blood-brain barrier

(noun)

A structure in the CNS that keeps substances found in the bloodstream out of the brain while allowing in substances essential to metabolic function such asoxygen.

Related Terms

(noun)

A structure in the central nervous system (CNS) that keeps various substances found in the bloodstream out of the brain while allowing in the substances essential to metabolic function, e.g., oxygen.

Related Terms

Examples of blood-brain barrier in the following topics:

  • Blood-Brain Barrier

    • Tight junctions present in the blood-brain barrier separate circulating blood from cerebrospinal fluid, regulating diffusion into the brain.
    • The blood-brain barrier (BBB) is a separation of circulating blood from the brain extracellular fluid in the central nervous system (CNS).
    • The concept of the BBB (then termed hematoencephalic barrier) was proposed by Lewandowsky in 1900.
    • Also, BBB cells actively transport metabolic products such as glucose across the barrier.
    • The BBB effectively protects the brain from many common bacterial infections, so brain infections are very rare.

  • Transcytosis

    • Transcytosis has been shown to be critical to the entry of Cronobacter sakazakii across the intestinal epithelium and the blood-brain barrier.
    • Pharmaceutical companies are currently exploring the use of transcytosis as a mechanism for transporting therapeutic drugs across the human blood-brain barrier.
    • Exploiting the body's own transport mechanism can help to overcome the high selectivity of the blood-brain barrier, which typically blocks the uptake of most therapeutic antibodies into the brain and central nervous system.

  • Circumventricular Organs

    • Circumventricular organs are situated adjacent to the brain ventricles and sense concentrations of various compounds in the blood.
    • They are among the few sites in the brain that have an incomplete blood-brain barrier.
    • As a result, neurons located in circumventricular organs can directly sense the concentrations of various compounds, particularly peptide hormones, in the bloodstream without the need for specialized transport systems that move those compounds across the blood-brain barrier.
    • A useful mnemonic device for remembering this aspect of their function, though not the source of the name, is that they allow factors to circumvent' the blood-brain barrier.
    • Median eminence: Allows for the transport of neurohormones between the CSF and the peripheral blood supply.

  • Axon Bundles

    • Cranial nerves innervate parts of the head and connect directly to the brain (especially to the brainstem).
    • The endoneurium has properties analogous to the blood–brain barrier, in that it prevents certain molecules from crossing from the blood into the endoneurial fluid.

  • The Brain

    • The human brain is the center of the human nervous system.
    • Despite being protected by the thick bones of the skull, suspended in cerebrospinal fluid, and isolated from the bloodstream by the blood-brain barrier, the human brain is susceptible to many types of damage and disease.
    • A number of psychiatric conditions, such as schizophrenia and depression, are thought to be associated with brain dysfunction, although the nature of such brain anomalies is not well understood.
    • The cerebral hemispheres form the largest part of the human brain and are situated above most other brain structures.
    • Distinguish between the cerebellum, cerebral cortex, and brain stem regions of the brain

  • Brain Tumors

    • A brain tumor is a pathological abnormal growth of cells in the brain.
    • A brain tumor is an intracranial solid neoplasm—a tumor (defined as an abnormal growth of cells)—within the brain or the central spinal canal.
    • They are created by an abnormal and uncontrolled cell division, usually in the brain itself, but also in lymphatic tissue, in blood vessels, in the cranial nerves, in the brain envelopes (meninges), skull, pituitary gland, or pineal gland.
    • Symptoms of solid neoplasms of the brain (primary brain tumors and secondary tumors alike) can be divided into three main categories:
    • Chemotherapy: is a treatment option for cancer, however it is seldom used to treat brain tumors as the blood and brain barrier prevents the drugs from reaching the cancerous cells

  • Cerebrospinal Fluid and Its Circulation

    • Between 50 to 70% of CSF is produced in the brain by modified ependymal cells in the choroid plexus, and the remainder is formed around blood vessels and along ventricular walls.
    • CSF is reabsorbed into venous sinus blood via arachnoid granulations.
    • Since the subarachnoid space around the brain and spinal cord can contain only 135 to 150 ml, large amounts are drained into the blood through arachnoid granulations in the superior sagittal sinus.
    • Chemical stability: CSF flows throughout the inner ventricular system in the brain and is absorbed back into the bloodstream, rinsing the metabolic waste from the central nervous system (CNS) through the blood-brain barrier.
    • Prevention of brain ischemia: Decreasing the amount of CSF in the limited space inside the skull decreases total intracranial pressure and facilitates blood perfusion.

  • Enteric Nervous System

    • Although it receives considerable innervation from the autonomic nervous system, it can and does operate independently of the brain and the spinal cord.
    • These tissues also send information back to the sympathetic pre-vertebral ganglia, the spinal cord, and the brain stem .
    • The enteric nervous system has been described as a "second brain. " There are several reasons for this.
    • In addition, ENS contains support cells, which are similar to astroglia of the brain, and a diffusion barrier around the capillaries surrounding ganglia, which is similar to the blood-brain barrier of cerebral blood vessels.
    • If the gut tract is irritated or distended, afferent nerves will send signals to the medulla of the brain for further processing.

  • Blood Flow in the Brain

    • Cerebral circulation is the movement of blood through the network of blood vessels supplying the brain, providing oxygen and nutrients.
    • Cerebral circulation refers to the movement of blood through the network of blood vessels supplying the brain.
    • The arteries deliver oxygenated blood, glucose and other nutrients to the brain and the veins carry deoxygenated blood back to the heart, removing carbon dioxide, lactic acid, and other metabolic products.
    • Since the brain is very vulnerable to compromises in its blood supply, the cerebral circulatory system has many safeguards.
    • Too much blood can raise intracranial pressure (ICP), which can compress and damage delicate brain tissue.

  • Physical Characteristics and Volume

    • Blood contains plasma and blood cells, some of which have hemoglobin that makes blood red.
    • The average blood volume in adult is five liters.
    • Blood contains red blood cells (RBCs), white blood cells (WBCs), platelets, and other cell fragments, molecules, and debris.
    • In order to maintain homeostasis, blood volume and blood pressure must be high enough that blood can reach all of the body's tissues, a process called tissue perfusion.
    • Most tissues can survive without perfusion for a short amount of time, but the brain needs a continuous supply of oxygen and glucose to stay alive.