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26 Cards in this Set

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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
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.
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.
Objective

Describe the role of muscle spindles in the knee-jerk reflex.
See study guide.
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.
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.
smooth muscle
Muscles that control the digestive system and other organs
striated (skeletal) muscle
Muscles that control movement of the body in relation to the environment
cardiac muscle
Heart muscles; have properties intermediate between those of smooth and skeletal muscles
neuromuscular junction
A synapse where a motor neuron axon meets a muscle fiber
antagonistic muscle
Opposing sets of muscles
flexor
Muscle that flexes or raises a limb
extensor
Muscle that extends or straightens a limb
myasthenia gravis
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
fast-twitch fibers
Muscle type that produces fast contractions but fatigues rapidly
slow-twitch fibers
Muscle type that produces less vigorous contractions without fatiguing
aerobic
Use of air (specifically oxygen) during movements; slow-twitch fibers do not fatigue because they are aerobic
anaerobic
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
proprioceptor
A receptor that detects the position or movement of a part of the body
stretch reflex
Reflex that occurs when a muscle is stretched (spinal cord sends reflexive signals as a result of the stretch)
muscle spindle
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
golgi tendon organ
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
reflex
Consistent automatic responses to stimuli
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