The Nervous System and Neurons

Is this even possible? Why or why not?

Network of connected cells, tissue, and organs Controls thoughts, movement, life processes Quick responses – Ex: Sunny day  pupils shrinking Nervous System

CNS and PNS

AKA: Highly specialized nerve cells – Transfer electrical impulses to/from the brain 4 Main Parts 1)Cell body: contains nucleus and organelles 2)Dendrites: branches that receive messages from neighboring cells 3)Axon: extension that carries messages away from the cell body 4)Axon Terminal: End of neuron Neurons

Three Types of Neurons: 1) Sensory – Detect stimuli and transmit signals to/from the brain – Detect sense (sight, smell, sound, taste, touch)

2) Interneuron – Located in the brain – Receive signals from the sensory neurons Three Types of Neurons:

3) Motor – Pass messages to other tissue – Ex: Nerve attached to muscle Muscle reacts by contracting and stretching Three Types of Neurons:

Resting Potential Defined: Neuron at rest Neuron Exterior is positive in charge – Due to abundance of Na + outside Neuron Interior is negative –Due to abundance of proteins and… – Some K + inside the cell K+ Interior

Action Potential Defined: The electrical impulse that is triggered & moves quickly down an axon Generating the Impulse – Na channels in the membrane open and allow Na + to diffuse into the cell – Area becomes positively charged (impulse) After the Impulse – K channels open to allow K + to exit the cell – Area returns to negative charge Process continues down the axon

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Na + K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ impulse

Cleaning Up the Mess Who? – Na/K pump What? – Na is pumped back out of the cell… – K is pumped back into the cell When? – After the impulse has passed Where? – Located in cell membrane Why? – To restore the initial charge inside & outside the cell How? – Active transport (REQUIRES ATP)

Na + K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+

Synapse Defined: Gap between neurons Problem: Impulse cannot cross the gap Solution: Neurotransmitter proteins are sent from one neuron to another Steps: 1) Impulse reaches axon terminal (end) 2) Vesicle releases neurotransmitters, which attach to receptors on neighbor 3) Channels open on dendrite of neighboring cell…new impulse created Neurotransmitter proteins

Impulse reaches the axon terminal Vesicle exits the cell and dissolves Terminal end of one cell Dendrite of another cell Na imp ulse K Na imp ulse K K

Neurotransmitters diffuse across the synapse and attach to receptors of a neighboring neuron Neurotransmitters cause Na channels to open… creating new impulse Terminal end of one cell Dendrite of another cell Na K K imp ulse Na imp ulse K

Feet Brain …. impulse neurotransmitters

and causes MOVEMENT! Impulses eventually reach the muscles…

1. What is the function of the nervous system? 2. List the 4 main parts and describe the purpose of the 4 main parts of a neuron. 3. The nervous system is divided into 2 parts. What are they and what do they include? 4. Describe the internal and external environment of a neuron in resting potential. How is resting potential reached? 5. What is a synapse and why is it a problem for neurons? 6. To what part of the nervous system do motor neurons, interneurons, and sensory neurons belong? 7. When an impulse is within a neuron it is electrical. When the signal moves to the next neuron it is _________________. What is the specific name for this? 8. Describe how an action potential moves down a neuron. ReView