Ventricular system

The entire CNS is covered by the meninges, which form a protective covering. The outermost is the dura, which is tough and leathery in consistency. It is highly vascularized and innervated, so it is sensitive to pain. The arachnoid membrane is a weblike, spongy layer beneath the dura. Beneath the arachnoid is the subarachnoid space, which is filled with cerebrospinal fluid. Beneath the subarachnoid space is a thin layer of cells called the pia, which covers the brain and spinal cord. Ventricular System... 

In addition, the epithelial cells of the choroid plexus facing the cerebrospinal fluid (CSF) constitute the blood-cerebrospinal fluid barrier (BCSFB). The BCSFB is also a significant area for exchange between the blood and the CSF. In rats the total calculated surface area of the choroid plexus is about 33% of that of the BBB [2]. In humans, based on the relative mass of the choroid plexus in comparison with the brain, the relative surface area of the choroid plexus may be in the region of 10% of that of the BBB. The CSF is secreted across the choroid plexus epithelial cells into the brain ventricular system [3] the remainder of the brain extracellular fluid (ECF) and the interstitial fluid (ISF) are secreted at the capillaries of the BBB themselves [4]. The ratio of fluid production from these sites is 40% 60%, respectively [5],... 

Fig. 22.1. A CT brain scan showing a primary intracerebral hemorrhage with rupture into the ventricular system (open arrow) and considerable mass effect (black arrow).

Fig. 30.1. These CT brain scans from a patient with a burst right middle cerebral artery aneurysm (arrow) show widespread subarachnoid blood, and rupture into the right cerebral hemisphere and the ventricular system.

Simpson KL, Fisher TM, Waterhouse BD, Lin RC (1998) Projection patterns from the raphe nuclear complex to the ependymal wall of the ventricular system in the rat. J Comp Neurol 399 61-72. 

According to the authors, this was the first case of encephalopathy after iohexol ventriculography, with the onset of symptoms several hours earlier than in myelography cases, probably owing to direct administration into the ventricular system. Awareness of this complication can be helpful in patient management after procedures in which iohexol is given intrathecally. 

In 1954 Leusen (20) demonstrated that the perfusion of the brain ventricular system with an acid fluid stimulated ventilation while perfusion with an alkaline fluid depressed ventilation. These ventilatory responses were assumed to be caused by direct stimulation or depression of chemosensitive elements within the respiratory center. Loeshcke and co-workers (21, 22) were the first to present evidence that respiratory H+ chemosensitivity might be located outside the medullary respiratory... 

The ependymal cells are ciliated cells that line the cavities (ventricles) of the CNS and the spinal cord. In some areas of the brain, the ependymal cells are functionally specialized to elaborate and secrete cerebrospinal fluid (CSF) into the ventricular system. The beating of the ependymal cilia allow for efficient circulation of the CSF throughout the CNS. The CSF acts as both a shock absorber protecting the CNS from mechanical trauma and a system for the removal of metabolic wastes. The CSF can be aspirated from the spinal canal and analyzed to determine whether disorders of CNS function, with their characteristic CSF changes, are present. 

Figure 6.9 Cerebrospinal fluid circulation through the central nervous system. This schematic diagram illustrates the pattern of fluid flow from formation in the choroid plexus, movement through the internal ventricular system, flow around the external surfaces of the brain and spinal cord, and absorption into the venous system through the arachnoid villi. Redrawn from The Ciba Collection of Medical Illustrations, Vol.

A Good Laboratory Practices (GLP) toxicology and biodistribution study was performed to determine the potential adverse effects of Ad5FGF-4 in healthy pigs after either intracoronary or left ventricular (systemic) administration (10 v.p. left ventricular, 10 -10 v.p. intracoronary). Systemic biodistribution of the product was also assessed. 

The brain contains grey matter and white matter substances that are easily distinguished upon gross examination. Grey matter contains a densely packed network of neural cell bodies and associated glial cells, whereas white matter contains myelinated axonal tracts, relatively few neuronal cell bodies, and a supporting environment of glial cells. The entire brain is surrounded by cerebrospinal fluid contained within an extensive ventricular system that occupies approximately one-tenth of the total brain volume. The ventricular system supports the brain as well as the spinal cord, and provides nutrients to and removes waste products from the central nervous system. 

I want to make one other comment regarding the difference between Dr. Sagawa s model and Dr. Welkowitz s model. Both are lumped models. Dr. Sagawa s model, however, is appropriate for only one point in time, namely end systole. Dr. Sagawa has extended the model to represent the ventricular system in the normal state. The lumped model that Dr. Welkowitz presented represents the full cardiac cycle. 

Neiurosarcoidosis may present as an acute explosive illness or in a slow, chronic fashion (143). Any part of the nervous system may be affected including the cranial nerves, meninges (Fig. 11), pituitary gland, hypothalamus, parenchyma of the brain, brainstem (Fig. 12), spinal cord (Fig. 13), subependymal layer of the ventricular system, peripheral nerves, and blood vessels supplying the nervous structures (143). 

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