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157 venous drainage

The veins of skin are organized along the same lines as the arteries in that there are both subpapillary and subdermal plexuses [11]. The main arteriole communication to these is the capillary bed. Copious blood is passed through capillaries when the core body is either feverish or overheated, far more than needed to sustain the life force of the epidermis, and this rich perfusion lends a red coloration to skin. When there is opposite physiological need, the capillary bed is short-circuited as blood is passed directly into the venous drainage by way of the arteriovenous anastomoses. Fair skin noticeably blanches when this occurs. These mechanisms act in part to regulate body temperature and blood pressure. [Pg.198]

The rate of absorption from an SC injection site may be retarded by immobilization of the limb, local cooling to cause vasoconstriction, or application of a tourniquet proximal to the injection site to block the superficial venous drainage and lymphatic flow. In small amounts, adrenergic stimulants, such as epinephrine, will constrict the local blood vessels and, therefore, slow systemic absorption. Conversely, cholinergic stimulants (such as methacholine) will induce very rapid systemic absorption subcutaneously. Other agents may also alter their own rate of absorption by affecting local blood supply or capillary permeability. [Pg.452]

The liver is uniquely situated to process and distribute dietary nutrients because the venous drainage of the gut and pancreas passes through the hepatic portal vein before entry into the general circulation. Thus, after a meal, the liver is bathed in blood containing absorbed nutrients and elevated levels of insulin secreted by the pancreas. During the absorptive period, the liver takes up carbohydrates, lipids, and most amino acids. These nutrients are then metabolized, stored, or routed to other tissues. Thus, the liver smooths out potentially broad fluctuations in the availability of nutrients for the peripheral tissues. [Pg.320]

There are many different procedures used for pancreas transplantation, and there is no one standard protocol used in all transplant centers. The important considerations, however, are that the arterial blood flow supply to the pancreas and duodenal segment, and venous outflow from the pancreas via the portal vein should be adequate. The recipient s right common or external iliac artery is used to restore vascularization of the artery in the pancreas. The Y graft of the tissue is anastomosed end-to-side and the venous vascularization is performed either systemically or portally, but mostly it is done with systemic venous drainage. [Pg.163]

FIGURE 7.1 Schematic illustration of the venous drainage of the human rectum. Drugs absorbed in the inferior and middle rectal veins that drain the lower part of the rectum will be delivered preferentially to the systemic circulation, bypassing the liver and avoiding first-pass metabolism. (Illustrated with modification from Nishimura, M., et al. (Eds.), Shin-Gekakgaku, 5th ed., Nanzando, Tokyo, 1979, 583. With permission.)... [Pg.137]

Many physiological aspects affect drug absorption from the rectum (Table 7.1). Influential factors include the pH of the rectal contents, state of the mucus layer, volume and viscosity of rectal fluid, luminal pressure from the rectal wall on the dosage form, enzymatic and microbacterial degradation by rectal epithelium, presence of stools, and venous drainage differences within the rectosigmoid regions. [Pg.138]

The suprachoroid is 30 pm in thickness and comprises thin interconnected lamellae of melanocytes, fibroblasts, and connective tissue fibers. These are separated by a thin space known as the suprachoroidal space. In this space hydrostatic pressure is a few mm of Hg lower than the IOP. The small gradient allows drainage of aqueous humor, through the tissue spaces of the ciliary muscles, into the suprachoroidal space. Venous drainage takes place through a series of large vortex veins each of these drains a sector of the choroid into the superior and inferior ophthalmic veins of the orbit. [Pg.485]

Functional disturbances within the spinal cord are caused by the venous congestion due to arteriali-zation and elevated pressure of the medullary veins (Aminoff et al. 1974). In addition, venous outlets are insufficient and thus reinforcing impairment of the venous circulation and chronic spinal hypoxia. In particular, Merland and coworkers (1980) introduced the concept of blocked venous drainage into the epidural space. [Pg.256]

Crawford SC, Digre KB, Palmer CA, Osborn AG (1995) Thrombosis of deep venous drainage of the brain in adults. Arch Neurol 52 1101-1108... [Pg.283]

The posterior cerebral artery supplies the occipital lobe and portions of the medial and inferior temporal lobe. The arterial supply of the spinal cord is derived from the vertebral arteries and the radicular arteries. The brain is supplied by the internal carotid arteries (the anterior circulation) and the vertebral arteries, which join at the pon tomedullary junction to form the basilar artery (collectively termed the posterior circulation). The brainstem is supplied by the posterior system. The medulla receives blood from branches of the vertebral arteries as well as from the spinal arteries and the posterior inferior cerebellar artery (PICA). The pons is supplied by paramedian and short circumferential branches of the basilar artery. Two major long circumferential branches are the anterior inferior cerebellar artery (AICA) and the superior cerebellar artery. The midbrain receives its arterial supply primarily from the posterior cerebral artery as well as from the basilar artery. The venous drainage of the spinal cord drains directly to the systemic circulation. By contrast, veins draining the cerebral hemispheres and brain stem drain into the dural sinuses. Cerebrospinal fluid also drains into the dural sinuses through unidirectional valves termed arachnoid villi. [Pg.21]

Each node, also called a lymph gland, has both arterial blood supply and venous drainage. Lymphocytes drain out of the arteries into the node interior, usually through a high endothelial venule that facilitates their entry. This venule (small vein) derives its name from the higher-than-usual tightly joined endothelial cells that line it. [Pg.170]

The vascular system and blood supply to the oral mucosa have been clearly described by Stablein and Meyer.Netter s excellent drawings of the blood supply to the mouth and pharynx, venous drainage of the mouth and pharynx, and lymphatic drainage of the mouth and pharynx have been published by Ciba. ... [Pg.1072]

An advantage of rectal over oral administration of lipid-soluble drugs is partial avoidance of the first-pass effect. The extent to which the first-pass effect is avoided appears to be less in dogs than in humans. Because venous drainage of the rectum of the horse. [Pg.3949]

Place a second cannula in the right ventricle via the pulmonary artery to collect coronary venous drainage. [Pg.368]

Epinephrine production is catalyzed by PNMT, which is induced by glucocorticoids (cortisol). The venous drainage of the adrenal cortex, which contains very high concentrations of newly released cortisol, bathes the adrenal medulla before entering the general circulation. [Pg.763]


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See also in sourсe #XX -- [ Pg.256 , Pg.269 , Pg.270 ]

See also in sourсe #XX -- [ Pg.92 ]




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157 venous drainage vertebral arteries

Cerebral venous drainage

Deep venous drainage

Drainage

Spinal cord venous drainage

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