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Results for “Digestive System Physiological Phenomena”

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PubMed1975

The influence of food intake on portal blood flow and heat production in the digestive tract of sheep.

1. Measurements were made of portal blood flow, heat production and oxygen consumption in the digestive tract of sheep either fasted or given the following diets: chopped, dried grass, pelleted, dried grass; chopped, dried lucerne; pelleted, dried lucerne, or a pelleted barley diet. 2. For sheep that had been fasted for 48 h, portal blood flow was 1.84 l/min, total visceral heat production was 62.3 kJ/kg body-weight 0.75 per 24 h and aerobic heat production, estimated from oxygen consumption, was 62.1 kJ/kg body-weight 0.75 per 24 h. 3. Portal blood flow was markedly influenced by food intake, increasing from 1.8 l/min for starved sheep to 2.4 and 4 l/min for sheep feed at maintenance and 2.5 times maintenance levels of intake respectively. Variations in the quality and physical form of the diets had no apparent effect on portal blood flow. 4. There was a curvilinear relationship between total heat production in the gut and metabolizable energy (ME) intake. The increase obtained for levels of intake below maintenance was greatest with lucerne diets, and least with pelleted, dried grass or pelleted barley diets. Above maintenance levels of intake the rate of increase in heat production, with all diets, was about 150 kJ/MJ ME intake. 5. The heat of fermentation, estimated from the difference between total visceral metabolism and the aerobic metabolism of the tissues of the gut wall, was 76, 60 and 22 kJ/MJ digestible energy intake for the dried grass, lucerne and barley diets respectively. 6. The contribution of fermentation heat and the aerobic metabolism of the gut to the total heat increment of feeding in sheep was assessed. It was concluded that about half the heat increment must be derived from tissues outside the digestive tract.

Aerobiosis↗
PubMed1995

Mechanism for the inhibition of fat digestion by chitosan and for the synergistic effect of ascorbate.

We investigated the mechanism for the inhibition of fat digestion by chitosan, and the synergistic effect of ascorbate. The important inhibition characteristics of fat digestion by chitosan from observations of the ileal contents were that it dissolved in the stomach and then changed to a gelled form, entrapping fat in the intestine. The synergistic effect of ascorbate (AsA) on the inhibition of fat digestion by chitosan is thought not to be acid-dependent but due to the specificity of AsA itself, according to the data resulting from using preparations supplemented with sodium ascorbate (AsN). The mechanism for the synergistic effect is considered to be 1) viscosity reduction in the stomach, which implies that chitosan mixed with a lipid is better than chitosan alone, 2) an increase in the oil-holding capacity of the chitosan gel, and 3) the chitosan-fat gel being more flexible and less likely to leak entrapped fat in the intestinal tract.

Animal Nutritional Physiological Phenomena↗
PubMedDate not supplied

Gender-specific physiology: how real is it? How important is it?

A predominantly male model of disease, and thus a tendency to restrict medical investigation to men, has led to a skewing of our perceptions of both normal human physiology and the pathophysiology of illness. Because of social and economic factors, research programs focused on aspects of women's health and disease (other than reproductive) have become more common over the past decade. The present literature review of gender-specific physiology covers the roles of gonadal hormones, especially in the nervous system; depression; the cytochrome P-450 system; the cardiovascular system, the immune system; saliva; and the gastrointestinal tract. All in all, there are revealed important differences, and some surprising similarities, between the genders in disease conditions and drug responses.

Cardiovascular Diseases↗
PubMed1990

Physicochemical properties and physiological effects of the (1----3)(1----4)-beta-D-glucan from oats.

In summary, despite the many uncertainties regarding mode of action, these results have established that the soluble dietary fibre from oats, mainly (1----3)(1----4)-beta-D-glucan, is physiologically active in a fashion similar to guar gum. Extraction processes reduce the molecular size of the beta-glucan relative to the native cell wall polymer, and the product was of lower viscosity than a guar gum used for comparison, but this did not appear to affect either in vivo or in vitro activity under the conditions used. There remains a need to develop a clearer picture of the relationship, if any, of viscosity to activity, through dose response studies with products of different viscosity.

Animals↗
PubMed2005

Does feeding limit cardiovascular modulation in the Dungeness crab Cancer magister during hypoxia?

Decapod crustaceans inhabit aquatic environments that are frequently subjected to changes in oxygen content. The physiological mechanisms that allow them to cope with periodic episodes of hypoxia have been well documented. Most crustaceans exhibit a bradycardia coupled with diversion of haemolymph from digestive organs towards ventral structures. However, all these experiments were conducted on animals that were starved prior to experimentation in order to avoid increases in metabolism associated with digestive processes. The present study sought to determine how the Dungeness crab Cancer magister balances the demands of physiological systems when they feed and digest in hypoxia. Cardiac parameters and haemolymph flow rates through each arterial system exiting the heart were measured using a pulsed-Doppler flowmeter. Scaphognathite beat frequency (ventilation rate) was calculated by recording changes in pressure in the branchial chamber. There was an increase in both cardiac and ventilatory parameters following feeding. Digestive processes were facilitated by an increase in haemolymph flow rates through the anterior aorta, hepatic arteries and sternal artery. Cancer magister showed a typical bradycardia during hypoxia (3.2 kPa). However, food intake caused a significant reduction in this response. Likewise, ventilation rate also showed effects of addivity, increasing in response to both food intake and hypoxia. Digestion during hypoxia was associated with a decrease in both stroke volume and cardiac output. Blood was diverted away from digestive structures, suggesting that blood flow events are prioritized during hypoxia. The changes in haemolymph flow rates paralleled those in previous reports on reductions in protein synthesis in the hepatopancreas during hypoxia. Haemolymph flow rates through the anterior aorta did not change; thus the blood supply to the supraoesophageal ganglion was maintained during feeding in hypoxia. The results show that the nutritional state of an animal is important in modulating its physiological responses to environmental perturbations. This underscores the importance of an integrative approach, studying physiological responses at the organismal level.

Analysis of Variance↗
PubMed1975

Fibre in nutrition.

The physical properties and the chemical variety of the substances which make up the plant cell wall are inadequately described by any one term such as "fibre". It would seem that an understanding of the role of the unavailable carbohydrates and lignin in the diet in the functioning of the gastro-intestinal tract and on possible pathological process must be based on a better knowledge of the chemical and physical properties of these substances as they occur in foods than is at present available. It is suggested that this knowledge can come from a synthesis of the findings of the plant anatomists, plant biochemists and structural organic chemists and the application of this synthesis to studies in man.

Animals↗
PubMed1998

Pathogenesis of enteric diseases.

The pathogenesis of digestive disease in poultry involves the cellular events and reactions that result in a deviation from normal structure and function. To a degree, the differentiation of disease and normal in commercial poultry also involves an economic perspective. Factors external to the digestive tract may mimic digestive disease, including reductions in the density of various nutrients and feed refusal. Antinutritional factors, such as certain storage polysaccharides and proteins, are inaccessible to endogenous enzymes and are either indigestible or act as blockers of the digestion of other nutrients. Changes in digestive secretions that result in either excess or deficiency also influence digestive structure and function. Infectious agents and toxins that cause degeneration and necrosis are especially injurious because a series of critical repair events must occur in order to regain function. The consequences range from lethal injury of the host animal to diminished performance. The digestive tract has a large component of lymphoid tissue and impairment of the immune system influences the course of protozoan, bacterial and viral enteric diseases.

Animal Feed↗
PubMedDate not supplied

Hyperosmolal feedings and gastrointestinal blood flow and oxygenation in newborn lambs.

Hyperosmolal feedings have been implicated as a cause of potential disruption to the physiology of the neonatal intestinal tract. To evaluate this we studied eight awake lambs (11 +/- 2 days old) with chronically implanted catheters in the portal sinus, descending aorta, and left and right ventricles. Blood flow (Q) was calculated with the radionuclide-labeled microsphere technique and O2 delivery (DO2) and consumption (VO2) by the Fick principle using blood O2 contents. Lambs were studied initially after a 4-h fast and sequentially at 2, 3, and 4 h after eating a hyperosmolal (590 mOsmol) formula. Cardiac output (mean +/- SEM, 332 +/- 22 ml.min-1.kg-1) and whole animal VO2 (16.5 +/- 2.5 ml O2.min-1.kg-1) remained stable. Total gastrointestinal (GI) blood flow increased 28% by 3 h. Small intestine Q increased 21% 3 h after feeding and then returned to baseline. Similarly, large intestinal Q increased 77% after feeding and remained elevated. There was no effect on stomach Q. Total GI vascular resistance fell 28% 3 h after feeding then returned to baseline. DO2 to the GI tract increased at 3 h and returned to baseline. There was no change, though, in GI VO2 (3.9 +/- 0.4 ml O2.min-1.100 g-1) or in the extraction (VO2/DO2) of oxygen (21.2 +/- 1.8%) during the study. Furthermore, there was no evidence for GI tract acidosis at any time. Systemic organ blood flow (except hepatic arterial blood flow) remained unchanged.(ABSTRACT TRUNCATED AT 250 WORDS)

Animal Nutritional Physiological Phenomena↗
PubMed1980

Gut hormones.

Explore the source record for details and available documents.

Adolescent↗
PubMed1978

Recent progress in dietary fiber (plantix) in human nutrition.

Dietary fiber was extensively discussed in an article by G.A. Spiller and R.J. Amen in this journal in 1975 (Volume 7 Issue 1). The progress in this field has been tremendous in the past 2 years. What was an uncertain field in 1975 and what at that time to some investigators still appeared as a hypothesis or fad without much proof has turned into a much more respected part of nutritional sciences. The scientific quality of recent studies on dietary fiber in human nutrition shows a great deal of sophistication and care. Improved analytical methodologies are being used more extensively. Many nutritionists and clinicians have accepted the fact that a reasonable increase in the dietary fiber intake in the U.S. and U.K would be advisable. In this article, the possible beneficial effects of dietary fiber on health, the possible harmful side effects, and the food science aspects are carefully discussed after an update on chemistry, analytical procedures, and nomenclature. Undoubtedly, dietary fiber has found a new niche in the sciences of nutrition, medicine, epidemiology, and foods.

Adult↗
PubMed2003

Digestive constraints on an aquatic carnivore: effects of feeding frequency and prey composition on harbor seals.

We hypothesized that increased feeding frequency in captive harbor seals would increase nutrient loads and thus reduce retention time and the digestive efficiency of natural prey. We measured daily feed intake and excretion during 6 feeding trials and fed herring (49% lipid), pollock (22% lipid) or an equal mix of each diet over 24 months. Animals were accustomed to feeding at either high or low frequency. Body mass and intake did not vary with season. Although mean retention times were similar between diets and feeding frequencies, solute and particulate digesta markers separated at high feeding frequency. Consistent dry matter digestibility resulted in greater gut fill from pollock than from herring. Digestible energy intakes from pollock were approximately 25% greater than from either herring or the mixed diet. Lipid digestibility of herring declined from 90% to 50% when lipid intake exceeded 60 g kg(-0.75) day(-1). Our hypothesis of a trade-off between intake and digestion was not supported for protein but was supported for lipid. Results of this study imply that a flexible digestive system for harbor seals can compensate for ingesting prey of lower energy density by increasing gut fill and enhancing protein and lipid assimilation, to sustain digestible energy intake.

Animal Feed↗
PubMed1996

The indigenous gastrointestinal microflora.

The indigenous gastrointestinal (GI) tract microflora has profound effects on the anatomical, physiological and immunological development of the host. The indigenous microflora stimulates the host immune system to respond more quickly to pathogen challenge and, through bacterial antagonism, inhibits colonization of the GI tract by overt exogenous pathogens. Indigenous GI bacteria are also opportunistic pathogens and can translocate across the mucosal barrier to cause systemic infection in debilitated hosts.

Animals↗