PHSI 208 Lecture Notes - Lecture 6: Ependyma, Growth Cone, Schwann Cell
Document Summary
Synapses = space contains extracellular matrix (proteins and carbohydrates) that hold the pre and post synaptic cells in close proximity. The proteins and carbohydrates link the pre and post synaptic cells. Neurons find correct targets by depending on chemical signals. Axons of embryonic nerve cells contain growth cones that sense and move towards particular chemical signals. Growth cones depend on growth factors, molecules in extracellular matrix and membrane proteins. Once reaching a target cell a synapse forms. Synapse must be maintained through repeated use, (cid:862)use it or lose it(cid:863) *it happens in waves, certain areas of the brain will become active at certain times to find their target. *whe(cid:374) (cid:449)e are (cid:271)or(cid:374), s(cid:455)(cid:374)apses are(cid:374)"t (cid:272)o(cid:373)pletel(cid:455) for(cid:373)ed though (cid:449)e ha(cid:448)e (cid:373)ost of the (cid:374)euro(cid:374)s that we will ever have as you grow you will increase the size of neurons in the formation of synapses. Initially believed to outnumber neurons by 10-50 to 1, more recently ~1-4 to 1.
