Chapter 38: Protection, Support, Movement: Skin, Skeleton, and Muscle

Fig Epidermis Dermis Hypodermis Adipose tissue Blood vessels Hair Sweat pore Muscle Nerve Sweat gland Oil gland Hair follicle

Fig a Bundle of muscle fibers Muscle Single muscle fiber (cell) Nuclei Z lines Plasma membrane Myofibril Sarcomere

Fig b TEM Thick filaments (myosin) M line Z line Thin filaments (actin) Sarcomere 0.5 µm

Fig Z Relaxed muscle M Z Fully contracted muscle Contracting muscle Sarcomere 0.5 µm Contracted Sarcomere

Fig Spinal cord Motor neuron cell body Motor neuron axon Nerve Muscle Muscle fibers Synaptic terminals Tendon Motor unit 1 Motor unit 2

Fig Sarcomere Ca 2+ ATPase pump Ca 2+ released from SR Synaptic terminal T tubule Motor neuron axon Plasma membrane of muscle fiber Sarcoplasmic reticulum (SR) Myofibril Synaptic terminal of motor neuron Mitochondrion Synaptic cleft T Tubule Plasma membrane Ca 2+ CYTOSOL SR ATP ADP P i ACh

Fig Thin filaments ATP Myosin head (low- energy configuration Thick filament Thin filament Thick filament Actin Myosin head (high- energy configuration Myosin binding sites ADP P i Cross-bridge ADP P i Myosin head (low- energy configuration Thin filament moves toward center of sarcomere. ATP ADP P i +

Fig Myosin- binding site Tropomyosin (a) Myosin-binding sites blocked (b) Myosin-binding sites exposed Ca 2+ Ca 2+ -binding sites Troponin complex Actin

Fig Summation of two twitches Tetanus Single twitch Time Tension Pair of action potentials Action potential Series of action potentials at high frequency

Fig. 40-5k Skeletal muscle Multiple nuclei Muscle fiber Sarcomere 100 µm

Fig. 40-5l Smooth muscle Nucleus Muscle fibers 25 µm

Fig. 40-5m NucleusIntercalated disk Cardiac muscle 50 µm