AP Psych Unit 3 Notes
^^Neural Communication^^
- Neurons, nerve cells are the basic building block of the nervous system
- Each neuron consists of a cell body and its branching fibers
- Bushy dendrites receive messages and conduct impulses toward the cell body
- Lengthy axons fiber passes the message through the terminal branches to other neurons, muscles, or glands.
Dendrites listen. Axons speak.
- Some axons are encased in a myelin sheath that insulates and speed their impulse.
- Neurons transmit messages when stimulated by signals from our senses or when triggered by neighboring neurons. In response neurons fire an impulse called action potential-a brief electrical charge that travels down its axon
- Like batteries neurons generate electricity from chemical events.
- Axons contain ions (electrically charged atoms) within its fluid which are negatively charged inside its membrane and positively charged outside its membrane.
- Positive-outside/negative-inside state is called resting potential
- Neurons receive signals from other neurons which are either excitatory (state of enhanced activity or potential activity) or inhibitory (brake).
- If excitatory signs exceed inhibitory signals by a minimum threshold the signals trigger an action potential and the neuron fires
- Neuron firing potential is an all-or-none response.
- Post-fire is a refractory period-which is a period of inactivity after a neuron has fired.
^^How Neurons Communicate^^
- Neurons are interwoven. However tiny gaps exist between the axon tip of the sending neuron and the dendrite or cell body of the receiving neuron called a synapse.
- When action potential reaches an axon’s end it triggers the release of chemical messengers called neurotransmitters. Neurotransmitters cross the synaptic gap and bind to the receptor sites on the receiving neurons.
- Neurotransmitters unlock tiny channels allowing ions to flow in which either excites or inhibits the receiving neuron. Excess neurotransmitters are reabsorbed by the sender-reuptake
- Endorphins a natural opiate-like neurotransmitter linked to pain control and pleasure
- Our bodies release several types of neurotransmitters molecules similar to morphine in response to pain and vigorous exercise-explains runners high