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26 Cards in this Set
- Front
- Back
Objective
Distinguish among the three types of vertebrate muscles. |
Smooth muscles, which control the digestive system and other organs
Skeletal or striated muscles, which control movement of the body in relation to the environment Cardiac muscles (the heart muscles), which have properties intermediate between those of smooth and skeletal muscles |
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Objective
Explain why antagonistic muscles are needed. |
Moving a leg or arm in two directions requires opposing sets of muscles, called antagonistic muscles. An arm, for example, has a flexor muscles that flexes or raises it and an extensor muscle that extends or straightens it. Walking, clapping hands, and other coordinated sequences require a regular alternation between contraction of one set of muscles and contraction of another.
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Objective
Indicate when fast-twitch and slow-twitch muscles are needed. |
Our muscle types range from fast-twitch fibers that produce fast contractions but fatigue rapidly to slow-twitch fibers that produce less vigorous contractions without fatiguing. We rely on our slow-twitch and intermediate fibers for non-strenuous activities. For example, you could talk for hours without fatiguing your lip muscles. You could probably walk for hours too. But if you run up a steep hill at full speed, you will have to switch to fast-twitch fibers, which will fatigue rapidly.
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Objective
Describe the role of muscle spindles in the knee-jerk reflex. |
See study guide.
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Objective
Discuss the extent to which a movement like walking is voluntary. |
You might think of walking as being purely voluntary, but even that example includes involuntary components. When you walk, you automatically compensate for the bumps and irregularities in the road. You probably also swing your arms automatically as an involuntary consequence of walking.
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Objective
Identify three reflexes that are present in infants but not in adults. |
Grasp Reflex: If you place an object firmly in an infant’s hand, the infant will reflexively grasp it tightly.
Babinski Reflex: If you stroke the sole of the foot, the infant will reflexively extend the big toe and fan the others. Rooting Reflex: If you touch an infant’s cheek, the head will turn toward the stimulated cheek, and the infant will begin to suck. It is not a pure reflex, as its intensity depends on the infant’s arousal and hunger levels. |
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smooth muscle
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Muscles that control the digestive system and other organs
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striated (skeletal) muscle
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Muscles that control movement of the body in relation to the environment
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cardiac muscle
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Heart muscles; have properties intermediate between those of smooth and skeletal muscles
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neuromuscular junction
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A synapse where a motor neuron axon meets a muscle fiber
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antagonistic muscle
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Opposing sets of muscles
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flexor
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Muscle that flexes or raises a limb
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extensor
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Muscle that extends or straightens a limb
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myasthenia gravis
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An autoimmune disease, in which the immune system forms antibodies that attack the individual’s own body; more specifically, the immune system attacks the acetylcholine receptors at neuromuscular junctions
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fast-twitch fibers
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Muscle type that produces fast contractions but fatigues rapidly
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slow-twitch fibers
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Muscle type that produces less vigorous contractions without fatiguing
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aerobic
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Use of air (specifically oxygen) during movements; slow-twitch fibers do not fatigue because they are aerobic
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anaerobic
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Using reactions that do not require oxygen at the time, although oxygen is eventually necessary for recovery; vigorous use of fast-twitch fibers results in fatigue because of the anaerobic process
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proprioceptor
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A receptor that detects the position or movement of a part of the body
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stretch reflex
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Reflex that occurs when a muscle is stretched (spinal cord sends reflexive signals as a result of the stretch)
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muscle spindle
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A proprioceptor parallel to the muscle that responds to a stretch; whenever the muscle spindle is stretched, its sensory nerve sends a message to a motor neuron in the spinal cord, which in turn sends a message back to the muscles surrounding the spindle, causing a contraction
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golgi tendon organ
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A proprioceptor that responds to increases in muscle tension; located in the tendons at opposite ends of a muscle and acts as a brake against an excessively vigorous contraction
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reflex
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Consistent automatic responses to stimuli
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grasp reflex
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If you place an object firmly in an infant’s hand, the infant will reflexively grasp it tightly
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babinski reflex
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If you stroke the sole of the foot, the infant will reflexively extend the big toe and fan the others
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rooting reflex
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If you touch an infant’s cheek, the head will turn toward the stimulated cheek, and the infant will begin to suck
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