Circulatory homeostasis

It is now becoming apparent that peripheral inhibition of sympathetic transmission, although effective in lowering blood pressure, does not restore circulatory homeostasis in the hypertensive patient, and in the light of recent progress in the... 

In 600 elderly patients with documented congestive cardiac failure there was a possible or probable link between NSAIDs and heart failure in 27 cases (32). In some, the mechanism was apparently a reduction in the effect of furosemide. In others the NSAID may have caused an imbalance in circulatory homeostasis. Preexisting renal impairment was not observed in any of the 27 cases. This study suggests that in elderly people congestive heart failure may be a complication of NSAIDs. 

FIGURE 14-4. Key components of the pathophysiology of cardiac remodeling. Myocardial injury (e.g., myocardial infarction) results in the activation of a number of hemodynamic and neurohormonal compensatory responses in an attempt to maintain circulatory homeostasis. Chronic activation of the neurohormonal systems results in a cascade of events that affect the myocardium at the molecular and cellular levels. These events lead to the changes in ventricular size, shape, structure, and function known as ventricular remodeling. The alterations in ventricular function result in further deterioration in cardiac systolic and diastolic function, which further promotes the remodeling process. 

Hotta et al. [92] reported on carvacrol acting on other receptors. They found that this substance, as a major part of the EO of thyme, is an activator of PPARa and y, leading to an inhibition of COX-2 expression. This finding is a strong indicator for the anti-inflammatory effect of carvacrol since COX-2 is known to play important roles in inflammation processes and circulatory homeostasis. 

Schayer, R. W., 1960, Relationship of stress-induced histidine decarboxylase to circulatory homeostasis and shock. Science 131 226-227. 

Edema is a condition of abnormally large fluid volume in the circulatory system or in tissues between the body s cells. For a healthy human body, the venous and lymphatic systems collaborate to maintain the micro- and macro-circulatory homeostasis of the tissues. Ulceration of the skin develops when the normal functions of these two systems are disturbed either as a result of diabetic diseases or by the application of excessive pressure on the tissue. This leads to large amounts of edema and wound exudate, with peri-wound skin having dermatitis, hyperemia or maceration, dark pigmentation, atrophy blanche, and fibrosis. Figure 8.1 shows an example of a patient with venous leg ulcers. 

All of the organ systems in the body, except the reproductive system, contribute to the maintenance of homeostasis (see Table 1.1). For example, the gastrointestinal tract digests foods to provide nutrients to the body. The respiratory system obtains oxygen and eliminates carbon dioxide. The circulatory system transports all of these materials and others from one part of the body to another. The renal system eliminates wastes and plays a role in regulating blood volume and blood pressure. 

Figure 1.2 Negative feedback. These types of responses are employed throughout the body in order to maintain homeostasis. In this example, any change in blood pressure, which is monitored within the circulatory system and processed within the CNS, will cause reflex changes in heart rate. The change in heart rate will be in the opposite direction of the change in blood pressure if blood pressure increases, then heart rate decreases if blood pressure decreases, then heart rate increases. In this way, blood pressure is adjusted back to its normal value.

The circulatory system carries out many important functions that contribute to homeostasis. It obtains oxygen from the lungs nutrients from the gastrointestinal tract and hormones from the endocrine glands and it delivers these substances to the tissues that need them. Furthermore, it removes metabolic waste products, such as carbon dioxide, lactic acid, and urea, from the tissues. Finally, it contributes to the actions of the immune system by transporting antibodies and leukocytes to areas of infection. Overall, the circulatory system plays a vital role in maintenance of optimal conditions for cell and tissue function. 

Jensen RK, Zile MH. 1988. Effect of dietary retinoic acid on circulatory vitamin A homeostasis in polybrominated biphenyl-treated rats. J Nutr 118 416-419. 

Insulin is a storage hormone produced by the pancreas. Insulin shuttles nutrients, such as carbohydrates, fats and amino acids (derived from proteins) into cells. The main function of insulin is to maintain homeostasis of circulatory glucose, and intracellular glycogen storage. It also aids in fat storage. 

Neurotoxicity can also occur as a result of indirect effects. For example, damage to hepatic, renal, circulatory, or pancreatic structures may result in secondary effects on the function and structure of the nervous system, such as encephalopathy or polyneuropathy. Secondary effects would not cause a substance to be considered neurotoxic, though at high enough doses, neurotoxicity could be evident. Thus, for the purpose of this review, a substance is defined as neurotoxic when it or its metabolites produce adverse effects as a result of direct interactions with the nervous system. It should be noted, nevertheless, that some chemicals may have multiple modes of action and affect the nervous system directly and indirectly. For example, several halogenated compounds (e.g., polychlorinated biphenyls (PCB), polybrominated diphenyl ethers (PBDE)) may interact directly with brain cells, and also affect the development of the nervous system by altering thyroid hormone homeostasis.7 8... 

The lymphatic system is a series of vessels for transporting back to the circulation, the fluid, cells and macromolecules that escape from the blood vascular system. It is therefore an essential part of the circulatory system. In normal physiology the lymphatics therefore play a key role in fluid homeostasis and immune cell trafficking. In pathological conditions aberrant lymphatic vessel function is associated with conditions such as lymphoedema and cancer (Baldwin et al 2002). 

The integumentary system (i.e., the skin) serves multiple functions in preserving homeostasis. Several of these functions, if disrupted, could result in fluid volume imbalance. The skin also provides invaluable data related to disturbance in sensory or circulatory status. Any injury to the skin, such as a laceration or tearing from trauma or friction, will disrupt the function of the skin. Five main physical functions of the skin include... 

The circulatory system contributes to the homeostasis of an organism by transporting and exchanging substances and information via blood. The heart of cotirse provides the mechanical energy needed to circulate blood through the... 

Guo, X.M., X. Lu, H.M. Ren, E.R. Levin, and G.S. Kassab. 2006b. Estrogen modulates the mechanical homeostasis of mouse arterial vessels through nitric oxide. American Journal of Physiology-Heart and Circulatory Physiology 290(5) H1788-97. 

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