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Ch.6 Muscles

QuestionAnswer
Muscle Fibers Muscle cells
Excitability the capacity of skeletal muscle to respond to a stimulus.
.Epimysium connective tissue surrounding the skeletal muscle
Myofibrils a threadlike structure that extends from one end of the fiber to the other
Actin myofilaments thin myofilaments
Myosin myofilaments thick myofilaments
Sarcomeres the basic structural and functional unit of the muscle.
Contractility the ability of skeletal muscle to shorten with force
Extensibility The ability to be stretched
Elasticity Ability to recoil to their original resting length after they have been stretched
Fascia another connective tissue located outside the epimysium
Muscle Fasciculi A muscle is composed of numerous visible bundles
Where do each sarcomere extend to? Each Z line disc
What shade is the I band? Light
What is the Z line an attachment for? Site for Actin
Where does the A band extend to? The length of the myosin
What shade is the A Band? Dark
What light area is in the center of the sarcomere? The H zone
What does the H zone contain? Only myosin
What anchors the myosin myofilaments? The M line
What shade is the M line? Dark
The charge of the outside cell membrane Positive
The charge of the inside of the cell membrane Negative
The charge difference across the membrane resting membrane potential
When muscles change back after being stimulated Action potential
Motor Neurons Nerve cells that carry action potentials to skeletal muscle fibers
Where do axons enter? The muscles and branch
Each connecting branch forms a ______ Synapse
Motor unit A single motor neuron and all the skeletal muscle fibers it innervates
How is a neuromuscular junction formed? An enlarged nerve terminal resting in an indentation
What is the enlarged nerve terminal Presynaptic terminal
presynaptic terminal the space between the presynaptic terminal nd the muscle cell
Synaptic vesicles Secrete acetylcholine
When an action potential reaches the nerve terminal ____ it causes the synaptic vesicles to releases acetylcholine into the synaptic cleft by exocytosis
The combination of acetylcholine with its receptor causes ____ an influx of sodium ions into the muscle fiber
What does that influx cause? an action potential in the muscle cell, which causes it to contract
Acetylcholinesterase acetylcholine released into the synaptic cleft between the neuron and muscle cell is rapidly broken down by an enzymes
How does muscle contraction occur? Occurs as actin and myosin myofilaments slide past one another causing the sarcomeres to shorten
Sliding filament mechanism The sliding of actin myofilaments past myosin myofilaments during contraction
What happens in the sliding filament mechanism? The H and I bands shorten, but the A bands do not change in length
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, at which point the muscle fiber will contract maximally
What is this phenomenon called? 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
adenosine triphosphate is needed for energy for muscle contraction.
Where is ATP produced? The mitochondria
What does anaerobic respiration mean? Without oxygen
What does aerobic respiration? With oxygen more efficient
Creatine phosphate .When at rest they can’t stockpile ATP but they can store another high-energy molecule
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 the result of ATP being used during muscle contraction faster than it can be produced in the muscle cells
Isometric the length of the muscle does not 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 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
Example of Fast twitch fibers White meat of a chicken breast
Example of a Slow-twitch fibers Dark meat of ducks breast or chicken leg
Origin 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 if one muscle plays the major role in accomplishing the desired movement
What are some ways muscles are described? Their location, size, orientation of fibers, shape, origin, insertion, and function
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 pucker the lips
Buccinator flattens the cheeck
Orbicularis oris and buccinator Kissing muscles
Zygomaticus smiling muscle
Levator labii superioris Sneering
Depressor anguli oris Frowning
Mastication chewing
Pairs of mastication muscles 2 pair of pterygoids, temporalis, and masseter
Intrinsic Tongue Muscles change shape of tongue
Extrinsic Tongue Muscles move 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 ribs during inspiration
Internal intercostals contract during forced expiration
diaphragm accomplishes quiet breathing.
What is it in the shape? The shape of a dome
Serratus anterior pulls scapula anteriorly
Deltoid attaches the humerus to the scapula and clavicle, and is the major abductor of the upper limb
Brachioradialis flexes and supinates the forearm
Retinaculum strong band of fibrous connective tissue that covers the flexor and extensor tendons and holds them in place around the wrist so that they do not “bowstring” during muscle contraction.
Quadriceps femoris extends the leg; anterior thigh muscles
Gastrocnemius and soleus form the calf muscle. They join to form the calcaneal tendon
intrinsic foot muscles 20 muscles located within the foot
Peroneus The lateral muscles of the leg,
Created by: kailleim