Le Cellule Gliali | NEUROSCIENZE - Lezione 3

La Biologia per tutti

25 Apr 202112:27

Summary

TLDRThis video delves into the world of neuroscience, focusing on glial cells, also known as neuroglia or simply glia. It explains their crucial role in protecting, supporting, and nourishing neurons, which are primarily responsible for signal transmission in the nervous system. The video outlines different types of glial cells, including astrocytes, oligodendrocytes, Schwann cells, and microglia, each with specific functions such as forming the blood-brain barrier, insulating axons with myelin, and acting as the primary immune defense within the central nervous system. The content is engaging and informative, providing insights into the complex cellular interactions that enable our nervous system to function effectively.

Takeaways

🧠 The nervous system is composed of two main types of cells: neurons and glial cells, also known as neuroglia or simply glia.
🔍 Glial cells have the role of protecting, supporting, and nourishing neurons, as neurons are primarily focused on signal transmission and not on their surrounding environment.
🌟 Astrocytes are stellate-shaped glial cells that play several important roles within the nervous system, including providing structural support to neurons in the brain.
🛡️ Astrocytes form the blood-brain barrier, which is not a strict separation but rather a control mechanism for what can pass from the blood into the brain.
🧬 Oligodendrocytes and Schwann cells are responsible for myelination, covering axons with myelin sheaths to insulate them and allow efficient electrical signal transmission with minimal energy dispersion.
🌐 Oligodendrocytes are found in the central nervous system (CNS) and can myelinate multiple axons, while Schwann cells are in the peripheral nervous system (PNS) and myelinate individual axons.
🛡️ Microglia are the primary immune cells in the CNS, acting as phagocytes to engulf harmful substances and pathogens, and present antigens to the immune system.
📈 Astrocytes are involved in the metabolic cycle of neurotransmitters, capturing, degrading, or recycling them to maintain an appropriate environment for neuronal function.
🤔 The distinction between a drug and a recreational substance is often minimal, with the main difference being the medical prescription and controlled use versus unregulated use for psychoactive effects.
🧠 Understanding the blood-brain barrier is crucial for comprehending the effects of psychoactive substances, as they must pass this barrier to affect the brain.
🔄 Glial cells, particularly astrocytes, contribute to maintaining the physiological cerebral environment necessary for neurons to perform their functions effectively.

Q & A

What is the main topic of the video?
-The main topic of the video is neuroscience, specifically focusing on glial cells, also known as neuroglia or simply glia.
What is the primary function of glial cells in the nervous system?
-Glial cells primarily function to protect, support, and nourish neurons within the nervous system.
What are the types of glial cells mentioned in the video?
-The types of glial cells mentioned in the video are astrocytes, oligodendrocytes, Schwann cells, and microglia.
What is the structural role of astrocytes?
-Astrocytes serve as a scaffold for neurons in the brain, filling the brain mass and providing structural support.
How do astrocytes contribute to the blood-brain barrier?
-Astrocytes control and constrict the capillaries that enter the brain, forming the blood-brain barrier which regulates what substances can pass from the blood into the brain.
What is the function of oligodendrocytes and Schwann cells in the nervous system?
-Oligodendrocytes and Schwann cells are responsible for myelination, which is the process of covering axons with myelin to insulate them and allow for efficient electrical signal transmission.
Where do oligodendrocytes and Schwann cells operate, and what is the difference between their functions?
-Oligodendrocytes operate within the central nervous system (CNS), specifically in the brain, while Schwann cells function along the entire peripheral nervous system (PNS). Oligodendrocytes can wrap around multiple axons, whereas Schwann cells typically myelinate only a part of a single axon.
What is the role of microglia in the nervous system?
-Microglia are the primary immune cells in the CNS. They act as phagocytes, engulfing harmful substances and pathogens within the CNS and presenting antigens to the immune system to initiate a specific response.
How does the blood-brain barrier relate to psychoactive substances?
-The blood-brain barrier is crucial for understanding the effects of psychoactive substances, as these substances must pass the barrier to affect the brain and produce their psychoactive effects.
What is the significance of the myelin sheath in signal transmission?
-The myelin sheath, provided by oligodendrocytes and Schwann cells, insulates axons and minimizes energy dispersion, allowing for efficient electrical signal transmission.
How do astrocytes contribute to the metabolic cycle of neurotransmitters?
-Astrocytes play a role in the metabolic cycle of neurotransmitters by reuptaking, degrading, or recycling certain neurotransmitters released into the synaptic cleft, thus maintaining an appropriate environment for neuronal function.
What will be the focus of the next video in the series?
-The next video will focus on how the electrical signal is transmitted within the axon, a topic known as action potential.

Outlines

00:00

🧠 Introduction to Glial Cells

This paragraph introduces the concept of glial cells, also known as neuroglia, which are crucial for supporting, protecting, and nourishing neurons in the nervous system. It explains that while neurons are responsible for signal transmission, glial cells assist neurons in their functions and maintain the necessary environment for neurons to work effectively. The paragraph also lists the types of glial cells, including astrocytes, oligodendrocytes, Schwann cells, and microglia, and briefly describes their roles and differences.

05:00

🧬 Functions of Astrocytes and Oligodendrocytes

This section delves into the specific functions of astrocytes and oligodendrocytes. Astrocytes are described as having a structural role in the brain, filling spaces in the brain mass, and forming the blood-brain barrier. They are also involved in the metabolic cycle of neurotransmitters, capturing and recycling them. Oligodendrocytes, on the other hand, are responsible for myelination in the central nervous system (CNS), wrapping around axons to facilitate efficient electrical signal transmission. The distinction between oligodendrocytes and Schwann cells is highlighted, with oligodendrocytes serving the CNS and Schwann cells serving the peripheral nervous system (PNS).

10:02

🛡️ Role of Microglia in Immune Defense

The final paragraph discusses the role of microglia in the immune defense of the CNS. Microglia act as the primary active immune defense within the CNS, similar to macrophages in the rest of the body. They engulf harmful substances and microorganisms, presenting antigens to the immune system to initiate a specific response. The paragraph also provides a visual representation of the distribution of different types of glial cells within the CNS and PNS, emphasizing the absence of microglia and astrocytes in the PNS, and the formation of the blood-brain barrier by astrocytes in the CNS.

Mindmap

Keywords

💡Neuroscience

Neuroscience is the scientific study of the nervous system, which includes the brain, spinal cord, and all the nerves that connect them. In the video, the main theme revolves around introducing various aspects of neuroscience, starting from the basic unit of the nervous system, the neuron, to other supporting cells like glial cells.

💡Neuron

Neurons are the primary cells in the nervous system responsible for transmitting signals. They have specialized structures like dendrites and axons that receive, process, and send electrical signals to other neurons or organs. The video emphasizes the role of neurons in the communication within the nervous system.

💡Glial Cells

Glial cells, also known as neuroglia or simply glia, are non-neuronal cells that provide support and protection for neurons. They play crucial roles in maintaining the nervous system's homeostasis, including providing structural support, nourishment, and forming the blood-brain barrier.

💡Astrocytes

Astrocytes are a type of glial cell that have a star-like shape with multiple processes. They perform various functions, including providing structural support to neurons in the brain, filling the brain mass, and forming the blood-brain barrier. Astrocytes are essential in maintaining the physiological environment around neurons suitable for their function.

💡Blood-Brain Barrier

The blood-brain barrier is a selective barrier that separates the circulating blood from the brain's extracellular fluid, protecting the brain from harmful substances in the bloodstream. Astrocytes contribute to the formation of this barrier by controlling what substances can pass from the blood into the brain.

💡Oligodendrocytes

Oligodendrocytes are glial cells found in the central nervous system (CNS) that wrap around the axons of neurons with their myelin sheaths. This myelination process increases the efficiency of electrical signal transmission along the axons by reducing energy loss and ensuring faster communication between neurons.

💡Schwann Cells

Schwann cells are glial cells found in the peripheral nervous system (PNS) that, similar to oligodendrocytes, produce myelin sheaths around axons. However, unlike oligodendrocytes, each Schwann cell typically myelinates only one segment of a single axon, providing insulation and increasing the speed of nerve impulses.

💡Microglia

Microglia are the primary immune cells within the central nervous system. They act as macrophages, constantly surveying their environment for signs of injury or infection, and upon detection, they engulf and digest harmful substances and pathogens, playing a critical role in the immune response within the CNS.

💡Myelin Sheath

The myelin sheath is a fatty insulating layer that wraps around the axons of neurons, allowing for efficient and rapid transmission of electrical signals. It is produced by glial cells such as oligodendrocytes in the CNS and Schwann cells in the PNS. The myelin sheath increases the speed and efficiency of nerve impulses by reducing energy loss.

💡Action Potential

Action potential refers to the electrical signal that neurons generate and propagate along their axons. This signal is crucial for communication within the nervous system, allowing neurons to transmit information to other neurons, muscles, or glands. The video promises to discuss how action potentials are transmitted within axons in a future lesson.

Highlights

The nervous system is composed of two main types of cells: neurons and glial cells.

Glial cells, also known as neuroglia or simply glia, protect, support, and nourish neurons.

Astrocytes are stellate cells with multiple projections and play a crucial role in the nervous system.

Astrocytes serve as a scaffold for neurons in the brain and help maintain the brain's mass.

These cells occupy various zones of the brain, providing structural support to neurons.

Astrocytes interact with blood vessels in the central nervous system, forming the blood-brain barrier.

The blood-brain barrier is not a strict separation but rather a control mechanism for what passes from blood to the brain.

Astrocytes are involved in the metabolism of neurotransmitters, capturing and recycling them.

Oligodendrocytes and Schwann cells are responsible for myelination, covering axons with myelin sheaths.

Myelin sheaths help efficient transmission of electrical signals with minimal energy dispersion.

Oligodendrocytes are found in the central nervous system, while Schwann cells are in the peripheral nervous system.

Oligodendrocytes can wrap around multiple axons, whereas Schwann cells typically myelinate only parts of a single axon.

Microglia are the primary immune defense cells in the central nervous system, acting like macrophages.

Microglia phagocytose harmful substances and pathogens, presenting antigens to the immune system.

Microglia make up about 20% of the total glial cell population in the brain.

The blood-brain barrier's function is crucial for understanding the effects of psychoactive substances.

The distinction between pharmaceuticals and drugs is minimal, with the main difference being medical prescription and control.

Substances like benzodiazepines, morphine, and ketamine can be both pharmaceuticals and drugs depending on their use.

In the next lesson, the focus will be on how the electrical signal is transmitted within the axon, known as action potential.