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Chapter 6 Muscle
muscle flashcards
| 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 | ability to recoil to their original resting length after they have been stretched. |
| What are four major functional characteristics of skeletal muscle? | contractility, excitability, extensibility, and elasticity |
| What do muscles help produce? | heat essential for maintenance of normal body temperature |
| Each skeletal muscle is surrounded by a connective tissue sheath called? | epimysium |
| Is another connective tissue located outside the epimysium. | fascia |
| A muscle is composed of numerous visible bundles called fasciculi(fascicle), which are surrounded by loose connective tissue called? | perimysium |
| The fasciculi are composed of single muscle cells called? | fibers |
| Each fiber is surrounded by a connective tissue sheath called the? | endomysium |
| The cytoplasm of each fiber is filled with? | myofibrils |
| What are myofibrils? | a threadlike structure that extends from one end of the fiber to the other. |
| Myofibrils consists of what two major kinds of protein fibers? | actin myofilaments and myosin myofilaments. |
| Actin and myosin myofilaments form highly ordered units called? | sarcomeres |
| What are actin myofilaments? | thin myofilaments |
| What do actin myofilaments resemble? | they resemble 2 minute strands of pearls twisted together. |
| What are myosin myofilaments? | thick myofilaments. |
| What do myosin myofilaments resemble? | they resemble bundles of minute golf clubs |
| What is a sarcomere? | the basic structural and functional unity of the muscle. |
| Each sarcomere extends from what? | from one Z line to another Z line |
| On each side of the Z line is a light area called what? | I band |
| What does the I band consist of? | actin |
| The A band extends what? | the length of the myosin |
| What is the darker central region in each sarcomere? | the A band |
| In the center of each sarcomere is another light area called what? | the H zone |
| What does the H zone consist of? | it consists of only myosin |
| The myosin myofilaments are anchored in the center of the sarcomere at a dark staining band called the? | M line |
| The charge difference across the membrane is called the? | resting membrane potential |
| The brief reversal back of the charge is called? | action potential |
| What are motor neurons? | are nerve cells that carry action potentials to skeletal muscle fibers |
| What do axons enter? | the muscles and branch |
| Each branch that connects to the muscle forms a? | neuromuscular junction or synapse |
| A single motor neuron and all the skeletal muscle fibers it innervates are called a ? | motor unit |
| What is a neuromuscular junction formed by? | an enlarged nerve terminal resting in an indentation of the muscle cell membrane |
| The enlarged nerve terminal is the? | presynaptic terminal |
| The space between the presynaptic terminal and the muscle cell is the? | synaptic cleft |
| Each presynaptic terminal contains what? | synaptic vesicles |
| Synaptic vesicles secretes a neurotransmitter called what? | acetylcholine |
| What diffuses across the synaptic cleft and binds to the postsynaptic terminal causing a change in the postsynaptic cell? | acetylcholine |
| What occurs when actin and myosin myofilaments slide past one another causing the sarcomeres to shorten? | muscle contraction |
| What is the sliding of actin myofilaments past myosin myofilaments during contraction called? | sliding filament mechanism |
| What is muscle twitch? | It is a contraction of an entire muscle in response to a stimulus that causes the actin potential in one or more muscle fibers. |
| A muscle fiber will not respond to stimulus until that stimulus reaches a level called what/ | threshold |
| What is threshold? | at which point the muscle fiber will contract maximally. |
| The time between application of a stimulus to a motor neuron and the beginning of a contraction is the? | lag phase |
| What is a contraction phase? | the time of contraction |
| What is the relaxation phase? | the time during which the muscle relaxes. |
| What is tetany? | where the muscle remains contracted without relaxing. |
| What is the increase in number of motor units being activated? | recruitment |
| What is needed for energy for muscle contraction? | ATP(adenosine triphosphate) |
| What is produced in the mitochondria? | ATP( adenosine triphosphate) |
| What respiration is without oxygen? | anaerobic |
| What respiration is with oxygen and (more efficient)? | aerobic |
| What is the 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. |
| What results when ATP is used during muscle contraction faster than it can be produced in muscle cells? | muscle fatigue |
| What are the 2 types of muscle contractions? | isometric and isotonic |
| The length of the muscle does not change, but the amount of tension increases during the contraction process. ( equal distance) | Isometric |
| The amount of tension produced by the muscle is constant during contraction, but the length of the muscle changes. ( equal tension) | isotonic |
| What is muscle tone? | it refers to constant tension produced by muscles of the body for long periods of time. |
| What contracts quickly and fatigue quickly? | fast-twitch fibers |
| Is fast-twitch fibers more adapted to anaerobic metabolism or aerobic metabolism? | anaerobic metabolism |
| What contracts more slowly and is more resistant to fatigue/ | slow-twitch fibers |
| Is slow-twitch fibers more adapted to anaerobic metabolism or aerobic metabolism? | aerobic metabolism |
| White meat is an example of which twitch fiber? | fast- twitch fiber |
| Dark meat is an example of which twitch fiber? | slow- twitch fiber |
| What is the most stationary end of the muscle? | origin (head) |
| What is the end of the muscle that undergoes the greatest movement? | insertion |
| The portion of the muscle between the origin and the insertion is the what? | belly |
| Muscles that work together to accomplish specific movements are called what? | synergists |
| Muscles that work in opposition to one another are called what? | antagonists |
| If one muscle plays the major role in accomplishing the desired movement that muscle is called what? | prime mover |
| Muscles are named according to their what? | location, size, orientation of fibers, shape, origin, insertion, and function |
| What muscle raises the eyebrow? | occipitofrontalis |
| What closes the eyelids and causes ''crows feet'' at the corners of the eyes? | orbicularis oculi |
| What muscle puckers the lips? | orbicularis oris |
| What muscle flattens the cheeks and is also known as the trumpeter's muscle? | buccinator |
| What is the smiling muscle? | zygomaticus |
| What is mastication? | chewing |
| What are the 4 pairs of mastication muscles? | 2 pairs of pterygoids, temporalis, and masseter |
| Which of the tongue muscles changes the shape of the tongue? | Intrinsic tongue muscles |
| Which of the tongue muscles moves the tongue? | extrinsic tongue muscles |
| Sternocleidomastoid is the what? | lateral neck muscle and the prime mover of the neck |
| What are group of muscles on each side of the back called? | erector spinae |
| What do external intercostals do? | elevate the ribs during inspiration |
| What do internal intercostals do? | contract during forced inspiration |
| What accomplishes quiet breathing? | the diaphragm |
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alysongue
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