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

- [Narratore] Il cervello umano e' isolato

dal sistema circolatorio
attraverso una barriera protettiva

chiamata la barriera emato-encefalica

che consiste in cellule endoteliali

che ricoprono i capillari
del sistema nervoso centrale.

La barriera emato-encefalica

è costituita anche da una membrana basale

e cellule neurali specializzate
chiamate astrociti

che sono a stretto
contatto con i capillari.

Questi componenti aiutano a prevenire

l'incrocio con sostanze indesiderate.

Questa barriera controlla
lo scambio chimico

tra il sangue e il fluido
interstiziale nel cervello

attraverso diversi tipi di proteine

che formano complessi giunzionali.

In generale, solo i composti liposolubili

possono diffondersi oltre la barriera,

mentre i composti solubili
in acqua si incrociano

tramite trasporto attivo o passivo.

Daneman, Richard e Alexandre Prat. "La barriera emato-encefalica". Cold Spring Harbor Perspectives in Biology 7, n. 1 (gennaio 2015). [<a href="https://doi.org/10.1101/cshperspect.a020412" target="__blank">Sorgente</a>]

Andreone, Benjamin J., Baptiste Lacoste e Chenghua Gu. "Interazioni neuronali e vascolari". Rassegna annuale di neuroscienze 38 (8 luglio 2015): 25–46. [<a href="https://doi.org/10.1146/annurev-neuro-071714-033835" target="__blank">Sorgente</a>]

la barriera ematoencefalica

The Blood-brain Barrier

<h4>Panoramica</h4>

La barriera emato-encefalica (BBB) si riferisce alla vascolatura specializzata che fornisce al cervello nutrienti nel sangue, mentre regola rigorosamente il movimento di ioni, molecole, agenti patogeni e altre sostanze. È composto da cellule endoteliali strettamente collegate da un lato e proiezioni astrocite dall'altro. Insieme forniscono una barriera semipermeabile che protegge il cervello e pone sfide uniche per la consegna di terapie.

<h4>Componenti cellulari</h4>

La BBB è costituito da una varietà di componenti cellulari, tra cui cellule endoteliali e astrociti. Queste cellule condividono una membrana seminterrato comune e insieme regolano il passaggio dei componenti tra la circolazione e il fluido interstiziale che circonda il cervello.

Il primo tipo di componente cellulare, cellule endoteliali specializzate, costituiscono le pareti dei capillari cerebrali. Sono collegati da giunzioni intercellulari estremamente strette e complesse. Queste giunzioni creano una barriera fisica selettiva, impedendo la semplice diffusione della maggior parte delle sostanze, comprese molecole da medie a grandi dimensioni come glucosio e insulina.

Un secondo tipo di cellula, gli astrociti, sono un tipo di cellula gliale del sistema nervoso centrale che influenza la funzione delle cellule endoteliali, il flusso sanguigno e l'equilibrio degli ioni nel cervello attraverso l'interazione e la stretta associazione con la vascolatura cerebrale. Forniscono un collegamento diretto tra la vascolatura e i neuroni: estendono i processi, chiamati "endfeet" (piedi finali) , che avvolgono i vasi sanguigni da un lato, facendo un contatto intimo con i neuroni alle sinapsi dall'altra parte.

<h4>Scambio chimico</h4>

La capacità di una sostanza di attraversare la BBB e l'efficienza con cui si verifica questo scambio dipende dalle proprietà chimiche e molecolari di ogni molecola o ione. In generale, piccoli componenti lipidi-solubili, come ossigeno e biossido di carbonio, subiscono una rapida, semplice diffusione attraverso lo strato endoteliale. Al contrario, i componenti più grandi o solubili in acqua spesso richiedono un processo più selettivo che può comportare il trasporto passivo o attivo attraverso una cellula endoteliale. Lo scambio di queste sostanze avviene generalmente più lentamente o non può verificarsi affatto, a seconda dell'abbondanza relativa e dell'efficienza dei recettori specifici delle molecole e del trasporto delle proteine sulla superficie delle cellule endoteliali, tra gli altri fattori.

<h4>La BBB protegge il cervello</h4>

La protezione neurale facilitata dalla BBB è fondamentale per la corretta salute e funzione del cervello. La disregolazione della BBB può portare a gravi malattie neurologiche tra cui la sclerosi multipla, l'infezione e l'ischemia a causa di un apporto di sangue inadeguato. Al contrario, l'attività del BBB può essere dannosa per il trattamento di alcune malattie neurologiche prevenendo o riducendo sostanzialmente il passaggio di farmaci neuroattivi nel sistema nervoso centrale. Per questo motivo, i farmaci con obiettivi neurologici devono essere progettati in modo da facilitare il passaggio attraverso la BBB.

La barriera ematoencefalica

Panoramica

La barriera emato-encefalica (BEE) si riferisce alla vascolarizzazione specializzata che fornisce al cervello i nutrienti nel sangue mentre è strettamente ...

Education

Didattica

JoVE Core

Biology

Biologia

Human Biology

Biologia umana

Nervous System

Sistema nervoso

KEY TERMS AND CONCEPTS

TERMINI E CONCETTI CHIAVE

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

JoVE Core series brings biology to life through over 300 concise and easy-to-understand animated video lessons that explain key concepts in biology, plus more than 150 scientist-in-action videos that show actual research experiments conducted in today’s laboratories.

biology

JoVE Core Biologia illustra i concetti chiave della biologia grazie a oltre 300 video-lezioni animate, concise e di facile comprensione. Inoltre, negli oltre 150 video di "scienziati in azione", i concetti scientifici vengono applicati e dimostrati da ricercatori attraverso esperimenti in laboratorio.

myJoVE Corporation

How the Blood-Brain Barrier Works

Description

Transcript

Tags