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chap 3.docx

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Steve Joordens

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Lec 3.1: Neurons and the Nervous System(lecture8) Nervous System Chart - Central nervous system: where the real/deep decisions in our system are made. Brain and spinal cord - Peripheral nervous system: takes messages from spinal cord out to muscles or from our sensory system to our spinal cord Nervous System - Central in Pink - Peripheral in blue - - our body has two modes that cannot co-exist - One system is responsible for keeping us alive on the short term, and the other is designed forfor short term, and once helps us live longer Autonomic: parasympathetic and sympathetic Parasympathetic system: The parasympathetic system (or the relaxation system): - When body is in full relaxation, the following takes place: - food digests your food - Deliver nutrients to rest of body - Keep tissues healthy, alive - Heart rate slows down, breathing rate slows down, not sweating, mouth gets wet, - When something alarming happens, the sympathetic system goes into action: heart rate gets faster, breathing is heavy, sweat glands open up to heal your body. This is known as the fight or flee response: fighting, fleeing, feeding, making love(fucking) - Teach people Systematic desensitization: a process to help relax someone - The fighting fleeing system is about short term survival. When you have a threat, you have to fight it off, to escape it. This requires an outburst of energy, and your body is always ready for that - you should stay in parasympathetic. Systematic is only for short term survival. - Parasympathetic is about keeping your body alive for the next day - If you’re in systematic mode for a long time, it will make u sick - Strong link between stress and sickness Examples To illustrate somatic system in action, consider the following two situations: 1. Touching a hot iron … - Sensory neurons detect the heat and send an excitatory message to inter-neurons in the spinal cord or brain. - These inter-neurons then send excitatory signals to the motor neurons to retract the hand immediately - Autonomic system 2. Carrying a hot casserole dish … again, - the heat may make you want to drop the dish via the same process described above, - BUT this message is temporarily countered by the brain by it sending inhibitory signals either to the inter-neurons or to the motor neurons Somatic nervous system: - voluntary control of the body - Actions that are in our control - Several things take place in the coordination of these two systems: - 3 kinds of neurons: 1. Sensory neurons: pick information up from the world 2. Interneuron’s: transmit information within the body 3. Motor neurons: directly connected to the muscles and move the body - These neurons send either excitory signals or inhibitory signals, they can make something happen or try to make something not happen - Hot iron example: sensory neurons feel extreme hit, send a signal to the interneurons, interneuron’s send signal to motor to pull hand away. - - Sensory inter motor - Lasagna example: you feel the same sensation and the autonomic system kicks in telling you to let go of it, but the somatic system is sending opposite signals, is telling you to hold on to it because you worked hard for it thus, (actions that are in our control). - Neurons - Neuron has 3 parts 1. Nucleus - This is the part where decisions are made - Thing that informs this decision is: dendrites 2. Dendrites- literally means tree - receiever of information - other neurons `talk`to dendrites The information they receive is processed in the nucleus - nucleus decides if it wants to send this information called action potential down the: axon - then the message will go through the axon to the axon terminals to other neurons - the dendrites are kind of like the ears of the neuron, the nucleus is the mind, and the axon is the mouth - what do we mean by send information: - Neurons do two things when they fire information 1. it tells other neurons to fire too- known as an excitatory signal 2. it tells other neurons not to fire- known as an inhibitory signal - a neuron is either born as a inhibitory neuron, or excitory. It either does one or the other - some neurons are inhibitors and others are exciters - if the neuron is an inhibitor, its trying to shut down other neurons from firing - if the neuron is an exciters, its trying to convince other neurons to fire - These signals are electro-chemical - Every chemical has a charge, positive or negative - When dendrites are getting signals, they are getting chemical reactions Action Potential - a short-lasting event in which the electrical membrane potential of a cell rapidly rises and falls - Action potentials occur in several types of animal cells, called excitable cells, which include neurons, muscle cells, and endocrine cells - In neurons, they play a central role in cell-to-cell communication. - In other types of cells, their main function is to activate intracellular processes. - In muscle cells, for example, an action potential is the first step in the chain of events leading to contraction. - Action potentials in neurons are also known as "nerve impulses" or "spikes", and the temporal sequence of action potentials generated by a neuron is called its "spike train". A neuron that emits an action potential is often said to "fire". Synapses Re- Uptake - Chemicals coming in and out through the axon and eventually causing something to happen at the synapses - Neurotransmitters: normally kept within the axon until an action potential happens - The vesicles then allow the neurotransmitter to be released - Where all the action happens with every drug we are sensitive to - All the drugs we have some way affect this process - The brain has specific chemicals that are the basis upon which almost all of these signals are sent - Dopamine: a neurotransmitter related to feeling good - When people take cocaine, that heightening of alertness, energeticness, awakeness, comes from the fact that cocaine is going to do something to the system that regulates dopamine - Serotonin: happiness - Drugs like ecstasy and Prozac affect the serotonin in your system - Cocaine literally blocks what re-uptakes the neurotransmitters - For example, dopamine gets released, but it doesn’t get brought back into the cell Lecture 3.2: The Brain! Part 1(lecture 9) Lec 3.2: The Brain Cortex vs. Midbrain - The cerebral cortex is the place where high level perception of the world occurs, and is also the place where controlled motor activities originate. In this sense, it is the place where all our controlled interactions with the external world occur. - This contrasts with a number of more basic brain regions which are more devoted to monitoring and controlling internal behaviors and automatic responses to external stimuli. - We have systems that can do really well one thing the brain can do, but we haven’t come up with a system that replicates the human brain - The range of problems the brain can tackle is astounding - the wrinkley part: that waterbed between our skull and brain, so when you bang your head, your brain is cushioned by the Meninges - Meningitis causes the drainage of meninges. The water gets reduced, the brain will hit the skull. This also causes concussions - evolution keeps our head a certain size - the more cortical tissue you have, the better The Cortex Primary vs. Association Cortex - the primary areas of each part of the brain seem to be directly linked to the rest of the world - Occipital cortex: visual processes. Info comes from our eyes, and eventually ends up at the occipital lobe. - Primary visual cortex: raw visual signal. When the signal comes from the rest of the world, the primary area is the area that receives the signal - The association cortex is what we use to actually interpret what we are seeing. - Interface between the sensory input and memory - Cat in the hat example: Association cortex takes this and matches it to your memory - Perception is a function of `raw visual input` then being interpreted from our memory. That interpretation is what our association cortex does Contralateral Organization
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