4.10.11 lect. 3 wk-2 GrijalvaThe Biology of The Mind-how neurons communicate-Within the neuron electrochemical signals are generated and passed down the axon of the neuron-The axon terminal releases chemical molecules called neurotransmitters which are released into the tiny gap junction called the synapse to influence a neighboring cell./vesicles are filled with neurotransmitters/ the second cell responds to neurotransmitters because of a receptor-the receptor is on the dendrites of the receiving cell or the cell body-something activates neuron to create impulse coming down axon and the second cell is inhibited-neuronSynapse soma (cell body) axonsynapse-probes can be inserted in a neuron to stimulate a neuron or take a part of it to study individual neurons- a shape of a neuron can tell you what it does- if there are a lot of dendrites on a neuron then it may be integrating a lot of information- an action potential is an impulse-depolarization: the inside of the cell becomes positive/- neurons have a cell membrane made up of two fatty layers/ certain things can be translated fast and some things slow through the cell membrane/ protein molecules, located on have channels that can open and close and be specialized for certain molecules/ there are electrically charged particles inside / these channels can be activated to open and they respond to a charge in the cell so they are voltage / receptorscan be activated chemically/ electrically charged particles(ions/potassium/ sodiumproteins) go through channels/ -negative voltage: resting potential/ alive but not sending a message-semi-permeable membrane: some proteins go through and some do not-permeability: if the protein has a high permeability it will go easily through the membrane-a negative charge ion(protein/sodium) will pull in positive charged ions and repel negative charge ions/ they are inside cells-if something is high in concentration than the other it will try to equal out which is why the negative ions will try to attract positive ions/ if the membrane is not permeable to the ion then it wont go throughthe cell membrane- between the cell body and the beginning of the axon is the axon hillock-the neuron is affected by neurotransmitters but something has to happen to the neuron for it to act at the axon hillock-the neurotransmitter opens up the channels to allow certain ions to enter - the more sodium channels opened up, the more positive the inside of the cell membrane becomes and the more it opens up and then the action potential happens-threshold of excitation: value of potential that must be reached to generate an action potential/ the more negative, the further away from the threshold-depolarize: become less negative-action potential: opening and closing of channels-the inside of the membrane becomes more positive when sodium rushes in and causes the neighbor to open up causes more sodium to come in/ as soon as one channel opens up it closes and others open to get it back to its resting state which is called the propagation of action potential- if the stimulus is too low the neurons do not fire/ if the neurons do fire it will send the signal in the same way (same size and shape) despite how strong the stimulus is/ a stronger stimulus will activate more neurons and cause it to fire faster but the size and shape will stay the same-voltage gated channels: as soon as the sodium rushes in it cause the voltage to change and activates neighboring channels/ entry of charged particles that activate other entries-axons are 10meters per second-adding myelin to the axon will speed up the transmission/ myelin is wrapped around the axon/ no protein can get into axon if myelin is on the axon/ the protein gets through on the unmyelinated part of the axon called nodes-if myelin gets destroyed disabilities can occur/ myelin is developed during the childhood-sodium potassium pump: neuron gets back to resting state- neurotransmitters bind to receptors site and if it’s the appropriate neurotransmitter the channel will open then the ion(neurotransmitter?) will rush into the cell/ if more sodium channels open then more sodium will go in-receptor sites are on the proteins-things that act like a naturally occurring neurotransmitters are agonists-seratonin and dopamine (localized in the midbrain) are neurotransmitters/ they are pathways-once a neurotransmitter is released it is taken up by the neuron that released it and be repackaged called a reuptake inhibitor/ leaves it in there longer-dopamine (neurotransmitter)- tied into pleasurable experiences/ increase activity in dopamine will cause pleasure and can be addictive-the endocrine system: certain molecules are released by a gland into the blood stream and the blood stream acts like a synapse and conveys messages-pituitary gland releases hormones that are inhibiting or excitatory factors/- the endocrine system regulates its self/ negative feedback system which turns off hormones-the hypothalamus monitors a lot of things that happen in the body/ it controls the pituitary gland-the pancreas can be regulated by the brain or activated by substances in the bloodstreamBrainHindbrain- brain stem (medulla, pons)/ breathing, coughing, life sustainThe medulla (vital reflexes such as breathingPons (contains nuclei of some of the cranial nervesMidbrain- reflexive behaviors linked to auditory and visual perception; pain perception; gross sensorimotor functionForebrain-hypothalamus and limbic system (motivation and emotion)/ neocortex (elaboration of sensory and motor functions, cognition, lang. etc. / outer layer of cerebrum)Reticular formation- arousal and attention/ descending portion controls certain motor functions in the spinal cord/ a network of neurons in the medulla and other parts of the brain stem(medulla, pons, midbrain, and certain parts of the forebrain)Cerebellum- voluntary movement, non-verbal learning, balance, refining sensory guided