69 terms

Unit 06 Muscles and Muscle Tissue

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perimysium
Connective tissue enveloping bundles of muscle fibers (fascicles)
neurotransmitter
Chemical released by neurons that may, upon binding to receptors of effector cells, stimulate or inhibit them
smooth muscle
Spindle shaped cells with one centrally located nucleus and no externally visible striations (bands). Found mainly in the walls of hollow organs.
skeletal muscle
Muscle composed of cylindrical multinucleate cells with obvious striations; the muscle(s) attached to the body's skeleton; voluntary muscle
acetylcholine
Chemical transmitter substance released by some nerve endings at neuromuscular junction; ACh
myofibril
Rodlike bundle of contractile filaments (myofilaments) found in muscle cells; organelle
myosin
One of the principal contractile proteins found in muscle; makes up the thick filament.
neuromuscular junction
Region where a motor neuron comes into close contact with a skeletal muscle cell
epimysium
Sheath of fibrous connective tissue surrounding a muscle
synapse
Functional junction or point of close contact between two neurons or between a neuron and an effector cell like a muscle
motor unit
A motor neuron and all the muscle cells (fibers) it stimulates
lactic acid
Product of anaerobic metabolism, especially in muscle; pyruvic acid is converted to this when insufficient oxygen is present within skeletal muscle fibers.
muscle fiber
A muscle cell
fascicle
Bundle of muscle fibers bound together by connective tissues
sarcomere
The smallest contractile unit of muscle; extends from one Z disc to the next
endomysium
Thin connective tissue surrounding each muscle cell; areolar connective tissue
twitch
The response of a muscle to a single brief threshold stimulus
actin
A contractile protein of muscle; make up part of the thin filament.
sarcoplasmic reticulum
The smooth ER of a muscle cell, enlarged and specialized to act as a Ca2+ reservoir. The SR winds around each myofibril in the muscle cell.
creatine phosphate
An energy storage molecule used by muscle tissue. The phosphate from this molecules can be removed and attached to an ADP to generate ATP quickly.
troponin
protein to which calcium binds to shift tropomyosin; regulatory protein
myoglobin
oxygen-storing, pigmented protein in muscle cells
acetylcholinesterase
enzyme that catalyzes breakdown of acetylcholine, preventing sustained muscle contraction from a single nerve impulse; AchE
sarcolemma
Plasma membrane of a muscle fiber
myofilament
contractile proteins, actin and myosin, of muscle cells. Also called microfilament
synaptic cleft
Space between axon terminal and muscle fiber
aerobic respiration
(with oxygen) glucose is completely oxidized to carbon dioxide and water the total oxidation allows for the maximum amount of energy (ATP) to be produced
oxygen debt
The amount of oxygen required after physical exercise to convert accumulated lactic acid to glucose (or glycogen)
tetany
Sustained contraction (tetanus); the summation of increasing neural stimulation of a muscle by the motor neuron
all or none response
When a muscle fiber contracts, it contracts completely
rigor mortis
A fixed muscular contraction after death; attributed to a lack of ATP to release attached actin and myosin molecules
b
the A band
a
the Z disc
c
the I band
d
the M line
e
myofibril made up of myofilaments (actin and myosin)
f
the H zone
g
one sarcomere - Z disc to Z disc
a
the epimysium
b
the perimysium
c
a fascicle (bundle of muscle fibers)
d
a muscle fiber (cell)
e
the endomysium surrounding a muscle fiber
f
a tendon - continuous with the epimysium
a, b, and f
membranes made of dense fibrous connective tissue
tropomyosin
covers myosin binding sites along the thin filament (actin), preventing actin and myosin from interacting; regulatory protein
acetylcholine (ACh)
most widely used neurotransmitter; used in brain and all neuromuscular junctions
action potential
neural impulse; a brief electrical charge that travels down an axon
axon terminals
branches at the end of the axon
creatine phosphate (CP)
phosphorylates ADP to form ATP in skeletal muscle cells
dark (A) bands
contains thick and thin filament; H zone in center; accounts for the striations in some muscle tissues
involuntary muscles
muscles that are not under conscious control
light (I) bands
thin filaments only; Z-disc runs down center; accounts for the striations in some muscle tissues
muscle fatigue
inability of muscle to maintain its strength of contraction or tension; may be related to insufficient oxygen, depletion of glycogen, and/or lactic acid buildup
muscle fibers
long slender cells that make up muscles; smooth muscle and skeletal muscle cells are also known as these
myofibrils
microscopic, fiber-like organelles that occupy most of the sarcoplasm in skeletal muscle cells; made up of sarcomeres stacked end to end
myofilaments
contractile proteins, actin and myosin, of muscle cells
neuromuscular junctions
the junction between a neuron and a muscle cell
sarcomeres
basic functional unit of myofibril, extends between two Z discs.
sarcoplasmic reticulum (SR)
organelle of the muscle fiber that stores calcium; specialized smooth ER
sliding filament mechanism
explanation of how thick and thin filaments slide relative to one another during striated muscle contraction to decrease sarcomere length
striated muscle
muscle that appears banded due to the arrangement of actin and myosin (myofilaments)
thick filaments
myosin
thin filaments
actin
glycolysis
anaerobic metabolic pathway in skeletal muscles that results in the production of two net ATPs per glucose; produces two pryruvic acid molecules
unitary (visceral) smooth muscle
smooth muscle found in the walls of hollow organs; most common type of smooth muscle
curare
a neurotoxin that causes paralysis by blocking acetylcholine receptors in muscle
somatic motor neurons
neurons that stimulate skeletal muscle to contract
autonomic motor neurons
neurons that control smooth muscles, cardiac muscles, and glands
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