Bio notes 6 - Notes Topic Nervous system Biology 103 Dr...

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Topic: Nervous system Reading: Chapter 38 Main concepts : Neurons are the cells that make up nervous tissue and most of the nervous system. Dendrites receive signals, the cell body integrates incoming signals, the axon conducts the signals, and the synaptic terminal passes the signal to the next neuron. Neurons: receive information, integrate and interpret information, conduct signals over distances, and transmit signals to receiving organs. Nerve signals involve the concentration of potassium and sodium ions on either side of the cell membrane. The signal is conducted when ion channels open briefly in a “wave” down the cell, allowing sodium and potassium to switch sides. The synapse is a small gap between two neurons, and is bridged by chemicals called neurotransmitters. these allow fine control of neural signals. Not every signal has to be transmitted. Four basic operations for information processing: Type of stimulus (auditory, visual, etc.) is determined by wiring patterns in the brain. Intensity is determined by frequency of signals. Information from the senses may converge from many sources. Divergence of signals from the brain to the body allows complex responses. The simplest neural signal is the reflex arc: a signal from sensory organs is directed to motor neurons in the spine and the response carried out before the brain gets the message. Other signals travel to the brain first. The brain sorts out sensory signals, may ignore some that are unimportant, and determines the correct response. The brain then sends signals to effectors: muscles, glands, organs. Human nervous system is divided into two parts: central nervous system (brain, spine) and peripheral nervous system (nerves, sensory organs). Peripheral nervous system (PNS) is divided into: Motor portion somatic system: controls voluntary muscles (though they can be involved in an involuntary response, such as a reflex arc) Autonomic system: controls involuntary responses (though conscious training, such as meditation or relaxation techniques, can allow people to affect the degree of response) Sympathetic division: “fight or flight” Parasympathetic division: “rest and rumination” Sensory portion Sensory receptors collect information: chemoreception, mechanoreception, photoreception, etc. Sensory neurons transmit signals, informing the brain of what is going on in the environment. Central nervous system is divided into: Brain Hindbrain made up of medulla, pons, and cerebellum Medulla controls autonomic functions, such as breathing and heart rate.
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Bio notes 6 - Notes Topic Nervous system Biology 103 Dr...

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