Academic literature on the topic 'Animal physiology - biophysics'
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Journal articles on the topic "Animal physiology - biophysics"
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Ravaeva, M. Yu, E. N. Chuyan, I. S. Mironyuk, I. V. Cheretaev, A. V. Pivovarchuk, V. V. Kolesnik, and T. V. Grishina. "THE INDICATORS OF THE CARDIORESPIRATORY SYSTEM OF RATS UNDER THE ACTION OF ACETYLSALICYLIC ACID IN DIFFERENT CONCENTRATIONS." Scientific Notes of V.I. Vernadsky Crimean Federal University. Biology. Chemistry 6(72), no. 1 (2020): 150–61. http://dx.doi.org/10.37279/2413-1725-2020-6-1-150-161.
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The present study is devoted to revealing the peculiarities of the reaction of tissue microhemodynamics and cardiorespiratory system of animals the action acetylsalicylic acid in different concentrations on in rats. The study was carried out on the basis of the Center for collective use of scientific equipment «Experimental Physiology and Biophysics» of the Department of Human and Animal Physiology and Biophysics of the V. I. Vernadsky Crimean Federal University. The animals were divided into six groups of 10 animals. The first group was biological control; in the animals of this group, the microcirculation parameters were recorded by the laser Doppler flowmetry (LDF) method. The second-sixth group of animals was registered parameters of microcirculation and cardiorespiratory system. The LDF-metry was performed with the help of the laser analyzer of the blood flow «LAZMA-MC». It was researched the action of 5, 10, 40, 80, and 120 mg/kg doses acetylsalicylic acid on cardiorespiratory parameters in rats. It was found that the effect of acetylsalicylic acid in all doses significantly decreased only heart rate. The maximum decrease in this indicator was registered in animals when acetylsalicylic acid was administered at a dose of 120 mg/kg by 24.4 % (p≤0.05) relative to the values in the control group of animals. When acetylsalicylic acid was administered in isolated doses, there was a significant change in the activity of almost all components of microvascular tone regulation. These changes were most pronounced when animals were administered acetylsalicylic acid at a dose of 80 mg/kg. Thus, the action of acetylsalicylic acid it was increased the endothelium-dependent vasodilation, blood flow to the nutritive microvasculars, improvement in venular outflow and decreased in peripheral resistance. The reported study was funded by RFBR, project number 20-33-70142.
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Duxbury, Zane, Chih-hang Wu, and Pingtao Ding. "A Comparative Overview of the Intracellular Guardians of Plants and Animals: NLRs in Innate Immunity and Beyond." Annual Review of Plant Biology 72, no. 1 (June 17, 2021): 155–84. http://dx.doi.org/10.1146/annurev-arplant-080620-104948.
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Nucleotide-binding domain leucine-rich repeat receptors (NLRs) play important roles in the innate immune systems of both plants and animals. Recent breakthroughs in NLR biochemistry and biophysics have revolutionized our understanding of how NLR proteins function in plant immunity. In this review, we summarize the latest findings in plant NLR biology and draw direct comparisons to NLRs of animals. We discuss different mechanisms by which NLRs recognize their ligands in plants and animals. The discovery of plant NLR resistosomes that assemble in a comparable way to animal inflammasomes reinforces the striking similarities between the formation of plant and animal NLR complexes. Furthermore, we discuss the mechanisms by which plant NLRs mediate immune responses and draw comparisons to similar mechanisms identified in animals. Finally, we summarize the current knowledge of the complex genetic architecture formed by NLRs in plants and animals and the roles of NLRs beyond pathogen detection.
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Wolff, Jonas O. "Locomotion and kinematics of arachnids." Journal of Comparative Physiology A 207, no. 2 (March 2021): 99–103. http://dx.doi.org/10.1007/s00359-021-01478-2.
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AbstractA basic feature of animals is the capability to move and disperse. Arachnids are one of the oldest lineages of terrestrial animals and characterized by an octopodal locomotor apparatus with hydraulic limb extension. Their locomotion repertoire includes running, climbing, jumping, but also swimming, diving, abseiling, rolling, gliding and -passively- even flying. Studying the unique locomotor functions and movement ecology of arachnids is important for an integrative understanding of the ecology and evolution of this diverse and ubiquitous animal group. Beyond biology, arachnid locomotion is inspiring robotic engineers. The aim of this special issue is to display the state of the interdisciplinary research on arachnid locomotion, linking physiology and biomechanics with ecology, ethology and evolutionary biology. It comprises five reviews and ten original research reports covering diverse topics, ranging from the neurophysiology of arachnid movement, the allometry and sexual dimorphism of running kinematics, the effect of autotomy or heavy body parts on locomotor efficiency, and the evolution of silk-spinning choreography, to the biophysics of ballooning and ballistic webs. This closes a significant gap in the literature on animal biomechanics.
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Helmuth, B. "How do we Measure the Environment? Linking Intertidal Thermal Physiology and Ecology Through Biophysics." Integrative and Comparative Biology 42, no. 4 (August 1, 2002): 837–45. http://dx.doi.org/10.1093/icb/42.4.837.
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Hammarlund, Emma U. "Harnessing hypoxia as an evolutionary driver of complex multicellularity." Interface Focus 10, no. 4 (June 12, 2020): 20190101. http://dx.doi.org/10.1098/rsfs.2019.0101.
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Animal tissue requires low-oxygen conditions for its maintenance. The need for low-oxygen conditions contrasts with the idea of an evolutionary leap in animal diversity as a result of expanding oxic conditions. To accommodate tissue renewal at oxic conditions, however, vertebrate animals and vascular plants demonstrate abilities to access hypoxia. Here, I argue that multicellular organisms sustain oxic conditions first after internalizing hypoxic conditions. The ‘harnessing’ of hypoxia has allowed multicellular evolution to leave niches that were stable in terms of oxygen concentrations for those where oxygen fluctuates. Since oxygen fluctuates in most settings on Earth's surface, the ancestral niche would have been a deep marine setting. The hypothesis that ‘large life’ depends on harnessing hypoxia is illustrated in the context of conditions that promote the immature cell phenotype (stemness) in animal physiology and tumour biology and offers one explanation for the general rarity of diverse multicellularity over most of Earth's history.
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Chuyan, E. N., I. S. Mironyuk, M. Yu Ravaeva, I. V. Cheretaev, and T. V. Grishina. "INDICATORS OF THE RAT CARDIORESPIRATORY SYSTEM UNDER THE ACTION OF ACETYLSALICYLIC ACID AND ITS COMPLEX COMPOUNDS WITH METALS." Scientific Notes of V.I. Vernadsky Crimean Federal University. Biology. Chemistry 6(72), no. 2 (2020): 267–80. http://dx.doi.org/10.37279/2413-1725-2020-6-2-267-280.
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The paper researches the effect of cobalt (АСCo2+) and zinc (АСZn2+), nickel (Ni2+) and manganese (Mn2+) acetylsalicylates in doses of 5 and 10 mg/kg on the characteristics of the rats’ cardiorespiratory system. The study was carried out on the basis of the Center for collective use of scientific equipment «Experimental Physiology and Biophysics» of the Department of Human and Animal Physiology and Biophysics of the V. I. Vernadsky Crimean Federal University. The research of the biological effect of the acetylsalicylic acid, АСCo2+, АСZn2+ , АСNi2+, АСMn2+was carried out during their intraperitoneal injection into rats in doses of 5 mg/kg and 10 mg/kg. Simultaneously the following characteristics of all the groups’ animals were registered: heart rate (HR), respiratory rate (RR), systolic blood pressure (SBP) and diastolic blood pressure (DBP). The pulse pressure (PP) was calculated on the basis of the SBP and DBP indices difference. BP, HR and RR of the rats were registered with the help of the system NIBP200A («BiopacSystems, Inc.», USA). The results of the current research allowed to determine that the coordinating compounds of the acetylsalicylic acid with such metals as Co, Zn, Ni2+, Mn2+ not only have more pronounced biological effect in comparison with the acetylsalicylic acid, but demonstrate new properties; the most effect on the cardiorespiratory system was achieved by АСZn2+. Thus, the results of the current research allow us to claim that the salts of the acetylsalicylates, having the metal-complexing in its molecules’ composition, have more pronounced and qualitatively new properties in comparison with the acetylsalicylic acid precursor’s properties; this makes the further search for biological and pharmaceutical activity of these coordinating compounds more perspective, as well as it makes the technology of complexingan inexpensive and highly efficient approach to the creation of new medicines. The reported study was funded by RFBR, project number 20-33-70142
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Gonzalez C, Carlos A., Orlando Zuñiga E, and Luis E. Padilla. "Detection of animal tissue thickness using simple vertical electric sounding (VES)." Physiological Measurement 18, no. 1 (February 1, 1997): 85–91. http://dx.doi.org/10.1088/0967-3334/18/1/007.
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McCafferty, D. J., G. Pandraud, J. Gilles, M. Fabra-Puchol, and P.-Y. Henry. "Animal thermoregulation: a review of insulation, physiology and behaviour relevant to temperature control in buildings." Bioinspiration & Biomimetics 13, no. 1 (December 28, 2017): 011001. http://dx.doi.org/10.1088/1748-3190/aa9a12.
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Chuyan, E. N., I. S. Mironyuk, E. A. Biryukova, A. I. Pridatkо, M. Yu Ravaeva, T. V. Grishina, E. R. Asanova, and A. R. Asanova. "INDICATORS OF THE CARDIOVASCULAR SYSTEM OF RATS UNDER THE ACTION OF ACETYLSALICYLIC ACID AND ITS COMPLEX COMPOUNDS WITH METALS." Scientific Notes of V.I. Vernadsky Crimean Federal University. Biology. Chemistry 7 (73), no. 3 (2022): 271. http://dx.doi.org/10.37279/2413-1725-2021-7-3-271-288.
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The effect of acetylsalicylic acid (ASA) and its complex compounds with the metals lithium (Li+), potassium (K+), magnesium (Mg2+) and calcium (Ca2+) with a single intraperitoneal injection at doses of 5, 10 and 20 mg/kg on cardiovascular system (CVS) of rats (blood pressure, heart rate, indicators of heart electrocardiogram). The structure-effect analysis showed that the coordination compounds of ASA, in which, in addition to the ligand with bioactive properties, a metal-microelement is present, caused multidirectional changes in the CVS indices. Those changes depended both on the metal included in the compound and on the dose of the administered substance. The study was carried out on the basis of the Center for collective use of scientific equipment «Experimental Physiology and Biophysics» (Department of Human and Animal Physiology and Biophysics, V.I. Vernadsky Crimean Federal University). The research of the biological effect of the acetylsalicylic acid, SLi+, SK+, SMg2+, SCa2+ was carried out during their intraperitoneal injection into rats in doses of 5, 10 and 20 mg/kg. Simultaneously the following characteristics of all the groups’ animals were registered: heart rate (HR), systolic blood pressure (SBP) and diastolic blood pressure (DBP) and electrocardiogram indicators. The pulse pressure (PP) was calculated on the basis of the SBP and DBP indices difference. BP, HR and RR of the rats were registered with the help of the system NIBP200A («Biopac Systems, Inc.», USA). The experimental data obtained in our studies confirm the literature data, which show that in the process of complexation there is not only an increase or decrease in certain effects that are characteristic of precursor molecules-salicylates, but also the appearance of new properties of derived substances. Тhe obtained data confirm the cardiotropic effectiveness of new coordination compounds, show the dose dependence of these effects and open up the prospects for further studies of their biological action when used repeatedly in chronic experiments.
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Chuyan, E. N., I. S. Mironyuk, I. V. Cheretaev, M. Yu Ravaeva, T. V. ,. Grishina, and R. N. Ablaeva. "DOSE-DEPENDENT CARDIOTROPIC EFFECTS OF ACETYLSALICYLATES." Scientific Notes of V.I. Vernadsky Crimean Federal University. Biology. Chemistry 6(72), no. 4 (2021): 175–96. http://dx.doi.org/10.37279/2413-1725-2020-6-4-175-196.
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The effect of acetylsalicylic acid and its complex compounds with the metals cobalt (Co2+), zinc (Zn2+), nickel (Ni2+) and manganese (Mn2+) at doses of 5, 10 and 20 mg/kg on the parameters of the rat cardiorespiratory system was studied. It is shown that in the process of complexation of acetylsalicylic acid with bimetals, there is not only an increase or decrease in certain effects inherent in the precursor molecule – acetylsalicylic acid, but also the appearance of new properties, the manifestation of which is dose-dependent. The study was carried out on the basis of the Center for collective use of scientific equipment «Experimental Physiology and Biophysics» of the Department of Human and Animal Physiology and Biophysics of the V. I. Vernadsky Crimean Federal University. The research of the biological effect of the acetylsalicylic acid, АСCo2+, АСZn2+, АСNi2+, АСMn2+was carried out during their intraperitoneal injection into rats in doses of 5, 10 and 20 mg/kg. Simultaneously the following characteristics of all the groups’ animals were registered: heart rate (HR), respiratory rate (RR), systolic blood pressure (SBP) and diastolic blood pressure (DBP). The pulse pressure (PP) was calculated on the basis of the SBP and DBP indices difference. BP, HR and RR of the rats were registered with the help of the system NIBP200A («BiopacSystems, Inc.», USA). The experimental data obtained in our studies confirm the literature data, which show that in the process of complexation there is not only an increase or decrease in certain effects that are characteristic of precursor molecules-salicylates, but also the appearance of new properties of derived substances. This suggests that certain biological effects of salicylates may be associated with interaction with metalloenzymes. Thus, the obtained data confirm the cardiotropic effectiveness of new coordination compounds, show the dose dependence of these effects and open up the prospects for further studies of their biological action when used repeatedly in chronic experiments.
Dissertations / Theses on the topic "Animal physiology - biophysics"
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Ferreira, Matos Gomes Rute. "Respiratory mechanics in small animals : influence of size and age." Thesis, McGill University, 2001. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=38188.
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Although rodents have been widely used in respiratory research, there are still only limited data comparing respiratory mechanics between different species of small animal. In order to provide further insight into the mechanical behavior of the respiratory systems of different sized small animals, accurate measurements of respiratory impedance (Zrs) were made in four different rodent species and in the developing rat over a broad range of frequencies at various levels of positive end-expiratory pressure (PEEP). PEEP dependencies of airway and tissue properties were interpreted in terms of physiological phenomena such as airway closure and airway-parenchymal interdependence forces. In adult animals, Zrs was fitted to a model including a Newtonian resistance (R) in series with a constant-phase tissue compartment. In general, rodent respiratory parameters obeyed the same scaling laws described in other species, but rabbits had a relatively higher elastance than one would predict from previously published allometric relationships. This is probably due to the rabbit's proportionately smaller airspace volume. R normalized to body weight was lower in smaller species suggesting that they have proportionately wider airways compared to larger animals. By using computer models of the asymmetric airway tree to estimate airway resistance (Raw), we confirmed that the larger of two isomorphic rodent species has relatively higher Raw. Moreover, we showed that both the airway dimensional scaling differences and the asymmetric arrangement of the individual airways are responsible for the relative differences in Raw between smaller and larger animals. Finally, in the developing rat, elastance and resistance normalized to lung weight decreased progressively with age, suggesting that intrinsic changes in the mechanical properties of the respiratory system occur with development. Parenchymal interdependence forces manifested themselves in animals as young as 10 days of age, with PEEP
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Beck, Jennifer 1968. "Effects of chest wall configuration and electrode positioning on human diaphragmatic EMG." Thesis, McGill University, 1994. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=22536.
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The measurement and analysis of the human diaphragm electromyogram (EMGdi), as obtained with an esophageal electrode, requires objective control of the disturbances and filtering effects which can influence the signal. One issue of importance is that an increase in the muscle-to-electrode distance (MEdist) acts as a low-pass filter, filtering out the high frequency components of the EMG power spectrum (the MEdist filter). Due to the numerous factors which can influence the EMGdi, control of signal quality is also of utmost importance. The aims of this study were: (1) to evaluate the effect of the MEdist filter on EMGdi, as measured with a multiple array esophageal electrode, (2) to take advantage of the MEdist filter in order to locate the position of the diaphragm with respect to the electrodes, and (3) to evaluate the influence of changes in chest wall configuration on EMGdi center frequency (CF) values, while controlling for both signal quality and the MEdist filter.Five normal male subjects performed static contractions of the diaphragm at seven predetermined chest wall configurations. The EMGdi was measured with an array of eight steel rings mounted on a catheter, forming seven sequential pairs of electrodes, with an interelectrode distance of 10 mm. EMGdi signal quality was evaluated by computer algorithms. The pair of electrodes whose EMGdi signals (and power spectrums) were the least influenced by the MEdist filter was assumed to be closest to the diaphragm.
The results of the study indicated (1) EMGdi power spectrums and their associated CF values were strongly affected by the position of the diaphragm with respect to the multiple array esophageal electrode. CF decreased by approximately 1 Hz per mm displacement away from the diaphragm. (2) By controlling for the MEdist filter, there was no relationship found between changes in chest wall configuration and CF values. These data demonstrate that changes in chest wall configuration, and hence diaphragm length, do not influence the CF values of the EMGdi, if the distance between the electrodes and the diaphragm and signal quality are controlled for.
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Krogh-Madsen, Trine. "Effects of single-channel noise on spontaneous beating and the phase-resetting response of cardiac oscillators." Thesis, McGill University, 2004. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=85562.
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From our everyday life, we know that our hearts beat with a rhythm which is not perfectly periodic. Even an isolated spontaneously beating cardiac cell, devoid of neural, hormonal, and intracardiac regulatory input, does not beat perfectly regularly. I investigate the hypothesis that the beat-to-beat fluctuations in transmembrane potential of spontaneously beating cardiac cells are due to stochastic gating of the ionic channels in the cell membrane.Recordings of transmembrane potential from small clusters of spontaneously beating 7-day-old embryonic chick ventricular cells were analyzed to characterize the voltage waveform and the regularity of beating. I constructed a deterministic Hodgkin-Huxley-type ionic model which reproduces spontaneous activity in our experimental recordings, as well as the experimental results of applying various ion channel blockers (D-600, almokalant, and Ba2+). The model consists of six currents: a calcium current (ICa), three potassium currents (IKs, I Kr, IK1), a background current ( Ib), and a seal-leak current (I seal).
The deterministic Hodgkin-Huxley-type model was then reformulated into a stochastic single-channel model. The single-channel model reproduces the irregularity of beating seen experimentally: e.g. the coefficient of variation of interbeat interval was 4.4% vs. 3.9% in the clusters. In the model, IKs is the current giving the major contributions to fluctuations in interbeat interval.
Phase resetting of the spontaneous activity of cardiac pacemaker cells by a brief stimulus pulse was simulated in Hodgkin-Huxley-type models and single-channel models of slow-upstroke (central) and fast-upstroke (peripheral) rabbit sinoatrial node cells. In the Hodgkin-Huxley-type models the phase-resetting response is continuous, but can be extremely delicate in the fast-upstroke model, in that a tiny difference in the stimulus timing can change the stimulus response from a delayed action potential to an advanced one. Therefore, the noise in the fast-upstroke single-channel model can cause a stimulus with fixed amplitude and fixed timing to have widely different effects: sometimes it will induce an action potential but in other cases it will delay an action potential, as seen previously in experiments on cardiac preparations.
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Lewis, Timothy J. "Modeling conduction in the ventricles." Thesis, McGill University, 1991. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=60501.
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Two models of electrical conduction in the cardiac ventricles are considered. The first model considered is that of a strand of ventricular muscle which uses the one-dimensional cable equation with the Beeler-Reuter model to represent the transmembrane currents. The effect of periodic stimulation on the strand is numerically simulated, and it is found that as simulation frequency is increased, the rhythms of synchronization are successively encountered. It is shown that this sequence of rhythms can be accounted for by considering the response of the strand to premature stimulation. This involves deriving a one-dimensional finite-difference equation or "map" from the response to premature stimulation, and then iterating this map to predict the response to periodic stimulation.The second model states that the highly ramified His-Purkinje system is reminiscent of a fractal branching structure, and that the ventricular myocardium is activated in a "fractal" (time-scale invariant) fashion, since it is activated via the His-Purkinje system. A 1/$f sp alpha$ power spectrum can sometimes be linked to fractal processes. The averaged power spectrum of single QRS complexes falls off as 1/$f sp alpha$ ($ alpha sim$ 4).
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Liu, Qingde 1963. "Molecular and physical determinants of fibrinogen-dependent platelet aggregation and adhesion in flow." Thesis, McGill University, 1998. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=35909.
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Fibrinogen (Fg) mediates platelet aggregation and adhesion to artificial surfaces by interacting with its receptor, glycoprotein IIb and IIIa complex (GPIIbIIIa, or integrin alphaIIbbeta 3), on the platelet membrane. Considerable evidence has demonstrated that the (H12) on the gamma chain carboxyl terminus is required for the binding of Fg from solution to activated platelet GPIIbIIIa, while the RGD sites, the universal integrin recognition domain on adhesive ligands, are not involved. In this study, using recombinant Fg, well-defined Fg plasmin digestion fragments, and specific monoclonal anit-Fg antibodies, we demonstrated that the same sequence, the H12, or more precisely, the AGDV on the extreme carboxyl terminus of the gamma chain (gamma408--411), is also required for platelet-bound Fg to support platelet aggregation (crosslinking), thus experimentally verifying the "two sticky ends" theory of Fg-mediated platelet aggregation The RGD-containing domains on the Aalpha chains are not involved in aggregation. The AGDV sequence on the gamma chain carboxyl terminus is also necessary and sufficient for activated platelets to adhere to surface-adsorbed Fg, while the RGD sequences we similarly not required. A receptor induced binding site (RIBS), the Fg RIBS-I site (gamma373--385), on Fg either bound to its GPIIbIIIa-receptor or on a surface, is not directly involved in interactions between platelet GPIIbIIIa and immobilized Fg. The inhibitory effects of the anti-Fg-RIBS-I antibody are due to steric hindrance of the accessibility of the AGDV site to platelet GPIIbIIIa. Thus, the extreme carboxyl terminus of the gamma chain is the only site in both fluid and solid phase Fg that is involved in platelet GPIIbIIIa-Fg interactions.Though resting platelets are able to adhere to surface-bound Fg, this adhesion efficiency is much lower than that of the adhesion of the activated platelets. The adhesion efficiency of both resting and activated platelets to surface-adsorbed Fg decreases with increasing shear rate from 100 s -1 to 2,000 s-1. However, the decrease of the adhesion efficiency of the resting platelets is more marked than the decrease of the adhesion efficiency of the activated ones. Thus, the higher the shear rates, the larger the difference in the adhesion efficiencies between resting and activated platelets. However, due to the higher collision frequencies at higher shear rates, the adhesion of resting platelets was maintained at a similar level from shear rates of 300--2,000 s-1, while the adhesion of activated platelets kept increasing from 100 s -1 to 2,000 s-1. These data indicate that platelet activation is an efficient regulation pathway for platelet adhesion to surfaces.
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Walker, Angela. "Electrochemical study of vesicular release in bovine chromaffin cells." Thesis, McGill University, 1995. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=23431.
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The time course of the spontaneous current spikes produced by the release of the catecholamines from individual vesicles was examined in bovine chromaffin cells by using the carbon filament technique in the amperometric mode.Frequency histograms of the rise and decay times of the current spikes showed a paucity of very short duration events. Scatterograms of the rise and decay times consistently showed a positive relation, and the best fitted lines intercepted the ordinate (the axis of the decay time) at: 16.06 $ pm$ 6.45 msec (n = 11).
The effect of temperature changes upon the time course of release of content of individual vesicles in chromaffin cells was also examined. The amplitudes of the current spikes did not change significantly, whereas the rise times and the decay times diminished from (23.2 $ pm$ 11.6 to 11.9 $ pm$ 2.7 msec, and from 76.6 $ pm$ 25.4 to 47.3 $ pm$ 9.3 msec respectively) as the temperature was raised from 15$ sp circ$C to 35$ sp circ$C (n = 5). Nevertheless, the Q$ sb{10}$ values of the rise and decay times were surprisingly low.
The experimental findings suggest that in bovine chromaffin cells the duration of the release of content of single vesicles is much longer than in synapses. The results also suggest that this mechanism does not involve processes that are strongly temperature sensitive.
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Young, Richard N. (Richard Norman). "The effect of muscle contractility on surface EMG /." Thesis, McGill University, 1989. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=60423.
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This study was designed as an investigation of the role of changes in muscle force and changes in muscle length on the EMG for the Tibialis Anterior (TA).Using surface electrodes we examined the EMG for 4 contraction levels at 5 ankle positions over 60$ sp circ$ of ankle rotation. The change in median frequency with muscle length identified a significant shift in the power spectrum to lower frequencies with increasing muscle length.
To further investigate our results we performed three other experiments: First, using X-rays to identify the relative change in distance between two intramuscular wire electrodes we found the change in TA muscle length for this study to be 15% over the 60$ sp circ$ of ankle rotation. Second, to test for synergist contamination we used fine wire electrodes in the Extensor Digitorum Longus and the Peroneus. We found no evidence to support significant contamination. Third, we examined the role of smaller electrodes with a smaller interelectrode distance on our findings. The EMG showed drastic changes with even a slight shift in electrode position most likely due to the large number of innervation zones.
Therefore, the results indicate a shift in the power spectrum with a change in muscle length. In addition, surface EMG results are heavily dependent on the innervation zones and on the electrode geometry, all of which are important considerations in developing the EMG as an accurate diagnostic tool.
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Deng, Xiaoyan. "The effects of disturbed flows on mass transfer to and from an arterial wall /." Thesis, McGill University, 1991. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=70234.
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The effect of disturbed flows on mass transfer to and from an arterial wall was studied both theoretically and experimentally using an idealized model of arterial stenoses in which an annular ring vortex was formed. It was found that the transport of macromolecules, including low density lipoproteins, from flowing blood to a semi-permeable vessel wall is greatly enhanced in regions of disturbed flow with a local maximum locating around the reattachment (stagnation) point. The surface concentration of macromolecules increases with increasing the filtration velocity and decreasing the flow rate. The disturbed flows also facilitated the transport of low molecular weight substances such as biochemicals but not macromolecules from arterial walls to flowing blood. These results strongly suggest that disturbed flows with slow recirculation flow provide favorable conditions for the genesis and development of atherosclerotic lesions by affecting local mass transport phenomena at the blood-vessel wall boundary.
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Chen, Yuejin. "Characterization of the Vasoactivity of Tachykinins in Isolated Rat Kidney: Functional Studies and in Vitro Receptor Autoradiography." Digital Commons @ East Tennessee State University, 1994. https://dc.etsu.edu/etd/2892.
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Although tachykinins have potent vascular actions, their effect on renal resistance blood vessels is currently unknown. The vasoactive properties of tachykinins and related analogs were assessed in isolated perfused rat kidney. At a basal perfusion pressure (PP) of 75 $\pm$ 6 mm Hg (n = 5), bolus injections of substance P (SP) had no significant vasoactive effect. Following a sustained increase in baseline PP (134 $\pm$ 10 mm Hg) produced by phenylephrine (1 $\mu$M), SP evoked a dose-dependent increase in PP. The largest dose of SP increased PP by 60 $\pm$ 5 mm Hg. The vasoconstrictor response to SP was not blocked by phentolamine when angiotensin II was used to increase basal tone. Thus, the response to SP is not mediated by norepinephrine. Pressor responses to SP were not potentiated by peptidase inhibitors, captopril and thiorphan. SP(1-7) had no effect on PP, suggesting that the pressor response to SP is C-terminal dependent and tachykinin receptor mediated. The selective NK-1 receptor agonist, (Sar$\sp9$,Met(O$\sb2)\sp{11}\rbrack$SP, had no effect on PP. In contrast, both the selective NK-2 and NK-3 receptor agonists, GR-64349 and (MePhe$\sp7$) NKB, produced dose-dependent pressor responses (116 $\pm$ 8 and 134 $\pm$ 15 mm Hg increases in PP at 33 nmol, respectively) and were more potent than SP. Infusion of capsaicin (500 nM) produced an initial increase in PP following by a more prolonged decrease in PP. Clamping the renal vein produced a marked increase in PP. The localization of NK-3 receptors in rat kidney evaluated by film autoradiography using $\sp{125}$I- (MePhe$\sp7\rbrack$NKB revealed a high density of specific binding sites on the proximal ureter and renal pelvis, moderate density in the renal vein and its large branches, and a low density in the inner strip of outer medulla, but no specific binding on the renal artery system and cortex. High resolution autoradiograms demonstrated $\sp{125}$I- (MePhe$\sp7\rbrack$NKB binding sites on the tunica media of the renal vein and tunica muscularises of renal pelvis and ureter. Specific binding of $\sp{125}$I-BHSP was found in association with the renal artery and renal pelvis. No specific SP binding sites were associated with renal vein. These data indicate that the pressor effect of tachykinins in the isolated rat kidney can be mediated by NK-2 and/or NK-3 receptors. The latter may be on the vascular smooth muscle of the renal vein.
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He, Dingsheng. "Connexins 40 and 43 form heteromeric gap junction channels in vascular smooth muscle cells." Diss., The University of Arizona, 1999. http://hdl.handle.net/10150/284991.
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Gap junction channels connect the cytoplasms of adjacent cells and provide a pathway for the exchange of materials between cells. The nature of the materials exchanged is determined by the biophysical characteristics of the channels. The functional gap junction channel is composed of paired hemichannels (connexons) from each cell. Connexons are hexamers of protein subunits called connexins (Cx). Of the 15 connexin genes found in the mammalian genome, the products of only two, Cx40 and Cx43 have been localized in vascular smooth muscle cells (SMC) (1;2). We have been interested in identifying the role of gap junctions in cardiac rhythmic activity and vascular function. Like many other cell types, mammalian heart and blood vessels express multiple gap junction connexins (3). These connexins may form heteromeric channels. A7r5 cells, a cell line derived from embryonic rat aortic smooth muscle cells, provide a good model because they express both connexins 40 and 43. From the previous studies in this laboratory, Moore and Burt reported the presence of channels with a wide range of unitary conductance with major peaks at 75, 110 and 145 pS. One explanation for the wide range of unitary conductance could be the presence of heteromeric Cx40 and Cx43 channels. Thus, the goal of this study was to investigate gating behaviors of gap junction channels in A7r5 cells to determine whether heteromeric Cx40/43 channels are formed. I will demonstrate that Cx40 and Cx43 form heteromeric channels with unique unitary conductances, voltage-dependent gating properties and enhanced sensitivity to halothane induced closure.
Books on the topic "Animal physiology - biophysics"
1
Folk, G. Edgar. Principles of integrative environmental physiology. San Francisco: Austin & Winfield Publishers, 1998.
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2
Folk, G. Edgar. Principles of integrative environmental physiology. Lanham, Maryland: Austin & Winfield Publishers, 1998.
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3
Newton rules biology: A physical approach to biological problems. Oxford: Oxford University Press, 1992.
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Birdi, K. S. Fractals in Chemistry, Geochemistry, and Biophysics: An Introduction. Boston, MA: Springer US, 1993.
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Honda, Yoshiyuki. Control of Breathing and Its Modeling Perspective. Boston, MA: Springer US, 1992.
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Shah, Vinod P. Topical Drug Bioavailability, Bioequivalence, and Penetration. Boston, MA: Springer US, 1993.
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Maibach, Howard I., Vinod P. Shah, and John Jenner. Topical drug bioavailability, bioequivalence, and penetration. New York: Springer, 2014.
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Petty, Howard R. Molecular Biology of Membranes: Structure and Function. Boston, MA: Springer US, 1993.
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Kilberg, Michael S. Mammalian Amino Acid Transport: Mechanism and Control. Boston, MA: Springer US, 1992.
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Gupta, Sudhir. Mechanisms of Lymphocyte Activation and Immune Regulation V: Molecular Basis of Signal Transduction. Boston, MA: Springer US, 1994.
Find full textBook chapters on the topic "Animal physiology - biophysics"
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Storz, Jay F. "Darwin’s molecule." In Hemoglobin, 201–32. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780198810681.003.0009.
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Chapter 9 discusses conceptual issues in protein evolution and provides a synthesis of lessons learned from studies of hemoglobin function. Using hemoglobin as a model molecule, we can exploit an unparalleled base of knowledge about structure-function relationships and we can characterize biophysical mechanisms of molecular adaptation at atomic resolution. It is therefore possible to document causal connections between genotype and biochemical phenotype at an unsurpassed level of rigor and detail. Moreover, since the oxygenation properties of hemoglobin provide a direct link between ambient O2 availability and aerobic metabolism, genetically based changes in protein function can be related to ecologically relevant aspects of organismal physiology. We therefore have a solid theoretical framework for making predictions and for interpreting observed associations between biochemical phenotype and fitness-related measures of whole-animal physiological performance. The chapter explores case studies that illustrate how experimental research on functional properties of a well-chosen model protein can be used to address some of the most conceptually expansive questions in evolutionary biology: Is genetic adaptation predictable? Why does evolution follow some pathways rather than others?
Conference papers on the topic "Animal physiology - biophysics"
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Chen, Cuiye, and Robert B. Roemer. "Simulation of Empirical Correlations Between Temperatures and Blood Perfusion During Heating Using a Temperature-Dependent Blood Perfusion Model." In ASME 2004 International Mechanical Engineering Congress and Exposition. ASMEDC, 2004. http://dx.doi.org/10.1115/imece2004-62061.
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This study applies a recently developed temperature-dependent blood perfusion model (TDBPM) coupled with a modified, one-dimensional Pennes bioheat transfer equation to predict the blood perfusion and temperature responses to step function microwave heating applied in the in vivo experiments performed by Sekins’ et al. [1] on human thigh muscle. The TDBPM model links the perfusion increase to the tissue temperature elevation based on physiological mechanisms underlying this temperature-blood-perfusion change phenomenon, i.e., a pharmacokinetic compartmental model. This physiology-based model avoids using ad hoc time delays between blood perfusion increases and tissue temperature elevations as done in previous efforts. It also includes a mechanism that produces the threshold temperature for blood flow increases that has been observed in vivo. In our recent study [2], the TDBPM model was used to simulate both the constant temperature water bath heating used in the in vivo experiments on rat leg muscle performed by Song et al. [3], and the step function microwave heating applied in the in vivo experiments on canine thigh muscle performed by Roemer et al. [4]. The blood perfusion rates predicted by the model are compared with those in vivo experimental data obtained in rat muscle and human muscle and good agreement was obtained. The TDBPM provides a possible explanation to the biochemical and biophysical origins of the relationships between temperature and blood flow that observed in rat muscle and human muscle. The physiology-based TDBPM is a simple, generic model of muscle blood flow responses of different animals to different heating conditions, which provides the type of fundamental information needed for the design of methods to thermally control blood flow in medical applications.