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62 Cards in this Set

  • Front
  • Back
three types of muscle
1. striated voluntary skeletal muscle
2. striated involuntary skeletal muscle
3. involuntary smooth muscle
functions of muscle tissue in animals
1. producing body mvmts
2. stabilizing body positions
3. regulating organ volume
4. regulating the flow of substances within the body
5. the production of heat
how is heat produced by one of the muscle types?
involuntary contractions of skeltal muscle (SHIVERING)
epimyseum
dense CT sheath encasing most skeletal muscle, corresponds to deep fascia
fasicles
bundles of muscle fibers encased by perimyseum
perimyseum
CT layer encasing fasicles of muscle fibers
muscle fibers
are the muscle cells, each separated by surrounding endomysium by an external lamina
sarcolemma
cell membrane of a muscle fiber or muscle cell
endomysium
layer of loose connective tissue that ensheaths a muscle fiber and is composed mostly from reticular fibers
tendons
dense, regular CT, attach muscle to bone, provide stability for muscle contraction and transmit the force of movement from muscle to bone
myoblasts
type of stem cells that can fuse together to form multinucleate skeletal muscle fibers
Myoblasts that do not form muscle fibers differentiate into satellite cells.
skeletal muscle nuclei
multiple (multinucleate)
located on the fiber periphery, immediately beneath the sarcolemma (plasma membrane)
myofibrils
bundles of myofilaments within the muscle cell, arranged in consistent alignment of repeated sarcomeres
sarcomeres
fundamental units of contraction
major myofilaments of the sarcomeres
(thin) actin and (thick) myosin II (with associated proteins)
thin filaments of sarcomere
actin filaments anchored by their + ends (barbed ends) to the Z-line

associated with nebulin (scaffolding protein)

and bound to troponin-tropomyosin regulatory complex
how and where is actin anchored in sarcomere?
by + ends (barbed ends) to the Z-line
nebulin
scaffolding protein associated with actin in sarcomeres
myosin II
thick filaments of sarcomeres
titin
protein associated with myosin II in sarcomere. prevemts sarcomere from overstretching
A band
(anisotropic) darker band in center of sarcomere associated with myosin (thicker fiber)
I band
lighter bands between Z discs and A band, contain only actin filaments
H zone
"Heller" (lighter) region in the middle of the A band, brighter (only myosin, no overlap
Z disc
"Zwischen discs" protein disks between each sarcomere
M line
"Mittel" of sarcomere, proteins including myomesin, titin and creatine kinase, structural proteins help titin and myosin maintain their 3-dimensional structure
sarcolemma is stabilized by
a membrane cytoskeleton composed of actin, dystrophin and other proteins
muscular dystrophy is characterized by defects in what?
dystrophin
dystrophin
protein essential for maintaining connection between cytoskeleton of muscle fiber and ECM (deficiency leads to muscular dystrophy)
myotendinous junction
integrins connect actin filaments of terminal sarcomere and the ECM
motor unit
a single axon, together with all the muscle fibers it innervates
neuromuscular junctions
location of motor end plate, where axon and muscle fibers meet
what triggers depolarization of the sarcolemma?
release of acetylcholine
myasthenia gravis
disease where autoantibodies against acetylcholine receptor result in impaired muscle function
Transverse tubules
invaginations of the membrane that facilitate the propogation of the depolarization of the sarcolemma throughout the muscle fiber
triads
found in skeletal muscle
association of two terminal cisternae of the sarcoplasmic reticulum with a T-tubule
facilitates calcium release from the SR
power stroke
the molecular contraction event, when crossbridge moves toward H zone
(myosin hydrolyzes ATP and goes through a series of conformational changes)
rigor state
when actin and myosin are strongly bound
characteristics of cardiac muscle cells
centrally located single nucleus (uninucleate)
branching
intercellular junctional complexes through intercalated disks
intercalated disks
combination of desmosomes, fascia adherens and gap junctions
dyads
association of the terminal cisternae of the SR and T-tubules of cardiac muscle cells (less elaborate then triads of skeletal muscle)
characteristics of smooth muscle cells
single, often fusiform cells
centrally located nucleus
often connected by gap junctions
no sarcomeres
no calcium-regulated troponin-tropomysin system
what provides structural framework for smooth muscle cells?
intermediate filaments
dense plaques
sites on plasma membrane of smooth muscle cells where actin filaments (interdigitating with myosin) are anchored
smooth muscle cells are activated by
the stimulation of myosin light chains by a myosin light chain kinase (MLCK) that triggers acto-myosin contraction
examples of possible activation of MLCK pathway
calcium-calmodulin pathway or cAMP activation
multiunit type of smooth muscle
under tight control, heavily innervated (such as pupillary muscles)
visceral or unitary type of smooth muscle
less-densely innervated, but has more gap junctions to permit a slow, coordinated contraction of the smooth muscle (as in peristalsis)
type of innervation associated with skeletal muscle
voluntary
type of innervation associated with cardiac muscle
involuntary
type of innervation associated with smooth muscle
involuntary
efferent innervation of skeletal muscle
somatic
efferent innervation of cardiac muscle
autonomic
efferent innervation of smooth muscle
autonomic
regulation of skeletal muscle contraction
binding of Ca2_ to TnC, causes tropomyosin movement and exposes myosin-binding sites on actin filaments
regulation of cardiac muscle contraction
binding of Ca2_ to TnC, causes tropomyosin movement and exposes myosin-binding sites on actin filaments
regulation of smooth muscle contraction
by phosphorylation of myosin light chian by myosin light chain kinase in the presence of Ca2+-calmodulin complex
what types of muscle can undergo mitosis?
only smooth muscle can undergo mitosis under normal conditions
What types of muscle cells can undergo regeneration?
smooth muscle cells
and limited capacity in skeletal muscle sattelite and myogenic cells from bone marrow
What types of muscle have cell-to-cell junctions?
1. The intercalated disks of cardiac muscle have: fascia adherens, macula adherens, and gap junctions
2. Smooth muscle cells are joined via gap junctions (nexus)
morphology of skeletal muscle cell
large, elongate
10-100 micrometers in diameter
up to 100 cm in length
morphology of cardiac muscle cell
short, narrow cell
10-15 micrometers in diameter
80-100 micrometers in length
morphology of smooth muscle cell
short, elongate, fusiform cell
0.2-2 micrometers in diameter
20-200 micrometers in length