lecture 15 Flashcards
how do neurons connect with other cells and make complex networks
through synapses
neurons can connect through what two things
electrical or chemical synapses
electrical
fast but limited communication (rare)
chemical
slower but diverse responses in post synaptic neuron
what do electrical AP cause
cause ions to travel through gap junction channels to another cell (neurons touching)
what do chemical AP cause
causes opening of CALCIUM channels that release NT (spaces between cells)
how do neurotransmitters (chemical signals) work
they bind to a receptor (ligand gated) channels in the post synaptic membrane and change ion diffusion and therefore local membrane potential
almost all cells have uneven distribution of ions which are (chemical gradient)
potassium and sodium
outside of cell is
positively charged sodium
inside of cell is
negatively charged potassium
synapses cause post synaptic potentials that are
graded, small, and decay with distance
if sodium enters a cell, the cells can use this to
start an AP
postsynaptic potential
change charge
cell body have what channels
ligand gated
axons have what channels
voltage gated
what is a summation
multiple synapses add together in time or over space influence threshold at the axon hillock
what can a summation to do a cell
mechanism of eliciting an AP in a neuron with input from multiple pre synaptic cells
more ancient/simple nervous systems are
diffuse focuses on reaction (sea anemone, seastar)
what does it mean a diffuse focused nervous system
sea anenome and sea stars have radial symmetry and diffuse nervous system based on nerve nets, NO CNS (all neurons talk to each other)
what is an advantage to this simple nervous system
if a predetor eats part of the animal, it can regenerate and existing cells connect with the new ones so its easier to replace
what is a limitation to these simple nervous systems
no complex tasks can be done
animals have evolved to become more
centralized causing cephalized nervous systems
cephalization
evolutionary trend in which the mouth, sense organs, and nerve ganglia become concentrated at the front end of an animal creating a head region
the areas responsible for integrating information cluster to make a
CNS
