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Functions of Nervous System: –Sensory Input-(from inside and outside of body) –Integration and regulation of body systems. –Motor output-(Muscles and glands) Two Divisions: –Central: Brain and spinal cord. –Peripheral: nerves of body. Attached to spinal cord.
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Motor Neuron Multipolar Cause muscles to contract or glands to secrete
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Sensory Neuron Unipolar Take signals from a sensory organ to CNS. Eyes, ears, pain receptors.
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Interneuron Multipolar Only in CNS Convey information and coordination of signals.
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Resting Potential Polarized membrane- + on outside, - on inside. Resting potential. Na/K pump, pumps Na out and K into axon. –Helps keep many more Na on outside and many more K ion inside.
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Fig. 8.3a
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Action Potential: –Axon is conducting nerve impulse. –Axon depolarized: inside becomes + and outside -. Na moves to the inside. –Then axon is repolarized: + Out, - Inside. K moves to the outside,
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Fig. 8.3b
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Conduction of Action Potentials: –Myelination helps speed up how fast nerve impulses can travel through the axon. Action potential jumps from node of ranvier to next node of ranvier. Called Saltatory conduction.
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Fig. 8.4
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Fig. 8.5a
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Fig. 8.5b
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Fig. 8.5c
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Brain and CNS
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Fig. 8.6b
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Cerebrum: –Largest. –Divided into hemispheres. –Coordinates other parts of the brain. –Center of higher thought processes. Learning Memory Language Speech –Divided into 4 lobes: Occipital, Temporal, Frontal and Parietal
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Fig. 8.9
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Diencephenon: –Contains the hypothalamus and thalamus Hypothalamus: regulates hunger, thirst, sleep, body temp. –Link between endocrine and nervous systems. Thalamus: Memory, emotions and signals to proper part of the brain. Pineal Gland: makes melatonin. Regulates body rhythms and biological clock..
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Cerebellum: –Regulates body posture and balance. –Regulates smooth body actions. Coordinates voluntary movements. Plays a huge role in learning new motor skills.
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Brain Stem: –Mid-brain: Relay station. –Pons: Bridge between cerebellum and rest of CNS and regulates breathing and reflex movement of head. –Medulla oblingata: Regulates heart rate, breathing, vomiting, coughing, swallowing, etc.
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Peripheral Nervous System
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Peripheral nervous system (PNS) is composed of the nerves and ganglia that are outside the CNS. –Nerve: Bundles of myelinated axons. –Ganglia: Swellings associated with nerves that contain cell bodies. ___________________________________________ System divided into the somatic and autonomic nervous systems. –Somatic: Serves skin, skeletal muscle and tendons. Includes sensory neurons. –Autonomic: Regulates cardiac and smooth muscle.
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Two Types of Nerves: –Cranial: Attached to brain directly. 12 pairs in humans. Most are somatic and control head neck and face. Vagus is an exception.: Autonomic and runs to most internal organs. –Spinal: Attached to spinal cord: 31 pairs in humans. Divided into cervical, thoracic, lumbar and sacral. Mixed nerves: –Sensory signals enter via posterior root. –Motor signals by the anterior root.
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Fig. 8.12
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Fig. 8.11b
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Somatic Nervous System: –Many actions are voluntary. Brains tells us to move arm, we send the signal via a somatic motor neuron to move the arm. –Some actions are involuntary. Reflexes.
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Fig. 8.13
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Autonomic System: –Sympathetic and parasympathetic divisions. –Both function automatically and involuntarily. –Both connect to internal organs. –Sympathetic: Fight of Flight. Accelerates heartbeat, dilates bronchi in lungs, inhibits digestive tract. –Parasympathetic: Housekeeping. Promotes food digestion, slows heart rate, helps body relax.
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