Write everything that is BLACK Section 29-2 “Neurons” Write everything that is BLACK

State Standards As a result of the coordinated structures and functions of organ systems, the internal environment of the human body remains relatively stable (homeostatic) despite changes in the outside environment. As a basis for understanding this concept: D. Students know the functions of the nervous system and the role of neurons in transmitting electrochemical impulses. E. Students know the roles of sensory neurons, interneurons, and motor neurons in sensation, thought, and response.

KEY CONCEPT The nervous system is made up of highly specialized cells.

Neurons are highly specialized cells. A neuron (nerve cell) has three parts: the cell body has nucleus and organelles Draw & Label Picture below 1 Cell body

Neurons are highly specialized cells A neuron (nerve cell) has three parts: the cell body has nucleus and organelles the dendrites receive (get) impulses 2 dendrites

Neurons are highly specialized cells A neuron (nerve cell) has three parts: the cell body has nucleus and organelles the dendrites receive (get) impulses the axon carries impulses 3 axon

Neurons have other structures to transmit signals: Schwann cell (shwän-\) these insulate the neuron (like the plastic coating around electrical cords)

Neurons have other structures to transmit signals: Schwann cell Synapse (si-naps) This is where the 2 neurons join together

Neurons have other structures to transmit signals Schwann cell synapse axon terminal (end of the axon)

Neurons receive and transmit signals Resting potential means no signal is being transmitted more Na+ outside of cell (Na + is sodium ion) more K+ inside of cell (K + is potassium ion)

An action potential is a moving electrical impulse It is generated by a stimulus. Na+ enters, and cell becomes positively charged. K+ leaves, and area of positive charge moves area of detail

There’s a little space where the synapse is so the neurons don’t actually touch …. they need a chemical messenger to get across the gap Neurotransmitter: chemical message that stimulates the next neuron in the chain You have lots of these in your brain and around your body: seritonin, adrenaline, dopamine They make you feel happy, sad, excited Depression can be caused by an imbalance of these neurotransmitters Drug use (heroin, cocaine) will also cause these to become imbalanced

A chemical signal passes between neurons Impulse reaches terminal These are 2 different neurons (axon to dendrite)

A chemical signal passes between neurons Impulse reaches terminal

A chemical signal passes between neurons Impulse reaches terminal Neurotransmitters released into synapse synapse impulse neurotransmitter vesicles receptor

A chemical signal passes between neurons Impulse reaches terminal Neurotransmitters released into synapse Neurotransmitters stimulate next cell synapse impulse neurotransmitter vesicles receptor Watch Neurons BrainPOP w/ Activity HO