The Nervous System

1. The Nervous System

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

3. CNS and PNS

4. Neurons • AKA: Nerve Cells • Transfer electrical impulses to/from the brain • 3 Main Parts • Cell body: contains nucleus and organelles • Dendrites: branches that receive messages from neighboring cells • Axon: extension that carries messages away from the cell body

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

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

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

8. Resting Potential • Defined: Neuron at rest • Neuron Exterior is positive in charge due to abundance of Na+ outside K+ Interior K+ K+ K+ K+ K+ K+ K+ K+ • Neuron Interior is negative due to abundance of proteins, but… • Some K+ inside the cell

9. Action Potential • Defined: Electrical impulse is triggered & moves quickly down axon • Generating the Impulse • Na channels open and allow Na+ to enter 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

10. impulse

11. Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ impulse K+ K+ K+ K+ impulse K+ K+ K+ impulse 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+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+

12. 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 (use of ATP)

13. Na+ Na+ Na+ Na+ K+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ K+ Na+ Na+ Na+ Na+ Na+ K+ K+ Na+ Na+ Na+ Na+ Na+ K+ Na+ K+ Na+ Na+ K+ K+ K+ K+ K+ Na+ K+ Na+ Na+ K+ K+ Na+ Na+ Na+ K+ K+ K+ K+ Na+ Na+ K+ Na+ K+ K+ K+ Na+ Na+ Na+ Na+ Na+ K+ K+ K+ Na+ Na+ Na+ Na+ Na+ K+ K+ K+ Na+ Na+ Na+ K+ Na+ Na+ K+ Na+ K+ K+ Na+ Na+ Na+ Na+ Na+ Na+ K+ Na+ Na+ Na+ Na+ K+ Na+ Na+ Na+ Na+ Na+ K+ Na+ Na+ Na+ Na+ K+ Na+ Na+ Na+ Na+ K+ Na+ Na+ K+ Na+ Na+ Na+ K+ Na+ Na+ Na+ K+ K+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ K+ Na+ Na+ K+ Na+ Na+ Na+ Na+ Na+ K+ K+ K+ K+ K+ K+ Na+ K+ Na+ Na+ Na+ Na+ Na+ K+ K+ Na+ K+ Na+ K+ K+ Na+ Na+ Na+ Na+ Na+ Na+ K+ Na+ Na+ Na+ K+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+

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

17. Na Na Na Vesicle exits the cell and dissolves impulse impulse impulse K K K Impulse reaches the axon terminal Dendrite of another cell Terminal end of one cell

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

19. Brain impulse …. neurotransmitters impulse …. neurotransmitters impulse …. neurotransmitters impulse …. neurotransmitters impulse Feet

20. Impulses eventually reach the muscles… and causes MOVEMENT!

21. Kobe Kuiz • What is the function of the nervous system? • List the 3 main parts and describe the purpose of the 3 main parts of a neuron. • Describe the internal and external environment of a neuron in resting potential. • What is a synapse and why is it a problem for neurons? • What are the roles of the following during an action potential? • NA+ • K+ • Neurotransmitters