Lecture 1: Neurons and Glia

Who came up with the first staining techniques that showed microscopic features of the brain?

Camillo Golgi

Who came up with the neuron hypothesis?

Santiago Ramon y Cajal

What is the neuron hypothesis?

The brain is made up of cells (neurons), like other biological tissue, and these neurons are like the basic signaling units for the nervous system

How does information flow through a neuron?

Collected from dendrites, processed in the cell body, passed on to the axon, then to the end feet where it is passed on to the target neuron

What do sensory neurons do and what are they made for?

Bring information to the central nervous system. Made for quick relay, not much processing

What are the inputs and outputs of the sensory neuron?

input = sensory receptors

output = other neurons

What do interneurons do and what are they made for?

Associate sensory and motor activity in the central nervous system. Made for processing

What are the inputs and outputs of the interneurons?

Inputs = other neurons

Outputs = other neurons

What do motor neurons do and what are they made for?

They send signals from the brain and spinal cord to the muscles. Made for some processing and only 1 output

What are the three ways in which neurons are unique?

Plasticity, longevity, and shape

Plasticity

neurons routinely change structure and biochemical properties, even after the “developmental” period has passed

Longevity

Most neurons are never replaced. (Can be older than 100 years in some cases)

Shape

Neurons are exceptionally long and thin. The longes neuron is from the tip of the toe to the base of the neck

What are the three main functions of the glial cells?

1. serve as supporting elements → provide firmness and structure to the brain
2. help form the blood brain barrier, the impermeable tight junctions in endothelial cells that like the blood vessels in the brain
3. Dilate blood vessels to support increased brain activity

What are the two types of glial cells?

1. oligodendrocyte in the central nervous system
2. Schwann cell in the peripheral nervous system

What do Schwann cells do and why is that important?

Schwann cells from myelin which helps electrical impulses travel faster and to sustain over long distances

What is myelin?

Insulating sheath that covers most axons

T/F: some glial cells are scavengers that remove debris after injury or cell death

True

T/F: Schwann cells supporting peripheral nerves do not aid in axonal targeting and regrowth after a cell injury

false

T/F: oligodendrocytes can help regrowth after an injury. Why or why not?

False because they don’t perform the same function in the brain and spinal cord. Hence why lifetime paralysis can result from a spinal injury

Explain how a Schwann cell helps regrow a neuron

1. When the peripheral axon is cut , the portion still attached to the cell body dies
2. Schwann cells shrink and the divide, forming glial cells along the axon’s former path
3. The neuron sends out axon sprouts, one of which finds the Schwann-cell oath and becomes a new axon
4. Schwann cells envelope it, forming new myelin

What type of cell is an Ependymal cell and what does it do? What are the purposes of that function?

It is a glial cell that secretes cerebrospinal fluid, which serves the purposes

* shock absorber
* helps eliminate waste
* may be a source of nutrients
* may help in brain cooling