Chapter 10 Flashcards
Types of muscle tissue
smooth, skeletal, cardiac
Functions of skeletal muscle
Body movement; maintenance of posture; protection and support; regulating elimination of materials, heat production
Characteristics of skeletal muscle tissue
Excitability, conductivity, contractility, extensibility, elasticity
Fascile
contains many muscle fibers
Epimysium
dense irregular connective tissue wrapping whole muscle
Perimysium
dense irregular connective tissue wrapping fascicle; houses many blood vessels and nerves
Endomysium
Areolar connective tissue wrapping individual fiber; delicate layer for electrical insulation, capillary support, binding of neighboring cells
Deep Fascia
Dense irregular CT superficial to epimysium, separates individual muscles; binds muscles with similar functions
Superficial fascia
Areolar and adipose CT superficial to deep fascia; separates muscle from skin
Myoblasts
Embryonic cell that is precursor to muscle cells
Tendon
cordlike structure of dense regular connective tissue
Aponeurosis
thin, flattened sheet of dense irregular tissue
Motor Unit
A motor neuron and all the muscle fibers it controls
I band
Contain only thin filaments; bisected by z disc; get smaller when muscle contracts
A band
contains thick filaments and overlapping thin filaments; contains H zone and M line; Makes up central region of sarcomere
Z disc
Specialized proteins perpendicular to myofilaments; anchors for thin filaments;
H Zone
Central portion of A band; only thick filaments present, disappears with maximal muscle contraction
M line
Middle of H zone; protein meshwork structure; attachment site for thick filaments
Myosin
Protein molecules that make up thick filament
Actin
G-actin has myosin binding site where myosin heads attach
Tropomyosin and Troponin
Regulatory proteins
Neuromuscular Junctions
Location where motor neuron innervates muscle
Synaptic Knob
expanded tip of the motor neuron axon; houses synaptic vesicles; Has Ca2+ pumps in plasma membrane and voltage-gated Ca2+ channels in the membrane
Synaptic Vesicles
Small sacs filled with neurotransmitter acetylcholine (ACh)
Synaptic Cleft
Narrow fluid-filled space that separates synaptic knob from motor end plate
Motor End Plate
Specialized region of sarcolemma with numerous folds; has many ACh receptors
ACh Receptors
Acetycholinesterase
enzyme that breaks down ACh molecules; housed in the synaptic cleft
Voltage Gated Ca2+ Channels
Allow for conduction of electrical signals
Sliding Filament Theory
The mechanism of contraction; actin and myosin filaments overlapping, resulting in the shortening of the muscle fiber length.
Sarcoplasm
Cytoplasm; Has typical organelles plus contractile proteins and other specializations
Sarcolemma
Plasma membrane; has t-tubules that extend deep into the cell; sarcolemma and t-tubules have voltage-gated ion channels and voltage-sensitive calcium chanels
T-Tubules
Transverse tubules that extend deep into the cell
Sarcoplasmic Reticulum
Binding and sequestering calcium; contains calcium pumps and calcium release channels;
Myofilaments
Contractile proteins within myofibrils
Myofibrils
Contractile unit; bundles of myofilaments enclosed in sarcoplasmic reticulum
Terminal Cisternae
Adjacent to T-tubules
