Neurons are the basic "brain" cells. They're the workhorses of the nervous system. Glial cells have a supporting role in getting neurons to work (this is an area of ongoing research).
Dendrites are the ears of the neurons.
Cell body - nucleus, DNA source, or energy.
Axon - long cable reaching out to next outpost leading to the axon terminals. These are the mouth.
A wave of excitation leads to sending out its message. It flows from the dendritic end to the axon terminal. It's started by the message received at the dendritic "ear."
The challenge is - what gets sent on? It's not a one on one deal; it's a 100 to 1 deal with tons of messages coming through and only some being listened to.
Resting potential - charged ions outside the neurons, waiting for activation. A whole bunch of sodium outside for quiet (potassium in). For screaming, sodium in, potassium out. Activation.
Neurons invest about half of their energy keeping these two separated. Now if you have insufficient energy to keep them separated, you are at risk for neurological disease.
Neurons spend a fortune being quiet.
Excitation begins at the dendrites. When they are triggered they send a wave of excitation down the cell body to the axon and axon terminal. But it must be enough of a wave to reach the level of an action potential. You've got to have summation (one neuron firing over and over again is temporal summation), which is a whole bunch of neurons also firing into it at once (spatial summation). The wave then must pass over the axon hillock. Get over this and it'll head on out as an action potential.
Individuals differ in the levels of all of these things. The differences are subtle but can account for individual differences in personality, disease and intelligence.
Hormones and context impact the axon hillock's willingness to listen (sometimes a mild stimulus will get passed on, other times a massive one won't).
Your average neurons have about 10,000 of all these parts (not really, just an estimate).
Myelin sheath (glial cells) accelerates the action potential. As we age, the developmental landmarks are associated with the myelination of the brain centers.
Multiple sclerosis - the immune system attacks the myelin.
Dendrites are the ears of the neurons.
Cell body - nucleus, DNA source, or energy.
Axon - long cable reaching out to next outpost leading to the axon terminals. These are the mouth.
A wave of excitation leads to sending out its message. It flows from the dendritic end to the axon terminal. It's started by the message received at the dendritic "ear."
The challenge is - what gets sent on? It's not a one on one deal; it's a 100 to 1 deal with tons of messages coming through and only some being listened to.
Resting potential - charged ions outside the neurons, waiting for activation. A whole bunch of sodium outside for quiet (potassium in). For screaming, sodium in, potassium out. Activation.
Neurons invest about half of their energy keeping these two separated. Now if you have insufficient energy to keep them separated, you are at risk for neurological disease.
Neurons spend a fortune being quiet.
Excitation begins at the dendrites. When they are triggered they send a wave of excitation down the cell body to the axon and axon terminal. But it must be enough of a wave to reach the level of an action potential. You've got to have summation (one neuron firing over and over again is temporal summation), which is a whole bunch of neurons also firing into it at once (spatial summation). The wave then must pass over the axon hillock. Get over this and it'll head on out as an action potential.
Individuals differ in the levels of all of these things. The differences are subtle but can account for individual differences in personality, disease and intelligence.
Hormones and context impact the axon hillock's willingness to listen (sometimes a mild stimulus will get passed on, other times a massive one won't).
Your average neurons have about 10,000 of all these parts (not really, just an estimate).
Myelin sheath (glial cells) accelerates the action potential. As we age, the developmental landmarks are associated with the myelination of the brain centers.
Multiple sclerosis - the immune system attacks the myelin.
