Cells Of The Nervous System

Question 1

What’s the overall role of glia?

Answer 1

• Maintain extracellular environment for neurons (feed it growth factors, provide structural support to guide the neurons in the shape they need to be.)
• Allow neurons to signal (help buffer the chemical messengers between the neurons, insulate neurons to help them conduct electricity)
• Receive/transmit signals
• Make cerebrospinal fluid and propel it around the CNS

Question 2

What is the overall role of neurons?

Answer 2

• Transfer & communicate information across the nervous system, web of connections b/w cells
• Form circuits from neuron to neuron and networks of neurons
• Sensing information
• Processing info between different regions of your brain and spinal cord

Question 3

How many neurons in the human body?

Answer 3

1 trillion

Question 4

How many glial cells in the human body?

Answer 4

50 trillion

Question 5

How many synapses (connections between neurons for communication) in the human body?

Answer 5

100 trillion

Question 6

Neuron Morphology has 4 compartments: soma, dendrites, axon, axon terminal. What is the soma?

Answer 6

• Cell body/perikaryon
• Has a Nucleus, the genetic machinery
• Protein synthesis/packaging through the Endoplasmic Reticulum, ribosomes, and Golgi apparatus.
• Pyramidal in shape

Question 7

Neuron Morphology has 4 compartments: Soma, dendrites, axon, axon terminal. What are dendrites?

Answer 7

• Receive info
• Apical & basal
• Receive synaptic inputs
• Dendritic spines

Question 8

Neuron Morphology has 4 compartments: Soma, dendrites, axon, axon terminal. What is the role of an axon?

Answer 8

• ALL neurons have ONE axon
• Multiple branches called collaterals
• Axon hillock
• Intrinsic vs. Extrinsic axon projections

Question 9

Neuron Morphology has 4 compartments: Soma, dendrites, axon, axon terminal. What is the role of the axon terminal?

Answer 9

• Junction with postsynaptic cells
• Synapses

Question 10

What is the Neuron Doctrine (Cajal)?

Answer 10

• Neurons are separate units
• Communicate across gaps
• Dendrites receive information

Question 11

What is the Reticular Theory (Golgi)?

Answer 11

• Reticulum of axons and neurons
• Continuous cytoplasm
• Dendrites provide nutrients

Question 12

What is the information flow in a neuron according to Cajal’s Neuron Doctrine?

Answer 12

Dendrites -> Soma -> Axon -> Terminal

Question 13

According to Cajal’s Neuron Doctrine, Dendrites have…

Answer 13

• Excitatory and inhibitory synaptic inputs
• Passive conductance of signals

Question 14

According to Cajal’s Neuron Doctrine, Axons have…

Answer 14

• Action potentials
• Active signal conductance

Question 15

According to Cajal’s Neuron Doctrine, Axon terminal has…

Answer 15

(Pre) synaptic transmission to postsynapse

Question 16

Cajal’s Neuron Doctrine says information flow in a neuron travels in one direction. What’s the one exception to this rule?

Answer 16

Backpropagation: Active signal conductance retrograde (backwards) via dendritic transmitters.

Question 17

Neuron Morphology: This type of neuron is…

Answer 17

Unipolar cell: 1 Cell body, 1 direction of communication

Question 18

Neuron Morphology: This type of neuron is…

Answer 18

Bipolar Cell: 2 poles, 1 cell body

Question 19

Neuron Morphology: This type of neuron is…

Answer 19

Pseudo-Unipolar Cell: 2 poles, 2 directions of communication, cell body extends

Question 20

What are the three types of multipolar cells?

Answer 20

Motor neurons, pyramidal of hippocampus , Purkinje cell of cerebellum

Question 21

What are the functional components of neurons?

Answer 21

Input: receptor potential/synaptic potential (passive potentials)

Integrative: suprathreshold input -> action potential (active signal)

Conductile: all-or-none conduction of AP to axon terminal

Output: release of neurotransmitters

Question 22

What is the flow of transformation of signals during transduction?

Answer 22

Mechanical -> passive electrical -> active electrical -> chemical