bluuebunny/crossref_metadata_2025_split huggingface dataset:
Double Hydropore in the Development of Asterias Glacialis
Authors: Narasimhamurti N. 
Published: April 2021

ABSTRACT
A tendency to form a “primary madreporic” pore on the right side as well as on the left side exists in Atterias gladatif as in other star-fish and in Echinoderms generally. Metschnikoff as far back as 1874 figured and described a late larva of Asteracanthion with left and right hydropores and hydrocoeles (water-vascular rudiments). According to Field (1892) the double pore is frequently met with in the early larvae of Arterias vulgaris. MacBride (1896) has described a larva of Asterias with a pair of water-pores as well as others in the case of Echinus miliaris (1919). Gemmill (1914, 1916) observed double-pored larvae in Asterias rubens in the proportion of one to ten and in Asterias glaciatis in a slightly greater proportion.
Phosphagen in the Electrical Organ of Torpedo
Authors: Baldwin Ernest 
Published: April 2021

ABSTRACT
The electrical organs of Torpedo marmorata contain creatine phosphoric acid, which was identified by the velocity constants of its hydrolysis under controlled conditions. This compound is of functional importance in the organ, being diminished in amount by activity, heat rigor, and by conditions which are unfavourable to the organism as a whole. The physiological parallel between the electrical organ and muscle appears, as far as this study has been carried, to be itself paralleled by the chemical mechanisms. Creatine has been isolated from the electrical organ and has been identified, in confirmation of the earlier work of other authors.
The Electrocardiogram of the Developing Chick
Authors: Bogue J. Yule 
Published: April 2021

ABSTRACT
In the investigation of the electrocardiogram of the chick embryo the same technique has been employed as that already described by the author (1932). The only point of difference is that in the present experiments after a record had been taken through the shell, the shell was opened, the embryo exposed and the electrodes placed in the most favourable position for obtaining a record.
Central Nervous Integration of Cardiovascular Control
Authors: Spyer K. M. 
Published: April 2021

ABSTRACTIn this account an attempt has been made to identify integrative interactions in the control of the cardiovascular system. Three main sites of such interaction have been considered, the nucleus of the tractus solitarius (NTS), the vagal preganglionic supply to the heart and sympathetic preganglionic neurones.In the case of the NTS the extent and range of afferent inputs from cardiovascular and respiratory receptors have been reviewed. In addition the interactions of these inputs on the activity of NTS neurones have been indicated although the details are as yet vague. With respect to the baroreceptor reflex, it is clear that its relay through the NTS permits the action of intrinsic drives, such as inspiratory activity, and extrinsic drives, for example the defence reaction, to modify to a greater, or lesser, extent the efficacy of the reflex. In the case of respiratory activity, changes in transmission of baroreceptor activity through the NTS are minimal, since a baroreceptor effect can be shown to exert itself on CVM activity throughout the respiratory cycle under appropriate experimental conditions (McAllen & Spyer, 1978b). The effectiveness of this excitatory input is, however, ‘gated’ by a direct inspiratory control of CVM activity. This indicates an essentially integrative role of vagal preganglionic neurones. The role of inputs from the lungs themselves evoked during inspiration, which also contribute to the respiratory modifications of the baroreceptor reflex, in the control of CVM activity is as yet uncertain although evidence is accumulating to suggest that they act by a mechanism different from that of inspiratory drive.The influence of the defence reaction on transmission through the NTS has yet to be fully documented, but it appears as if there may be the potential for a marked modification. However, it is now certain that an inhibitory control of CVM activity can be evoked from the hypothalamus which is independent of any modification of the baroreceptor input at that level of the NTS and acts rather through an inhibitory synaptic influence directly onto CVMs.In much the same way the baroreceptor influence on sympathetic preganglionic neurones is determined by their excitability, an excitability which is dependent on the balance of activity in several bulbospinal inhibitory and excitatory pathways, as well as segmental inputs. The role, if any, of direct hypothalamo-spinal pathways and the nature and organization of the descending pathways involved in the defence reaction requires elucidation. Existing data, however, make it clear that the thoracic intermedio-lateral cell column is an important site in the integration of cardiovascular control.
Respiratory and Circulatory Control at High Altitudes
Authors: West John B. 
Published: April 2021

ABSTRACT
Hyperventilation is one of the most important features of acclimatization to high altitude. Resting ventilation at extreme altitudes increases up to fourfold and exercise ventilation for a given work level increases to the same extent. Hypoxic stimulation of the peripheral chemoreceptors is the chief mechanism for the hyperventilation but there is also evidence that central sensitization of the respiratory centres occurs. Permanent residents of high altitude have a blunted hypoxic ventilatory response compared to acclimatized lowlanders. Cardiac output increases in response to acute hypoxia but returns to normal in acclimatized lowlanders. Oxygen uptake at extreme altitudes is markedly limited by the diffusion properties of the blood gas barrier. As a consequence the maximal oxygen consumption of a climber near the summit of Mount Everest is near his basal oxygen requirements. Maximal oxygen consumption is so sensitive to barometric pressure that it may be that day-to-day variations will affect the chances of a climber reaching the summit without supplementary oxygen.
Cardiopulmonary Coupling During Exercise
Authors: Whipp Brian J. , Ward Susan A. 
Published: April 2021

ABSTRACT
Muscular exercise imposes the most potent sustained stress to cellular energetics. At work rates below the anaerobic threshold (i.e. no sustained lactic acidosis), the ventilatory and cardiovascular responses regulate arterial , [H+] and at or close to their resting levels in the steady state. However, dynamic forcing and systems-analytic techniques reveal two phases of the non-steady-state response dynamics. In the first phase, increased gas flow to the lungs results solely from increased pulmonary blood flow , with alveolar gas tensions being maintained at their resting levels by a coupled increase in ventilation : evidence for cardiopulmonary coupling being provided by experimentally-altered in man and dog. Arterial chemoreception does not impose humoral feedback control in this phase. Rather, rapid feedforward mechanisms operate, with both intrathoracic (largely cardiac) and exercising-limb mechanoreception proposed as afferent sources. In the second phase, cardiogenic gas flow to the lungs is augmented by altered mixed venous blood gas contents ; ventilation responding exponentially with a time constant (τ) which is an inverse function of carotid body gain. The close dynamic coupling of with CO2 output in this phase results in arterial and [H+] being maintained close to their resting levels. However, the kinetic dissociation between and O2 uptake, with , leads to an appreciable transient fall of arterial . The respiratory compensation for the sustained lactic acidosis at higher work rates is predominantly mediated by the carotid bodies in man: the aortic bodies subserving no discernible role. Control of the respiratory and circulatory responses to exercise is therefore mediated by both neural and humoral mechanisms : and an important control link appears to couple the responses, via feedforward ventilatory control of cardiac origin.
Role of Peripheral Chemoreceptors and Central Chemosensitivity in the Regulation of Respiration And Circulation
Authors: O’regan R. G. , Majcherczyk S. 
Published: April 2021

ABSTRACT
Adjustments of respiration and circulation in response to alterations in the levels of oxygen, carbon dioxide and hydrogen ions in the body fluids are mediated by two distinct chemoreceptive elements, situated peripherally and centrally. The peripheral arterial chemoreceptors, located in the carotid and aortic bodies, are supplied with sensory fibres coursing in the sinus and aortic nerves, and also receive sympathetic and parasympathetic motor innervations. The carotid receptors, and some aortic receptors, are essential for the immediate ventilatory and arterial pressure increases during acute hypoxic hypoxaemia, and also make an important contribution to respiratory compensation for acute disturbances of acid-base balance. The vascular effects of peripheral chemoreceptor stimulation include coronary vasodilation and vasoconstriction in skeletal muscle and the splanchnic area. The bradycardia and peripheral vasoconstriction during carotid chemoreceptor stimulation can be lessened or reversed by effects arising from a concurrent hyperpnoea.
Central chemoreceptive elements respond to changes in the hydrogen ion concentration in the interstitial fluid in the brain, and are chiefly responsible for ventilatory and circulatory adjustments during hypercapnia and chronic disturbances of acid-base balance. The proposal that the neurones responsible for central chemoreception are located superficially in the ventrolateral portion of the medulla oblongata is not universally accepted, mainly because of a lack of convincing morphological and electrophysiological evidence. Central chemosensitive structures can modify peripheral chemoreceptor responses by altering discharges in parasympathetic and sympathetic nerves supplying these receptors, and such modifications could be a factor contributing to ventilatory unresponsiveness in mild hypoxia. Conversely, peripheral chemoreceptor drive can modulate central chemosensitivity during hypercapnia.
Apnoea in Amphibians and Reptiles
Authors: Shelton G. , Boutilier R. G. 
Published: April 2021

ABSTRACT
The amphibian ancestor had two gas exchangers, one working in water and one in air. It also ventilated the aerial exchanger in an intermittent fashion. The functional repercussions of this ancestry can be seen in all amphibians and reptiles. During periods of apnoea, which almost all amphibians and reptiles show in their breathing patterns, there are variable fluctuations in lung and arterial and, . Arterial and pH show only small fluctuations during apnoea induced by voluntary dives, and blood lactate does not build up. More considerable acidoses and lactate accumulations occur in forced dives which the animals can readily survive, even when the dives are prolonged. Anaerobic metabolism plays an important role in their capacity to survive prolonged apnoea. Amphibians ventilate their lungs with a buccal pump whose pattern of activity differs from species to species. Short periods of apnoea characterize the more terrestrial forms. Long dives punctuated by bursts of lung ventilation, or irregular bouts of breathing with no distinctive pattern occur in more aquatic forms. Similar differences in pattern can be seen in terrestrial and aquatic reptiles. The most striking characteristic of ventilation is its extreme variability, even in a single individual. Responses occur to decreasing oxygen tensions and increasing carbon dioxide tensions in inspired air, alveolar air, and arterial blood, the animals almost always increasing lung ventilation and decreasing the duration of apnoea. However, no simple relationship can be seen between the tensions of respiratory gases in lungs or arterial blood and the beginning or end of an apnoeic period. Periods of apnoea are accompanied by vasoconstriction in the lung vasculature. This has the effect of decreasing blood flow to the lung and increasing right to left shunt in the incompletely divided heart.
Peripheral Receptors Affecting Breathing and Cardiovascular Function in Non-Mammalian Vertebrates
Authors: Jones David R. , Milsom William K. 
Published: April 2021

ABSTRACT
Most vertebrates show respiratory and circulatory reflexes which can be traced to stimulation of various extero-or interoceptors. Widely distributed groups of exteroceptors, with a variety of stimulus modalities, are associated with defence reflexes which protect the respiratory passages and gas exchange surfaces. Other exteroceptors are associated only with the gas exchange surfaces. These are either mechanoreceptors or chemoreceptors and have a range of different dynamic characteristics, but are none-the-less amazingly uniform in their role in control of the normal breathing pattern. Intravascular receptors stimulated by the arterial blood pressure are located on all the gills in fishes, yet appear to be restricted to the pulmocutaneous arteries in anuran amphibians and to the truncal region or aortic root in reptiles and birds. On the other hand, the distribution of glomus-sustentacular-nerve cell complexes, associated with intravascular chemoreception, appears to be much more diffuse in higher than lower vertebrates. The wide distribution of these cell complexes may be attributed to their embryological origin from neural crest cells. Even so, the presence of these complexes does not appear to be essential for respiratory responses to environmental hypoxia since they have not been located in teleost fishes.
The role of peripheral receptors in controlling cardiovascular and respiratory functions, under steady state conditions in non-mammalian vertebrates, is not well defined and it may be that they are only modulators of circulatory and respiratory patterns arising from hormonal or humoral effects on the central nervous system.
Thermoregulation and Control of Head Temperature in the Sphinx Moth, Manduca Sexta
Authors: Hegel Jeri R. , Casey Timothy M. 
Published: April 2021

ABSTRACT
Head and thorax temperatures (Th and Tth) were tightly coupled during pre-flight warm-up over a range of ambient temperatures (Ta). A.t Ta= 21 °C, the head reached a significantly higher temperature (Tth= 32 °C) than during exogenous heating of dead moths to the same thoracic temperature (Th = 26 °C). In free-flying moths, slopes of linear regressions for both Tth and Th versus Ta were about 0·4. At any Ta, Th remained only about 7 °C below Tth. Abdominal temperature varied with Ta with a slope of 1·2 and remained 2·5 degrees above Ta. Cooling constants (min−1) for the head, calculated from cooling experiments with the thorax either at Ta or maintained constant at about 40 °C, yielded similar values. During free flight, as Ta increased from 17 to 32 °C, thoracic heat loss decreased from 36 to 20 % of the total heat production, head heat loss decreased from 27 to 8%, and abdominal heat loss increased from 17 to 37%. During warm-up at all Ta’s the largest component of energy expenditure was the heat storage and heat loss that occurred from the thorax, followed by that from the abdomen and then by that from the head. Exogenous heating of some live moths resulted in cyclic temperature fluctuations in which Th and Tth changed simultaneously and in opposite directions. During each cycle, the heart beat pattern changed, becoming irregular when Tth was increasing and returning to a regular pattern when was decreasing. Smaller temperature fluctuations in the head occurred at the same rate as the heart beat. These data suggest that the head temperatures observed during pre-flight warm-up and flight are the result of active heat transfer from the thorax via the blood circulation.
Electrical Coupling Between Supernumerary Motor Neurones in the Locust
Authors: Siegler Melody V. S. 
Published: April 2021

ABSTRACT
While recording from a slow tarsal levator motor neurone of the locust metathoracic ganglion, a second neurone of this type was discovered in the same half of the ganglion. In thirty animals from which recordings were subsequently made, the additional neurone was found in only one. Since two motor neurones could not be found routinely, other tests were made to determine how many motor neurones normally innervated the levator muscle. The tibial nerve containing the motor axons was stimulated whilst intracellular recordings were made from the levator muscle fibres; recordings were made simultaneously from the cell body of a levator motor neurone, from the tibial nerve and from the levator muscle fibres; and the composition of fine nerve branches that terminate on the levator muscle was examined by electron microscopy. It is concluded that normally the levator muscle is innervated by one excitatory motor neurone and two inhibitory ones. The single excitatory motor neurone has the synaptic inputs ascribed in earlier studies to the ‘slow’ motor neurone. It can, however, evoke movements of the tarsus ranging from slow smooth ones, to rapid twitchlike ones. No evidence was found for a second, ‘fast’ motor neurone previously reported (Hoyle & Burrows, 1973). In the two locusts found to possess a supernumerary levator motor neurone, the two motor neurones were electrically coupled by non-rectifying junctions that were strong enough to ensure that the pair invariably spiked in 1 : 1 fashion. The coupled levator motor neurones received different synaptic inputs. One pair of coupled motor neurones was stained intracellularly with cobalt-silver. The cell bodies were some 50 μm apart, but their neurites converged as they entered the neuropil. The neurites and major side branches followed similar courses in the neuropil, and the two neurones shared the major anatomical features of the single levator motor neurones stained in other animals.
Free Amino Acids as Regulators of Osmotic Pressure in Aquatic Insect Larvae
Authors: Edwards H. A. 
Published: April 2021

ABSTRACT
Microanalytical techniques are used to show that organic molecules play an important role is osmoregulation. Changes in the inorganic ion composition of haemolymph from fourth instar larvae of Aedes aegypti are correlated with the changes in the concentration of organic ions. Free amino acids have a significant role in regulating haemolymph osmotic pressure with respect to the osmotic pressure of the water in which the animal lives. Mechanisms by which amino acid levels could respond to changes in salt concentration are discussed.
A Spiking Stretch Receptor with Central Cell Bodies in the Uropod Coxopodite of the Squat Lobster Galathea Strigosa (Crustacea, Anomura)
Authors: Maitland D. P. , Laverack M. S. , Heitler W. J. 
Published: April 2021

ABSTRACT
A proprioceptor located at the base of the uropod coxopodite in the telson of Galathea strigosa is described. The main component of this organ is an elastic strand in which are embedded dendrites from several neurones (approximately 11) whose cell bodies are located within the 5th (last free) abdominal ganglion. A small accessory muscle runs parallel to this strand. Several afferent axons innervating the receptor conduct action potentials in a phasic manner in response to stretch. Information conveyed to the CNS by the receptor causes reflex modulation of the discharge in at least two motoneurones. When afferent spikes from the receptor are blocked by sucrose, reflexive discharges are still recorded in response to stretching the receptor. This suggests that certain reflexes may be mediated by transmission of graded electrotonic potentials from the uropod proprioceptor to the CNS. When sensory hairs on the margins of the uropods are displaced, feedback via the nerves innervating the uropods results in efferent output to the receptor complex (elastic strand and accessory muscle). The receptor also receives bouts of efferent impulses during attempted tail-flips in a restrained animal.
Is the Locust DCMD A Looming Detector?
Authors: Pinter Robert B. , Olberg Robert M. , Abrams Thomas W. 
Published: April 2021

ABSTRACT
To a prey, a salient visual characteristic of an approaching predator is ‘looming’, a figure of average subtended visual angle increasing as some function of time. If the approach is at constant velocity, two important characteristics of the looming figure are an ever increasing velocity (i.e. acceleration) of sideways motion of edges away from the centroid of the figure, and the opposed motion of opposite edges. These characteristics make looming objects distinct from translation of single objects across the visual field, so that the visual looming characteristics may have value in warning of approaching predators. In the locust, a visual neurone, the DCMD (descending contralateral movement detector) in the ventral nerve cord forms an important input to the interneurones triggering the jump response in the locust (Pearson, Heitler & Steeves, 1980; Pearson & Robertson, 1981). Thus it is of considerable interest to determine whether the DCMD responds preferentially to looming visual stimuli.
The Specific Location of Zinc in Insect Mandibles
Authors: Hillerton J. Eric , Vincent Julian F. V. 
Published: April 2021

ABSTRACT
The cutting edges of the mandibles in the locust have been shown to be twice as hard as the rest of the mandible (Hillerton, Reynolds & Vincent, 1982) and this was related to the cutting action employed by the insect. We have investigated the elemental composition of the mandibles of insects from several taxa to see if the hardness is due to ‘mineralization’ as in the ‘teeth’ of several other invertebrates e.g. the radular teeth of Patella, which contain iron and silica (Runham et al. 1969). For the first time we report the specific location, in the cutting edges (incisors) of insect mandibles, of large quantities of two transition elements, zinc and manganese. Metals have been found previously in only a few types of insect cuticle-in exceptional dipteran puparia and some phasmid eggs (Neville, 1975)-but their presence has not been related to any of the mechanical properties of the cuticle.
Simultaneous Measurement of Water Loss and Carbon Dioxide Production in the Cricket, Acheta Domesticus
Authors: Hadley Neil F. , Quinlan Michael 
Published: April 2021

ABSTRACT
The relationship between respiration and its contribution to total water loss in arthropods is based almost entirely on correlations obtained from independent plots of gravimetrically-determined transpiration rates and manometrically-determined gas exchange (Ahearn, 1970; Hadley, 1970). Recently a new system, the ‘transpiration monitor’ has been developed to detect the amount of water released by an arthropod into a moving air stream (Hadley, Stuart & Quinlan, 1982). The transpiration monitor not only permits the continuous recording of very small and sporadic losses of moisture, but can be interfaced with either an oxygen or carbon dioxide analyser to provide a simultaneous measure of the arthropod’s gas exchange. Thus, peaks that correspond to bursts of moisture can be correlated with concurrent increases in respiratory activity. We report here the application of this system to measure water loss and carbon dioxide production in the cricket, Acheta domesticas, under isothermal conditions and at increasing temperatures.