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Slide 1 ___________________________________ ___________________________________ Chapter Two ___________________________________ The Biological Perspective ___________________________________ ___________________________________ ___________________________________ ___________________________________ Slide 2 ___________________________________ Biological Psychology -- branch of psychology concerned with ___________________________________ the links between biology and behavior. ___________________________________ Neuroscience- ___________________________________ ___________________________________ ___________________________________ ___________________________________ Slide 3 ___________________________________ Neural Communication Neuron - basic building block of the nervous system. Components that make up the neuron ___________________________________ • Cell Body- the neurons life support center. Dendrite - branching fibers located on the cell body, that receives information from other neurons. • Axon -single, slender, fiber extending from the cell body ___________________________________ carrying outgoing messages to other neurons, muscles, or glands in the form of neural impulses. • Tract -group of axons bundled together that carry information to a specific area (i.e. spinal cord tract) • Myelin sheath - layer of fatty substance made by the ___________________________________ oligodendrocytes and schwann cells that insulate certain axons and speeds up the transmission of the neural impulse ___________________________________ ___________________________________ ___________________________________

Slide 4 ___________________________________ Types of Neurons • Sensory (afferent) Neurons- neurons that ___________________________________ collect messages from sense organs and carry those messages to the spinal cord or brain. • Motor (efferent) Neurons -neurons that carry ___________________________________ messages from the spinal cord or the brain to the muscles and glands • Interneurons (association) Neurons - neurons that carry messages from one neuron to ___________________________________ another. ___________________________________ ___________________________________ ___________________________________ Slide 5 ___________________________________ Neural Impulse-method of communication between neurons ___________________________________ • A neural impulse is an electrical charge that travels down the axon causing the neuron to fire. • This electrically charged impulse ___________________________________ allows the neuron to communicate with other neurons and is called an Action Potential ___________________________________ ___________________________________ ___________________________________ ___________________________________ Slide 6 ___________________________________ Composition of Intra and Extra- cellular Fluid • Electrically charged ions on either side of the ___________________________________ membrane. Intra-cellular fluid is predominately negative and extra-cellular fluid is predominately positive in relation to each other. • Intra-cellular fluid-Higher concentration of: – Negative Ion-(Cation)-A- ___________________________________ – K+ • Extra-cellular fluid- – Na+ – Cl- ___________________________________ ___________________________________ ___________________________________ ___________________________________

Slide 7 ___________________________________ Action Potential • Resting Potential- small negative electrical charge across the neuron ___________________________________ due to the concentration of positive ions on the outside and negative ions on the inside. • Due to negative electrical charge, the neuron at rest is said to be in a state of polarization. • Incoming signals from other neurons stimulate receiving neurons at the dendrites through binding of Neurotransmitter. ___________________________________ • When the NT binds, local channels open and briefly change the polarity which results in a graded potential. • When there are enough graded potentials in succession, channels open allowing positive ions from the outside to enter the interior of the neuron. • Entrance of the positive ions into the cell body depolarizes the neuron, changing the interior from negative to more positive, setting ___________________________________ off a chain reaction that eventually sends an electrical charge (action potential), down the axon. ___________________________________ ___________________________________ ___________________________________ Slide 8 ___________________________________ Selective Permeability • Neuron is semi-permeable, meaning some ions can flow freely in and out while other ions cannot ___________________________________ due to different types of channels which are open or closed. • Channels-( open when neuron is at rest) – Both K+ and Cl- channels are open while neuron is at ___________________________________ rest and freely cross the semi-permeable membrane. – Although the K+ and Cl- ions are free to move in and out of the neuron when it is at rest, whether ions move in or out is influenced by the electrical and concentration of ions. • Pumps-Na+/K+ pump ___________________________________ -3 Na+ ions are pumped out -2 + ions are pumped in -helps to maintain the concentration and electrical gradient. ___________________________________ ___________________________________ ___________________________________ Slide 9 ___________________________________ Voltage gated Channels • Voltage gated channels are closed when ___________________________________ membrane is at rest • Voltage gated channels begin to open when there is a change in the voltage of the neuron. • Different voltage gated channels open and close ___________________________________ and different times. – Sodium (Na+) channels-open FIRST and more quickly than K+  initiate depolarization – Potassium ions (K+)- open later than Na+ gates, but close more slowly-contribute to hyperpolarization through the efflux ( leaving the cell ) of K+ = neuron ___________________________________ becomes more negative.. ___________________________________ ___________________________________ ___________________________________

Slide 10 ___________________________________ Propagation of Action Potential aka. When the Neuron fires. • Neurotransmitters stimulate the neuron via dendrites, ___________________________________ which influence the opening and closing of voltage channels. – Action potential is a sequence of events – Na+ channels open first, allowing positive ions to rush in and allowing the inside of the neuron to be more positive. • Graded potential -stimulation via NT is not always ___________________________________ enough to open enough gates to cause a change in polarity that is enough to reach threshold. Therefore a brief sudden change in polarity is a graded potential and the neuron remains at rest. ___________________________________ ___________________________________ ___________________________________ ___________________________________ Slide 11 ___________________________________ Action Potential • Threshold Potential- As more NT ___________________________________ stimulates the dendrites, we see a summation of graded potentials, which isis enough to begin the sequence of events that changes the polarity of the neuron ___________________________________ when the neuron reaches threshold. • All or None Response- once the axon reaches threshold it fires, it does not fire at any greater speed or stronger response. It ___________________________________ either fires, or it does not. ___________________________________ ___________________________________ ___________________________________ Slide 12 ___________________________________ Sending the Message to other cells. • Propagation- the action potential begins at the ___________________________________ axon hillock of the soma and continues down the axon. • As Na+ gates open the electrical impulse ___________________________________ continues to travel down the axon. • As Na+ gates close, no more positive ions can enter from the Na+ gates. ___________________________________ • K+ gates open later, and stay open longer which allows K+ to leave the neuron while it has a positive charge. ___________________________________ • ___________________________________ ___________________________________

Slide 13 ___________________________________ ___________________________________ ___________________________________ ___________________________________ ___________________________________ ___________________________________ ___________________________________ Slide 14 ___________________________________ C ___________________________________ ___________________________________ ___________________________________ ___________________________________ ___________________________________ ___________________________________ Slide 15 ___________________________________ Hyperpolarization • The action potential sequence takes less ___________________________________ than one-thousandth of a second. • After the action potential fires, the neuron re-polarizes to its former resting state. ___________________________________ • After the Na+ voltage gated channels close, the K+ voltage gated channels remain open, allowing the neuron to be ___________________________________ more negative than resting potential which is called Hyperpolarization. ___________________________________ ___________________________________ ___________________________________