Henry gauer reflex. Henry

Cardiovascular physiology in space flight

henry gauer reflex

Although these results occur because of microgravity influences and mission requirements, they raise questions concerning which systems modulate, integrate, and regulate these physiological changes. Submitted for publication February 1995. This is largely mediated via an increase in heart rate and facilitated by an increase in venous return. These facts, coupled with the function of select neuropeptides and neurotransmitters, have extended the definition of neuroendocrinology to include brain secretions regardless of whether they enter the blood stream. According to Reichlin , the endocrine and nervous systems regulate most of the metabolic and homeostatic functions of an organism. In several instances, the results from these investigations have directly contradicted the predictions based on established models. When post-flight plasma testosterone values were measured in rats that were in microgravity for less than 2 wk, these animals had significantly lower concentrations than controls.

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The effects of stimulation of the left atrial receptors on sympathetic efferent nerve activity

henry gauer reflex

Flight results summarized by Cogoli and by Huntoon et al. Although the mechanisms remain to be elucidated, one hypothesis is that the beta-receptors had been up-regulated. In addition to aldosterone, cortisol can also enhance the resorption of sodium and the urinary excretion of potassium. In fact, the 10-fold increase in precursors of neutrophils measured in Spacelab-1 was explained by the transient changes in glucocorticoid and catecholamine concentrations. The results provide further evidence for the selective nature of the pattern of reflex responses to left atrial receptor activation and show for the first time a directionally fractionated response from sympathetic efferent neurones. Blood and plasma volume consistently decrease with spaceflight; hence, blood endocrine and immune constituents will be modified by both gravitational and measurement influences. The effects of left atrial distension upon urine flow from the isolated perfused kidney.

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CiteSeerX — Challenge of Renal Protection in Acute

henry gauer reflex

We feel the water immersion model is not the most desirable because the Henry-Gauer reflex has not been effectively demonstrated in space, the compression of soft tissue and the large pressure gradient across the chest wall are not features of microgravity, and because there is insufficient time to test countermeasures. Norepinephrine and Epinephrine Catecholamine changes are generally included when neuroendocrine responses to stress are mentioned and their urinary concentrations were elevated after Mercury flights, which lasted from 15 min to less than 2 d. Section Editor s : Tipton, Charles M. If similar results occur in humans, then decreases in testosterone and erythropoietin, coupled with the increased destruction of erythrocytes by the reticuloendothelial system, would help explain the reduction in red cell mass with microgravity. Although it is tempting to attribute the loss in muscle mass to elevation of plasma cortisol concentrations, the in-flight data do not support this possibility.

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CiteSeerX — Challenge of Renal Protection in Acute

henry gauer reflex

The main cardiovascular response to isotonic exercise is an increase in cardiac output to elevate oxygen delivery to exercising muscle. Consequently, for long-term flights, moderate rather than intense exercise is recommended for crew members to maximize the functioning of the immune system. With longer flights from 65 to 237 d, this lymphokine was lower than the pre-flight baseline value. Specifically, what neuroendocrine and immune system functions are altered by microgravity; and what effects, if any, do these functions have in minimizing the changes depicted in? Granulocytes are subgrouped as neutrophils, basophils, and eosinophils, which can be distinguished by their morphology, histological staining, and function. The mechanisms by which distension of the left atrium produces diuresis in anaesthetized dogs. Since B-cells represent a small percentage of the circulating blood lymphocytes, these contrasting results should be expected. The location of atrial receptors in the dog: a physiological and histological study.

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Applied cardiovascular physiology

henry gauer reflex

Similar studies should be conducted in humans. Sodium and chloride concentrations are decreased in the plasma and increased in the urine during the first few weeks of microgravity. Of the animal studies, two deserve mention. After 7-d missions, post-flight calcitonin concentrations were elevated, whereas after 150 d or longer, they were lower than the pre-flight mean. J Physiol Paris 1957 Jan-Mar; 49 1 :33—36. Because the majority of studies on the relationship between microgravity and immunology focus on the protective role of the immune system against foreign proteins, a similar approach will be followed. The influence of triiodothyronine T3 and thyroxine T4 on protein synthesis also requires further investigation, as limited data are available.

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Neuroendocrine and immune system responses with spaceflights : Medicine & Science in Sports & Exercise

henry gauer reflex

However, the cytotoxicity index was not always depressed below baseline values. Because of mutual interactions between these respective integrative systems, it is inappropriate to assume that the responses of one have no impact on functions of the other. Results suggest associations between space flight's effects on other organ systems and those on the cardiovascular system. As noted previously, in-flight plasma aldosterone concentration is decreased in flights lasting 8 d, which would accentuate the reduction in plasma volume measured after landing. One class of lymphokines is the interleukins of which more than 12 have been characterized. The results provide additional evidence that the reflex increase in the heart rate following stimulation of the left atrial receptors is mediated by selective activation of cardiac sympathetic nerve fibres.

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Gauer

henry gauer reflex

Results from a variety of investigations have established that the intrinsic and extrinsic factors associated with launch, cabin confinement, flight, extra-vehicular activity, re-entry, and landing elicit biochemical and physiological changes that are frequently characterized as stress responses. This decline in mass in humans is observed predominately in the lower extremities presumably because arm muscles are used more for locomotion and posture stability. ScienceDirect ® is a registered trademark of Elsevier B. This hypovolemia coincides with a decrease in red cell number and hemoglobin mass that ranges from 3% to 31%. After landing, these two hormones remained elevated regardless of flight duration.

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