Wed 2 4 15 Lecture 10 Receptor Activation Decrease Communication Messenger catabolize Receptor o Decrease Affinity o You catabolize the ligand so it doesn t bind to the receptor You change the shape or charge o hide receptors endocytosis catabolize 2nd messenger inactivate o Ex we could go after JAK kinase or the G protein You could inactivate the secondary messenger either JAK kinase or G protein to halt the activity even though the original 1st receptor was activated by a ligand o Only applies to membrane bound receptor because intracellular receptors don t have 2nd messenger Increase communication Increase the number of receptors o For membrane bound we would exocytose o For intracellular receptors we anabolize Nervous System 2 main groupings Central and Peripheral o Central o Peripheral Brain and spinal cord Acts like the integrating center all other nerves except the brain and spinal cord acts as affector to send messages to brain and acts as effector to send messages back to the body Rapid control system central peripheral Contrast to endocrines o It is a faster communication pathway and more specific Start at the smallest unit neuron Anatomy of a Neuron Like every cell it has a main area of the cell called the cell body Cell body has nucleus Wed 2 4 15 o Not every cell has the nucleus ex red blood cells Processes o connection to other cells o The points where we see input and output happening o Perform input output o 2 categories of processes 1 Dendrites Some neurons could have 400 000 More dendrites able to communicate to more cells Gather information o Neurotransmitters o Environmental stimuli Falling and hitting your head puts pressure put directly on neurons and stimulates them hence why you see stars when you fall Increase surface area o Allows for more receptors so we are more likely to pick up neurotransmitters Some long up to a meter long aka 3feet ALS Lou Gehrig s Disease the protein that support the structure of the nerve start breaking down and so mechanically bending nerve ex bend your knee breaks the nerves 2 Axon aka nerve fiber Cell body to effector o Delivers information o Via Axon terminals o Release neurotransmitters Collaterals o Branch that comes off the side of an axon Can communicate with other cells more o Allows further influence of neurons Myelin o Other cells o It is one cell that has wrapped itself around and around and around the axon o Specialized extension of plasma membrane o Wrapped around axons for insulation Wed 2 4 15 Think about wire in a house that have protective coverings around them In the PNS Schwann cells cover one axon Schwann cell creates myelin in the nervous system One cell myelinates one section of one axon Longer axon need more Schwann cells In CNS oligodendrocytes cover several Covers multiple parts of an axon and can also cover several different axons Oligo a few it covers a few different axons o Nodes of Ranvier Breaks exposes axon to interstitial fluid Openings gaps in between the myelinated part of the axon Gives us access to interact with the interstitial fluid CNS Composition Neurons glial cells aka neuroglia o Physically and metabolically support neurons o 90 of the cells but 50 of the volume of CNS 4 Types of glial cells o Oligodendrocytes see above Type of glial cell Provide myelin on axon Its actual cell body is NOT on the axon it just send out a projection of its membrane to wrap around the axon o Microglial There are immune like cells There are Macrophage like cells Cells of your immune system that go around and eat things that aren t supposed to be there This is basically like out immune system being present in our CNS Don t use normal marcophages because they travel through the blood and the brain has a blood brain barrier BBB Physically and metabolically support the neurons o Ependymal cells Eh PEN deh mal Barrier between cerebral spinal fluid CSF and the interstitial fluid Barrier between two extracellular fluids Wed 2 4 15 o Keeps pathogens out of our brain and spinal cord o The cells form this barrier o Do not constitute blood brain barrier They are NOT epithelial cells Only in the CNS Regulate the amount of fluid present in CSF have tight junctions between themselves Know this Keeps the CSF clean o Astrocyte Nutrients metabolic support Delivers glucose to neurons and remove ammonia Regulates CSF composition Removes K and neurotransmitters o Higher level of potassium inside the cell o Remove neurotransmitters so the signal doesn t stay bound to a receptor and keep the signal going o Analogy leaving a note otherwise the signal keeps going Stimulates tight junctions in capillary walls of the CNS Blood Brain Barrier o They don t make tight junctions they just make the junctions tighter o Keeps pathogens away from neurons because it doesn t allow an plasma flow Metabolic support glucose and ammonia o Make glucose available and removes The make sure the good things are present and the ammonia Neural growth bad things are not Signal system They can act like neurons
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