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Chapter 6 Anatomy
muscles
Question | Answer |
---|---|
Contractility | the ability of the 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 |
each muscle is surrounded by a connective tissue sheath called what | the epimysium |
another connective tissue located outside the epimysium that surround and separates muscles | facsia |
a muscle is composed of of numerous visible bundles called what | muscle fasciculi |
Muscle fasciculi are surrounded by loose connective tissue called | the perimysium |
the fasciculi are composed of single muscle cells called | fibers |
T or F? Each muscle fiber is a single cylindrical cell containing several nuclei. | True |
each fiber is surrounded by a connective tissue sheath called the | endomysium |
the cytoplasm of each fiber is filled with | myofibrils |
define myofibrils | a thread like structure that extends from one end of the fiber to the other. |
Myofibrils consist of two major kinds of protein fibers which are | actin and myosin microfilaments |
define actin microfilaments | thin myofilaments |
define myosin microfilaments | thick myofilaments |
actin and myosin myofilaments form highly ordered units called | sarcomeres |
sarcomeres are joined end to end to form the | myofibril |
basic structural and functional unit of the muscle | sarcomeres |
the H zone consists only of | myosin |
The charge difference across the membrane is called the | resting membrane potential |
the brief reversal back of the charge is called | action potential |
nerve cells that carry action potentials to skeletal muscle fibers | motor nuerons |
each branch that connects to the muscle forms a ______ near the center of the cell | neuromuscular junction, or synapse |
a single motor neuron and all the skeletal muscle fibers it innervates are called a | motor unit |
many motor units form | a single muscle |
formed by an enlarged nerve terminal resting in an indentation of the muscle cell membrane | a neuromuscular junction |
the enlarged nerve terminal is the | presynaptic terminal |
the space between the presynaptic terminal and the muscle cell is the | synaptic cleft |
the muscle fiber is the | postsynaptic terminal |
each presynaptic terminal contains | synaptic vesicles |
synaptic vesicles secrete a neurotransmitter called | acetylcholine |
diffuses across the synaptic cleft and binds to the postsynaptic terminal causing a change in the postsynaptic cell | acetylcholine |
acetylcholine releases into the cynaptic cleft between the neuron and muscle cell is rapidly broken down by | acetylcholineesterase |
the sliding of actin myofilaments past myosin myofilaments during contaction is called the | sliding filament mechanism of muscle contraction |
a contraction of an entire muscle in response to a stimulus the causes the action potential in one or more muscle fibers | muscle twitch |
point at which the muscle fiber will contract maximilly | threshold |
time between application of a stimulus to a motor neuron and the beginning of a contraction is the | lag phase |
the time of contraction is the | contraction phase |
the time during the muscle relaxes is called the | relaxation phase |
the muscle remains contracted without relaxing | tetany |
the increase in number of motor units being activated is called | recruitment |
ATP | adenosine triphosphate |
atp is needed for | energy for muscle contaction |
atp is produced in | the mitochondria |
anaerobic respiration | without oxygen |
aerobic | with oxygen |
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 |
2 types of muscle contraction | isometric and isotonic |
muscle refers to | constant tension produced by muscles of the body for long periods of time |
contract quickly and fatigues quickly | fast-twitch fibers |
contract more slowly and are more resistant to fatigue | slow-twitch fibers |
the most stationary end of the muscle | origin (head) |
the end of a muscle undergoing the greatest movement | insertion |
portion of the muscle between the origin and the insertion | the belly |
synergists | muscles that work together to accomplish specific movements |
muscles that work in opposition to one another are called | antogonists |
occipitofrontalis | raises the eyebrows |
orbicularis oculi | closes the eyelids and causes "crow's feet" |
orbicularis oris | puckers the lips |
buccinator | flattens the cheeks |
zygomaticus | smiling muscle |
levator labii superioris | sneering |
depressor anguli oris | frowning |
mastication means | 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 |
flexor carpi | flexes the wrist |
extensor carpi | extends the wrist |
flexor digitorium | flexes the fingers |
extensor digitorium | extends the fingers |