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Ch. 6: Muscles

Muscle Cells Muscle Fibers
Contractility the ability of skeletal muscle to shorten with force
Excitability the capacity of skeletal muscle to respond to a stimulus
Elasticity ability to recoil to their original resting length after they have been stretched
Epimysium connective tissue sheath that surrounds the skeletal muscle
Fascia connective tissue located outside the epimysium
Perimysium loose connective tissue that surrounds muscle fasciculi
Endomysium connective tissue sheath that surrounds each fiber
Myofibrils threadlike structure that extends from one end of the fiber to the other
actin myofilaments thin myofilaments
myosin myofilaments thick myofilaments
Sarcomeres highly ordered units formed by actin and myosin myofilaments
resting membrane potential the charge difference across the membranes
action potential the brief reversal back of the charge
motor neurons nerve cells that carry action potentials to skeletal muscle fibers
motor unit a single motor neuron and all the skeletal muscle fibers it innervates
presynaptic terminal the enlarged nerve terminal
synaptic cleft the space between the presynaptic terminal and the muscle cell
postsynaptic terminal the space between the presynaptic terminal and the muscle fiber
Synaptic vesicles found in each presynaptic terminal
Sliding filament mechanism the sliding of actin myofilaments past myosin myolfilaments during contraction
Muscle twitch a contraction of an entire muscle in response to a stimulus that causes the action potential in one or more muscle fibers
threshold point in which a muscle fiber will contract maximally
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) needed for energy for muscle contraction
Where is ATP produced? mitochondria
creatine phosphate high-energy molecule
anaerobic respiration without oxygen
aerobic respiration 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
isometric length of the muscle does not change, but the amount of tension increases
isotonic the amount of tension is constant, but the length of the muscle changes
Holding a ball isometric
Throwing a ball isotonic
muscle tone constant tension produced by muscles of the body for long periods of time
fast-twitch fibers contract quickly and fatigue quickly
slow-twitch fibers contract more slowly and are more resistant to fatigue
white meat of chicken breast fast-twitch
dark meat of chicken legs slow-twitch
origin most stationary end of the muscle
insertion 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 the muscle that plays the major role in accomplishing the desired movement
How are muscles named? location, size, shape
occipitofrontalis raises the eyebrows
orbicularis oculi closes the eyelids
orbicularis oris puckers the lips
buccinator flattens the cheeks
zygomaticus smiling muscle
levator labii superioris sneering
depressor anguli oris frowning
Kissing muscles Orbicularis oris and Buccinator
mastication chewing
how many pairs of mastication muscles 4
What are the tongue muscles Intrinsic and Extrinsic
Intrinsic changes the shape of the tongue
Extrinsic moves the tongue
Sternocleidomastiod lateral neck muscle and prime mover
Platysma sheetlike muscle that covers the anterolateral neck
Erector spinae group of muscles on each side of the back
Thoracic muscles muscles that move the thorax
Most involved in breathing? External and internal intercostals
External intercostals elevate the ribs during inspiration
Internal intercostals contract during forced expiration
Diaphragm accomplishes quiet breathing
linea alba consist of white connective tissue rather than muscle
rectus abdomis on each side of the linea alba
tendinous inscriptions cross the rectus abdominis at three or more locations
Created by: tscott2203