Muscles Terms Word Scramble
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Question | Answer |
contractility | the ability of skeletal muscle to shorten with force. |
excitability | the capacity of skeletal muscle to respond to a stimulus. |
extensibility | the ability to be stretched. |
elasticity | ability to recoil to their original resting length after they have been stretched. |
epimysium | connective tissue sheath surrounding skeletal muscle. |
fascia | connective tissue located outside the epimysium. It surrounds and separates muscles. |
perimysium | Surrounds muscle fascicles. |
fascicles | bundles of muscle tissue. |
endomysium | surrounds each muscle fiber (cell). |
muscle cells | muscle fibers |
myofibrils | a threadlike structure that extends from one end of the fiber to the other. |
actin myofilaments | thin myofilaments. They resemble 2 minute strands of pearls twisted together. |
myosin myofilaments | thick myofilaments. They resemble bundles of minute golf clubs. |
sarcomeres | units formed by Actin and myosin myofilaments which are joined end to end to form the myofibril. basic structural and functional unit of the muscle. |
Z line | borders of sarcomeres. attachment site for actin. |
cause of banded appearance of muscles | arrangement of actin and myosin |
I band | On each side of the Z line is a light area, [term]. Consists of actin. |
A band | extends the length of the myosin. It is the darker central region in each sarcomere. |
H zone | In the center of each sarcomere is another light area called the [term], which consists of only myosin. |
M line | The myosin myofilaments are anchored in the center of the sarcomere at a dark staining band called the [term]. |
resting membrane potential | The outside of most cell membranes is positively charged compared to the inside of the cell membrane, which is negatively charged. The charge difference across the membrane is called the [term]. |
action potential | When a muscle cell is stimulated the membrane characteristics change briefly. The brief reversal back of the charge is called [term]. |
motor neurons | nerve cells that carry action potentials to skeletal muscle fibers. |
synapse | neuromusclular junction |
neuromusclular junction | Axons enter the muscles and branch. Each branch that connects to the muscle forms a [term]. formed by an enlarged nerve terminal resting in an indentation of the muscle cell membrane. |
motor unit | single motor neuron and all the skeletal muscle fibers it innervates. |
presynaptic terminal | enlarged nerve terminal. |
synaptic cleft | space between the presynaptic terminal and the muscle cell. |
postsynaptic terminal | the receiving part of the connection (synapse) between two nerve cells (neurons). muscle fiber. |
synaptic vesicles | vesicles that secrete a neurotransmitter called acetylcholine |
acetylcholine | neurotransmitter which causes muscle contraction. |
acetylcholinesterase | enzyme that breaks down acetylcholine. |
Muscle Contraction | Occurs as actin and myosin myofilaments slide past one another causing the sarcomeres to shorten. When the sarcomeres shorten it causes the muscle to shorten. |
sliding filament mechanism | The sliding of actin myofilaments past myosin myofilaments during contraction. The H and I bands shorten, but the A bands do not change in length. |
threshold | point at which stimulus becomes strong enough for muscle to respond by contracting maximally. This phenomenon is called the all-or-none response. |
lag phase | The time between application of a stimulus to a motor neuron and the beginning of a contraction. |
contraction phase | The time of contraction. |
relaxation phase | The time during which the muscle relaxes |
Tetany | where the muscle remains contracted without relaxing. |
recruitment | The increase in number of motor units being activated. |
ATP | (adenosine triphosphate) is needed for energy for muscle contraction. |
mitochondria | produces atp |
ADP | (adenosine diphosphate) plus phosphate. what atp degenerates into. |
creatine phosphate | more stable high energy molecule stored in muscles. |
oxygen debt | The amount of oxygen needed in chemical reactions to convert lactic acid to glucose and to replenish the depleted stores of creatine phosphate stores in muscle cells. |
Muscle fatigue | results when ATP is used during muscle contraction faster than it can be produced in the muscle cells. |
isometric | (equal distance) – the length of the muscle does not change, but the amount of tension increases during the contraction process. |
isotonic | (equal tension), the amount of tension produced by the muscle is constant during contraction, but the length of the muscle changes. |
Muscle tone | Muscle tone refers to constant tension produced by muscles of the body for long periods of time. Keeps head up and back straight. |
Fast-twitch fibers | contract quickly and fatigue quickly. Well adapted to perform anaerobic metabolism. Ex. white meat of a chicken’s breast. |
Slow-twitch fibers | contract more slowly and are more resistant to fatigue. They are better suited for aerobic metabolism. Ex. dark meat of a duck’s breast or the legs of a chicken). |
origin | (head) is the most stationary end of the muscle. |
insertion | the end of the muscle undergoing the greatest movement. |
belly | The portion of the muscle between the origin and the insertion. |
synergists | Muscles that work together to accomplish specific movements. |
antagonists | Muscles that work in opposition to one another. |
prime mover | Among a group of synergists, if one muscle plays the major role in accomplishing the desired movement. |
Occipitofrontalis | raises the eyebrows. |
Orbicularis oculi | closes the eyelids and causes “crows feet” wrinkles in the skin at the lateral corners of the eye. |
Orbicularis oris | puckers the lips. |
Buccinator | flattens the cheeks. Trumpeter’s muscle. Orbicularis oris and buccinator are the kissing muscles. |
Zygomaticus | smiling muscle. |
Levator labii superioris | sneering |
Depressor anguli oris | frowning |
Mastication | chewing |
4 pairs of mastication muscles | 2 pair of pterygoids, temporalis, and masseter. |
Intrinsic Tongue Muscles | change the shape of the tongue. |
Extrinsic Tongue Muscles | move the tongue. |
Sternocleidomastoid | lateral neck muscle and prime mover. Rotates and abducts the head |
Erector spinae | group of muscles on each side of the back. Responsible for keeping the back straight and the body erect. |
Thoracic Muscles | muscles that move the thorax |
External intercostals | elevate the ribs during inspiration |
Internal intercostals | contract during forced expiration. |
Diaphragm | accomplishes quiet breathing. Dome-shaped muscle. Aids in breathing. |
Trapezius | rotates scapula |
Serratus anterior | pulls scapula anteriorly |
Created by:
onjarre
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