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Lecture 5

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Human Biology

Lecture 5-Nervous system II Membrane potential, used to communicate  UPSH: pink, green or yellow. Some individuals called backyard brains. You see a bunch of different colors and you have one common nerve and you attach it to an electrode, every time a base note is hitting, you will see the chromoferes being released. Watch the video\  Actual nervous system is like a circuit board, you can pass the electricity from an electron server to a living organism.  This is all because of changes of membrane potential\  In a cell, you will have a resting membrane potential thatwill vary. Resting membrane around -70. If there is in flux of more postivie ions and cells become more + on the inside =depolarization, if its negative on the inside called repolarization  Your gonna have a lot more Na on the outside and K on the inside. WHY? The sodium potassium pump is gonna be regulating the amouints which lead to a resting membrane potential.  With regards your gonna have a more – on the inside because you have + outside. 3 sodium OUT 2 potassium IN. The inside of the cell has a more – charge.Neurons have a resting membrane potential. Neurons are excitable. Excitable is a rapid change inMV. DEPOL- interiorbecoming more positive; Na comes in. HYPERPOLARIZATIOn- interioris becoming morenegative; k comes in.repolarization- your membrane returns to its resting value. Changes in the membrane potentials act as electrical signals  Neurons receive from receptor, cgoes through the intergrating centre. Cell body + dendrites receive the info. It gets integrated in the axon hilack. At the axon hilack is where the cell determines if there is going to be an axon potential . IF YESH; it goes through mylenated sheath [go fast] + signal comes out through the axon terminal. Since it’s a muscle cell, its going to be a neurotransmitter SIGNALS IN DENDRITES + CELL BODY Receptors on the cell body + dendrites. WHAT HAPPENS? The receptor is gonna transducer the info into the cell. USUALLY their voltage gated that will lead to changes in the ion. With the receptor your transducing a chemical reaction. Electrical cell is the ion permeability. The change in the ion permeabiklity causes a gradient condition. Within the dendrites + cell body, there is always a gradient bodyl Its limitied by distance + size. Stimulus strength + graded potential Graded potentials vary in magnitude depending on the strength of stimulus. If it has a lot of neurotransmitters= bigger signal. More neurotransmitter: more ion channels will open . If it’s a electric signal: WATCH THIS PART**** Chemical synapse: ligand from a foreign cell Eklectrical signal: More direct Ligand gated will only open when a ligand binds. Can depolarize cell: open Na+/Ca2+ Can hyperpolzarize cell –open K+/Cl- channels Graded potentials are dependent on the type of stimulus -GP can vary in size: depending on the binding, the amount of neurotransmitters. AN AP is always gonna be one size: ALL OR NONE. Graded potentials are short distance signals Electrotonic spread: + charge spreads throughou
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