w-1 cells of the nervous system

Question 1

Golgi’s Method - First published by Camillo Golgi in 1873

Answer 1

• Microcrystallization of silver salts in neurons
• Stochastically labels a small subset of cells (<1%)

Question 2

Santiago Ramon y Cajal

Answer 2

• Nobel Prize in Physiology/Medicine with Golgi in 1906
• Discovered the axon growth cone
• Demonstrated that nerve cells (neurons) are contiguous not continuous

Question 3

dendritic spines:

Answer 3

• small protrusions in dendrites that serve as post synaptic sites
• changes in the morphology of spines are considered to indicate synaptic plasticity and my contribute to learning and memory disorders or neurological disorders

not all neurons have dendritic spines, but they still have synapses and synaptic plasticity. the synapse site may be anywhere along the dendrite or the soma

Question 4

The soma (cell body) of a neuron:

Answer 4

• Contains the nucleus and
  many of the protein-
  synthesizing organelles
• Not all protein synthesis may
  occur in the soma (RNA can be
  transported down axons)
• Many mitochondria can be
  found near synapses (so that you dont have to transport it)

Question 5

how do neurons facilitate neuronal transport?

Answer 5

they use MOLECULAR MOTORS such as KINESINS and DYNEINS to move cargo (often in small vesicles) up and down the axon

Question 6

define anterograde and retrograde transport

Answer 6

retrograde: towards the soma (waste, signaling molecules, etc.)
anterograde: toward the synaptic terminal (nt, orgnaelles, etc.)

Question 7

how can neurons be categorized and give examples:

Answer 7

shape
* pyramidal neurons
location
* retinal ganglion cell
function
* motor, sensory
neurotranmitters
* excitatory (glutamate), inhibitory (GABA)
developmental origin

Question 8

what are some examples of other types of neurons and their cells?

Answer 8

photoreceptors: respond to light
Auditory hair cells: respond to movement

Question 9

TPS: why do we have neurons with such distinct morphologies?

Answer 9

they all have different functions

Question 10

what are the two types of electrical signaling used by neurons

Answer 10

graded potentials and action potentials

Question 11

graded potentials:

Answer 11

small inputs that cause local changes in neuron membrane potential, limited distance due to passive electrical properties

Question 12

action potential:

Answer 12

• nerve impulse or spike often generated when graded potentials pass a “threshhold”
• rapid propagation over long distances

Question 13

Key Points of the Tripartite Synapse:

Answer 13

1. How Neurons & Glia Communicate:
   * Traditionally, synapses were seen as two-way interactions between presynaptic and postsynaptic neurons.
   * The tripartite synapse model adds astrocytes, which interact with synapses and influence communication.
2. Astrocytes Contact Many Synapses:
   * A single astrocyte can interact with 100,000+ synapses in rodents and over 1 million in humans.
3. Neurotransmitters Affect Glia:
   * When neurons release neurotransmitters (e.g., glutamate, GABA), astrocytes detect them via receptors. this means glial cells are not just passive support cells—they actively respond to neuronal signals.
4. Glia Trigger Calcium (Ca²⁺) Waves:
   * Astrocytes can generate calcium waves, which travel between nearby glial cells.
   * This allows glia to communicate with each other and modulate neural activity across larger networks.
5. Glia Release “Gliotransmitters”:
   * Astrocytes can release neurotransmitter-like molecules called gliotransmitters, such as:
   Glutamate – Excitatory signaling or GABA – Inhibitory signaling
   These gliotransmitters influence neuronal activity, synaptic strength, and plasticity.

Question 14

why are astrocytes critical in recycling neurotranmitters

Answer 14

• they recycle GLUTAMATE (primary excitatory nt in the cns)
• thsi prevents excitotoxicity which is the overactivation of neurons that leads to cell death

Question 15

astrocytes have different…

Answer 15

morphologies in the various layers of the cortex and the white matter

Question 16

____________ ________: are the astrocytes in the cerebellum

Answer 16

bergmann glia

Question 17

multiple sclerosis:

Answer 17

• potentially disabling disease of the brain and spinal chord
• immune system attacks myelin sheath
• signs/symptoms vary widely depending on amount of nerve damage and which nerves
  - some ppl lose the ability to walk while others experience long periods of remission w/o new symptoms
• there is no cure only treatments that speed recovery from attacks, modify the course of it, and manage symptoms

Question 18

what are microglia derived from?

Answer 18

yolk-sack progeniors (during development)

BUT they persist through adulthood

Question 19

Microglia:

Answer 19

• Derived from yolk-sack (YS) progenitors
  during development (persist through adulthood)
• Blood-brain barrier normally prevents other
  monocyte or macrophage populations from
  entering the brain
• Bone marrow (BM) – derived macrophages
  can become microglia-like resident cells
  after inflammation/injury

Question 20

what are the three kinds of “other” glia?

Answer 20

• glia stem cells
• ependymal cells
• satellite glia cells

Question 21

glia stem cells:

Answer 21

• can replenish neurons, astrocytes, and oligodendrocytes (in specific regions of the brain under specific functions)
• neurons are post mitotic and cannot proliferate

Question 22

ependymal cells:

Answer 22

line the ventricals and produce cerebral spinal fluid (CSF)

Question 23

satellite glia cells:

Answer 23

• closely envelop cell bodies of neurons in sensory, sympathetic, and parasympathetic ganglia.
• thought to control microenviornment and excitability of neurons (implicated in pain)