1. Neurons and Synapses
Key words: Types of neurons; sensory neurons; motor neurons; interneurons; afferent nerves; efferent nerves

2. Cells in the brain 2 types: Neurons – communication specialists
Glia or Glial cells – make up 90% of the brain’s cellls
cells that support, nurture, and insulate neurons, clean up dead cells, and modify neural functioning
The uses & functions of glial cells not yet fully understood
Used to think glial cells were scaffolding (greek for “glue) for the brain, but more recent studies indicate a more important role in thinking: memory, learning, etc. May facilitate creation or maintenance of neural pathways.
Interesting facts:
The DNA in the nucleus of the cell has lost its ability to divide. therefore, when a neuron dies,for the most part, the adult brain cannot simply grow new neurons. (Note there are a few exceptions to this rule.)
The relative inability to grow new neurons leads to two interesting questions:
Q1: How do brain tumors (cancer) occur?
A: Unlike neurons, glial cells can divide and grow new cells throughout one's lifetime. Most brain tumors are limited to glial cells, not neurons.
Q2: If a person cannot grow new neurons, how does the brain change in order to accomodate new learning?
A: One mechanism by which the brain adapts to help you learn new information involves the structure on the next slide: the dendrites.

3. Neurons Basic building Blocks of the Nervous System
Body’s communication wiring
Transmit messages from one part of the body to another
3 different types we need to know
Afferent neurons, efferent neurons, interneurons
Some neurons go all the way down your spinal column
Interesting facts:
The DNA in the nucleus of the cell has lost its ability to divide. therefore, when a neuron dies,for the most part, the adult brain cannot simply grow new neurons. (Note there are a few exceptions to this rule.)
The relative inability to grow new neurons leads to two interesting questions:
Q1: How do brain tumors (cancer) occur?
A: Unlike neurons, glial cells can divide and grow new cells throughout one's lifetime. Most brain tumors are limited to glial cells, not neurons.
Q2: If a person cannot grow new neurons, how does the brain change in order to accomodate new learning?
A: One mechanism by which the brain adapts to help you learn new information involves the structure on the next slide: the dendrites.

4. Soma - the cell body Contains the cell’s Nucleus
Round, centrally located structure
Contains DNA
Maintains the cell
No role in neural signaling
Key words: Cell body; soma; cell nucleus
Interesting facts:
The DNA in the nucleus of the cell has lost its ability to divide. therefore, when a neuron dies,for the most part, the adult brain cannot simply grow new neurons. (Note there are a few exceptions to this rule.)
The relative inability to grow new neurons leads to two interesting questions:
Q1: How do brain tumors (cancer) occur?
A: Unlike neurons, glial cells can divide and grow new cells throughout one's lifetime. Most brain tumors are limited to glial cells, not neurons.
Q2: If a person cannot grow new neurons, how does the brain change in order to accomodate new learning?
A: One mechanism by which the brain adapts to help you learn new information involves the structure on the next slide: the dendrites.

5. Dendrites Information collectors; neurotransmitter receivers
Receive inputs from neighboring neurons
Inputs may number in thousands
If enough inputs are received, the cell’s AXON may generate an output
Interesting facts:
- The word DENDRITE comes from the Greek word for tree. This may serve as a useful analogy in discussing the dendrites for several reasons:
1. The dendrites branch repeatedly from the cell body (to increase the surface area of the cell to better allow the cell to receive incoming information). These radiations from the cell body are often referred to as a dendritic tree.
2. In terms of function, the dendrites function similiarly to the roots of a tree. Just as the roots take water and other nutrients from the soil and carry them to other parts of the tree, the dendrites collect information and and spread it to other parts of the neuron.

6. Dendritic Growth Mature neurons generally can’t divide
But new dendrites can grow
Provides room for more connections to other neurons
New connections are the basis for learning
Interesting facts:
- The word DENDRITE comes from the Greek word for tree. This may serve as a useful analogy in discussing the dendrites for several reasons:
1. The dendrites branch repeatedly from the cell body (to increase the surface area of the cell to better allow the cell to receive incoming information). These radiations from the cell body are often referred to as a dendritic tree.
2. In terms of function, the dendrites function similiarly to the roots of a tree. Just as the roots take water and other nutrients from the soil and carry them to other parts of the tree, the dendrites collect information and and spread it to other parts of the neuron.

7. Axon The cell’s output structure One axon per cell, 2 distinct parts
tubelike structure branches at end that connect to dendrites of other cells
Interesting facts:
- The diameter of an axon may vary from approximately 1mm-20mm.
- An axon may travel long distances to reach it's destination (longest axon is approximately 3 feet in humans and 10 feet in giraffes).

8. Terminal Buttons (Axon terminals)
Swellings at the ends of axons
Store and release neurotransmitters
Messages are sent to neighboring neurons

9. Myelin sheath
White fatty casing on axon which acts as an electrical insulator
Not present on all cells
When present increases the speed of neural signals down the axon
Divided by Nodes of Ranvier
Myelin Sheath
Interesting facts:
- The myelin sheath is NOT a part of the axon. The myelin sheath is actually formed of glial cells (oligodendricytes and Schwann cells) that wrap around the axon.
- You may have often heard the brain referred to as either white matter or gray matter. The myelin sheath appears white in nature. Hence, the term white matter refers to areas of the brain that are myelinated. Gray matter refers to areas of the brain that are unmyelinated.
- When you accidentally cut yourself, you often visually notice that you've cut yourself before you actually feel any pain from the cut. The reason for this is that visual information uses myelinated axons; whereas, pain information uses unmyelinated axons.
- The loss of myelin is a significant factor in the disease multiple sclerosis (MS). When myelin is lost, the high-speed transmission of information is slowed down or blocked completely, which could lead the person with the inability to walk, write or speak.