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Chapter 6 Muscle
muscle
| 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 do muscles help? | muscles help produce heat essential for maintenance of normal body temperature |
| Each skeletal is surrounded by a connective tissue sheath called the? | epimysium |
| Another connective tissue located outside the epimysium | fascia |
| A muscle is composed of numerous visible bundles called muscle fasciculi, 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 consist of what 2 kinds of protein fibers? | actin myofilaments and myosin myofilaments |
| What are actin myofilaments? | thin myofilaments. They resemble 2 minute strands of pearls twisted together |
| What are myosin myofilaments? | thick myofilaments. They resemble bundles of minute golf clubs. |
| Actin and myosin myofilaments form highly ordered units called? | sarcomeres |
| 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 |
| What do the arrangement of actin and myosin give? | a banded appearance |
| On each side of the Z line is a light area called what? | an I band |
| What does the I band consist of? | actin |
| The A band extends what? | the length of the myosin |
| In the center of each sarcomere is another light area called what? | the H zone |
| What does the H zone consist of? | myosin |
| The myosin myofilaments are anchored in the center of the sarcomere at a dark staining band called what? | the M line |
| The charge difference across the membrane is called what? | the resting membrane potential |
| The brief reversal back of the charge is called what? | action potential |
| Motor Neurons | nerve cells that carry action potentials to skeletal muscle fibers |
| Each branch that connects to the muscle forms a? | neuromuscular junction. or synapse near the center of the cell |
| A single motor neuron and all the skeletal muscle fibers it innervates are called? | a motor unit |
| What do many motor units form? | a single muscle |
| The enlarged nerve terminal is the? | presynaptic terminal |
| The space between the presynaptic terminal and the muscle is the? | synaptic cleft |
| Each presynaptic terminal contains? | synaptic vesicles |
| Synaptic vesicles secrete a neurotransmitter called? | acetylcholine |
| What does acetylcholine do? | it diffuses across the synaptic cleft and binds to the postsynaptic terminal. |
| What does the combination of acetylcholine with its receptor cause? | an influx of sodium ions into the muscle fiber |
| What does the enzymatic breakdown ensure? | that one action potential in the neuron yields only one action potential in the skeletal muscle, and only one contraction of the muscle cell |
| The sliding of actin myofilaments past myosin myofilaments during contraction is called? | sliding filament mechanism |
| Muscle twitch | a contraction of an entire muscle in response to a stimulus. |
| The time between application of a stimulus until that stimulus reaches the level called? | lag phase |
| What is the time of contraction called? | contraction phase |
| What is the time during which the muscle relaxes called? | relaxation phase |
| Tetany | where the muscle remains contracted without relaxing |
| The increase in number of motor units being activated is called? | recruitment |
| What is needed for energy for muscle contraction? | ATP |
| What does ATP stand for? | adenosine triphosphate |
| Where is ATP produced? | in the mitochondria |
| What does ADP stand for? | adenosine diphosphate |
| What does anaerobic respiration stand for? | without oxygen |
| What does aerobic respiration stand for? | with oxygen |
| What is oxygen debt? | the amount of oxygen needed in chemical reactions |
| What are two types of muscle contractions? | isometric and isotonic |
| Muscle tone | Muscle tone refers to 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 resistant to fatigue |
| What is the origin? | it is the most stationary end of the muscle |
| What is insertion? | it is the end of the muscle undergoing the greatest movement |
| What is the portion of the muscle between the origin and the insertion? | the belly |
| Muscles that work together to accomplish specific movements are called? | synergists |
| Muscles that work in opposition to one another are called? | antagonists |
| If someone winks at you they are using? | the orbicularis oculi |
| The hip muscle commonly called the buttocks is also called what? | the gluteus maximus |
| A muscle is composed of numerous bundles called? | muscle fasicle |
| A muscle fiber will not respond to stimuli until the stimulus reaches a level called? | threshold |
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alexismnelson
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