TECIDO NERVOSO | Histologia

Summary

In this lesson, Professor Natália Reineck explains the structure and function of nervous tissue, focusing on neurons and glial cells. Neurons, responsible for transmitting nerve impulses, have key components like the cell body, dendrites, axon, and axon terminals, which are essential for communication within the nervous system. Glial cells, such as astrocytes, oligodendrocytes, and Schwann cells, support and protect neurons, including the formation of the myelin sheath that enhances nerve impulse speed. The lecture also touches on related diseases like multiple sclerosis and the importance of the glial cells in maintaining neuronal function.

Takeaways

• 😀 The nervous tissue is made up of two types of cells: neurons and glial cells (neuroglia).
• 😀 Neurons are specialized cells responsible for conducting nerve impulses and integrating them to control functions like muscle activity and gland secretion.
• 😀 Glial cells protect, support, and assist neurons in carrying out their functions.
• 😀 Neurons have three main parts: the cell body, dendrites (branches for receiving nerve impulses), and the axon (which transmits nerve impulses).
• 😀 The axon can vary in length, with some stretching up to 1 meter, like those from the spinal cord to the lower limbs.
• 😀 The myelin sheath, produced by glial cells, insulates axons and speeds up nerve impulse transmission. This sheath is intermittent, with gaps known as nodes of Ranvier.
• 😀 Myelin sheaths are formed by Schwann cells in the peripheral nervous system and oligodendrocytes in the central nervous system.
• 😀 The white matter of the brain contains myelinated axons, while the gray matter consists of neuron cell bodies without myelin.
• 😀 Glial cells also include astrocytes (support and nutrient supply), microglia (immune function), ependymal cells (lining brain cavities), Schwann cells (myelination in peripheral nerves), and satellite cells (supporting neuron bodies in ganglia).
• 😀 Diseases like multiple sclerosis damage the myelin sheath, impairing the conduction of nerve impulses.
• 😀 The video provides resources for further learning, including PDF notes and online courses related to human anatomy and physiology.

Q & A

What is the primary function of neurons in the nervous system?

Neurons are specialized cells responsible for conducting nerve impulses and integrating them to generate functions like muscle control, gland secretion, and complex processes such as thought and memory.

What role do glial cells play in the nervous system?

Glial cells, or neuroglia, support, protect, and assist the function of neurons. While neurons perform complex tasks, glial cells work in the background to ensure neurons can perform their functions effectively.

How do neurons vary in size and shape?

Neurons can vary greatly in both size and shape, depending on their type and location in the body. Despite these variations, all neurons share common structures like the cell body, dendrites, axon, and axon terminals.

What is the significance of dendrites in a neuron?

Dendrites are projections of the neuron's cytoplasm that function to receive nerve impulses and transmit them toward the cell body. The term 'dendrite' comes from the Greek word for tree, as their branching structure resembles tree branches.

What is the function of the axon in a neuron?

The axon is a long projection that transmits nerve impulses from the cell body to other neurons, muscles, or glands. The length of axons can vary greatly, with some extending up to a meter in the case of neurons that connect the spinal cord to the limbs.

What is the myelin sheath, and what is its function?

The myelin sheath is a lipid-rich membrane that surrounds the axons of many neurons. It serves to isolate the axon and increase the speed at which nerve impulses are conducted. Myelin allows for saltatory conduction, where nerve impulses jump between gaps in the sheath called nodes of Ranvier.

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

Nodes of Ranvier are the gaps between segments of myelin on the axon. These nodes are crucial for the rapid conduction of nerve impulses, as the electrical signal 'jumps' between the nodes, increasing the speed of transmission.

What are the six types of glial cells mentioned in the transcript?

The six types of glial cells are astrocytes, oligodendrocytes, microglia, ependymal cells, Schwann cells, and satellite cells.

What is the difference between Schwann cells and oligodendrocytes?

Schwann cells form the myelin sheath in the peripheral nervous system (PNS), while oligodendrocytes form the myelin sheath in the central nervous system (CNS).

What is multiple sclerosis, and how does it relate to myelin?

Multiple sclerosis is a disease that attacks and progressively destroys the myelin sheath, impairing nerve impulse conduction. This destruction affects the nervous system's ability to function properly.