Chapter 38: Protection, Support, Movement: Skin, Skeleton, and
Muscle
Fig. 40-11
Epidermis
Dermis
Hypodermis
Adipose tissue
Blood vessels
Hair
Sweatpore
Muscle
Nerve
Sweatgland
Oil glandHair follicle
Fig. 50-25a
Bundle ofmuscle fibers
Muscle
Single muscle fiber(cell)
Nuclei
Z lines
Plasma membrane
Myofibril
Sarcomere
Fig. 50-25b
TEM
Thickfilaments(myosin)
M line
Z line Z line
Thinfilaments(actin)
Sarcomere
0.5 µm
Fig. 50-26
Z
Relaxedmuscle
M Z
Fully contractedmuscle
Contractingmuscle
Sarcomere0.5 µm
ContractedSarcomere
Fig. 50-30Spinal cord
Motor neuroncell body
Motor neuronaxon
Nerve
Muscle
Muscle fibers
Synaptic terminals
Tendon
Motorunit 1
Motorunit 2
Fig. 50-29
Sarcomere
Ca2+
ATPasepump
Ca2+ released from SR
Synapticterminal
T tubule
Motorneuron axon
Plasma membraneof muscle fiber
Sarcoplasmicreticulum (SR)
Myofibril
Synaptic terminalof motor neuron
Mitochondrion
Synaptic cleft T Tubule Plasma membrane
Ca2+
Ca2+
CYTOSOL
SR
ATP
ADPP i
ACh
Fig. 50-27-4
Thinfilaments
ATP Myosin head (low-energy configuration
Thick filament
Thin filament
Thickfilament
Actin
Myosin head (high-energy configuration
Myosin binding sites
ADPP i
Cross-bridgeADP
P i
Myosin head (low-energy configuration
Thin filament movestoward center of sarcomere.
ATP
ADP P i+
Fig. 50-28
Myosin-binding site
Tropomyosin
(a) Myosin-binding sites blocked
(b) Myosin-binding sites exposed
Ca2+
Ca2+-binding sites
Troponin complexActin
Fig. 50-31
Summation oftwo twitches
Tetanus
Singletwitch
Time
Tens
ion
Pair ofaction
potentials
Actionpotential Series of action
potentials athigh frequency
Fig. 40-5k
Skeletal muscle
Multiplenuclei
Muscle fiber
Sarcomere
100 µm
Fig. 40-5l
Smooth muscle
Nucleus
Musclefibers
25 µm
Fig. 40-5m
Nucleus Intercalateddisk
Cardiac muscle
50 µm