Name: how the blood-brain barrier works
Uploaded: 2025-10-23T11:47:15.000Z
Duration: 49 s
Channel: JoVE

述者】人脑通过一种叫做 血脑屏障的保护屏障 从循环系统中分离出来 这种屏障由 衬于中枢神经系统毛细血管内表面的内皮细胞组成 该屏障也由一层基底膜 和与毛细血管密切接触的 称为星形胶质细胞的专门神经细胞组成 这些成分有助于防止 不受欢迎的物质穿过 这种屏障通过 形成连接复合体的不同类型的蛋白质来 控制血液和大脑间质液体 之间的化学交换。
 一般情况下，只有脂溶性化合物可以通过扩散， 穿过屏障，而水溶性化合物通过屏障的方式 则是通过主动或被动运输。

Daneman、Richard 和 Alexandre Prat. "血脑屏障"。冷泉港生物学观点 7，第 1 期（2015 年 1 月）。[<a href="https://doi.org/10.1101/cshperspect.a020412" target="__blank">来源</a>]

Andreone、Benjamin J.、Baptiste Lacoste 和 Chenghua Gu. "神经元和血管相互作用。"神经科学年鉴 38（2015 年 7 月 8 日）:25-46。[<a href="https://doi.org/10.1146/annurev-neuro-071714-033835" target="__blank">来源</a>]

血脑屏障

The Blood-brain Barrier

<h4>概观</h4>
"“
血脑屏障（blood-brain barrier，bbb）是指在严格调节离子、分子、病原体和其它物质运动的同时，为大脑提供血液中营养物质的特殊血管系统。它由紧密相连的内皮细胞和星形胶质细胞投射物组成。它们共同提供了一个半透膜屏障，保护大脑，并对提供治疗方法提出了独特的挑战。”"
<h4>细胞成分</h4>
 
 BBB由多种细胞成分组成，包括内皮细胞和星形胶质细胞。这些细胞共享一个共同的基底膜，共同调节循环和大脑周围间质液体之间的成分通过。
 
 第一种细胞成分，专门的内皮细胞，构成了脑毛细血管的壁它们通过极其紧密和复杂的细胞间连接连接起来。这些连接创造了一个选择性的物理屏障，阻止了大多数物质的简单扩散，包括葡萄糖和胰岛素等大分子的平均扩散。
 
 第二种细胞类型，星形胶质细胞，是中枢神经系统的一种胶质细胞，通过与脑血管系统的相互作用和密切联系，影响脑内内皮细胞功能、血流和离子平衡。它们在血管系统和神经元之间提供了直接的联系：它们延伸了一种被称为“末端脚”的过程，这种过程在一端缠绕血管，另一端与突触处的神经元亲密接触。
 
<h4> 化学交换</h4>
 
 物质通过BBB的能力和交换的效率取决于每个分子或离子的化学和分子性质。一般来说，小的脂溶性组分，如氧气和二氧化碳，通过内皮层经历快速、简单的扩散。相反，较大的或水溶性成分通常需要一个选择性更强的过程，可能涉及通过内皮细胞的被动或主动运输。根据内皮细胞表面的分子特异性受体和转运蛋白的相对丰度和效率等因素，这些物质的交换通常发生得比较慢，或者根本不会发生。
 
<h4> BBB保护大脑</h4>
 
 BBB促进的神经保护对大脑的健康和功能至关重要。血脑屏障的失调可导致严重的神经系统疾病，包括多发性硬化、感染和由于血液供应不足而引起的缺血。相反，BBB的活性可能通过阻止或实质上减少神经活性药物进入中枢神经系统而对某些神经疾病的治疗不利。因此，具有神经靶点的药物必须设计成便于通过血脑屏障的方式。

概述

血脑屏障（BBB）指一种特化的血管结构，可将血液中的营养物质输送至大脑，同时严格……

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Biology

生物学

Human Biology

人类生物学

Nervous System

神经系统

KEY TERMS AND CONCEPTS

关键术语与概念

how the blood-brain barrier works

The blood-brain barrier is a specialized system of blood vessels that helps control what enters the brain. It delivers nutrients from the blood while tightly regulating ions, molecules, pathogens, and other substances. This semipermeable barrier protects the brain and also makes it harder to deliver some therapies.

The blood-brain barrier includes several cellular parts, especially endothelial cells and astrocytes. These cells share a common basement membrane and regulate movement between the circulation and the fluid around the brain. Specialized endothelial cells form the walls of cerebral capillaries. They are joined by very tight intercellular junctions, which create a selective physical barrier. This barrier blocks simple diffusion of most substances, including molecules as large as glucose and insulin.

Astrocytes are glial cells in the central nervous system. They influence endothelial cell function, blood flow, and ion balance in the brain. Astrocytes connect closely with the cerebral vasculature. Their processes, called endfeet, wrap around blood vessels on one end and make contact with neurons at synapses on the other. This gives them a direct link between blood vessels and nerve cells.

What crosses the barrier depends on a molecule's chemical and molecular properties. Small lipid-soluble substances, such as oxygen and carbon dioxide, move across by rapid simple diffusion. Larger or water-soluble substances usually need a more selective process. They may move through an endothelial cell by passive or active transport. In many cases, this exchange is slower, or it may not occur at all, depending on receptors and transport proteins on the endothelial surface.

The blood-brain barrier is essential for brain health and normal function. When it does not work properly, severe neurological diseases can occur, including multiple sclerosis, infection, and ischemia from poor blood supply. The barrier can also make treatment difficult because it can reduce the passage of neuroactive drugs into the central nervous system. For that reason, medicines aimed at the brain must be designed to pass through the blood-brain barrier.

How the Blood-Brain Barrier Works

what is a nervous system?

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The nervous system is a network of specialized cells that keeps the body working and helps it respond to the world around it. It controls essential functions such as heart rate and breathing. It also supports movement that helps an organism escape danger. In vertebrates, the nervous system has two major parts: the central nervous system, or CNS, and the peripheral nervous system, or PNS. The CNS includes the brain, spinal cord, and retina, which is the sensory tissue of the visual system. The...

the parasympathetic nervous system

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The parasympathetic nervous system helps the body stay calm and return to a rested state. It is one of the two major divisions of the autonomic nervous system, which controls many unconscious functions such as heart rate and digestion. Its neurons are found in the brain and the peripheral nervous system, and they send axons to muscles, organs, and glands. This system is often called the “rest and digest” system because it supports body processes that restore homeostasis. It is most active...

the sympathetic nervous system

Sympathetic Stress Response and Body Changes

The sympathetic nervous system helps the body respond to stress and danger. It is one of the two main divisions of the autonomic nervous system. When it turns on, it prepares the body for action and puts lower-priority functions, such as digestion, on hold. This response is often called the fight-or-flight system. A surprise exam can trigger it, and students may notice a tight stomach, a dry mouth, and a fast heartbeat. In a real threat, the system shifts blood away from the digestive system...

the blood-brain barrier

The blood-brain barrier is a specialized system of blood vessels that helps control what enters the brain. It delivers nutrients from the blood while tightly regulating ions, molecules, pathogens, and other substances. This semipermeable barrier protects the brain and also makes it harder to deliver some therapies. The blood-brain barrier includes several cellular parts, especially endothelial cells and astrocytes. These cells share a common basement membrane and regulate movement between the...

neuron structure

How Neurons Send Signals

Neurons send signals through a clear set of structures that let them receive, process, and pass on information. They are the main cells of the nervous system and use electrochemical signals to communicate. Neurons also talk to other cells through neurotransmitters at junctions called synapses. Most neurons share three main parts: a cell body, also called the soma, dendrites, and an axon. The soma holds the nucleus and other organelles needed for cell function. Dendrites usually receive...

glial cells

Glial Cells and Nervous System Support

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action potentials

How Nerve Signals Travel in Axons

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the resting membrane potential

How Neurons Keep a Negative Resting Charge

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long-term potentiation

Synaptic Strengthening in Learning and Memory

Long-term potentiation, or LTP, is a form of synaptic strengthening in the brain. It changes the strength of chemical synapses over time between pre- and postsynaptic neurons. LTP works against long-term depression, or LTD, which weakens synapses. Together, LTP and LTD are major mechanisms behind learning and memory. LTP can happen when a presynaptic neuron fires again and again and keeps stimulating a postsynaptic neuron. This is called Hebbian LTP, based on Donald Hebb’s idea that neurons...

long-term depression

Synaptic Pruning in Long-term Depression

Long-term depression, or LTD, is a form of synaptic plasticity that weakens chemical synapses over time. It acts between presynaptic and postsynaptic neurons. LTD works in opposition to long-term potentiation, or LTP, which strengthens synapses. Together, LTD and LTP are two of the main mechanisms behind learning and memory. LTD helps the brain avoid staying locked in a fully strengthened state. If synapses were always maximally strengthened, the brain would become less efficient and it would...

the synapse

How Neurons Signal at Synapses

Neurons communicate through synapses, the points where two neurons meet to pass on signals. At a synapse, the sending neuron is the presynaptic cell, and the receiving neuron is the postsynaptic cell. Most neurons can serve in both roles because they send and receive information. Electrical synapses move signals directly between cells. The presynaptic and postsynaptic cells are linked by gap junctions, which are proteins that physically connect them. This type of synapse can pass electrical...

key terms and concepts

Learn how the blood-brain barrier protects the brain, which cells build it, what can cross it, and why it matters for disease and drug delivery.

How the Blood-Brain Barrier Works | JoVE K12

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How the Blood-Brain Barrier Works

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