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Unformatted text preview: Ch. 2: Biological Foundations of Psych 29/09/2008 19:18:00 ← Neurons, The Building Blocks of The Nervous System • Neuron – a specialized cell that transmits neural impulses or messages to other neurons, glands and muscles • Dendrites – receive neural impulses from adjacent neurons • Axon – a slender tube that extends from the soma and transmits these messages to other neurons (or to muscles and glands). • Synaptic Terminals – the ends of axons that divide into a number of tiny branches. The ends of these branches have tiny swellings called the synaptic terminals • Synapse – a slight gap between the terminal button and the cell body or dendrites of the receiving neuron. The gap is called the synaptic gap . • Neuro-transmitter – a chemical that diffuses across the synaptic gap and stimulates the next neuron • Sensory Neurons – transmit impulses received by receptors to the central nervous system • Motor neurons – carry outgoing signals from the brain or spinal cord to muscles and glands • Interneurons – receive the signals from the sensory neurons and send impulses to other interneurons or to motor neurons. Found only in the brain, eyes and spinal cord • Nerve – a bundle of elongated axons belonging to hundreds or thousands of neurons • Nucleus – in the brain and spinal cord, a group of cell bodies of neurons • Ganglion – a group of neuronal cell bodies found outside the brain and spinal cord • Glial Cells – the nervous system has a large number of nonneural cells. Outnumber neurons 9:1 and take up more than half the volume of the brain. Greek work for “glue”. Holds neurons together. Action Potentials • Action Potential – an electro-chemical impulse that travels from the cell body down to the end of the axon • Ions – electrically charged neurons that cause action potential by moving • Semipermeable – some ions can pass through the cell membrane easily and others are not allowed to pass through except when special passageways in the membrane open. • Ion Channels – donut shaped protein molecules that form pores across the cell membrane. These pores allow ions to pass thru. • Resting Neuron – a neuron that is not generating action potential • Ion Pumps – found in resting neurons. Help maintain the uneven distribution of ions across the cell membrane by pumping them into or out of the cell. • Resting membrane potential – the electrical potential of a neuron at rest • Depolarization – when a neuron is excited and electricity is released...
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- Spring '08
- Psychology, neuron Sensory Neurons, adjacent neurons Axon