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Ch.6 Muscles
| Question | Answer |
|---|---|
| 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
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