Biology: Chapter 11: Musculoskeletal System Flashcards
what is skeletal muscle
involved in support and movement, propulsion of blood, and thermoregulation; appears striated, under voluntary control, polynucleated; red fiber and white fibers
what are red fibers
Slow twitch fibers that carry out oxidative phosphorylation
what are white fibers
fast twitch fibers that carry out anaerobic metabolism
what is smooth muscle
respiratory, reproductive, cardiovascular, and digestive systems; nonstriated, involuntary, uninucleated; displays myogenic activity
what is cardiac muscle
contractile muscle of the heart; striated, involuntary, uninucleated (sometimes binucleated); myogenic activity; cells connected with intercalated discs that contain gap junctions
what is the basic unit of muscle
sacromere
what are sarcomeres
made of thick (myosin) and thin (actin) filaments; troponin and tropomyosin found on thin filament and regulate actin-myosin interactions
what are Z lines
define the boundaries of each sarcomere
what is the M line
located in the middle of sarcomere
what is the I band
contains only thin filaments
what is the H zone
consists of only thick filaments
what is the A band
contains thick filaments in their entirety; only part of the sarcomere that maintains a constant size during contraction
what are myofibrils
sarcomeres attached end to end; surrounded by the sarcoplasmic reticulum
what is the sarcoplasmic reticulum
calcium containing modified endoplasmic reticulum
what are T tubules
connected to the sarcolemma and oriented perpendicularly to the myofibrils allowing the action potential to reach all parts of the muscle
what is the first step of muscle contraction
begins at the NMJ where the neuron releases Acetylcholine that binds to receptors on the sarcolemma causing depolarization
what is the second step of muscle contraction
depolarization spreads down the sarcolemma to the T tubule triggering the release of calcium ions
what is the third step of muscle contraction
calcium binds to troponin causing a shift in tropomyosin and exposure of the myosin binding sites on the actin thin filament
what is the four step of muscle contraction
shortening of the sarcomere occurs as myosin heads bind to the exposed sites on action, forming cross bridges and pulling actin filament along the thick filament which results in contraction (sliding filament model)
what is the fifth step of muscle contraction
acetylcholine is degraded by acetylcholinesterase and the muscle relaxes allowing calcium to be brought back into the SR; ATP binds to the myosin head allowing its release from actin
what is a simple twitch
all or nothing muscle response
what is frequency summation
addition of multiple twitches before muscle has opportunity to relax
what is oxygen debt
difference between oxygen needed and oxygen present
what is tetanus
simple twitches occur so frequently as to not let the muscle relax at all leading to a stronger more prolonged contraction
what is creatine phosphate
can transfer a phosphate group to ADP forming ATP
what is myoglobin
heme containing protein that is a muscular oxygen reserve
what is the axial skeleton
skull, vertebral column, rib cage, and hyoid bone
what is the appendicular skeleton
consists of the bones in the limbs, pectoral girdle, and pelvis
what is bone derived from
embryonic mesoderm
what is compact bone
provides strength of the bone and is dense
what is spongy/cancellous bone
lattice like structure consisting of spicules known as trabeculae; cavities filled with bone marrow
what is the periosteum
layer of connective tissue surrounding the bone
what are tendons
attaches bone to muscle
what are ligaments
attaches bone to bone
what is the structure of long bones
shafts called diaphyses flare to form metaphyses and terminate in epiphyses
what are epiphyses
contain an epiphyseal growth plate that causes linear growth of the bone
what is the bone matrix
composed of organic (collagen, glycoproteins and peptides )and inorganic compounds (hydroxyapatite)
what is the structural unit of a bone
osteon
what are lamellae
concentric rings that organize bones
what are lacunae
between lamellar rings where osteocytes reside; connected with canaliculi to allow for nutrient and waste transfer
what are osteoblasts
build bone
what are osteoclasts
cells that resorb bone
what is cartilage
firm, elastic material secreted by chondrocytes; avascular and not innervated
what is endochondral ossification
fetal cartilage turns into bone
what is intramembranous ossification
bones form directly from undifferentiated tissue
what are immovable joints
joints that are fused together to form sutures or similar fibrous joints
what are movable joints
usually strengthed by ligaments and contain a synovial capsule
what is synovial fluid
secreted by synovium; aids in motion by lubricating the joing
what is articular cartilage
each bone in the joint is coated with it to aid in movement and provide cushioning
