1. Chapter 48- The Nervous System

2. Background Nerve cells = neurons
Simple animals only have nerve nets, but not a central processing area
Central Nervous System (CNS)- Brain and longitudinal nerve cord
Peripheral Nervous System (PNS)- All of the remaining nerves

3. Overview of the Nervous system animation

4. Information Processing
Sensory neurons pass information to interneurons for integration (in brain) and then pass the information to motor neurons that communicate with effector cells

5. Neurons Structure of Neurons
Contains a cell body (where nucleus is located) and two extensions
1. Dendrites- Receive signals and are short
2. Axons- Transmits signals and are long
- Often covered with a myelin sheath
- Ends at synaptic terminals
- Communication will take place across a synapse by chemicals called neurotransmitters

7. Glia- “Supporting” cells
- Schwann Cells- Make up the myelin sheath

8. Signal Reception and Conduction
- Membrane Potential- The voltage across a membrane
- Neurons have a common resting potential of -60 to -80 mV

9. Signal Reception and Conduction
If a neuron is stimulated, then depolarization will occur. If the depolarization passes a certain threshold value, then an action potential will be reached and information will be carried a fairly long distance.
What causes depolarization?
Gated channels that allow the movement and flow of charged molecules/ions. (Na+/K+ ions)

10. Animation of Action Potential and Depolarization

11. https://youtu.be/oa6rvUJlg7o

12. Signal Reception and Conduction
Conduction of membrane potentials along nerve pathways
- Depolarization (enough to push over threshold) will move down a pathway
- Increase diameter of axon, increase speed of movement (less resistance)
- Cover axon with myelin sheath, increase speed of movement (insulation)

14. Synapses- Junctions between neurons
- Neurotransmitters are released which will trigger the opening of gated channels of adjacent neuron
- Acetylcholine (most common neurotransmitter)
Animation

15. Structure of the Nervous System in Vertebrates
Cerebrospinal fluid- Fluid that fills any empty spaces in the brain or spinal areas, will wash away waste products and will also cushion tissue.
White matter- Brain tissue that has a large concentration of axons with myelin sheaths
Grey matter- Brain tissue that is mainly composed of dendrites with not much myelin

17. PNS- Two parts *Peripheral Nervous System
1. Somatic nervous system- Skeletal muscles, external stimuli, voluntary
2. Autonomic nervous system- Regulates internal environment
- Sympathetic division- Arousal and energy
- Parasympathetic division- Relaxation
- Enteric division- Digestive tract, pancreas, gallbladder, etc…

19. Brain Parts
Brainstem- Homeostasis, coordination, involuntary movement/control, conduction of other information going to brain (*medulla oblongata- blood pressure, pons breathing)

20. Brain Parts
Cerebellum- Coordination and learning new motor skills (hand/eye coordination) *ball in the back of the brain!

21. Diencephalon- Two main parts
- Thalamus- Main input area for sensory information to be sorted and distributed
- Hypothalamus- Homeostatic regulation

22. Brain Parts
Cerebrum (with associated cerebral cortex) Sensory information analyzed, motor commands issued, language generated

23. Limbic system- Ring of structures around the brainstem that deals with emotions

24. Diseases/Disorders
- Schizophrenia- Cannot distinguish reality from non-reality
- Depression (both Bipolar disorder and major depression)
- Alzheimer’s- Mental deterioration
- Parkinson’s- Death of neurons in the midbrain