1. Ch. 7: Neurons: Matter of the Mind Ch. 8: The Nervous System
Chapters 7 & 8

2. OUTLINE OF CONCEPTS
Cells of the Nervous System – neurons and neuroglia
Structure of Neurons and types of neurons
Synaptic Transmission - neurotransmitters
Nerves- structure
CNS – Brain and spinal cord
Spinal Cord: Message Transmission and Reflex Center
Peripheral nervous system – differences between somatic and autonomic nervous systems -sympathetic and parasympathetic nervous systems
Brain – Brain: Command Center: Limbic System – Emotions and Memory
Nervous System Disorders: stroke, paralysis, Alzheimer’s disease, Parkinson’s disease, comas, headache, migraine, multiple sclerosis

3. Overview of the Nervous System
Function
Integrates and coordinates the body’s activities
Composition: two types of specialized cells
Neurons - Excitable cells that generate and transmit messages
Neuroglial cells - Provide structural support, growth factors, and insulating sheaths around axons

4. Neuroglial Cells Several types Each with different job to do
structural support for neurons (brain, spinal cord)
Steady supply of chemicals (nerve growth factor) that stimulate nerve growth. Without NFG, neurons die.
Form insulating sheaths around axons
Can communicate with one another and with neurons

5. Three main types or categories of neurons
Sensory (or afferent) neurons – sensory organs to brain
Interneurons (association)– connect sensory to motor neurons
Motor (or efferent) neurons – brain to muscles and glands

6. Figure 7.1 Neurons may be sensory neurons, interneurons, or motor neurons.6

7. ALS - Amyotrophic Lateral Sclerosis
Motor neurons (brain and spinal cord) die and stop sending messages to skeletal muscles
Without stimulation, the muscles gradually weaken
Lose control over arms, legs and body
Muscles that control breathing (diaphragm, rib cage) eventually die
Cause of death is respiratory failure
Sensory and interneurons not affected – maintain awareness and reasoning.

8. Figure 7.2 The structure of a neuron.8

9. Nerves are long-distance communication lines
Consist of parallel axons, dendrites, or both from many neurons
Covered with tough connective tissue
Classified as sensory, motor, or mixed (sensory and motor together) depending on the type of neurons they contain

12. Multiple Sclerosis
A disease in which the myelin sheaths (brain, spinal cord) are progressively destroyed
Damaged regions become hardened scars called scleroses
Interferes with the transmission of nerve impulses
The results can be paralysis or the loss of sensation, including vision.

13. Synaptic Transmission
Communication between a neuron and an adjacent cell occurs by neurotransmitters
Synapse
Junction between a neuron and another cell
Synaptic cleft: Gap between two cells
Neurotransmitters diffuse across the gap
In the case of two neurons, the presynaptic neuron sends a message to the postsynaptic neuron

14. Figure 7.6 Structure of a synapse.14

15. Figure 7.8 A neuron may have as many as 10,000 synapses.15

16. Roles of Different Neurotransmitters
There are dozens of neurotransmitters
Some neurotransmitters produce different effects on different types of cells
Example: acetylcholine
Acts in both the PNS and the CNS
Released at every neuromuscular junction
Myasthenia gravis: autoimmune disease that attacks the acetylcholine receptors at neuromuscular junctions, resulting in little muscle strength

17. Roles of Different Neurotransmitters
In the CNS, different neurotransmitters are associated with different behavioral systems
Norepinephrine regulates mood, hunger, thirst, and sex drive
Serotonin promotes a feeling of well-being
Dopamine regulates emotions and complex movements

18. Health Issue: Neurotransmitters and Disease
Changes in the levels of neurotransmitters cause disorders
Alzheimer’s disease
Associated with decreased levels of acetylcholine
Clinical depression
Associated with decreased levels of serotonin, dopamine, and norepinephrine
Parkinson’s disease
Associated with decreased levels of dopamine

19. In Some Disorders, Brain Neurons Break Down
Parkinson’s disease (PD): Basal nuclei of the thalamus begin to die
Dopamine and norepinephrine are not made
Symptoms: muscle tremors and balance problems - tremor, or trembling in hands, arms, legs, jaw, and face; rigidity, or stiffness of the limbs and trunk; bradykinesia, or slowness of movement; and postural instability, or impaired balance and coordination.
No cure
Treatments: drugs and/or surgery

20. Alzheimer’s disease Progressive degeneration of brain neurons
Buildup of amyloid protein leads to loss of memory and intellectual functions,
Neurofibrillary tangles (NFTs), found inside neurons, are abnormal collections of a protein called tau.
Loss of connections between neurons responsible for memory and learning.

21. Figure 7.3 The myelin sheath.21

22. Myelin Sheath Multiple Sclerosis (MS)
A disease in which the myelin sheaths in the brain and spinal cord are progressively destroyed
Results from the destruction of the myelin sheath that surrounds axons in the CNS
The resulting scars (scleroses) interfere with the transmission of nerve impulses
Can result in paralysis and loss of sensation, including loss of vision