Functional reaction of the human body to different ways of respiration regulation

Reactions of the body to different ways of regulation of respiration, i.e., through the elastic resistance to respiratory movements and external dead space volume, as well as voluntary hyper- and hypoventilation, were studied. An increased elastic resistance to respiratory movements was established to create conditions for intense loading of respiratory musculature and to determine an increased in oxygen consumption. An increase in the external dead space produces a marked complex reaction of the body to the hypoxichypercapnic content of the inhaled gas mixture, causing hyperventilation and heightened work of the respiratory musculature and stimulating metabolism. Voluntary hyperventilation during muscular effort leads to a state of relative hypocapnia, gross loss of efficiency, and economic external respiration and gas exchange. Voluntary hypoventilation in the course of muscular effort brings about marked shifts in gas homeostasis towards alveolar hypoxia and hypercapnia. A concurrent increase in the efficiency and economy of external respiration and gas exchange is observed.     

Monitoring of gas exchange cycles and ventilatory movements in the pine weevil Hylobius abietis: respiratory failures evoked by a botanical insecticide

The large pine weevil, Hylobius abietis (L.) (Coleoptera: Curculionidae), is the most important insect pest of young coniferous plants. The implementation of new control methods requires not only a profound knowledge of the ecology and behaviour of the pest, but particularly of its physiology. Standard metabolic rate (SMR) and discontinuous gas exchange cycles (DGCs) were recorded in parallel with abdominal ventilation movements in adults of H. abietis using a differential electrolytic respirometer‐actograph. Quiescent weevils displayed DGCs of the constriction, flutter, and ventilation phases of the CFV type, while bursts of carbon dioxide were always accompanied by abdominal pumping movements, i.e., muscular ventilation in the closed subelytral cavity (SEC). In some beetles the C phase was absent and thus (C)FV cycles were recorded. In addition, at the beginning and often at the end of a burst, the SEC was rhythmically opened and closed by movements of the last abdominal segments. Continuous pumping movements and an absence of DGCs were signs of stress imposed by handling or by a new environment, even if the beetle was not moving. All individuals showed clear DGCs after recovering from handling and apparatus stress lasting 2–3 h. The results show that in the monitoring of DGCs, it is essential to determine whether they are of the constriction, flutter, and open phases (CFO), or the CFV subtype of the constriction, flutter, and burst (CFB) cycles. Use of our simple closed‐system respirometer enables non‐invasive simultaneous recording of SMR, oxygen uptake, DGCs, and active ventilation in H. abietis and other beetles. The topical application of adult H. abietis with sublethal doses of a botanical insecticide, NeemAzal T/S, caused essential respiratory failures: cyclic gas exchange was lost and irregular pumping movements appeared. In the treated beetles normal DGCs did not resume.     

The importance of perivitelline fluid convection to oxygen uptake of Pseudophryne bibronii eggs

The ciliated epithelium of amphibian embryos produces a current within the perivitelline fluid of the egg that is important in the convective transfer of oxygen to the embryo's surface. The effects of convection on oxygen uptake and the immediate oxygen environment of the embryo were investigated in Pseudophryne bibronii. Gelatin was injected into the eggs, setting the perivitelline fluid and preventing convective flow. Oxygen consumption rate (M(.)o?) and the oxygen partial pressure (Po?) of the perivitelline fluid were measured in eggs with and without this treatment. M(.)o? decreased in eggs without convection at Gosner stages 17-19 under normoxia. The lack of convection also shifted embryos from regulators to conformers as environmental Po? decreased. A strong Po? gradient formed within the eggs when convection was absent, demonstrating that the loss of convection is equivalent to decreasing the inner radius of the capsule, an important factor in gas exchange, by 25%. M(.)o? also declined in stage 26-27 embryos without cilia-driven convection, although not to the extent of younger stages, because of muscular movements and a greater skin surface area in direct contact with the inner capsule wall. This study demonstrates the importance of convective flow within the perivitelline fluid to gas exchange. Convection is especially important in the middle of embryonic development, when the perivitelline space has formed, creating a barrier to gas exchange, but the embryos have yet to develop muscular movements or have a large surface area exposed directly to the jelly capsule.     

Standardized estimation of external respiration function

External respiration in healthy males has, in addition to eupnea, six functionally active variants with one or several indices deviating from the normal values. Hyperpnea and hypopnea are determined by deviations in general oxygen consumption accompanied by adequate changes in pulmonary ventilation and gas exchange. Inhibition of gas exchange in the respiratory parts of the lungs is a typical primary event of hyperventilation, a fact indicated by a decrease in the coefficient of oxygen consumption and a compensatory increase in the minute respiratory volume during hyperventilation. Tension of the respiratory system is especially pronounced during enhanced oxygen consumption (O₂C). Highly effective bradypnea is characterized by infrequent and deep breathing. No tension of the respiratory system is observed even for increased O₂C. This state may be considered a genotypic and phenotypic variant of normal respiration. The data obtained may be used to automate the assessment of gas exchange in the respiratory parts of the lungs.     

The compensatory role of an increased air content of the respiratory regions of the lungs

The external respiration parameters were studied in healthy workers of a chemical enterprise (246) and cadets of a police academy (82) for the normal state of the system of external respiration and under the conditions of an increased air content of the respiratory regions of the lungs. It was established that, in healthy subjects, an increased air content is a manifestation of the compensatory reaction of the external respiration system to long-term or regular hypoergosis. The reaction is aimed at increasing gas exchange in the lungs in cases where, for some reason, the oxygen demand of the body is not met completely.     

The respiratory basis of locomotion in Drosophila

The respiratory system of insects has evolved to satisfy the oxygen supply during rest and energetically demanding processes such as locomotion. Flapping flight in particular is considered a key trait in insect evolution and requires an increase in metabolic activity of 10-15-fold the resting metabolism. Two major trade-offs are associated with the extensive development of the tracheal system and the function of spiracles in insects: the risk of desiccation because body water may leave the tracheal system when spiracles open for gas exchange and the risk of toxic tracheal oxygen levels at low metabolic activity. In resting animals there is an ongoing debate on the function and evolution of spiracle opening behavior, focusing mainly on discontinuous gas exchange patterns. During locomotion, large insects typically satisfy the increased respiratory requirements by various forms of ventilation, whereas in small insects such as Drosophila diffusive processes are thought to be sufficient. Recent data, however, have shown that during flight even small insects employ ventilatory mechanisms, potentially helping to balance respiratory currents inside the tracheal system. This review broadly summarizes our current knowledge on breathing strategies and spiracle function in the genus Drosophila, highlighting the gas exchange strategies in resting, running and flying animals.     

Environmental influences on the development of the cardiac system in fish and amphibians

In poikilothermic animals body temperature varies with environmental temperature, and this results in a change in metabolic activity (Q10 of enzymatic reactions typically is around 2-3). Temperature changes also modify gas transport in body fluids. While the diffusion coefficient increases with increasing temperatures, physical solubility and also hemoglobin oxygen affinity decrease. Therefore, an increase in temperature typically requires adjustments in cardiac activity because ventilatory and convectional transport of respiratory gases usually are tightly coupled in adults in order to meet the oxygen demand of body tissues. Hypoxic conditions also provoke adaptations in the central circulatory system, like the hypoxic bradycardia, which has been described for many adult lower vertebrates, combined with an increase in stroke volume and peripheral resistance. In embryos and larvae the situation is much more complicated, because nervous control of the heart is established only late during development, and because the site of gas exchange changes from mainly cutaneous gas exchange during early development to mainly pulmonary or branchial gas exchange in late stages. In addition, recent studies in amphibian and fish embryos and larvae reveal, that at least in very early stages convectional gas transport of the hemoglobin is not essential, which means that in these early stages ventilatory and convectional gas transport are not yet coupled. Accordingly, in early stages of fish and amphibians the central cardiac system often does not respond to hypoxia, although in some species behavioral adaptations indicate that oxygen sensors are functional. If a depression of cardiac activity is observed, it most likely is a direct effect of oxygen deficiency on the cardiac myocytes. Regulated cardiovascular responses to hypoxia appear only in late stages and are similar to those found in adult species.     

CUTANEOUS GAS EXCHANGE IN VERTEBRATES: DESIGN, PATTERNS, CONTROL AND IMPLICATIONS

1. The exchange of oxygen and carbon dioxide between skin and environment is commonplace in the vertebrates. In many lower vertebrates, the skin is the major or even sole avenue for respiration.
2. As implied by the physical laws governing diffusion of gases, the skin diffusion coefficient, surface area, gas diffusion distance and transcutaneous gas partial pressures may independently or jointly affect cutaneous respiration. In vertebrates, each of these variables has undergone modification that may be related to dependence upon cutaneous gas exchange.
3. Both theoretical models and experimental data suggest that cutaneous gas exchange is limited by the rate of diffusion. However, changes in convection of the respiratory medium and of blood may partially compensate for diffusion limitation, and potentially function in the regulation of cutaneous gas exchange.
4. Typically, the skin is one of several gas exchangers, although many salamanders and some species in other vertebrate groups breathe solely through the skin. The cutaneous contribution to overall gas exchange is often most important in small animals, at cool temperatures, at low levels of activity and in normoxic and normocapnic conditions. Branchial and pulmonary respiration increasingly predominate in other circumstances.
5. Often, the skin figures more prominently in CO₂, excretion than in O₂, uptake.
6. Cutaneous gas exchange emerges in vertebrates as a process perhaps less effective and more constrained than branchial or pulmonary exchange but also less energetically costly. Its utility is indicated by its wide and successful exploitation in vertebrates occupying a diverse array of habitats.     

The insect abdomen--a heartbeat manager in insects?

Different possibilities of coordination between circulation, respiration and abdominal movements were found in pupae of Pieris brassicae, Tenebrio molitor, Galleria mellonella and Leptinotarsa decemlineata. Coordination principles depend on metabolic rate: the need to support circulation with abdominal movements appears only at higher metabolic rates. Integration between different abdominal movements and circulation depends on species, on physiological state and, supposedly, on internal morphology. At low metabolic rates, there is no need for a very intensive hemolymph flow, and the dorsal vessel is capable of initiating and/or maintaining necessary hemolymph flow. Starting from a certain metabolic level, it is possible that the abdomen is used to accelerate hemolymph flow in the case of a large amount of hemolymph. When the necessary flow speed has been reached, relatively weak pulsation of the dorsal vessel with accessory pulsatile organs and diaphragms can easily maintain the necessary flow intensity. Heart activity may sometimes be initiated by abdominal movements via cardiac reflex or mechanical excitation. Sometimes, when heart function is weakened by histolysis, the abdomen may temporarily take over the main circulatory function or occasionally contribute to acceleration of low-speed hemolymph flow. In this case the functions are simultaneous and may be triggered by some mediator(s). In active adult insects the whole body is moving, and hence hemolymph circulates and the tracheal system is effectively ventilated by a whole body ensemble consisting of the dorsal vessel, moving organs, body appendages and accessory pulsatile organs. The mechanism of autocirculation (analogous to autoventilation in gas exchange) is a probable mechanism in circulation in adult insects.     

Life history traits and dispersal shape neutral genetic diversity in metapopulations

Journal of Mathematical Biology - In insect respiration, oxygen from the air diffuses through a branching system of air-filled tubes to the cells of the body and carbon dioxide produced in cellular...     

The structure and behaviour of Notiphila riparia and Erioptera squalida, two root-piercing insects

Two species of root-piercing insect, Notiphila riparia (Ephydridae) and Erioptera squalida (Tipulidae) are described. The insertion of the spiracles into the plants is dependent on a firm environment which provides the main bracing element for the movements of the spiracles. The structural features of root-piercing spiracles are described. The spiracles are long enough to reach the gas spaces of the roots of the plants on which the insects are commonly found. The plant epidermis may act as a limiting factor in the respiration of the insects. The emergence of the adults of Erioptera squalida involves a change in buoyancy in the pharate adult as the adult emerges at the surface.     

Ontogeny of tracheal dimensions and gas exchange capacities in the grasshopper, Schistocerca americana

How does body size affect the structure and gas exchange capacities of insect tracheae? Do insects become more oxygen-limited as they grow? We addressed these questions by measuring the dimensions of two transverse tracheae within the abdomen of American locusts of different ages, and evaluating the potential for diffusion or convection to provide adequate gas exchange. The grasshopper abdomen has longitudinal tracheae that run along the midgut, heart, nerve cord, and lateral body wall. Transverse tracheae run from each spiracle to the longitudinal tracheae. Dorsal air sacs attach near each spiracle. In both transverse tracheae studied, diffusive capacities increased more slowly than metabolic rates with age, and calculated oxygen gradients necessary to supply oxygen by diffusion increased exponentially with age. However, surgical studies demonstrated that transport of gas through these transverse tracheae occurred by convection, at least in adults. Convective capacities paralleled metabolic rates with age, and the calculated pressure gradients required to sustain oxygen consumption rates by convection were independent of age. Thus, in growing grasshoppers, tracheal capacities matched tissue oxygen needs. Our morphological and physiological data together suggest that use of convection allows older grasshoppers to overcome potential limitations on size imposed by diffusion through tracheal systems.     

Ontogeny of tracheal dimensions and gas exchange capacities in the grasshopper, Schistocerca americana

How does body size affect the structure and gas exchange capacities of insect tracheae? Do insects become more oxygen-limited as they grow? We addressed these questions by measuring the dimensions of two transverse tracheae within the abdomen of American locusts of different ages, and evaluating the potential for diffusion or convection to provide adequate gas exchange. The grasshopper abdomen has longitudinal tracheae that run along the midgut, heart, nerve cord, and lateral body wall. Transverse tracheae run from each spiracle to the longitudinal tracheae. Dorsal air sacs attach near each spiracle. In both transverse tracheae studied, diffusive capacities increased more slowly than metabolic rates with age, and calculated oxygen gradients necessary to supply oxygen by diffusion increased exponentially with age. However, surgical studies demonstrated that transport of gas through these transverse tracheae occurred by convection, at least in adults. Convective capacities paralleled metabolic rates with age, and the calculated pressure gradients required to sustain oxygen consumption rates by convection were independent of age. Thus, in growing grasshoppers, tracheal capacities matched tissue oxygen needs. Our morphological and physiological data together suggest that use of convection allows older grasshoppers to overcome potential limitations on size imposed by diffusion through tracheal systems.     

Surviving submerged—Setal tracheal gills for gas exchange in adult rheophilic diving beetles

The gas exchange in adult diving beetles (Coleoptera: Dytiscidae) relies on a subelytral air store, which has to be renewed in regular intervals at the water surface. The dive duration varies from a few minutes to 24 h depending on the species, activity, and temperature. However, some species remain submerged for several weeks. Stygobiont species do not ascend to the surface and gas exchange of these species remains unclear, but it is assumed that they require air filled voids for respiration or they use cutaneous respiration. In this study, we investigate the gas exchange in the running water diving beetle Deronectes aubei, which survive submerged for over 6 weeks. The diffusion distance through the cuticle is too great for cutaneous respiration. Therefore, the dissolved oxygen uptake of submerged beetles was determined and an oxygen uptake via the rich tracheated elytra was observed. Fine structure analyses (SEM and TEM) of the beetles showed tracheated setae mainly on the elytral surface, which acts as tracheal gills. Prevention of the air bubble formation at the tip of the abdomen, which normally act as physical gill in Dytiscidae, resulted in no effect in oxygen uptake in D. aubei, but this was the sole way for a submerged Hydroporus palustris to get oxygen. The setal gas exchange technique explains the restriction of D. aubei to rivers and brooks with high oxygen concentration and it may also be used by subterran living diving beetles, which lack access to atmospheric oxygen. The existence of setal tracheal gills in species in running water which are often found in the hyporheic zone and in stygobiont species supports the known evolution of stygobiont Dytiscidae from species of the hyporheic zone. For species in running water, setal tracheal gills could be seen as an adaptation to avoid drifting downstream by the current. J. Morphol., 2009. © 2009 Wiley‐Liss, Inc.     

The Adhesive Organ of Larval Pike Esox Lucius L., (Pisces)

Newly hatched pike laryae swim by lateral movements of the trunk. The swimming path is directed upwards. They do not avoid obstacles but interrupt any movements immediately when colliding a substrate. Paired cement glands in rostro-nasal position excrete an elastic connection between larva and the touched substrate. Larvae spend yolk sac stage in a motionless position. The glands were studied by scanning electron microscope, by lightmicroscope and transmission electron microscope. The organs consist of two rostro-lateral areas which have a striking sculptured surface. The glandular cells are of the high prismatic type with basic nuclei and granulae in the apical parts. The granulae are already reduced in size and number after hatching against the prehatching stage. This indicates an early secretory activity before an attachement occured. There are grounds to consider mainly two ecological aspects in favour of pike larvae attached to substrates. One is the distance from the bottom water layers which are often characterized by oxygen deficiency and low water currents. Because pike larvae develop their gills later the gas exchange occurs with the body surface. Favourable water circulation normally exists in some distance from sediment and improves the respiration. The second aspect is governed by immobility and pigmentation which camouflage larvae against predators.     

Physiological effects of an ultra-marathon run

Autonomic functions of the body and gas exchange have been studied in one athlete (master of sports in skiing, aged 27 years, with a maximal oxygen consumption of 67 mL/(min kg)); during a 6-h indoor ultra-marathon race; at an average speed of 2.7 m/s. Continuous monitoring of the heart rate was carried out using a Polar RS 800 heart rate monitor. Gas analysis of the exhaled air and recording of the parameters of external respiration were carried out during the first hour with subsequent repetitions during 20?C30 minutes each hour, using a Metamax mobile device (Germany) mounted on the subject throughout the race. Before and after the subject passed the intervals of a distance when these parameters were measured, the blood lactate content was measured. Our data demonstrate a number of features that accompany fatigue at the final stage of the race, such as a decrease in efficiency of body functions, which is expressed by an increased heart rate and oxygen usage, an activation of anaerobic glycolysis path of energy production, and intensification of the external respiration. In addition, the methods of correlation and regression analysis revealed the changes (increase and decrease) of the relationship between the functions depending on whether muscular performance is at the stage of warming up, sustainably high performance, or in at a stage of extreme fatigue. These findings suggest interference of the effects of the central and tissue mechanisms of fatigue on the organization of oxygen transportation in the body. Apparently, in the instance of an ultra-marathon run, i.e., a prolonged performance of moderate power, autonomic functions, rather than the energy resources of the body, play the role of the main limiting factor.     

Oxygen reperfusion damage in an insect

The deleterious effects of anoxia followed by reperfusion with oxygen in higher animals including mammals are well known. A convenient and genetically well characterized small-animal model that exhibits reproducible, quantifiable oxygen reperfusion damage is currently lacking. Here we describe the dynamics of whole-organism metabolic recovery from anoxia in an insect, Drosophila melanogaster, and report that damage caused by oxygen reperfusion can be quantified in a novel but straightforward way. We monitored CO(2) emission (an index of mitochondrial activity) and water vapor output (an index of neuromuscular control of the spiracles, which are valves between the outside air and the insect's tracheal system) during entry into, and recovery from, rapid-onset anoxia exposure with durations ranging from 7.5 to 120 minutes. Anoxia caused a brief peak of CO(2) output followed by knock-out. Mitochondrial respiration ceased and the spiracle constrictor muscles relaxed, but then re-contracted, presumably powered by anaerobic processes. Reperfusion to sustained normoxia caused a bimodal re-activation of mitochondrial respiration, and in the case of the spiracle constrictor muscles, slow inactivation followed by re-activation. After long anoxia durations, both the bimodality of mitochondrial reactivation and the recovery of spiracular control were impaired. Repeated reperfusion followed by episodes of anoxia depressed mitochondrial respiratory flux rates and damaged the integrity of the spiracular control system in a dose-dependent fashion. This is the first time that physiological evidence of oxygen reperfusion damage has been described in an insect or any invertebrate. We suggest that some of the traditional approaches of insect respiratory biology, such as quantifying respiratory water loss, may facilitate using D. melanogaster as a convenient, well-characterized experimental model for studying the underlying biology and mechanisms of ischemia and reperfusion damage and its possible mitigation.     

Breathing,voice, and movement therapy: Applications to breathing disorders

Elsa Gindler (1885–1961) developed a holistic approach to the human body and psyche via the movement of breath. Gindler experimented with movements to strengthen the deeper layers of the muscular system and improve the circulation of oxygen, movements that reduced tensions that had been preventing the breathing muscles from functioning properly. Subsequently, she founded a school for breathing and body awareness. The biggest breathing muscle in the human body is the diaphragm, the lowering of which can only take place when the jaw and the throat are relaxed, the belly is free, and the psoas (major and minor) and hip joints allow free leg-movement and flexibility in the lower back. When these conditions do not obtain, the body compensates by lifting the shoulders, pulling up the chest bone, and contracting the sphincter muscles in the throat, movements which weaken the muscles which assist the breathing process. Thus, the compensatory muscles are overburdened and the fine organization of the body is disturbed; the natural capacity to use the breath as a healing force is lost. The goal of breath therapy is to recognize and reestablish this capacity. Training sessions are devoted to relaxation; to exercises to rebuild muscle tone, strengthen weakened muscles, release contracted areas, and the use of the voice to stimulate the respiratory system. Sessions typically consist of (a) relaxation, (b) activation (experimenting with new, freer ways of moving), and (c) integration (application to everyday life). The therapist analyzes incidents of stress in the client's life where breathing is likely to be disturbed. This is especially important for asthmatics who can learn how to deal with an attack by relaxing rather than contracting. This work is especially beneficial for problems in (a) the skeletal structure, (b) respiration, (c) vital organs, and (d) general symptoms.     

Techniques for biochemical respiration measurements.

A small membrane-covered oxygen electrode is described. This electrode is used either as a stationary electrode in stirred solutions or as a vibrating electrode in unstirred solutions. An amplifier system for registration of the electrode current and its time derivative is also described as are two specialized reaction vessels, a miniature vessel of ca. 7-μl volume and a closed vessel for sampling during respiration measurements. The kinetics of oxygen uptake from the atmosphere of respiring solutions is investigated. The uptake follows first-order kinetics and may be calculated from simple equations. The uptake may be prevented by continuously adjusting the air space oxygen tension to the oxygen tension of the solution. This is done with the controlled gas mixer which is described. It makes possible reliable respiration measurements in open reaction vessels (e.g., photometric cuvettes). The techniques described have been developed for work with mitochondria but they have wide applicability.     

Beyond aerodynamics: The critical roles of the circulatory and tracheal systems in maintaining insect wing functionality

Insect wings consist almost entirely of lifeless cuticle; yet their veins host a complex multimodal sensory apparatus and other tissues that require a continuous supply of water, nutrients and oxygen. This review provides a survey of the various living components in insect wings, as well as the specific contribution of the circulatory and tracheal systems to provide all essential substances. In most insects, hemolymph circulates through the veinal network in a loop flow caused by the contraction of accessory pulsatile organs in the thorax. In other insects, hemolymph oscillates into and out of the wings due to the complex interaction of several factors, such as heartbeat reversal, intermittent pumping of the accessory pulsatile organs in the thorax, and the elasticity of the wall of a special type of tracheae. A practically unexplored subject is the need for continuous hydration of the wing cuticle to retain its flexibility and toughness, including the associated problem of water loss due to evaporation. Also, widely neglected is the influence of the hemolymph mass and the circulating flow in the veins on the aerodynamic properties of insect wings during flight. Ventilation of the extraordinarily long wing tracheae is probably accomplished by intricate interactions with the circulatory system, and by the exchange of oxygen via cutaneous respiration.