7-15-04 Chapter 3 Doug comes in saying "Just when you thought you might escape." There is a test on Tuesday covering everything from last Tuesday. Test format will be all varried and what-not. Today is what Doug would call the MOST EXCITING CHAPTER of the book. ----------------------------------------------------------------------------- A good deal of your behavior is dependent on Biology. Does behavior we see depend on the "Nature" of an individual. (Biology) Or is it the "Nuture"? (Which is the environment.) There are instances where biology does dictate certain behavior. (Some genetic diseases) There are other more frequently found instances for environmental influences. (Twins being raised in different places and acting differently) Nature and Nuture go together to form behavior. certain environmental stimuli can act upon a certain possibly predisposed behavior set. (Alcoholics whose father was one.) Function of the Nervous System - central - brain and spinal cord - Peripheral - everything else classified as... ---> Symatic ---> Autonomic is composed of... ---> Sympathetic ---> Para Sympathetic Two Cell types: 1.) Glia - "Greek" for glue 2.) Neurons cells all have the same components in them. Called Organelles - parts of the cell that make it work. Organelles ----------------------- 1.) Cellular Membrane - seperates everything in the cell from outside - Bi-lipid substances(made of two fats) - Semi-permeable (Somethings can flow accross them, some can't) - Small charged particles can move freely, big proteins don't 2.) Nucleus - Large organelle containing all the chromosones. 3.) Mitochondria - powerhouses of the cell... (Making ATP from Krebb's Cycle) 4.) Ribosomes - They make Proteins 5.) Endoplasmic Reticulum - Like a hi-way system moving things through the cell, sometimes ribosomes are attached to the E.R. W/=SMOOTH W/O=ROUGH 6.)Lysosomes - contain essentially a detergent which destroys the cell - suicide packets - Apotocysis - program cell death (Lysosomes are necessary for this) 7.) Cytoplasm - A sort of soup/slurry that everything is contained within. - Within the nucleus Types of Glial ----------------------- The Stickyness of the brain is due to the Glial cells. There are four kinds of Glial Cells 1.) Radial Glia - Hold neurons together 2.) Astrocytes - They take care of the garbage cells (dead cells etc..) 3a.) Schwann Cells - (Doug wrote schwinn like the bike) only exist in Peripheral Nervous system 3b.) Oligodendrocytes - only located in the central nervous system. ---- 3a and 3b =They both do the same things just in different locations. They increase the speed at which action potentials propogate down the axon Structure of the Neuron ----------------------- A neuron will have little tails that are called Dendrytes. - Most information comes through the Dendrytes. - The More Dendrytes the more locations exist for information. Dendritic Spines - small nodes on the Dendrytes - These exist on the dendrytes which facilitate information coming into the dendryte Soma - Is the cell body - the Nucleus contains the ribosomes becuase it needs to be close to the DNA Axon Hilock - swollen area at the end of cell - Creates the Axon which projects outward to an area called... The Bouton - Flat circular area at the end of the axon - Informatino leaves from this area Mylin (Depending on nervous system area is made up 3a or 3b) - They cover the axon in certain areas - They are Schwann/ Oligodendrocytes (They are wrapped around axons) Node of Ravier - Its the spots were there is no Mylin - It could be called the uncovered areas of the Axon (Doug does some silly motion with his hands to indicate a DOUBLE HELIX and asks if I'll put them in the notes) There is a gap between each neuron which is called a Synapse We have synaptic responses The synapse was discovered when a knee reflex was measured and the time it took for the signal to go to the spinal cord and back to the knee was longer than if it were just a connected cord. So it was assumed there had to be an area of space between them that took longer to pass information through. Cajal was the first to see the actual synapse area. Afrint and Efrint - The Cell that projects to Aphrint - The Cell that is projected to Ephrint If we measure the voltage of a neuron body we get a voltage of -70mV This is the resting membrane potential. So this voltage that exists across the membrane while the cell is at rest. Is -70mV. This number is due to the relationship of two charged ions. - which is made up of a charged atom (either more or less electrons than normal in its outer shell) The charged ions are K+ and Na+ (Sodium and Potassium) You'll have a high concentration of Na+ on the outside of a cell and low concentration on the inside of the cell. You'll have a high concentration of K+ on the inside of a cell and a low concentration on the outside of the cell. There exists an equilibrium potential, which is the charge needed to maintain the balance of these two chemicals. The one of these chemicals that has the most influence controls the larger amount of influence over the resting membrane potential. Na has +40mV potential K+ has -80mV potential (which is closer to -70mV) Influence in Neuro-physiology is equal are equatable to Permeability. K+ is more permeable. openings in the cell membranes are called channels. Should Na+ and K+ have the same permeability the membrane potential would be. -20mV Hypo Polarization (A lessening of the polarization) Hyper Polarization (A enlarging of the polarization) Action Potential conveys information contained within any given cell by this method. Voltage I +40 /-\Threshold (for Potassium) I 0 / \ I / \ I -40 Threshold (For sodium) I / \ I _/ \ I Hypo / \ I /--\ / voltage dependent channels I /--\ / \ / \ I----/ \---/ \--/ \------- (Resting Membrane I -70 Hyper Potential) I________________________________________ Time. Once the threshold is reached then channel will open on a timed basis for the certain Ion. Multiple Sclerosis is a disease that kills the Mylin. Which means they are actually losing nerve impulse sending lines. Inside the nerve cells are some neurotransmitters that chemically convey the information. When an action potential propogates down the bouton, it causes neurotransmitters to be released into the synapse. In the synapse 1 of 4 things can happen 1.) The neurotransmitters can get taken back into the bouton that released it. 2.) It can just float away somewhere in the synapse area. 3.) It can be eaten up by enzymes. 4.) They can diffuse all the way accross the synapse. A lock and key will exist for the neurotransmitters in the dendryte. This will open a channel in the neighboring neuron that will allow the propogation of the same message in the next neuron. Flow: Electrical--> Chemical--> Electrical--> Chemical etc... If a drug is taken then its chemical nature will be present in the synapse. Different Drugs do different things in the synapse area. Alcohol can even act as a neurotransmitters. If more and more drug presence exists in the brain sometimes it will modify its own structure by taking away some of those key holes for receptors. In the end it can produce tremmors or alcohol induced seizures, death. The health curve for Smoking is instantly bad. The health curve for alcohol use (ideally red wine) starts out positively but after about a drink every 1 or 2 days, goes into the bad zone.