Question | Answer |
Contractility | The ability of skeletal muscles to shorten with force. |
Excitability | The capacity of skeletal muscles to respond to a stimulus. |
Extensibility | The ability to be stretched. |
Elasticity | The ability to recoil to their original resting length after they have been stretched. |
What do muscles do? | They help produce heat essential for maintenance of normal body temperature. |
Epimysium | Skeletal muscle that is surrounded by a connective tissue sheath. |
Fascia | Another connective tissue located outside the epimysium. |
Perimysium | Loose connective tissue. |
Endomysium | Fiber that is surround by connective tissue. |
myofibrils | A threadlike structure that extends from one end of the fiber to the other. |
What are the two major types of protein fibers? | Actin and myosin myofilaments |
Actin Myofilaments | They are thin myofilaments: they resemble two minute strands of pearls twisted together. |
Myosin Myofilaments | They are thick myofilaments: they resemble bundles of minute golf clubs. |
Sacrcomeres | Highly ordered units that are joined end to end to form the myofibrils |
Resting membrane potential | The change difference across the membrane. |
Action potential | The brief reversal back of the charge |
Motor Neurons | They are nerve cells that carry action potentials to skeletal muscle fibers. |
Neuromuscular junction | Axons that enter the muscles and branch. Each branch that connects to the muscle. |
Synapse | Near the center of the cell. |
Motor unit | A single motor neuron and all the skeletal muscle fibers its innervates. |
Presynaptic terminal | The enlarged nerve terminal. |
Synaptic cleft | The space between the presynaptic terminal and the muscle cell. |
Postsynaptic terminal | Muscle fiber is a. |
Synaptic vesicles | Presynaptic terminal. |
Acetylcholine | Secrete neurotransmitter. |
Acetylcholinesterase | The acetylcholine released into the synaptic cleft between the neuron and muscle cell that is rapidly broken down by an enzymes. |
Sliding filament mechanism | The sliding of actin myofilaments past myosin myofilaments during contraction. |
Muscle twitch | Is a contraction of an entire muscle in response to a stimulus that causes the action potential in one or more muscle fibers. |
Threshold | A muscle fiber will not respond to stimulus until that stimulus reaches a level. |
All-or-none-response | This phenomenon is called. |
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. |
Creatine phosphate | When at rest they can't stockpile ATP but they can store another 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 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: holding a ball |
Isotonic | Equal tension: throwing a ball |
Muscle tone | Muscle tone refers to 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. |
Origin | Head: is the most stationary end of the muscles. |
Insertion | Is then end of the muscle undergoing the greatest movement. |
Belly | The portion of the muscle between the orgin and intersection. |
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. |
How are muscles classified? | their location, size, orientation of fibers, shape, origin, insertion, and function. |
Occipitofrontalis | Raises eyebrows |
Orbicularis Oculi | Closes eyelid: crow's feet |
Orbicularis Oris | Puckers the lips |
Buccinator | Flattens the cheeks: trumpeter's muscles |
Zygomaticus | Smiling |
Levator Labili Superioris | Sneering |
Depressor Anguli Oris | Frowing |
Mastication | Chewing: Masseter(1 Pairs), Temporalis(1 Pairs) |
What are the kissing muscles? | Orbicularis Oris and Buccinator |
Extrinstic Muscle | Moves the tongue |
Intrinstic Muscle | Changes the shape of the tongue |
Sternocleidomastoid | Prime mover lateral neck muscles. Rotates and abducts the head. |
Where does the A Band extend to? | The length of the myosin. |
What does the H Zone consist of? | Only myosin. |
When does the muscle contract? | It occurs as the actin and myosin myofilaments slide past one another causing the sarcomeres the shorten. |
Skeletal Muscles | Voluntary |
Cardiac Muscles | Involuntary |
Smooth Muscles | Involuntary |
What are the functions of muscles? | Producing movement, maintaining posture, stabilizing joints, and generating heat. |
Where do muscles attach? | At it's origin and insertion. |
Some muscles have multiple origins or head? | True |
Where is a neuromusclular junction formed at? | An enlarged nerve terminal resting in an indention of the muscle cell membrane. |
Platysma | Creates a downward sag of the mouth. |
Pectoralis Major | Adducts and flexes the arm. |
Rectus Abdominis | Flexes vertebral column |
External Oblique | Flexes and rotates vertebral column. |