epimysium
Collagen fibers around entire muscle
muscle fibers contain 100s to 1,000s of
myofibrils
myosin
thick filaments, has a head and tail (head contains ATP = energy)
an electric signal is transferred as the chemical ______ across synaptic cleft
acetylcholine
rigor mortis
sustained contractions following death
muscle fatigue
no longer contract effectively
atrophy
lack of muscle stimulation
perimysium
Separates individual muscle bundles;
collagen and elastin
myofilaments
thick filaments and thin filaments
actin
thin filaments
motor end plate
picks up acetylcholine
motor unit
all of the muscle fibers in a nerve under one control
endurance-related fatigue
glycogen, lipid, and amino acid reserves are gone – no more energy
intercalated discs of cardiac muscles
communication and harmony
endomysium
Relatively loose; separates individual
muscle cells
sarcoplasmic reticulum (SR) stores
calcium ions
titin
elastic protein
• Connects thick filament to Z line
• Helps maintain alignment and max stretch
power stroke
When active site is revealed, snaps into action
muscle tone
resting tension
sprinter fatigue
not enough oxygen, too much lactic acid buildup
sphincters of smooth muscle
at organ openings, control material passage
muscle fiber
do not divide and replace
themselves
• Myosatellite stem cells
myofilaments are arranged in repeating units
sarcomere (A, I bands, Z lines)
the 4 parts of actin
• Nebulin = center anchor
• G-actin = globular, with active site
- Interacts with thick filament
• Tropomyosin = long, covers active site
• Troponin = security guard, keeps tropomyosin in place (the lock)
when contraction stops
SR pulls calcium back in, tropomyosin moves back into place
remember
aerobic respiration and ATP production
roles of blood and liver in latin acid conversion
• Lactic acid can decrease blood pH
• Travels to liver for detoxification – conversion via gluconeogenesis
• New molecules travel back through blood to muscle
• Stored as glycogen
• Pay your oxygen debt!
smooth muscle characteristics
• Not organized into sarcomeres – no striations
• Central nucleus, relatively short
• No T tubules, SR less organized
muscle fiber plasma membrane
sarcolemma
A bands
thick and thin filaments (contraction)
cross-bridge formation
Each head interacts with active site on
G-actin
myosin heads works in unison to pull sarcomere
One end of skeletal muscle is fixed in position (origin), while the other end moves (insertion)
important chemicals in muscle
glucose, mitochondria, glycogen, and oxidative phosphorylation
fast muscle fibers
• Most skeletal muscles, very quick response
• Densely packed myofibrils
• Massive glycogen reserves and few mitochondria
• Fatigue rapidly
• Prolonged activity by glycolysis
muscle fiber cytoplasm
sarcoplasm
I bands
tethering proteins and thin filaments to Z line (the anchor
action potentials
travels through neuron, axon, axon terminal, and to neuromuscular junction
tetanus
causes uncontrolled muscle contractions
resting skeletal muscle uses
fatty acids
slow muscle fibers
• Take longer to contract
• Numerous mitochondria and oxygen reserves in myoglobin
• Dark red color
• Most fibers in humans are intermediate
contraction sent through
transverse tubules (T tubules)
Z lines
the sarcomere
synapse
connection point
how long will a muscle contract?
• Length of neuron stimulation
• How much free calcium is present
• Availability of ATP
contracting muscle uses
glucose
- glycolysis
hypertrophy
exhaustive muscle stimulation