Download muscular system

Figure 50.37
Ball-and-socket joint
Head of
humerus
Hinge joint
Pivot joint
Humerus
Scapula
Ulna
Ulna
Radius
Figure 50.26a
Muscle
Bundle of
muscle fibers
Nuclei
Single muscle fiber (cell)
Plasma membrane
Myofibril
Z lines
Sarcomere
Figure 50.26b
Z lines
Sarcomere
Thick
filaments
(myosin)
Thin
filaments
(actin)
TEM
M line
Z line
Sarcomere
0.5 m
Z line
Figure 50.30a
Synaptic
terminal
T tubule
Sarcoplasmic
reticulum (SR)
Myofibril
Plasma
membrane
of muscle fiber
Axon of
motor neuron
Mitochondrion
Sarcomere
Ca2 released
from SR
Figure 50.29
Ca2-binding sites
Tropomyosin
Actin
Troponin complex
(a) Myosin-binding sites blocked
Ca2
Myosinbinding site
(b) Myosin-binding sites exposed
Figure 50.28a-5
1
Thin filament
Myosin head (lowenergy configuration)
ATP
ATP
2
Thick
filament
5
Thin filament moves
toward center of sarcomere.
Actin
ADP
Low-energy
configuration
Pi
Pi
Pi
4
High-energy
configuration
3
ADP
ADP
Myosinbinding sites
Cross-bridge
Figure 50.31
Spinal cord
Motor
unit 1
Motor
unit 2
Synaptic
terminals
Nerve
Motor neuron
cell body
Motor neuron
axon
Muscle
Muscle fibers
Tendon
Figure 50.30b
1
Synaptic terminal of motor neuron
T tubule Plasma membrane
Synaptic cleft
2
Sarcoplasmic
reticulum (SR)
ACh
3
Ca2
Ca2 pump
ATP
6
7
4
CYTOSOL
Ca2
5
Figure 50.32
Tension
Tetanus
Summation of
two twitches
Single
twitch
Action
potential
Time
Pair of
action
potentials
Series of action
potentials at
high frequency