Advanced A&P: Unit 2c study guide - Neuromuscular Physiology

tendons

skeletal muscles connect to bones by ______

skeletal muscle fiber

single muscle cell

multinucleated

forms from many undifferentiated cells that fuse during development

sacrolemma

muscle cell membrane

sarcoplasm

muscle cell cytoplasm; contains many small, oval nuclei, mitochondrion, and abundant, long parallel structures (myofibrils), sarcoplasmic reticulum

myofibrils

any of the threadlike bundles a filaments in striated muscle cells; play a fundamental role in muscle contraction; composed of thick and thin filaments

myosin

thick filaments

thin filaments

actin and troponin-tropomyosin complex

sarcomere

functional unit of muscle contraction; units that shorten

sarcoplasmic reticulum

specialized endo. reticulum for calcium storage and release

transverse tubules

sarcolemma divides in towards the interior of the fiber

neuromuscular junction

synapse where a motor neuron axon and a skeletal muscle fiber meet

motor end plate

specialized part of a muscle fiber membrane @ a neuromuscular junction; rich in nicotinic receptors

neuromuscular junction steps

1. impulse reaches the axon terminal of the lower motor neuron

2. this causes calcium ion channels to open and calcium diffuses into axon terminal

3. calcium stimulates exocytosis of vesicles containing ACh

4. ACh diffuses across synaptic cleft & binds to nicotinic receptors on motor end plate of a muscle fiber

5. provided a threshold is reached, a muscle impulse is generated

motor unit

motor neuron and all the muscle fibers it innervates