Chapter 17 Nervous System in Muscle pg 308 1 Nervous system responsible for the reception and processing of sensory information 1 17 2020 from both the external and internal environments a Nervous tissue i Neurons communicate via electrical potentials 1 Cells that transmit nerve impulses between parts of the nervous system ii Glial cells support and nourish neurons 1 Neuronal homeostasis b Central nervous system brain and spinal cord Located in the midline of the body i i i ii c Peripheral nervous system consists of nerves that carry sensory messages to the central nervous system and motor commands from the central nervous system to the muscles and glands autonomic nervous system and reflex arcs and somatic nervous system d Three types of nerves Sensory neurons takes messages to the central nervous system 1 May be equipped with specialized endings known as sensory receptors that detect changes in the environment Interneurons lies entirely within the central nervous system and they can receive input from sensory neurons to sum up all of the messages before they communicate with motor neurons iii Motor neurons takes messages away from the central nervous system to an effector to carry out the responses into the environment 2 Neuromuscular Junction a Somatic motor neurons serves the skin skeletal muscles and tendons i Skeletal muscle b Synaptic cleft gap between axon terminals and muscle fiber Neurotransmitter release Axon terminal end of neuron i ii iii Muscle fiber muscle cell c Action potential in muscle fiber muscle cell i Ionic currents carry electrical potential First Na in neuron 1 2 Then Ca 2 in muscle cells ii Eventually calcium release d Calcium binds to troponin Opens myosin binding sites on actin i ii Myosin can form cross bridge 1 Contraction of muscle 2 Sarcomere shortens 3 Smooth muscle Involuntary a b Lacks striations c Uninucleate d Gap junctions e No troponin i Calmodulin f Aerobic metabolism
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