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Muscles
Anatomy Chapter 6
| Question | Answer |
|---|---|
| Contractility | the ability of skeletal muscle to shorten with force |
| Excitability | the capacity of skeletal muscle 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 |
| actin myofilaments | -thin myofilaments -they resemble 2 minutes strands of pearls twisted together |
| myosin myofilaments | -thick myofilaments -they resemble bundles of minutes golf clubs |
| What is the cytoplasm of each fiber filled with> | -myofibrils |
| What is the fasciculi composed of? | -a single muscle cell called fibers |
| Four major characteristics | -contractility -excitability -extensibility -elasticity |
| myofibrils | -a threadlike structure that extends from one end of the fiber to the other |
| What is each fiber surrounded by? | -endomysium -connective tissue sheath |
| 2 kinds of myofibrils | -Actin Myofilaments -Myosin Myofilaments |
| What is the skeletal muscle surrounded by? | -epimysium -connective tissue sheath |
| Fascia | -is another connective tissue located outside the epimysium -surrounds and separates muscles |
| Sarcomeres | -actin and myosin myofilaments -highly ordered units -joined end to end to form the myofibril -basic structural and functional unit of the muscle |
| Motor Neurons | -are nerve cells that carry action potentials to skeletal muscle fibers |
| 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 |
| Presynaptic terminal | -enlarged nerve terminal |
| synaptic clef | -the space between the presynaptic terminal and the muscle cell |
| Postsynaptic terminal | -the muscle fiber |
| Tetany | -where the muscle remains contracted without relaxing |
| Recruitment | -increase in number of motor units being activated |
| Anaerobic respiration | -without oxygen |
| Aerobic respiration | -with oxygen (more efficient) |
| Muscle fatigue | -results when ATP is used during muscle contract faster than it can be produced in the muscle cells |
| 2 types of muscle contractions | -isometric -isotonic |
| Isometric | -equal distance -the length of the muscle does not change -the amount of tension increases |
| isotonic | -equal tension -the amount of tension produced by the muscle is constant during contraction -the length of the muscle changes |
| Muscle tone | -the constant tension produced by muscles of the body -keeps heads up and backs straight |
| Fast-twitch fibers | -contracts quickly and fatigue quickly -EX: white meat -performs anarobic metabolism |
| slow-twitch fibers | -contracts slowly and more resistant to fatigue -aerobic metabolism -Ex: chicken legs |
| Origin | -The head -the most stationary end of the muscle |
| Insertion | -the end of the muscle undergoing the greatest movement |
| the Belly | -the portion of the muscle between the origin and the insertion |
| Synergists | -muscles that work together to accomplished specific movements |
| Antagonists | -Muscles that work opposite to one another |
| Prime Mover | -one muscles that plays a major role in accomplishing the desired movement |
| Oxygen Debt | -the amount of oxygen to pay back the oxygen debt |
| Motor Unit | -single motor neuron and all the skeletal muscle fibers |
| ATP | -in muscle contraction -produced in the mitochondria -short lived and unstable |
| Action Potential | -brief reversal back of the charge |
| Resting membrane potential | -the charge difference across the membrane |
| I Band | -consist of actin |
| A Band | -extends the length of the myosin -the darker central region |
| H zone | -in the center of each sarcomere -light area -consists only of myosin |
| M Line | -where the myosin myofilaments are anchored -center of sarcomere |
| Synaptic Vesicles | -secretes a neurotransmitter |
| all or none response | -when a muscle fiber will contract maximally |
| lag phase | -time between application of a stimulus to a motor neuron |
| contraction phase | -time during which the muslce contracts |
| relaxation phase | -time when the muscle relaxes |
| sliding filament mechanism | -the sliding of actin myofilaments past myosin myofilaments during contractions |
| threshold | -at the point where the muscle fiber contract maximally |
| occipitofrontalis | -raises the eyebrows |
| orbicularis oculi | -closes the eyelids and causes 'crow's feet' -wrinkles in the skin at the lateral corners of the eyes |
| orbicularis oris | -puckers the lips |
| buccinator | -flattens the cheeks -trumpeter's |
| zygomaticus | -smiling muscles |
| levator labi superioris | -sneering |
| depressor anguli oris | -frowning |
| Mastication | -chewing |
| 4 pairs of mastication muscles | -2 pairs of pterygoids -temporalis -masseter |
| Intrinsic tongue muscle | -changes the shape of the tongue |
| extrinsic tongue muscles | -moves the tongue |
| sternocleidomastoid | -lateral neck muscle -prime movers -rotates and abducts head |
| Erector spinae | -group of muscles on each side of the back -responsible for keeping the back straight and the body erect |
| Retinaculum | -strong band of fibrous connective tissue that covers the flexor -holds the extensor tendons and holds them in place |
| Flexor carpi | -flexes the wrist |
| Extensor carpi | -extends the wrist |
| Flexor digitorum | -flexes the fingers |
| Extenso digitorum | -extends the fingers |
| Intrinsic hand mucles | -19 hand muscles -Located between the metacarpals -responsible for abductions and adduction |
| Gluteus maximus | -buttocks -most of the mass of the buttocks |
| Quadriceps femoris | -extend the leg -anterior thigh muscles |
| Hamstring | -posterior thigh muscles -flexes the leg and extends the thigh |
| Intrinsic foot muscles | -20 muscles in the foot -muscles flex extend, abduct, and adduct the toes |
| Gastrocnemius and soleus | -from the calf muscle -joined from the calcaneal tendon |
| Calcaneal tendon (Achilles tendon) | -flexes the foot and toes |
Created by:
maddie_5
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