Muscular System Flashcards
Properties of Skeletal muscle
Support & movement, blood propulsion, thermoregulation, striated
• Voluntary (somatic) control
• Multinucelated
Can be red or white fibers
Skeletal muscle red fibers
Slow twitch. Support (dark meat). Carry out oxidative
phosphorylation.
White Fibers:
Skeletal muscle
Fast-twitch. Active (white meat). Anaerobic metabolism.
Properties of smooth muscle, where is it found?
Respiratory, reproductive, cardiovascular, digestive
• Involuntary (autonomic) control
• Uninucleated
• Can display myogenic activity without neural input
Properties of cardiac muscle?
Contractile tissue of the heart • Involuntary (autonomic) control • Uninucleated (sometimes binucleated) • Can display myogenic activity • Cells connected with intercalated discs that contain gap junctions
Which germ layer is the skeletal system dervived from?
Mesoderm
Axial Skeleton
Skull, vertebral column, ribcage, hyoid bone
Appendicular Skeleton
Bones of limbs, pectoral girdle, pelvis.
Bones of limbs, pectoral girdle, pelvis.
Lattice-like structure of bony spicules known as trabeculae.
Cavities filled with bone marrow
Red bone marrow
Filled with hematopoietic stem cells
yellow bone marrow
Yellow: fat
Long Bones
Shafts called diaphysis that flare to form metaphyses and
that terminate in epiphyses. Epiphyses contain
epiphyseal (growth) plate.
Periosteum:
Connective tissue that surrounds bone.
Ligaments:
Attach bones to other bones
Tendons
: Attach bones to muscles.
Bone Matrix: Osteons
Osteons are the chief structural unit of compact bone,
consisting of concentric bone layers called lamellae, which
surround a long hollow passageway, the Haversian canal.
Between rings are lacunae, where osteocytes reside,
which are connected with cancaliculi.
Osteoblasts
build bone
Osteoclasts
Reabsorb bone
What does parathyroid hormone release do to bone reabsorption and calcium levels?
Increases reabsorption of bone and increases blood calcium
What effect does vitamin D have on bone reabsorption and blood calcium
Increase both
What effect does calcitonin have on bone formation and calcium in the blood
Increases bone formation and decreases blood calcium concentration
What secretes cartilage?
Chondrocytes
Is cartilage innervated?
No
Immovable joints
Fused together to form sutures
Movable joints
Strengthened by ligaments and contain a synovial capsule
Synovial fluid
Secreted by synovium and it lubricates joints
Fetal bones
Bones form from cartilage through endochondroal
ossification. Skull bones form directly from mesenchyme
in intramembranous ossification.
Sacromeres
Basic contractile unit of striated muscle
Are myosin thick or thin?
Thick
Are actin thick or think filaments?
Thin
Where are troponin and tropomyosin found and what do they do?
Troponin & tropomyosin found on the thin filament and regulate actinmyosin interactions
Z-lines:
Define the boundary of each sarcomere
M-line
Middle of sarcomere
o I-band:
Only actin filaments.
H-zone:
Only myosin filaments.
A-band
Contains both actin and myosin. Only part that
maintains a constant size during contraction.
What happens to the z lines and the I bands as the sarcomere contracts?
Gets closer together
What happens to the A band when the sarcomere contracts?
Stays the same
Sarcoplasmic Reticulum:
Ca2+ filled modified endoplasmic reticulum.
Sarcolemma:
Cell membrane of a myocyte
T-tubules:
Connected to sarcolemma. Carry signals
Describe the process of contraction and relaxation
Begins at neuromuscular junction, where the efferent neuron release
acetylcholine that binds to receptors on the sarcolemma, causing
depolarization
• Depolarization spreads down sarcolemma to T-tubules, triggering the
release of Ca2+
• Ca2+ binds to troponin, causing a shift in tropomyosin and exposure of
the myosin-binding sites on the actin filament
• Shortening of the sarcomere occurs as myosin heads bind to the
exposed sites on actin, forming cross bridges and pulling the actin
filament along the thick filament. “Sliding filament model”
• Muscles relax when acetylcholine is degraded by acetylcholinesterase,
terminating the signal and allowing Ca2+ to return to the SR.
• ATP binds to myosin head, allowing it to release form actin
Simple Twitch:
: Single muscle fiber responds to brief stimulus.
Frequency Summation:
Addition of multiple simple twitches before the
muscle has a chance to fully relax.
Oxygen Debt:
Difference between O2 needed and O2 present.
Creatine Phosphate:
Adds a phosphate group to ADP, forming ATP
Myoglobin:
Heme-containing protein that is a muscular
oxygen reserve.
