYSTEM Flashcards
What are muscle cells (fibers)?
- Has the ability to contract
- Mediate motion
- Converts chemical energy (ATP) into mechanical energy
What is the function of actin and myosin filaments?
- Form the bulk of cytoplasmic volume of muscle cells
2. Mediate and contract muscle cells
What are the functions of muscular tissue? (6)
- Produce body movement
- Maintain posture
- Joint stabilization
- Heat generation (involuntary contractions: shivering)
- Regulate organ volume
- Movement of substances within the body (blood, lymph, urine, air, food, and sperm)
What are 4 basic properties of muscles?
- Contractility (Muscle tissue responds to stimuli by contracting lengthwise, or shortening; GENERATE PULLING FORCE)
- Extensibility (Stretch with contraction of an opposing muscle)
- Elasticity (Recoils passively after being stretched)
- Excitability (Nerve fibers cause electrical impulse to travel)
What are skeletal muscles?
- Striated appearance
- More powerful
- Less resistant to fatigue
- Part of somatic nervous system
- Attach to bones, cartilage, skin, ligaments, fascia, sclera, mucous membrane of the tongue, upper part of esophagus
- moves bones and other structures
- each is surrounded by a cell membrane (sarcolemma)
What is Cardiac muscles?
- Striated appearance
- Less powerful
- More resistant to fatigue
- Part of the Autonomic nervous system
- Part of the Heart and walls of large veins as they enter the heart
What is Smooth Muscles?
- Unstriated appearance
- Less powerful
- Sustained contractions
- Part of the Autonomic nervous system
- Found in walls of the viscera, tunica media of blood vessels, dermis (arrector pili), intrinsic muscles of eye, and Dartos muscle
What are skeletal muscle fibers?
- Long, cylindrical multinucleated
- Do not branch
- Sacrolemma surrounds cell (excitable membrane)
- Contain myofibrils (bundles/fascicles of myofilaments: Actin: Thin and Myosin: Thick)
- Nuclei just beneath sacrolemma
What are RED FIBERS? (6)
- Slow twitch fibers
- Small fibers (single contraction)
- Contract slowly
- Prolonged sustained activity
- Major fibers in Humans
- Maintain an erect posture
What are WHITE FIBERS? (6)
- Fast twitch fibers
- Large fibers
- Rapid contraction
- Fatigue more easily
- Extraocular muscles
- Digits muscles
What are the 2 classification of skeletal muscle fibers?
- Red fibers
2. White fibers
What are Type 2 A (intermediate) skeletal muscle fibers? (8)
- Contain properties of both white and red fibers (White fibers tho)
1. Medium diameter
2. Intermediate Smooth reticulum and t tubules
3. Intermediate Mitochondria
4. Abundant blood vessels
5. Aerobic/Anaerobic
6. High glycogen
7. Narrow Sarcomeres
8. Intermediate myoglobin
What is Type 1 Red fiber properties? (8)
- Small diameter
- Least amount of SR and t-tubules
- Abundant mitochondria
- Abundant blood vessels
- Aerobic
- Low glycogen
- Wide sarcomeres
- Abundant myoglobin
What is Type 2 White fiber properties? (8)
- Large diameter
- Most amount of SR and t-tubules
- Sparse mitochondria
- Sparse blood vessels
- Aerobic/Anaerobic
- High glycogen
- Narrow sarcomeres
- Sparse myoglobin
What is a basement membrane is skeletal muscles?
- Contain Satellite cells (precursors to skeletal muscle cells)
- Represent persistent myoblasts
- Regenerate muscle after injury
What is Endomysium?
- Found in skeletal muscles
- A network of loose CT (collagenous and reticular fibers)
- Contains a network of capillaries
- Contain the terminal ends of nerve fibers
What is Perimysium?
- Found in skeletal muscles
2. Surrounds each fascicle
What is Epimysium?
- Found in skeletal muscles
2. Dense CT that surround a collection of fascicles
What is the Functions of Connective Tissues in skeletal muscles?
- Nutrition (blood vessels, capillaries, nerve)
- Protection and shaping the muscles
- Force transduction
*Transfer forces developed by skeletal muscles to their site of attachment
What are the different shapes of CT in skeletal muscles?
- Cords or straps (Tendons)
- Broad and thin sheet (Aponeurosis)
- Thin layer (Fasciae)
What is a muscle contraction?
- An attempt on the part of muscle to approximate one end to the other end of the muscle
What is Agonist?
- “Prime mover” muscles that cause a movement to occur through their own contraction
* Active in initiating and maintaining the desired movement
What is Antagonists?
- Muscles perform opposite functions and are generally located on the opposite sides of the joint
* Oppose the action of agonist
What is Synergists?
- Assist to accomplish the desired movement by preventing movement at joints other than the joints involved in the desired movement
- Muscles that contract together in accomplishing a particular movement
*EX: Flexion of the fingers at interphalangeal joints
Ex: Contraction of the extensor muscles (prevent flexion of the hand at the wrist)
What is Fixator?
- Steady proximal parts of a limb while movement are occurring in the distal part
What are 2 contractile properties of muscles?
- Isotonic Contraction
2. Isometric Contraction
What is Isotonic Contraction?
- Tension remains constant
- Length of muscle changes
*Load is moved
What is Isometric Contraction?
- Tension changes
- Length of muscle remains constant
*NO MOVEMENT OCCURS
