PS263 Lecture Notes - Lecture 2: Excitatory Synapse, Motor Neuron, Sensory Neuron
Document Summary
Reflex arc: most joints can move in 2 directions, have 2 opposing muscles that allow this movement, activate one muscle, relax/deactivate/suppress opposing muscle. I(cid:374)hi(cid:271)itor(cid:455) s(cid:455)(cid:374)apse (cid:271)et(cid:449)ee(cid:374) i(cid:374)ter(cid:374)euro(cid:374)/(cid:373)otor so does(cid:374)(cid:859)t fire: causing this muscle to relax (not contract) Knee-jerk reflex: sensory neuron detects hit into spinal cord, connects to one motor neuron activates muscle that contracts knee, also interneuron to cause hamstring muscle to relax. Inside and outside the cells are ions (so(cid:373)e (cid:272)a(cid:374) (cid:373)o(cid:448)e/(cid:272)a(cid:374)(cid:859)t (cid:373)o(cid:448)e: sodium: na, potassium: k, calcium: ca+2, chlorine: cl- Ions move down gradients: chemical gradient, want to equalize concentration (high con. Low con. : more likely to move where there are fewer ions, electrical gradient, larger positive charge lower positive charge, want to equalize electrical gradient. 2 k to inside: uses molecule of atp to do so, creates ion gradient, lots of na outside the cell and lots of k inside the cell.
