PSYCH261 Lecture : Biological Psychology 10th Edition Chapter 8
16 Oct 2011
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Skeletal (aka striated); control movement in relation to environment; cardiac: for heart. Each muscle comprised of fibres, connected to axons. Neuromuscular junction:synapse b/w motor neuron axon and muscle fiber. Antagonistic muscles: opposing sets; eg. flexor (hand->shoulder); & extensor (straightens arm. Acetylcholine: released at n. m. junction -> contraction; deficits -> impaired movement. Myasthenia gravis: immune system makes antibodies; attacks acetylcholine @ n. m junction. Fast-twitch: fast contraction, rapid fatigue; anaerobic; uses fatty acids. Slow-twitch: slow contractions, no fatigue; aerobic (use oxygen); uses glucose. Prolonged exercise -> switch from slow to fast-twitch muscles. Diff % of fast and slow twitch fibres; depends on genetics/training. Proprioceptor: detects position (movement of body parts); send messages to brain. Eg. muscle spindle: assoc"d w/ stretch reflex; detect stretch->opposite contraction. Eg. golgi tendon organs: respond to ^ muscle tension; stop excessive vigorous contraction. Eg. speaking, walking; depends on diff. kinds of control by ns. Reflexes: involuntary: insensitive to motivations; voluntary actions: sometimes inhibit involuntary.
