Question | Answer |
Muscle Cells | Muscle Fibers |
M -Line | A dark band that anchors the myosin myofilaments in the center of the sarcomere |
H- zone | - Light area in the center of sacomere
- consists of only myosin |
A-band | -extends the length of the myosin
-darker central region in each sarcomere |
I-band | -each side of Z-line
- consists of actin |
The arrangement of actin and myosin give a _______ appearance. | banded |
basic structural and functional unit of the muscle | sarcomeres |
sarcomeres | joined end to end to form the myofibril.
(Z-line to Z-line) |
myosin myofilaments | thick myofilaments |
actin myofilaments | thin myofilaments |
myofilaments consist of 2 major kinds of protein fibers | -actin myofilaments
- myosin myofilaments |
minute | small |
four major functional characteristics | -contractility
-excitability
-extensibility
-elasticity |
contractility | the ability of skeletal muscle to shorten with force |
excitability | the capacity of skeletal muscle to respond to stimulus |
extensibility | the ability to be stretched |
elasticity | the ability to recoil to their original resting length after they have been stretched |
epi | upon |
epimysium | connective tissue that wraps the entire muscle |
fascia | another connective tissue located outside the epimysium. It surrounds and separates muscles. |
fasciculi (fascicle) | bundles of muscle |
perimysium | surrounds the fascicle |
muscle fibers (fibers) | single muscle cell |
endomysium | surrounds muscle fibers |
myofibrils | a thread-like structure that extends from one end of the fiber to the other |
motor unit | a single motor neuron and all skeletal muscle fibers it innervates |
presynaptic terminal | enlarged nerve terminal |
synaptic cleft | the presynaptic terminal and the muscle cell |
postsynaptic terminal | muscle fiber |
synaptic vesicles | secretes neurotransmitter called acetylcholine |
acetylcholine | a neurotransmitter |
acetylcholinesterase | enzymes that rapidly break down neuron and muscle cells |
sliding filament mechanism | the sliding of actin myfilaments past myosin myofilaments during contraction |
muscle twitch | a contraction of an entire muscle in response to a stimulus |
threshold | the point where muscle fibers contract maximally |
all-or-none response | when threshold is reached |
lag phase | time between application of a stimulus to a motor neuron and the beginning of a contraction |
contraction phase | time of contraction |
relaxation phase | the tie during which the muscle relaxes |
tetany | the muscle remains contracted without relaxing |
recruitment | the increase in number of motor units being activated |
ATP | -needed for energy for muscle contraction
-produced in mitochondria
-short-lived and unstable |
creatine phosphate | another high-energy molecule |
anaerobic respiration | without oxygen |
aerobic respiration | with oxygen (more efficient) |
oxygen debt | the amount of oxygen needed in chemical reactions to convert lactic acid to glucose |
muscle fatigue | results when ATP is used during muscle contraction faster than it can be produced in the muscle cells |
2 types of muscle contractions | - isometric
-isotonic |
isometric | the length of the muscle doesn't change, but the amount of tension increases during the contraction process |
isotonic | the amount of tension produced by the muscle is constant during contraction, but the length of the muscle changes |
muscle tone | constant tension produced by the muscle is constant during contraction |
fast-twitch fibers | contract quickly and fatigue quickly |
slow-twitch fibers | contract more slowly and are more resistant to fatigue |
the points of attachment of each muscle are its _____ and ______ | - origin
- insertion |
origin (head) | the most stationary end of the muscle |
insertion | the end of the muscle undergoing the greatest movement |
neuromuscular junction | - each branch that connects to the muscle
- near the center of the cell |
platysma | a sheet-like muscle that covers the anterolateral neck |
sternocleidomastoid | lateral neck muscle and prime mover |
extrinsic tongue muscles | move the tongue |
intrinsic tongue muscle | change of shape of the tongue |
4 pairs of mastication | 2 pairs of pterygoids, temporalis, and masseter |
mastication | chewing |
depressor anguli oris | frowning |
levator labii superioris | sneering |
zygomaticus | smiling muscle |
buccinator | flattens the cheeks |
orbicularis oris | puckers the lip |
orbicularis oculi | closes the eyelids and causes wrinkles to form |
occipitofrontalis | raises the eyebrow |
prime mover | one muscle playsa major role in accomplishing the desired 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 |
muscles are named according to their ____, ____, ____, ____, ____, ____, and ____ | - location
-size
- orientation of fibers
- shape
- origin
- insertion
- function |
motor neurons | nerve cells that carry action potentials to skeletal muscle fibers |
action potential | the brief reversal back of the charge |
resting membrane potential | the charge difference across the membrane |