1. The Cooperation of Muscles and Skeletons in Movement – antagonistic movements occur

2. The Structure of Skeletal Muscle

3. Thick Filaments: Thin Filaments: Myosin Actin
Skeletal Muscle
Thick Filaments: Thin Filaments:
Myosin Actin
Nuclei
Striations

4. Other Vertebrate Muscles
Smooth Muscle :
Lacks striations
Has less myosin than skeletal muscle
Found in walls of hollow organs (e.g. digestive tract organs)
Cardiac Muscle:
Structurally similar to skeletal muscle
Differs in action potential generation:
Action potentials spread throughout the heart through direct contact between cells

5. The Sliding-Filament Model of Muscle Contraction
length
of the
filaments
stays
the same
as the
muscle
fiber contracts.

6. Myosin head is bound to ATP Binding a new molecule
One Hypothesis for How Myosin-Actin Interactions Generate the Force for Muscle Contraction
Myosin head is bound to ATP
Binding a new molecule
of ATP releases myosin
from actin
ATP -> ADP + P
Releases ADP + P and
returns to low-energy configuration

7. Mechanism for the control of muscle contraction
Regulatory protein
that controls the
position of tropomyosin
Regulatory protein that blocks myosin
binding sites
Ca ions bind to the
troponin complex, which controls the position of tropomyosin.

8. The roles of the muscle fiber’s sarcoplasmic reticulum and T (Transverse) tubules in contraction
Acetylcholine
released
infoldings of
the plasma
membrane
a specialized ER

9. Review of skeletal muscle contraction

10. Each muscle fiber has a single synapse with one motor neuron, but each motor neuron typically synapses with several or many muscle fibers.

11. Motor Units in a Vertebrate Muscle
Skeletal
Muscle Fiber
Axon
Branch
Axon Terminal