1. Neurons and Neural Anatomy

2. Nervous System Central nervous system (CNS): Brain Spinal cord
Peripheral nervous system (PNS):
Sensory neurons
Motor neurons (somatic and autonomic)

3. The Nervous System The Nervous System Central Nervous System (CNS)
Peripheral Nervous System (PNS)
Brain
Spinal Cord
Motor Neurons
Sensory Neurons
Somatic Nervous System
voluntary movements via skeletal muscles
Autonomic Nervous System
organs, smooth muscles
Sympathetic
- “Fight-or-Flight” responses
Parasympathetic
- maintenance

4. Divisions of the autonomic nervous system
Rest
Action
Figure 3.20 on page 89
The sympathetic division of the nervous system prepares the body for action, whereas the parasympathetic returns it to a resting state.

5. Cells of the Nervous System
There are 2 main kinds of cells
Neurons
Glial

6. Neurons Basic units (cells) of the nervous system
Receive, integrate, and transmit information
Operate through electrical impulses
Communicate with other neurons through chemical signals

7. Glial cells 100 billion neurons 10x more glial cells Glial cells
Support neurons (literally, provide physical support, as well as nutrients)
Cover neurons with myelin
Clean up debris
Includes Schwann cells

8. Three main types of neurons

9. Three main types of neurons
Sensory Neurons (peripheral N.S.)
They transmit signals from the receptors to the central nervous system

10. Three main types of neurons
Sensory Neurons (peripheral N.S.)
They transmit signals from the receptors to the central nervous system
Interneurons (or association neurons) (central N.S.) They process and integrate info to form a response

11. Three main types of neurons
Sensory Neurons (peripheral N.S.)
They transmit signals from the receptors to the central nervous system
Interneurons (or association neurons) (central N.S.) They process and integrate info to form a response
Motor Neurons (peripheral N.S.)
Transmits the response from the CNS to effectors

12. Sensory (Afferent) vs. Motor (Efferent)
sensory (afferent) nerve
CNS
e.g., skin
Neurons that send signals from the senses, skin, muscles, and internal organs to the CNS
motor (efferent) nerve
CNS
e.g., muscle
Neurons that transmit commands from the CNS to the muscles, glands, and organs
Gray’s Anatomy

13. Structure of a Typical Neuron

14. The Reflex Arc (or withdrawal reflex)
Figure 2.5B from:
Kassin, S. (2001). Psychology, third edition. Upper Saddle River, NJ: Prentice Hall.

15. Neural Anatomy Dendrite
They receive messages from other neurons and conduct impulses toward the cell body

16. Neural Anatomy Dendrite Cell Body
They receive messages from other neurons and conduct impulses toward the cell body
Cell Body
It determines if the signal will be inhibited or relayed

17. Neural Anatomy Dendrite Axon Cell Body
They receive messages from other neurons and conduct impulses toward the cell body
Cell Body
It determines if the signal will be inhibited or relayed
Axon
It transmits the signal from the cell body to the axon terminal endings.

18. Neural Anatomy Dendrite Axon Cell Body Synapse
They receive messages from other neurons and conduct impulses toward the cell body
Cell Body
It determines if the signal will be inhibited or relayed
Axon
It transmits the signal from the cell body to the axon terminal endings.
Synapse
The gap between axon terminals and dendrites

19. Neural Transmission

20. Neural Transmission Along The Axon
Fatty material made by glial (Schwann) cells form the myelin sheath which insulates the neural transmission along the axon.
The transmission along the axon is due to
Na-K pumps embedded in the membrane. These pumps “fire” in succession and initiate an electrical impulse called an action potential (AP).
In high speed transmission (Saltatory conduction), the impulse jumps gap to gap in the myelin sheath (Nodes of Ranvier).

21. Neural Transmission Along The Axon
Figure 2.6 from:
Kassin, S. (2001). Psychology, third edition. Upper Saddle River, NJ: Prentice Hall.
Source:

22. The 3 Functions of the Neuron1. 3. 2.
Figure 2.6 from:
Kassin, S. (2001). Psychology, third edition. Upper Saddle River, NJ: Prentice Hall.
Source:
Neurons = 3 functions: Reception, Conduction, Transmission

23. Action Potential (AP) Depolarization:
The stimulus “threshold” is reached and the sodium-potassium pumps are activated and positively charged Na ions rush into to “fire” the pumps in succession.

24. Action Potential (AP) Repolarized:
At maximum depolarization, the sodium gates close and
the potassium gates open. Positively charged K ions
rush out of the neuron.
Refractory Period:
The potassium gates close and, after a brief overshoot,
resting membrane potential restored (~ 70 mV)

25. The Action Potential is like a “Wave”

26. How an Action Potential Works

27. Saltatory Conduction

28. Neural Transmission At The Synapse

29. Synaptic Transmission
synaptic gaps =
1 millionth inch gap
Impulses reaching the pre-synapse will release neurotransmitter (NT) from vesicles into the gap
Figure 2.7 from:
Kassin, S. (2001). Psychology, third edition. Upper Saddle River, NJ: Prentice Hall.
Source:

30. Synaptic Transmission
NT crosses the synaptic
gap and binds to receptors
on the post-synaptic
membrane to initiate an
AP on post-synapse
Enzyme in gap denatures NT
Denatured NT returned to pre-synapse to be reassembled and packaged into vesicles.
Impulse continues in the next neuron.
Figure 2.7 from:
Kassin, S. (2001). Psychology, third edition. Upper Saddle River, NJ: Prentice Hall.
Source:

31. Examples of Neurotransmitters
Receptor binding movie