-Prevents the skull from being crushed along with the spinal cord d.iii.6.Olgodenrocytes d.iii.6.a.Myelination of the Central nervous system axons d.iii.6.b.“think of taking gum out of your mouth and keeping it on your finger and wrapping it around your finger” d.iii.7.Satellites cells d.iii.7.a.Similar to astrocytes d.iii.7.b.They are support cells, surround cell bodies and ganglia d.iii.8.Schwann cells
d.iii.8.a.Myelination of the peripheral nervous system d.iii.8.b.Can only myelinate one at a time d.iv.Internode and Node d.iv.1.Internode where is there is myelin d.iv.2.Node where there isn’t myelin -3 types of capillaries -continous capillaries – endothelial cells with tight junctions -fenestrated capillaries – kind of leaky – found where you want blood to diffuse-sinusoid capillaries – huge gaps between endothelial cells – found where you want blood to move – i.e. bone marrow3.Neurophysiology a.The Resting Membrane Potential a.i.Passive forces a.i.1.Chemical gradients a.i.1.a. Potential energy a.i.1.b. Resistance a.i.1.b.i.Bilayer is a resistor a.i.1.c. Potassium leak channelsa.i.1.c.i.When potassium leaves, it causes a current which all leads to the RMP a.i.1.c.ii.Plasma membrane can actually store a charge a.i.2.Electrical gradients a.i.2.a. Capacitance a.i.2.a.i.The ability to hold a charge a.i.3.Electrochemical gradient a.ii.Active Forces a.ii.1.Sodium potassium pump
a.ii.2.3 sodium out, 2 potassium in b.Changes in transmembrane potential b.i.Ligand gated channels b.ii.Voltage gated channels b.ii.1.Opens when there is a change in voltage in the plasma membrane b.ii.2.When you polarize the membrane, the inside of the cell is less negative so the gate opensb.ii.3.Extracellular gate b.ii.3.a.Activation gate - closed at - 70b.ii.4.Intracellular gate b.ii.4.a.Inactivation gate - closed at +30b.iii.Mechinical gated channel c.Graded Potentials (local potential) c.i.Dendrites contain ligand gated channels c.ii.Stimulus, acetychloride, binds to the ligand gate which causes the gate to open leads to a graded potential c.iii.The distribution and importance of graded potential c.iii.1.Axon hillock c.iii.1.a.“the brain area of the nerve” c.iii.1.b.The integration area of the nerve c.iii.2.Initial segment of an axon c.iii.2.a.Originates action potential c.iii.2.b.Contains voltage gated channels c.iii.3.Spike initiation zone c.iii.3.a.Sodium is coming into the axon hillock c.iii.4.Local potential/graded potential c.iii.4.a.Occurs as a result of ligand gated channels
c.iii.4.b.Rmp via voltage gated potassium channelsc.iii.4.c.Less widespread, change in membrane potential doesn’t go very far c.iii.4.d.Chloride ions coming in means you getting hyperpolarized c.iii.4.e.Sodium and calcium come in means you are getting depolarization c.iii.4.e.i.More sodium getting in means more depolarizationc.iii.5.Action potential c.iii.5.a.Can be spread all along an axon c.iii.5.b.Occurs due as a result of voltage gated channels c.iii.5.c.