Nerves/synapse 1 Flashcards
what is the CNS comprised of?
comprised of the brain and spinal cord
What is the PNS comprised of and the enteric nervous system?
The PNS contains all of the sensory neurons that carry information from the outside world to the CNS, from the neurons in the organs to the CNS, and signals from the CNS to the organs- the efferent and afferent and afferent fibers connect to the enteric nervous system.
characteristics of neurons
1) neurons are complex electrical cells which allow them to transmit information from one place to another
2) they can communicate with each other (this takes places in synapses)
Human nervous system contains hundreds of trillions of synapses, creating neural networks of vast complexity
3) neurons come in an emormous range of shapes and sizes
what is a soma (cell body)
keeps the neuron alive
includes the nucleus, DNA and protein synthesis
what are dendrites?
“processes” that branches out from the cell body, receiving input that is coming in from other Neurons (kind of like antennae), they also contain the synapses
cells with more dendrites= more synapses= more info they can receive
what is an axon?
1) propagates electrical signals from one part of the nervous system to another
2)they extend from one part of the body to another ( it is what connects the one part of the body to the brain)
3) they can extend from millimeters to more than one meter
what is a presynaptic terminal?
the end of an axon
describe the informational flow of neurons
Neurons are “functionally polarized” meaning that info flows
into the synapses on the dendrites —> soma —> Axons—> out to a different neuron
describe the resting membrane potential of a neuron?
The voltage inside of the neuron is 60 to 70 mV more negative compared to the outside of the cell, caused by a small excess of negatively charged ions inside the cell. therefore, the resting membrane potential of a neuron is -60 mV to -70 mV
2 properties that created the resting membrane potential
2 properties that created the resting membrane potential: concentration gradient for various ions such as Na+, K+, Cl- and A- (any anion) AND the fact that the membrane is selectively permeable to K+ ions at rest
why is the inside of the cell more negative?
The charges inside and outside the cell both add up to 0, the membrane is selectively permeable to K+ meaning that K+ ions will escape the cell at rest and create a relative negative charge inside the cell
the - charges ions are left behind but the K+ ions escape into the ISF.
