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Muscles Chapter 6
Anatomy
| Question | Answer |
|---|---|
| Contractility | ability of skeletal muscle to shorten with force |
| Excitability | capacity of skeletal muscle to respond to a stimulus |
| Extensibilty | ability to be stretched |
| Elasticity | ability to recoil to their original resting length after they have been stretched |
| Muscles help | Helps produce heat essential for maintenance of normal body temperature |
| Epimysium | connective tissue sheath that surrounds each skeletal muscle directly upon it |
| Fascia | most superficial connective tissue outside the epimysium which surrounds and separates the muscles |
| Fasciculi | numerous visible bundles that compose muscle |
| Perimysium | loose connective tissue which surrounds that fasciculi |
| Four major functional characteristics of muscles | contractility, excitability, extensibility, elasticity |
| Muscle cells | muscle fibers |
| What fasciculi are compose of | muscle fibers (muscle cells) |
| Single cylindrical cell containing several nuclei | each muscle fiber |
| Endomysium | connective tissue sheath that surrounds each muscle fiber |
| Cytoplasm of each fiber is filled with this | myofibrils |
| Myofibril | threadlike structure that extends from one end of the fiber to the other |
| 2 major kinds of myofibrils | actin and myosin myofilaments |
| Actin myofilament | thin myofilaments which resemble 2 pearl strands twisted together |
| Myosin myofilaments | thick myofilaments that resemble bundles of golf clubs |
| Sarcomere | highly ordered unit formed by actin and myosin filaments that join end to end and form a myofibril. Basic structural and functional unity of the muscle that Extends from z line to z line |
| Z line | attachment point for actin |
| I band | light area on each side of a z line that consists of actin |
| A band | darker central region in each sarcomere that extends the length of the mysoin |
| H zone | light center of each sarcomere that consists of only myosin |
| M line | myosin myofilaments are anchored in the center of the sacromere at a dark staining band |
| Resting Membrane Potential | the charge difference across the membrane |
| Positive Charge | outside of most cell membranes |
| Negative Charge | inside of most cell membranes |
| Action Potential | Reversal back of the charge when a muscle cell is stimulated that characteristics change briefly |
| Motor Neurons | nerve cells that carry action potentials to skeletal muscle fibers |
| Where Axons enter | The muscles and branch |
| Neuromuscular Junction (synapse) | what forms near the center of the cell when a branch connects to the muscles |
| Motor Unit | a single motor neuron and all the skeletal muscle fibers it innervates. motor units form a single muscle |
| How a neuromuscular junction is formed | when an enlarged nerve terminal resting in an indentation of the muscle cell membrane |
| Presynaptic terminal | enlarged nerve terminal |
| Synaptic cleft | space between the presynaptic terminal and the muscle cell |
| Postsynaptic terminal | the muscle fiber |
| Acetylcholine | diffuses across the synaptic cleft and binds the postsynaptic terminal causing a change in the postsynaptic cell |
| Synaptic Vessels | within each presynaptic terminal and secrete a neurotransmitter called acetylcholine |
| Acetylcholinesterase | rapid enzymatic breakdown when acetylcholine is released into the synaptic cleft between the neuron and the muscle cell which ensures that one action potential in the neuron yields only one action potential in the skeletal muscle, and only one contraction |
| Muscle contraction | 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. |
| H and I bands during muscle contraction | shorten |
| A bands during muscle contraction | do not change length |
| Threshold | when a muscle fiber will not respond to stimulus |
| all-or-none response | when threshold happens and the muscle fiber contracts maximally |
| 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 | time during which the muscle relaxes |
| Successive twitches | occur when successive stimuli are given so frequently, the muscle doesn't have time to fully relax |
| Tetany | where the muscle remains contracted without relaxing |
| Recruitment | increase in number of moror units being activated |
| ATP | adenosine triphosphate needed for energy for muscle contraction. Produced through mitochondria, short-lived and unstable. |
| ADP | adenosine diphosphate is was ATP degenerates too. more stable |
| Muscle cells constantly produce | ATP |
| Creatine phosphate | ATP can't stockpile, but is stored as this high energy molecule |
| Anaerobic respiration | with out oxygen |
| Aerobic respiration | with oxygen |
| oxygen debt | 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 | when ATP is used during muscle contraction faster than it can be produced in the muscle cells |
| 2 typed of muscle contraction | isometric and isotonic |
| Isometric | equal distance, the length of the muscle does not change, but the amount of tension increases during the contraction process |
| Isotonic | equal tension, the length of the muscle changes but the tension remains constant |
| muscle tone | refers to constant tension produced by muscles of the body for long periods of time. (keep up and back straight) |
| fast-twitch fibers | contract quickly and fatigue quickly. well adapted to perform anaerobic metabolism (white meat of chicken breast) |
| slow-twitch fibers | contract more slowly and are more resistant to fatigue. They are better suited for aerobic metabolism (dark meat of chicken legs) |
| Attachment points for muscle | origin and insertion |
| Origin | most stationary end of a muscle |
| Insertion | end of a muscle undergoing the greatest movement |
| Belly | portion of muscle between the origin and insertion |
| Multiple origins | some muscles have multiple origins or head |
| Synergists | muscles that work together to accomplish specific movements |
| Antagonists | muscles that work in opposition to one another |
| Prime mover | a muscle that plays a major role in a group of synergist |
| Nomenclature | how muscles are named by location, size, orientation of fibers, shape, origin, insertion, and function |
| frontalis | raises eyebrows |
| orbicularis oculi | closes eyes |
| orbicularis oris | moves mouth |
| buccinator | flattens cheeks |
| zygomatic | smiling |
| levator labil superioris | sneering |
| depressor anguli oris | frowning |
| mastication | chewing |
| 4 pairs of chewing muscles | temporalis, masseter, and pterygoid |
| 2 types of tongue muscles | intrinsic and extrinsic |
| Intrinsic tongue muscles | changes shape of tongue |
| extrinsic tongue muscles | moves tongue |
| Soft palate muscles | close the posterior nasal cavity to keep liquid and food from entering it |
| swallowing | constriction of the pharynx and larynx, elevation of the pharynx |
| pharyngeal elevators | elevate pharynx |
| pharyngeal constrictors | constrict pharynx |
| sternocleidomastoid | lateral neck muscle that rotates and abducts the head |
| torticollis | twisted/wry neck |
| sacrolemma | oval nuclei that can be seen beneath the plasma |
| axon | neuron process that carries impluses away from the nerve cell body; the conducting portion of a nerve cell |
| fixators | muscles acting to immobilize a joint or bone; fixes the origin of a muscle so the muscle action can be exerted at the insertion |
| motor unit | motor neuron and all the muscle cells it supplies |
| internal intercostals | inhale |
| external intercostals | forced exhale (sigh) |
| diaphragm | dome shaped muscle that divides thoracic cavity from the abdominal cavity (quiet breathing) |
| Abdominal muscle | keeps guts in |
| lines alba | white line down the middle of the abdomen |
| rectus abdominis | abdominals; external obliques; flexes the vertebral column |
| tendinous inscriptions | white connective tissue that crosses the rectus abdominis to give a segmented look (abs) |
| arrector spinea | on each side of the vertebral column; keep back straight and body erect |
| Face and Neck muscles | temporalis, frontalis, orbicularis oculi, zygomaticus, orbicularis oris, sternocleidomastiod, masseter, platysma |
| arm muscles | deltoid, triceps brachii, biceps brachii, brachialis, brachioradialis, flexor carpi radialis |
| Trunk muscles | pectoralis major, rectus abdominis, external oblique, latissimus dorsi, gluteus medius, gluteus maximus |
| leg muscles | quadriceps, satorius, hamstrings, gastrocnemius, soleus, extensor digitorum longus, calcaneal (achilles) tendon |
Created by:
lucyjw12
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