1. Central Nervous System (CNS): brain and spinal cord.
CNS contains tracts
Peripheral Nervous System (PNS): nerves of the body
PNS contains nerves
                   -- Includes 31 pairs of spinal nerves
                   -- And  12 pairs of cranial nerves

2. Basic Divisions of the Nervous System
Figure 12.2

3. THREE BASIC FUNCTIONS OF THE NERVOUS SYSTEM
Sensory -  gathers info
Integrative - information is brought together
Motor - responds to signals, homeostasis

4. Peripheral Nervous System
Afferent  -  transmits action potentials from sensory organs to the CNS
Efferent - transmits action potentials from the CNS to effector organs such as muscles - glands

5. Peripheral Nervous System Efferent divided further
SOMATIC NERVOUS SYSTEM  -  skeletal muscles, under voluntary control
AUTONOMIC NERVOUS SYSTEM - smooth muscles, glands, involuntary

6. Peripheral Nervous System Autonomic divided further
Sympathetic – Fight or Flight
Parasympathetic – Rest and Digest

7. Common Neurotransmitters
Epinephrine/Adrenaline
NorEpinephrine/Noradrenaline
Acetylcholine

8. Neurons

9. Factors Affecting Nerve Impulse Velocity
Diameter of the neuron
Temperature
Myelinated or Unmyelinated

10. Neuroglial Cells - support cells for the neurons
1.  Microglial : scattered throughout, digest debris or bacteria
2.  Oligodendrocytes:  provide insulation around the axons
3. Astrocytes:  connect blood vessels to neurons
4.  Ependymal Cells:  form a membrane that covers brain-like parts

11. 5.  Schwann cells:  form the insulating sheath around the neurons within the PERIPHERAL nervous system
Neurilemma = thin, membranous covering over Schwann cells that allows cells to slowly repair/regenerate themselves if injured
*Myelin Sheaths - necessary for insulation of neurons

12. Supporting Cells in the CNS
Microglial cells respond to immunological alarms

13. Supporting Cells in the CNS
Creates the myelin sheath that insulates axons

14. Supporting Cells in the CNS
Astrocytes connect neurons to blood vessels

15. Supporting Cells in the CNS
Figure 12.12a

16. Supporting Cells in the CNS

17. Supporting Cells in the CNS

18. Supporting Cells

20. Neuron Structure
Neurofibril -  fibers
Chromatophilic substance (rough ER) - transport system
Myelin -insulation surrounding axons
Nodes of Ranvier - gaps in the insulation

21. White vs Grey Matter
Myelinated (white matter) – myelinated axons
Unmyelinated (grey matter) - unmyelinated

22. Label

23. NEURON (main cell of the nervous system)
All neurons do three things:
Receive a signal. Can be any type of stimulus (change in environment, signal from another neuron, etc).
Transmit a signal to another location. E.g. finger touching something • signal to spinal cord or brain.
Stimulate another cell
Another neuron • transmit signal
Muscle • contraction
Gland • secretion

24. Other special characteristics
The Neuron
Other special characteristics
Longevity – can live and function for a lifetime
Do not divide – fetal neurons lose their ability to undergo mitosis; neural stem cells are an exception
High metabolic rate – require abundant oxygen and glucose

25. Types of Neurons
Functional: Sensory, Motor, Interneurons
Structural: (A) Bipolar (B) Unipolar (C) Multipolar

26. Nerve Impulses

28. Nerve Impulses
At rest, the inside of a neuron's membrane has a negative charge. As the figure shows, a Na+ / K+ pump in the cell membrane pumps sodium out of the cell and potassium into it. However, because the cell membrane is a bit leakier to potassium than it is to sodium, more potassium ions leak out of the cell. As a result, the inside of the membrane builds up a net negative charge relative to the outside.

29. Animations of Nerve Impulses

30. The Synapse Synapse - junction between two communicating neurons
Nerve pathway - nerve impulse travels from neuron to neuron
Synaptic Transmission Dendrite ' cell body ' along axon ' synapse (gap)
To complete the signal, a NEUROTRANSMITTER is released at the gap to signal the next neuron

31. Structure of a Synapses
Figure 12.8a, b

32. Neurotransmitters
Excitatory - increase membrane permeability, increases chance for threshold to be achieved
Inhibitory - decrease membrane permeability, decrease chance for threshold to be achieved

34. Types of Neurotransmitters
Acetylcholine - stimulates muscle contraction
Monoamines - Norepinephrine & Dopamine (sense of feeling good, low levels = depression)
Serotonin (sleepiness)
Endorphins (reduce pain, inhibit receptors)

35. Drugs that Affect Synapses and Neurotransmitters
Curare
Strychnine
Cocaine, morphine, alcohol, ether and chloroform
Mescaline and LSD
Ecstasy

36. Antidepressants
Zoloft is part of a class of drugs called selective serotonin reuptake inhibitors, or
 SSRIs for short. SSRIs act on a specific chemical within the brain known as serotonin. This is one of several chemicals used to send messages from one nerve cell to another.

37. Impulse Processing
Neuronal pool - groups of neurons that make hundreds of synaptic connections and work together to perform a common function

38. Types of Nerves
Dorsal Root/Sensory Nerves - conduct impulses into the brain or spinal cord
Ventral Root/Motor Nerves - carry impulses to muscles of glands
Mixed Nerves - contain both sensory and motor nerves

39. Problem
If Mary has a spinal cord injury to just her ventral portion of the spinal cord what would happen to her?
HINT** Will she lose feeling, movement or both?

40. Neurons Classified by Function: Sensory vs. Motor Neurons
Figure 12.11

41. Nerve Pathways
Reflex arc - only includes a few neurons
Reflex Behavior - automatic, subconscious responses
Knee-jerk reflex - maintains uprightedness
Withdrawal reflex - avoidance of painful stimuli