Blood vessels capillaries

Telangiectasia Permanent dilation of preexisting small blood vessels (capillaries, arterioles, and venules), usually in the skin or mucous membranes, which presents as a coarse or fine red mark. 

Nootropics. The nootropic medications (of which piracetam is the best known) are believed to enhance nerve cell activity by improving circulation in the tiniest of blood vessels (capillaries) that provide oxygen-rich blood to the nerve cells. In addition to enhancing nerve cell metabolism, these medications should theoretically protect nerve cells in the same manner as the anticoagulants. Although theoretically sound, the nootropics have not shown any significant benefit for demented patients. Therefore, we cannot recommend their use. 

Capillaries The tiniest blood vessels capillary networks connect the arterioles (the smallest arteries) and the venules (the smallest veins)... 

A base, formed by the bacterial degradation of histidine, and present in ergot and in many animal tissues, where it is liberated in response to injury and to antigen-antibody reactions. If injected it causes a condition of shock with dilatation of many blood vessels, loss of plasma from the capillaries to the tissues and a rapid fall in blood pressure. It is normally prepared from protein degradation products. 

The bioflavanoids (vitamin P complex) are substances which maintain the small blood vessel walls. The substances are widely distributed among plants, eg, all citms fmits, and have been used medicinally to decrease capillary permeability and fragility. 

Resistance vessels Microcirculatory blood vessels (arterioles, pre-capillary... 

MAINTAINING ADEQUATE TISSUE PERFUSION. When a patient is in shock and experiencing ineffective tissue perfusion tiiere is a decrease in oxygen resulting in an inability of die body to nourish its cells at die capillary level. If die patient has marked hypotension die administration of a vasopressor (a drug diat raises die blood pressure because of its ability to constrict blood vessels) is required. The primary health care provider determines die cause of die hypotension and then selects the best mediod of treatment. Some hypotensive episodes require die use of a less potent vasopressor, such as metaraminol, whereas at other times a more potent vasopressor, such as dobutamine (Dobutrex), dopamine (Intropin), or norepinephrine (Levoplied) is necessary. 

A third type is a disseminated fibrin deposit in very small blood vessels or capillaries. 

Perfusion imaging techniques study pathophysiologic events that occur in capillaries and other microscopic blood vessels that cannot be seen by angiographic techniques like CTA or MRA. The perfusion imaging techniques in most widespread clinical use are performed using CT or MRl, and generally obtain or... 

Bone is a porous tissue composite material containing a fluid phase, a calcified bone mineral, hydroxyapatite (HA), and organic components (mainly, collagen type). The variety of cellular and noncellular components consist of approximately 69% organic and 22% inorganic material and 9% water. The principal constiments of bone tissue are calcium (Ca ), phosphate (PO ), and hydroxyl (OH ) ions and calcium carbonate. There are smaller quantities of sodium, magnesium, and fluoride. The major compound, HA, has the formula Caio(P04)g(OH)2 in its unit cell. The porosity of bone includes membrane-lined capillary blood vessels, which function to transport nutrients and ions in bone, canaliculi, and the lacunae occupied in vivo by bone cells (osteoblasts), and the micropores present in the matrix. 

Heparin is biosynthesized and stored (probably as a complex with histamine and other basic species) in basophilic granules of mast cells of many animal tissues. (Mast cells, whose function remains largely obscure, are located in connective tissues, near the capillaries, and in the walls of blood vessels.10 28 27)... 

The movement of substances between the blood and the extracellular fluid surrounding the cells in most tissues of the body occurs very readily. This exchange takes place at the level of the capillaries, the smallest blood vessels in the cardiovascular system whose walls are formed by a single layer of endothelial cells. Lipid-soluble substances are able to move across this layer of endothelial cells at any point because they can move directly through the plasma membrane by passing between the phospholipid molecules of the bilayer. The movement of water-soluble substances is limited to the multiple pores found between the cells however, it also takes place rapidly and efficiently. 

The adenohypophysis does not have a direct anatomical connection with the hypothalamus therefore, regulation of hormone secretion by way of neuronal signals is not possible. Instead, these two structures are associated by a specialized circulatory system and the secretion of hormones from the adenohypophysis is regulated by hormonal signals from the hypothalamus (see Figure 10.2). Systemic arterial blood is directed first to the hypothalamus. The exchange of materials between the blood and the interstitial fluid of the hypothalamus takes place at the primary capillary plexus. The blood then flows to the adenohypophysis through the hypothalamic-hypophyseal portal veins. Portal veins are blood vessels that connect two capillary beds. The second capillary bed in this system is the secondary capillary plexus located in the adenohypophysis. 

The circulatory system is composed of several anatomically and functionally distinct blood vessels including (1) arteries, (2) arterioles, (3) capillaries, and (4) veins. 

The sympathetic system also innervates vascular smooth muscle and regulates the radius of the blood vessels. All types of blood vessels except capillaries are innervated however, the most densely innervated vessels include arterioles and veins. An increase in sympathetic stimulation of vascular smooth muscle causes vasoconstriction and a decrease in stimulation causes vasodilation. Constriction of arterioles causes an increase in TPR and therefore MAP. Constriction of veins causes an increase in venous return (VR) which increases end-diastolic volume (EDV), SV (Frank-Starling law of the heart), CO, and MAP. 

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