University:
College
Course:
College Psychology
Academic year:

2023
Views:

206

Pages:

14
Author:

Ehelizenza0

Psychology Biological Psychology Essential Task 3-2: Describe the electric process of neural firing (ions, resting potential, action potential, threshold of excitation, all-or- none law, subthreshold excitations, sumnation, absolute refractory period, relative refractory period.) Evolutionary Endocrine System We are here Building Blocks Biological Psychology Genetics Neurons Nervous System Central Nervous System Peripheral Nervous System Motor Brain Brain Imaging Spinal Cord Autonomic Sympathetic Neurotransmitters Sensory Somatic Parasympathetic Essential Task 3-2: Outline • Describe the electric process of neural firing – – – – – – – – Ions resting potential (Polarized) action potential (Depolarization) all-or- none law threshold of excitation sub-threshold excitations Sumnation Refractory Period • absolute refractory period • relative refractory period Before a neuron fires – Resting Potential Outline • Resting Potential – – – – Neuron is not transmitting information It is not firing, it is resting Negatively charged ions are in the axon. At this stage the neuron is said to be ‘polarized’ Before a neuron fires – Resting Potential Outline  Resting Potential  Nothing is happening. The gates of the axon are closed.  Positive ions are on the outside with the negative ions on the inside of the cell. – “Negative Ions inside the Neuron is Natural” Neural Firing! Outline  Action Potential  a brief electrical charge that travels down an axon  Also called neural impulse or nerve firing or depolarization  generated by the movement of positively charged ions into the axon.  This process starts due to stimulation of the receptor sites for the neuron that is firing Neural Firing! Outline Stimulation causes the gates to open and the positive ions enter the cell. An electrical spark is produced by the process call depolarization. The positive ions are then pumped out. Cell body end of axon This chain reaction can occur up to 100 a second. Direction of neural impulse: toward axon terminals Neural Firing! Outline • Polarization – When the inside of the Neuron is negatively charged relative to the outside – Resting potential • Depolarization – When the electrical charge of a cell moves toward zero – Action potential Thank your glial cells Outline 400 ft per second (Myelinated) to 3 ft per second The Neural Impulse Outline • All-or-None Law – A neuron either fires or it does not – When it does fire, it will always produce an impulse of the same strength – Intensity of a stimulus is seen by the frequency of action potentials frequency frequency frequency frequency frequency frequency frequency frequency What starts this whole process? Outline • Graded Potentials – A shift in the electrical charge in a tiny area of a neuron. – Many subthreshold depolarizations are added together to produce an action potential (a process known as summation)  The stimulation must exceed the threshold of excitation in order for the neuron to fire.  Threshold is the minimum level of charge needed for an action potential When can it fire again? Outline • Refractory Period – The time it takes for the positive ions to be pumped out. 1. Absolute Refractory period - Period immediately after an action potential when another action potential CANNOT occur. (1/1000th of a second) 2. Relative refractory period - Period following absolute refractory period when a neuron will only respond to a stronger than normal impulse Refractory Period Outline OA: Dominos Simulation Give examples of the following terms according to the dominos simulation 1. Resting Potential 2. Graded Potential 3. Threshold 4. Action Potential 5. All or None Law 6. Refractory Period