Glial Cells: Protection and Support for Neurons

Question 1

What does the term “glia” mean?

Answer 1

“Glia” means “glue” in Greek, reflecting the early belief that glial cells simply held neurons together.

Question 2

What is the primary function of glial cells in the nervous system?

Answer 2

Glial cells provide support to neurons, supplying raw materials, chemical signals, and structural components, and assist in neuronal processes.

Question 3

How many types of glial cells are there in the human nervous system?

Answer 3

There are four main types of glial cells in the human nervous system.

Question 4

What are the four main types of glial cells?

Answer 4

The four main types are oligodendrocytes, Schwann cells, astrocytes, and microglia.

Question 5

What is the role of oligodendrocytes?

Answer 5

Oligodendrocytes myelinate axons in the central nervous system (CNS), insulating multiple axons and speeding up signal transmission.

Question 6

What is the role of Schwann cells?

Answer 6

Schwann cells myelinate axons in the peripheral nervous system (PNS), with each Schwann cell wrapping around one segment of an axon.

Question 7

What is the role of astrocytes?

Answer 7

Astrocytes provide structural support to neurons, regulate blood flow, maintain the blood-brain barrier, and help in neuronal signaling and waste removal.

Question 8

What is the role of microglia?

Answer 8

Microglia act as the immune cells of the CNS, responding to injury and infection, and removing dead cells and debris.

Question 9

What is myelination, and which glial cells are involved in it?

Answer 9

Myelination is the process of insulating axons with a fatty substance (myelin). Oligodendrocytes provide myelin in the CNS, and Schwann cells provide myelin in the PNS.

Question 10

What is the appearance of a myelinated axon?

Answer 10

A myelinated axon appears as a string of elongated beads, with each bead representing a myelin segment, and the gaps between beads are called nodes of Ranvier.

Question 11

What are the nodes of Ranvier, and why are they important?

Answer 11

Nodes of Ranvier are uninsulated gaps between myelin segments on axons, allowing electrical signals to jump from one node to the next, increasing transmission speed.

Question 12

What effect does myelination have on neural signals?

Answer 12

Myelination speeds up the transmission of electrical signals along the axon by insulating it and enabling saltatory conduction.

Question 13

What is saltatory conduction?

Answer 13

Saltatory conduction is the process by which electrical impulses jump from one node of Ranvier to the next, speeding up signal transmission along myelinated axons.

Question 14

What happens in Multiple Sclerosis (MS) related to myelination?

Answer 14

In MS, myelin is damaged, disrupting electrical signal transmission and causing neurological symptoms like muscle weakness and coordination problems.

Question 15

What does myelin insulation do for axons?

Answer 15

Myelin insulation increases the speed of electrical signal transmission along the axon and ensures efficient communication between neurons.

Question 16

What shape are astrocytes, and how do they interact with neurons?

Answer 16

Astrocytes have a star-like shape and weave around and between neurons with tentacle-like extensions.

Question 17

What role do astrocytes play in regulating blood flow in the brain?

Answer 17

Astrocytes stretch between neurons and blood vessels, controlling local blood flow to increase the amount of blood reaching more-active brain regions.

Question 18

What structural support do astrocytes provide to the brain?

Answer 18

Astrocytes help form the tough outer membranes that surround the brain.

Question 19

How do astrocytes influence synaptic transmission?

Answer 19

Astrocytes secrete chemical signals that affect synaptic transmission and the formation of synapses.

Question 20

What are microglial cells (microglia), and what is their primary function?

Answer 20

Microglial cells are tiny and mobile. Their primary function is to contain and clean up sites of injury in the brain.

Question 21

How can astrocytes and microglia negatively affect the brain?

Answer 21

Astrocytes and microglia can worsen harmful swelling (edema) following brain injury and contribute to degenerative diseases like Alzheimer’s and Parkinson’s.

Question 22

What types of conditions can astrocytes and microglia contribute to?

Answer 22

These glial cells can contribute to conditions like brain swelling (edema), Alzheimer’s disease, and Parkinson’s disease.

Question 23

How do astrocytes and microglia contribute to the formation of brain circuits?

Answer 23

Glial cells, including astrocytes and microglia, support neurons, which communicate through synapses to form the vast circuits responsible for brain function.