Joints 1
What are the three types of fibrous joints?
Suture, gomphoses, and syndesmoses
Which types of joints are called synostosis?
Bony joints
______ neurons stimulate muscles using _______ as a neurotransmitter.
Motor; acetylcholine
What are the sources of ATP for muscles?
stored ATP, stored creatinine phosphate, anaerobic and aerobic respiration
What is myasthenia gravis and how is it treated?
autoimmune attacks of ACh receptors inhibit muscle contraction. Treated with immunosuppressants or AChase inhibitors
What are the basic components of a synovial joint?
Articular (hyaline) cartilage, articular capsule (outer fibrous layer and inner synovial membrane), joint cavity with synovial fluid, bursae and tendon sheaths, menisci
What causes the three major types of arthritis?
Osteoarthritis: age-related breakdown of cartilage. Rheumatoid: autoimmune attacks on synovial membranes. Gouty: excessive uric acid deposited in soft tissues.
Perimysium divides a muscle into _______.
Fascicles (bundles of fibers)
What neurotransmitter leads to the opening of Na+ and K+ channels in a muscle cell?
Acetylcholine
What is the difference between a weak and a strong muscle contraction?
The number of motor units contracting
What makes up the shoulder joint?
Head of humerus and glenoid cavity of scapula
What is the difference between synchondroses and symphyses? Give an example of each.
Hyaline cartilage (epiphyseal plates) vs. fibrocartilage (between vertebrae)
What is a myofibril made of?
thick filaments (myosin) and thin filaments (actin)
What are the phases of a muscle twitch (singular contraction)?
latent period, contraction, and relaxation
What is muscular dystrophy?
Genetic mutation causing non-functional proteins- muscles waste away and can't be repaired.
What determines the stability of a synovial joint?
shape of articular surfaces, ligaments, and muscle tone
Where is synovial fluid found and what is its function?
Inside joint cavities, bursae, and tendon sheaths. Cushions joint, reduces friction, nourishes articular cartilage.
What do troponin and tropomyosin do?
Regulate muscle contraction. Troponin binds calcium to move tropomyosin. Tropomyosin blocks active sites on actin.
What does the action potential graph represent, in general?
Changes in membrane potential as Na+ and K+ move across the membrane to send signals.
What are curare and sarin and how do they work?
Poisons. Curare binds to ACh receptors to prevent muscle contraction. Sarin binds to AChase, leading to constant muscle contraction.
Which joint is most complicated, and what are its major parts?
What makes up the elbow joint?
hinge between trochlea of humerus and trochlear notch of ulna; gliding joint between capitulum of humerus and head of radius
What does the sarcoplasmic reticulum do in muscle contraction?
Releases Ca2+ from terminal cisternae in response to muscle cell depolarization; Ca2+ binds to troponin to move tropomyosin and allow cross bridge formation.
What is the process of muscle contraction, from nerve impulse to muscle relaxation?
Ca2+ into nerve, ACh released from nerve and binds to sarcolemma, depolarization spreads and causes terminal cisternae to release Ca2+, Ca2+ binds to troponin and shifts tropomyosin, myosin heads form cross bridges with actin, ATP binds to release myosin heads. End of nerve signal- ACh broken down by AChase, Ca2+ returns to terminal cisternae and tropomyosin shifts back.
Ca2+ leaks from sarcoplasmic reticulum. Tropomyosin moves and myosin binds to actin. Without ATP, cross bridges cannot detach.