BPK 105 Midterm: Module 3 - Objectives - Part 2
27 Apr 2018
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Module 3 - Objectives - Part 2
● Sketch the neuromuscular junction and describe the function of its
components.
the junction between the branch of an axon and a muscle fiber, formed by a cluster of enlarged
axon terminals resting in indentations of the muscle fiber's cell membrane
Motor neurons are specialized nerve cells that stimulate muscles to contract. Motor neurons
generate action potentials that travel to skeletal muscle fibers. Axons of these neurons enter
muscles and send out branches to several muscle fibers. Each branch forms a junction with a
muscle fiber, called a neuromuscular junction (figure 7.5). Neuromuscular junctions are located
near the center of a muscle fiber.
● Draw a detailed flow chart illustrating the cross-bridge movements involved in
muscle contraction and relaxation.
RELAXATION
1. Ca2+ actively transported back into sarcoplasmic reticulum (needs ATP. active transport)
2. as Ca diffuses away from troponin molecules, tropomyosin covers/blocks attachment sites on
the actin molecules ---> cross bridges cannot reform/cross bridge formation is prevented
3. tension from muscle fibers decreases
Breakdown of ATP and Cross-Bridge Movement During Muscle Contraction
As a new ATP molecule attaches to the head of the myosin molecule, the cross-bridge is
released, the ATP breaks down to ADP and P (which both remain bound to the myosin head),
and the myosin head returns to its original position, where it can attach to the next site. As long
as Ca2+ remains attached to tro- ponin, and as long as ATP remains available, the cycle of
cross- bridge formation, movement, and release repeats (figure 7.9). A new ATP must bind to
myosin before the cross-bridge can be released.
● Describe, and distinguish between, the ways ATP can be derived for the
energy requirements of different intensities of exercise.
aerobic- occurs mostly in mitochondria, requires o2, glucose ----> ATP, co2, h2o
anaerobic- does not require o2, breaks down glucose to form ATP and lactate
This energy comes from either aerobic (with O2) or anaerobic (without O2) ATP production (see
chapter 17).
Generally, ATP is derived from four processes in skeletal muscle:
- Aerobic production of ATP during most exercise and normal conditions
- Anaerobic production of ATP during intensive short-term work
- Conversion of a molecule called creatine phosphate to ATP
Document Summary
Motor neurons are specialized nerve cells that stimulate muscles to contract. Motor neurons generate action potentials that travel to skeletal muscle fibers. Axons of these neurons enter muscles and send out branches to several muscle fibers. Each branch forms a junction with a muscle fiber, called a neuromuscular junction (figure 7. 5). Neuromuscular junctions are located near the center of a muscle fiber. Draw a detailed flow chart illustrating the cross-bridge movements involved in muscle contraction and relaxation. Breakdown of atp and cross-bridge movement during muscle contraction. As long as ca2+ remains attached to tro- ponin, and as long as atp remains available, the cycle of cross- bridge formation, movement, and release repeats (figure 7. 9). A new atp must bind to myosin before the cross-bridge can be released. This energy comes from either aerobic (with o2) or anaerobic (without o2) atp production (see chapter 17). Generally, atp is derived from four processes in skeletal muscle:
