1. AP Biology
Nervous Systems
Part 1

2. Step 1: Reception

3. Step 2: Transduction

4. Step 3: Response

5. 150 mM KCl 150 mM NaCl –92 mV +62 mV Inner chamber Outer chamber Inner
Ions and Energy
–92 mV
+62 mV
Inner
chamber
Outer
chamber
Inner
chamber
Outer
chamber
150 mM
KCl
5 mM
KCl
15 mM
NaCl
150 mM
NaCl
Cl– K+
Na+
Cl–
Potassium
channel
Sodium
channel
Artificial
membrane

6. Evolution of a Nervous System
Everything starts with the evolution of an organism-wide nerve net in Cnidarians  helps to control movement.
Then, evolution of a “brain” helps lead to greater control  utilization of a nerve cord to span the whole body.
Cephalization through the evolution of a “head region” allows for reception and response to many different stimuli.

7. Evolution of a Nervous system in Animals

8. Overview of the Nervous System
Sensory Input: sending information into the brain or spinal cord.
Sensory receptors found within the body receive a stimulus from outside environment.
A stimulus is a form of energy such as light, chemicals, pressure or sound waves.

9. Overview of the Nervous System
2. Integration: this is the interpretation of the energy by the CNS.
This interpretation of the stimulus leads to a determination of what the appropriate response will be.

10. Overview of the Nervous System
3. Motor Output: sending out impulses from the brain and spinal cord to glands or muscles to create a response.
This response is carried out by effector cells – these structures can have an effect on the body.

11. CNS vs. PNS Central Nervous System (CNS)
- This includes the brain and spinal cord.
This part of the nervous system does the overall “thinking” about stimuli that the body receives.
Peripheral Nervous System (PNS)
This includes all sensory receptors and motor nerves that spread out throughout the body.
This part of the nervous system carries out the response to stimuli.

12. Neuron structure
Neuron Structure: cell body, dendrites, axon, myelin sheath, synaptic terminal, synapse, neurotransmitters, presynaptic cell, postsynaptic cell

13. Synapse and Neurotransmitter
Nerve signals must move through local communication (synaptic communication). This means that each neuron does not physically touch the next. All signals must transition between electrical and chemical messages.
This all takes place at the synapse!

14. Schwann Cells OR Oligiodendrocytes
Nodes of Ranvier
Layers of myelin
Axon
Schwann
cell
Schwann
cell
Axon
Nodes of
Ranvier
Nucleus of
Schwann cell
Myelin sheath
0.1 µm