1. WARM UP “The secret of action is to begin.”
What does this mean to you?
How can you apply this to Biology II?

2. Nerve Tissue

3. Levels of Organization
Organism
Organ System
Organ
Tissue
Cell
Organelle
Molecule
– Atom…
Each level depends on many cooperating structures at the levels below

4. Nervous System Quick control over all body functions
Electrochemical signals

5. Nervous Organs
Brain
100 billion neurons forming connections

6. Nervous Organs Spinal cord Bundled neuron pathway
Protected by meninges and vertebrae

7. Nervous Organs Spinal cord con’t…. Structure
White matter: axons w/ sheath
Gray matter: dendrites, cell bodies, neuroglials
Central canal

8. Nerve Tissue Made of connected neurons and neuroglial cells
Control over responses
Transmit electrical and chemical signals

9. Nerve Cell – The Neuron Dendrites receive info
Cell body, with trigger zone at end
Axon sends impulses

10. Nerve Cell – The Neuron Axon sends impulses
Myelin sheath, made of Schwann cells, wraps around axons and speeds up signals

11. Electrochemical Nerve Signal
Reversal of charge
(– to + to –)
Travels down axon

12. Electrochemical Nerve Signal
Controlled by ion flow
Sodium+ pumped in
Potassium+ pumped out

13. Electrochemical Nerve Signal
Neurotransmitters cross synapse
Acetylcholine
Serotonin
Norepinephrine
Dopamine
GABA
Received by receptors

14. WRAP UP
Which part of a neuron is most important, and why?

15. WARM UP
Explain why nerve signals are described as “electrochemical.”

16. WRAP UP
List the 3 parts of a neuron and describe the function of each.