Chapter 9/ Muscle Physiology Flashcards
Skeletal
cardiac
smooth
muscle tissue
Has myofibrils and sarcomeres
skeletal muscle
Has special structures called transverse tubules
skeletal muscle
-Contain many mitochondria
-Multinucleated
skeletal muscle cell
Sarcolemma
Plasma membrane
Sarcoplasm
Cytoplasm
Sarcoplasmic reticulum
Smooth ER
-Transverse tubules
-sarcoplasmic reticulum
-myofibrils
-cytosol
-plasma membrane
-mitocondria
-terminal cisternae
-opening of transverse tubule to extracellular fluid
structure of a muscle fiber
Give skeletal
muscle striated
appearance
(skeletal muscle )
Myofibrils
Orderly
arrangement of
thick and thin
filaments
(skeletal muscle)
myofibrils-
Composed almost entirely of myosin proteins
Thick filamant
Two large polypeptide chains
Myosin
Two globular heads and two intertwined tails
Myosin
-Globular heads extend out, form cross bridges
– Globular heads contain binding sites for actin and
ATP
Myosin
Primarily composed of actin
(Also, troponin and tropomyosin)
thin filament
-Each G actin subunit has a binding site for myosin
-Form polymers of two intertwined, helical chains.
(thin filament)
actin
– Regulatory protein
– Overlaps binding sites on actin for myosin, inhibits
interaction when muscle fiber is relaxed
(thin filament)
tropomyosin
– Regulatory protein
– Forms complex with actin and tropomyosin
(thin filament)
troponin
– Reversibly binds Ca2+
– When Ca2+ is bound troponin changes
conformation to pull tropomyosin away from the myosin binding sites
(thin filament)
troponin
spring-like protein, prevents overstretching
Titin
Homologous to endoplasmic reticulum
sarcoplasmic reticulum
Stores and releases Ca2+ following membrane
excitation
sarcoplasmic reticulum
deep invaginations of the
sarcolemma
T-tubules
Connected to sarcoplasmic reticulum
T-tubules
One motor neuron +
all skeletal muscle
fibers it innervates
motor units
Muscle fibers are
innervated by only
one
motor neuron
Many motor units
within a whole
muscle organ
Skeletal muscle is under voluntary/unvoluntary control
voluntary
Stimulation by motor neurons is the only
mechanism by which action potentials are
initiated in
skeletal muscle
Axons of motor neurons are myelinated and
are BLANK -diameter axons in the body
diameter
Propagate action potentials at BLANK velocity
high
The axon terminal of a motor neurons release (ACH)
acetylcholine
