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

- [Narrador] El cerebro
humano está aislado

del sistema circulatorio
por una barrera protectora

llamada la barrera hematoencefálica,

lo cual consiste en células endoteliales

que forran los capilares del
sistema nervioso central.

La barrera hematoencefálica
también tiene una membrana basal

y células especializadas
llamadas astrocitos

que tienen contacto
cercano con los capilares.

Estos componentes ayudan para prevenir

la entrada de sustancias no deseadas.

Esta barrera controla
el intercambio químico

entre la sangre y el liquido
intersticial en el cerebro

mediante varios tipos de proteínas

que forman complejos de uniones.

[Proteínas Unificadoras]

Solo los compuestos solubles
en lípidos pueden difundirse

por la barrera, mientras que
los compuestos solubles en agua

cruzan por transporte activo o pasivo.

Daneman, Richard y Alexandre Prat. "La barrera hematoencefálica". Cold Spring Harbor Perspectives in Biology 7, no. 1 (enero de 2015). [<a href="https://doi.org/10.1101/cshperspect.a020412" target="__blank">Fuente</a>]

Andreone, Benjamin J., Baptiste Lacoste y Chenghua Gu. "Interacciones neuronales y vasculares". Annual Review of Neuroscience 38 (8 de julio de 2015): 25–46. [<a href="https://doi.org/10.1146/annurev-neuro-071714-033835" target="__blank">Fuente</a>]

la barrera hematoencefálica

The Blood-brain Barrier

<h4>Descripción general</h4> La barrera hematoencefálica (BHE) se refiere a la vasculatura especializada que proporciona al cerebro nutrientes en la sangre mientras regula estrictamente el movimiento de iones, moléculas, patógenos y otras sustancias. Está compuesto por células endoteliales estrechamente unidas por un lado y proyecciones de astrocitos por el otro. Juntos, proporcionan una barrera semipermeable que protege el cerebro y plantea desafíos únicos para la administración de terapias. <h4>Componentes celulares</h4> La BBB está formada por una variedad de componentes celulares, incluidas células endoteliales y astrocitos. Estas células comparten una membrana basal común y juntas regulan el paso de componentes entre la circulación y el líquido intersticial que rodea al cerebro. El primer tipo de componente celular, las células endoteliales especializadas, forman las paredes de los capilares cerebrales. Están conectados por uniones intercelulares extremadamente estrechas y complejas. Estas uniones crean una barrera física selectiva que impide la difusión simple de la mayoría de las sustancias, incluidas las moléculas de tamaño medio a grande, como la glucosa y la insulina. Un segundo tipo de células, los astrocitos, son un tipo de célula glial del sistema nervioso central que influye en la función de las células endoteliales, el flujo sanguíneo y el equilibrio iónico en el cerebro a través de la interacción y la estrecha asociación con la vasculatura cerebral. Proporcionan un vínculo directo entre la vasculatura y las neuronas: extienden procesos,llamados pies terminales, que envuelven los vasos sanguíneos en un extremo mientras hacen contacto íntimo con las neuronas en las sinapsis en el otro extremo. <h4>Intercambio químico</h4> La capacidad de una sustancia para cruzar la BBB y la eficiencia con la que se produce este intercambio depende de las propiedades químicas y moleculares de cada molécula o ion. En general, los pequeños componentes solubles en lípidos, como el oxígeno y el dióxido de carbono, experimentan una difusión rápida y simple a través de la capa endotelial. Por el contrario, los componentes más grandes o solubles en agua a menudo requieren un proceso más selectivo que puede implicar transporte pasivo o activo a través de una célula endotelial. El intercambio de estas sustancias generalmente ocurre más lentamente o puede no ocurrir en absoluto, dependiendo de la relativa abundancia y eficiencia de los receptores específicos de moléculas y las proteínas de transporte en la superficie de las células endoteliales, entre otros factores. <h4>La BBB protege el cerebro</h4> La protección neuronal facilitada por la BBB es fundamental para la salud y el funcionamiento adecuados del cerebro. La desregulación de la BHE puede provocar enfermedades neurológicas graves, como esclerosis múltiple, infección e isquemia debido a un suministro de sangre inadecuado. Por el contrario, la actividad de la BHE puede ser perjudicial para el tratamiento de algunas enfermedades neurológicas al prevenir o reducir sustancialmente el paso de fármacos neuroactivos al sistema nervioso central. Por este motivo, los fármacos con dianas neurológicas deben diseñarse de forma que faciliten el paso a través de la BHE.

La barrera hematoencefálica

Visión general

La barrera hematoencefálica (BBB) se refiere a la vasculatura especializada que proporciona al cerebro los nutrientes de la sangre, mientras que ...

Education

Educación

JoVE Core

Biology

Biología

Human Biology

Biología Humana

Nervous System

Sistema nervioso

KEY TERMS AND CONCEPTS

TÉRMINOS Y CONCEPTOS CLAVE

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?

Nervous System Parts and Control

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

Rest and Digest: Parasympathetic Control

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

Glial cells support the nervous system and work alongside neurons. They are one of the two main cell types in the nervous system. Unlike neurons, glia do not send electrical signals, but they help with nearly every other part of nervous system function. In humans, glial cells are about as numerous as neurons in the brain. In the central nervous system, glia include astrocytes, oligodendrocytes, microglia, and ependymal cells. Astrocytes are the most common glial cells. They form organized,...

action potentials

How Nerve Signals Travel in Axons

Neurons send signals through action potentials, the rapid electrical changes that move along the axon. These signals lead to neurotransmitter release at axon terminals, which passes information through the nervous system. An action potential is an all-or-none change in membrane potential, the voltage across a cell membrane. A neuron usually has a resting membrane potential of about -70 millivolts. When it receives signals from neurotransmitters or sensory input, the membrane can become more...

the resting membrane potential

How Neurons Keep a Negative Resting Charge

Neurons keep a negative resting charge across their membrane. This electrical difference, called the membrane potential, comes from how ions move and how the membrane lets them pass. In a resting neuron, the inside is typically around -70 millivolts and is more negative than the outside, so the cell is polarized. Two main factors create this resting state. First, the membrane is selectively permeable, which means most ions and molecules cannot cross the lipid bilayer without help from ion...

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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