Muscloskeletal system (11) Flashcards
Skeletal Muscle
Striated, Voluntary, Somatic innervation, Many nuclei per cell. Calcium required for contraction.
Cardiac Muscle
Striated, Involuntary, Autonomic innervation, 1-2 nuclei per cell. Calcium required for contraction.
connected by intercalated discs that contain many gap junctions.
Smooth Muscle
Non-striated, Involuntary, Autonomic innervation, 1 nucleus per cell. Calcium required for contraction.
Red fibers ( slow-twitch fibers)
have high myoglobin content and primarily derive their energy aerobically.
Muscle fibers have high levels of mitochondria and thus have to use oxidative phosphorylation to make ATP.
White fibers ( fast-twitch fibers)
contain less myoglobin.
Muscle fibers have fewer mitochondria and must rely on glycolysis and fermentation to make ATP under most circumstances.
Sacromere
basic contractile unit of skeletal muscle
Troponin and Tropomyosin
found on the thin filament and regulate actin-myosin interactions.
Calcium binds to troponin, leading to a conformational change in tropomyosin, which exposes the myosin-binding sites of actin.
Z-line
boundaries of each sacromere
M-line
middle of the sacromere
I-band
contains only thin filaments
H-zone
contains only thick filaments
A-band
contains thick filaments in thier entirety. It is only part of the sacromere that maintains a constant size during contraction.
Neuromuscular junction
motor neurons release ACh that binds to receptors on the sarcolemma, causing depolarization.
- This depolarization spreads down the sarcolemma to the T-tubules, triggering release of calcium ions.
- Calcium binds to troponin, causing shift in tropomyosin and exposure of myosin-binding sites on the actin thin filament
Sliding filament model
shortening of the sarcomete occurs as myosin heads binds to the exposed sites on actin, forming cross bridges and pulling the actin filament along on the thick filament, results in contraction.
Muscle relax
muscle relaxes when ACh is degraded by acetylcholinesterase. terminating the singal and allowing to calcium to brought back into SR, ATP binds to the myosin head, allowing it to release from actin.
Simple twitch
the response of a single muscle fiber to a brief stimulus at or above threshold.
- Latent period: time between reaching threshold and onset of contraction. AP spreads along the muscle and allows for calcium to be released from the sarcoplasmic reticulum.
- Contraction period
- Relaxation period
Tetanus
contractions become so frequent that the muscle is unable to relax at all.
Frequency summation
multiple simple twitches before the muscle has an opportunity to fully relax.
Oxygen debt
difference between amount of oxygen needed and the amount of oxygen present.
Creatine phosphate
created by transferring a phosphate group from ATP to creatine during times of rest.
Tendon
connect muscle to bone
Ligament
hold bone to bone
Osteoblasts
build the bone
Osteoclasts
macrophage of bone, resorb it.
Parathyroid horomone
response to low blood calcium, promotes resorption of bone, increasing the concentration of calcium and phosphate in the blood.
Vitamin D
promotes resorption of bone leads to the production of strong bone.
Calcitonin
Peptide hormone released by parafollicular cells in the thyroid. increases bone formation, decreasing calcium level in bone.
Synovial fluid
secreted by synovium, aids in motion by lubricating the joint.
Articular cartilage
aid in movement and provide cushioning.
Events that initiates the muscle contraction
Release of Ach from motor neuron –> activation of Ach receptor in sarcolemma –> depolarization of sarcolemma –> spreading signal using T-tubules –> release of calcium from SR –> binding of calcium to troponin –> conformational shift in tropomyosin –> exposure of myosin-binding sites –> myosin binds to actin
Red marrow
filled with hematopoietic stem cells, which are responsible for the generation of all cells in our blood
Yellow marrow
composed primarily of fat and is relatively inactive
Compact bone
provides strength and is dense
Epiphysis
contains epiphyseal (growth) plate that causes linear growth of the bone
Periosteum
bone is surrounded by a layer of connective tissue
Osteoblasts and Osteoclasts
Osteoblasts build bone and Osteoclast chew bone.
Endochondral ossification
responsible for the formation of most of the long bones in the body.
Antagonistic pair
one relaxes, other contracts (Bicep and tricep)
Synergistic
working together to accomplish the same function.
Abductor
moves a part of the body away from the midline
Adductor
moves a part of the body toward the midline
