Anatomy and Physiology Answer Key

B the central nervous system cns processes the

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Unformatted text preview: d (b) any two in any order: • Nervous control involves transmission across synapses, hormonal control involves transport of chemicals in the blood. • Nervous control is rapid, hormonal control is slower. • Nervous control acts in the short term and its effects are short lived, hormonal control is longer acting. • Nervous control is direct and through specific pathways, hormonal control is widespread, affecting target cells throughout the body (although these may be quite specific). • Nervous control causes muscular action directly, hormonal control generally acts by changing metabolic activity. Biozone International 2009 Photocopying Prohibited Anatomy and Physiology Fast twitch fibers are large, pale fibers with rapid contraction rates, rapid rates of ATP production, and high power generation. They work anaerobically, but fatigue quickly, and these properties suit them to short bursts of activity where maximal force is required quickly (as in sprinting or power lifting). Slow twitch fibers, in contrast, are darker (red) due to the presence of large amounts of myoglobin, they are small in diameter and have a slower rate of ATP production and a slower contraction rate. They work aerobically, but fatigue slowly, so they are suited to activities where endurance and prolonged activity at a sustainable level is required. Note: Fast twitch fibers will be (preferentially) developed and recruited in sprint trained athletes. Slow twitch fibers will be (preferentially) developed and recruited in endurance trained athletes. Muscle contains a mix of fiber types, providing the capacity for both explosive effort and endurance. The Nervous System (page 71) 12 relax the external urethral sphincter. Because both conscious and unconscious controls are involved, urination can be voluntarily stopped and started at will (recognition of and response to the cues for bladder emptying develop around two years of age). 3. (a) Myelination increases the speed of impulse conduction. (b) Oligodendrocytes (c)...
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