HUMAN SYSTEMS QUESTION 1986: L. PETERSON/AP BIOLOGY
Beginning at the presynaptic membrane of the neuromuscular junction, describe
the physical and biochemical events involved in the contraction of a skeletal
muscle fiber. Include the structure of the fiber in your discussion.
STANDARDS:
Presynaptic (must be a motor neuron)
1 - Nature of impulse +++
---
1 - Increase of permeability of Ca 2+
1 - Movement of vesicles
1 - Fusion of vesicles with membrane
1 - Transmitter release
1 - Acetylcholine
1 - Diffusion of transmitter (20 nm)
1 - Cholinesterase
1 - Motor end plate or terminal bouton
Postsynaptic (muscle be a muscle fiber)
A. Transmitter Effects
1 - Specific receptor sites
1 - Causes depolarization/action potential
1 - Action potential sweeps fiber membrane/T. tubules
1 - Release of Ca 2+ from Sarcoplasmic reticulum (T. cisternae)
B. Calcium Effects
1 - Calcium floods sarcomere
1 - Calcium binds to troponin
1 - Bound troponin displaces tropomyosin
1 - Calcium returned by active transport (Ca2+ pump)
C. Actinomyosin Complex
1 - Binding sites actin exposed by tropomyosin displacement
1 - Myosin cross bridges bind actin
1 - ATP used
1 - Power stroke, recovery flip
1 - ATP needed to separate actin-myosin
1 - Rigor Mortis
D. Other
1 - Sliding Filament Theory
1 - Diagram/explanation contracted muscle
1 - Muscle twitch, tetany, fatigue
1 - Lactic acid, O2 debt
1 - Creatine phosphate--ATP
Muscle Fiber Structure
1 - Definition
1 - Characteristics
2 - Striations, banding multi-nucleated, many mitochondria
1 - Myofibrils (as sub-units)
1 - Sarcomere (as unit of myofibril)
1 - Sarcoplasmic reticulum (cell membrane, etc.) (terminal cisternae)
1 - T. tubules (cell membrane connection, etc.)
1 - Banding Pattern (explain or diagram)
1 - Actin/myosin (protein or thin, thick, etc.)
1 - Actin a globular protein
1 - Myosin a linear protein w/cross bridges
1 - Troponin/tropomyosin associated with actin