The Distribution of P O2 and Hydrostatic Pressure Changes Within the Branchial Chambers in Relation to GILL VENTILATION OF THE SHORE CRAB CARCINUS MAENAS L

1969 ◽  
Vol 51 (1) ◽  
pp. 203-220
Author(s):  
G. M. HUGHES ◽  
B. KNIGHTS ◽  
C. A. SCAMMELL
Keyword(s):  
Hydrostatic Pressure ◽  
Ventilation System ◽  
Carcinus Maenas ◽  
Pressure Change ◽  
Shore Crab ◽  
Positive Pressure ◽  
Transparent Plastic ◽  
Gill Lamellae ◽  
Minimum Disturbance ◽  
Pressure Changes

1. A technique is described for replacing part of the branchiostegite of Carcinus maenas by a transparent plastic ‘window’ for direct observation of the gills in situ with minimum disturbance. 2. Observation of dye streams shows that most water enters the hypobranchial space through the Milne-Edwards openings above the chelae, flowing anteriorly and/or posteriorly to ventilate most of gills 3-8. Water also enters above the pereiopods to ventilate the rest of the gills. Water passes from the hypobranchial to the epibranchial space, confirming that there is a counterflow with respect to the circulation of blood through the gill lamellae. 3. By sampling water at different points in the branchial system, patterns of oxygen removal were studied. The gradients confirmed the direction of water flow observed by the use of dyes. 4. Rhythmic changes in hydrostatic pressure in normal forward-pumping of 3-12 mm. H2O were recorded from the branchial cavities, superimposed on a maintained negative pressure relative to that outside the crab of 0-10 mm. H2O. Reversals produced a brief positive pressure change of 0-22 mm. H2O. 5. The possible relationships of the rhythmic pressure changes to scaphognathite movements are discussed. 6. The role of reversals is discussed and it is concluded that their primary function during ventilation is in helping to clean the ventrally facing gill surfaces. But they are also important in respiration under certain special conditions which arise during the normal life of the animal. 7. The utilization of O2 during its passage over the gills is low (7-23%) in spite of the counterflow. Possible explanations of this are discussed in relation to a model of the whole ventilation system.

Integration of Hydrostatic Pressure Information by Identified Interneurones in the Crab Carcinus maenas (L.); Long-Term Recordings

2001 ◽  
Vol 54 (1) ◽  
pp. 71-79 ◽  
Author(s):  
P. J. Fraser ◽  
A. G. Macdonald ◽  
S. F. Cruickshank ◽  
M. P. Schraner
Keyword(s):  
Hydrostatic Pressure ◽  
Gas Phase ◽  
Progress Monitoring ◽  
Carcinus Maenas ◽  
Shore Crab ◽  
Pressure Sensitive ◽  
Animal Navigation ◽  
Tidal Changes ◽  
Pressure Changes

This paper was first presented at the RIN97 Conference held in Oxford under the auspices of the Animal Navigation Special Interest Group, April 1997.Migrating species may utilise hydrostatic pressure. In the aquatic environment, hydrostatic pressure changes much more rapidly than in air. In shallow water, tidal changes will impose larger percentage changes on organisms than those experienced in deep water. Small changes in pressure often cause locomotion (barokinesis) accompanied by orientation to light or gravity, often partially compensating for the equivalent depth change. Until recently, identification of hydrostatic pressure receptors without a gas phase has proved elusive, but it is now known that thread hair receptors in the statocyst of the shore crab Carcinus maenas respond to small changes in hydrostatic pressure. Using a tide machine, the responses of thread hairs to sinusoidally changing pressure cycles have been examined, and this paper reports progress monitoring this receptor and making long-term recordings from hydrostatic pressure sensitive pathways in the crab's nervous system.

Study of Toynbee Phenomenon by Combined Intranasopharyngeal and Tympanometric Measurements

1988 ◽  
Vol 97 (2) ◽  
pp. 199-206 ◽  
Author(s):  
Yehuda Finkelstein ◽  
Yuval Zohar ◽  
Yoav P. Talmi ◽  
Nelu Laurian
Keyword(s):  
Middle Ear ◽  
Negative Pressure ◽  
Pressure Change ◽  
Positive Pressure ◽  
New Information ◽  
Pressure Changes ◽  
Rapid Pressure

The Toynbee maneuver, swallowing when the nose is obstructed, leads in most cases to pressure changes in one or both middle ears, resulting in a sensation of fullness. Since first described, many varying and contradictory comments have been reported in the literature concerning the type and amount of pressure changes both in the nasopharynx and in the middle ear. In our study, the pressure changes were determined by catheters placed into the nasopharynx and repeated tympanometric measurements. New information concerning the rapid pressure variations in the nasopharynx and middle ear during deglutition with an obstructed nose was obtained. Typical individual nasopharyngeal pressure change patterns were recorded, ranging from a maximal positive pressure of + 450 to a negative pressure as low as −320 mm H2O.

Effects of transmural pressure on brachial artery mean blood velocity dynamics in humans

2002 ◽  
Vol 93 (6) ◽  
pp. 2137-2146 ◽  
Author(s):  
Mary E. J. Lott ◽  
Michael D. Herr ◽  
Lawrence I. Sinoway
Keyword(s):  
Brachial Artery ◽  
Pressure Change ◽  
Blood Velocity ◽  
Voluntary Contraction ◽  
Transmural Pressure ◽  
Positive Pressure ◽  
Myogenic Response ◽  
Vascular Responses ◽  
Pressure Changes ◽  
Handgrip Contractions

The effects of changes in transmural pressure on brachial artery mean blood velocity (MBV) were examined in humans. Transmural pressure was altered by using a specially designed pressure tank that raised or lowered forearm pressure by 50 mmHg within 0.2 s. Brachial MBV was measured with Doppler directly above the site of forearm pressure change. Pressure changes were evoked during resting conditions and after a 5-s handgrip contraction at 25% maximal voluntary contraction. The handgrip protocol selected was sufficiently vigorous to limit flow and sufficiently brief to prevent autonomic engagement. Changes in transmural pressure evoked directionally similar changes in MBV within 2 s. This was followed by large and rapid adjustments [−2.14 ± 0.24 cm/s (vasoconstriction) during negative pressure and +2.14 ± 0.45 cm/s (vasodilatation) during positive pressure]. These adjustments served to return MBV to resting levels. This regulatory influence remained operative after 5-s static handgrip contractions. Of note, changes in transmural pressure were capable of altering the timing of the peak MBV response (5 ± 0, 2 ± 0, 6 ± 1 s ambient, negative, and positive pressure, respectively) as well as the speed of MBV adjustment (−2.03 ± 0.18, −2.48 ± 0.15, −0.84 ± 0.19 cm · s−1 · s−1ambient, negative, and positive pressure, respectively) after handgrip contractions. Vascular responses, seen with changes in transmural pressure, provide evidence that the myogenic response is normally operative in the limb circulation of humans.

The Responses of Nephtys (Polychaeta: Annelida) to Changes in Hydrostatic Pressure

1969 ◽  
Vol 50 (2) ◽  
pp. 501-513
Author(s):  
ELFED MORGAN
Keyword(s):  
Hydrostatic Pressure ◽  
Phase Angle ◽  
Pressure Change ◽  
Stimulus Level ◽  
Rate Of Change ◽  
Swimming Activity ◽  
Sine Function ◽  
Pressure Changes

1. An increase in pressure elicited swimming in Nephtys, the number of worms induced to swim being related to the amplitude of the pressure change within the range of stimuli investigated. A decrease in pressure inhibited swimming. 2. The latency of the response to both an increase and a decrease also appears to be related to the magnitude of the stimulus, the worms responding more rapidly to the bigger pressure changes. 3. Brief pulses of pressure lasting 1 sec. elicited neither increase nor decrease in the level of swimming, but pulses of 5 sec. duration induced some individuals to swim. Releasing the pressure at the end of the 5 sec. period resulted in a decrease in the swimming activity below the pre-stimulus level. It is suggested that the different responses may be mediated via separate receptor mechanisms. 4. Phase-angle analysis of the responses to cyclical changes in pressure suggested that the worms were responding primarily to the rate of change of pressure, but the response did not appear to be a simple sine-function of the stimulus. The worms also seemed to be responding in part to some component occurring at twice the basic cycle.

Control of ‘Pulmonary’ Pressure and Coordination with Gill Ventilation in the Shore Crab Carcinus Maenas

1991 ◽  
Vol 155 (1) ◽  
pp. 147-164
Author(s):  
K. P. RAJASHEKHAR ◽  
J. L. WILKENS
Keyword(s):  
Muscle Activity ◽  
Pressure Fluctuations ◽  
Carcinus Maenas ◽  
Circulatory System ◽  
Muscular Activity ◽  
Pattern Generator ◽  
Shore Crab ◽  
Positive Pressure ◽  
Gill Ventilation

In the shore crab, Carcinus maenas (L.), forward ventilation creates negative pulses of hydrostatic pressure while reversed ventilation causes dramatic positive pressure fluctuations in the branchial chamber. These pressures are transmitted via the gills to the haemolymph of the open circulatory system. The branchiostegal sinus, which is a compliant chamber, may function as a reservoir for displaced haemolymph and may operate as an accessory pump driven by the action of the dorsoventral (DV) muscles. A band of dorsoventral muscles controls the volume of the branchiostegal sinuses. The muscular activity is coordinated with ventilatory activity and may assist in regulating pressure fluctuations caused by ventilatory pressure pulses. During a ventilatory reversal, the haemolymph displaced from the gills is added to the volume of haemolymph in the open circulatory system and this haemolymph may be accommodated in the branchiostegal sinus by relaxation of the DV muscles. Artificially regulating the pressure either in the branchial chamber or in the branchiostegal sinus reflexively alters DV muscle activity, which suggests the occurrence of baroreceptors in this crab. The branchiostegal nerve that innervates the DV muscles contains five neurones identified by cobalt backfills. Three of them are median and two are contralateral. The dendritic field of each neurone is confined to its respective hemiganglia. The electrical activity of one of the motoneurones in the branchiostegal nerve corresponds to the activity of the DV muscles. In vitro observations of the activity of branchiostegal motoneurones in relation to ventilatory motoneurone activity indicate that both are centrally coupled and support the hypothesis that the branchiostegal motoneurones are influenced by the ventilatory central pattern generator.

Waterborne copper causes gill damage and hemolymph hypoxia in the shore crab Carcinus maenas

1993 ◽  
Vol 71 (8) ◽  
pp. 1569-1576 ◽  
Author(s):  
L. Nonnotte ◽  
F. Boitel ◽  
J. P. Truchot
Keyword(s):  
Carcinus Maenas ◽  
Lactate Concentration ◽  
Gill Tissue ◽  
Major Effect ◽  
Blood Oxygenation ◽  
Shore Crab ◽  
Structural Alterations ◽  
Arterial Blood ◽  
Shore Crabs ◽  
Gill Lamellae

The ultrastructure of gill lamellae was studied in shore crabs, Carcinus maenas, exposed to sublethal (0.5 mg∙L−1) and lethal (2 mg∙L−1) concentrations of waterborne copper for various durations. Oxygen tension, pH, and lactate concentration in arterial blood were determined in parallel studies. Extensive structural alterations involving cellular hyperplasia, vacuolization, and necrosis were found after 5–6 days of exposure to both sublethal and lethal copper levels. This led to considerable thickening of the gill epithelium and reduction of haemolymph spaces, resulting in restriction of respiratory gas exchange as shown by a marked hypoxemia. Ensuing lactacidemia suggests that tissue hypoxia was probably the major effect of the toxicant at lethal levels. In sublethal conditions, partial repair of gill tissue and recovery of normal blood oxygenation and pH were observed after 18 days of exposure.

Description of Maritrema portucalensis sp. nov. (Digenea, Microphallidae) parasite of Carcinus maenas (Crustacea, Decapoda) from Aveiro estuary, Northern Portugal

2011 ◽  
Vol 56 (4) ◽  
Author(s):  
Susana Pina ◽  
Fernanda Russell-Pinto ◽  
Pedro Rodrigues
Keyword(s):  
New Species ◽  
Carcinus Maenas ◽  
Morphological Characterization ◽  
The Body ◽  
Shore Crab ◽  
Northern Portugal ◽  
The Family ◽  
Its1 Rdna ◽  
Second Intermediate Host ◽  
Gill Lamellae

AbstractMaritrema portucalensis sp. nov. (Digenea, Microphallidae) from Aveiro estuary, northern Portugal, is described on the basis of excysted metacercariae obtained from the gill lamellae of the shore crab Carcinus maenas (L.). M. portucalensis sp. nov. most closely resembles Maritrema subdolum Jägerskiöld, 1909, a species that also frequently uses C. maenas as second intermediate host. The new species differs from M. subdolum in having a narrower body at the level of testes and a smaller ovary and testes. Also, the digestive caeca presented various folds along their length, thickening in the terminal region. Moreover, the body surface was fully covered by tegumental spines provided with several teeth. To complement our morphological characterization and to identify M. portucalensis metacercariae, the ITS1 rDNA region of the cysts isolated from C. maenas was sequenced and compared with the corresponding available sequences of digenean trematodes belonging to the family Microphallidae. Alignments revealed 28 base-pair differences between the query-ITS1 and that of M. subdolum, and more importantly a 100% similarity with the sequence of Microphallidae sp. no. 15 cercaria from the snail Hydrobia ulvae. The last observation allowed us to establish an unequivocal association between cercaria known as Microphallidae sp. no. 15, and the metacercaria of M. portucalensis sp. nov. characterized in this work, contributing decisively to the clarification of its life cycle.

Ion transport across posterior gills of hyperosmoregulating shore crabs (Carcinus maenas): amiloride blocks the cuticular Na+ conductance and induces current-noise

2002 ◽  
Vol 205 (4) ◽  
pp. 523-531 ◽  
Author(s):  
Horst Onken ◽  
Sven Riestenpatt
Keyword(s):  
Short Circuit ◽  
Noise Analysis ◽  
Carcinus Maenas ◽  
Low Frequency ◽  
Short Circuit Current ◽  
Current Noise ◽  
Corner Frequency ◽  
Shore Crab ◽  
Shore Crabs ◽  
Gill Lamellae

SUMMARYSplit gill lamellae and gill cuticles of shore crabs (Carcinus maenas) adapted to 10 ‰ salinity were mounted in a modified Ussing-type chamber. With NaCl saline on both sides, split gill lamellae generated a short-circuit current (Isc) of –301±16 μA cm–2 at a conductance (Gte) of 40±2 mS cm–2. The net influxes of Na+ and Cl– were 8.3±2.6 and 18.2±2.7 μmol cm–2 h–1, respectively. External amiloride (100 μmol l–1) reduced Gte to approximately 50 % of the original value at unchanged Isc; Cl– fluxes remained unaffected, whereas Na+ fluxes were markedly reduced by 70–80 %. The Isc in the presence of external amiloride was almost completely inhibited by internal ouabain. At a clamp voltage of 50 mV (outside-positive), a positive current was measured at unchanged Gte. Under these conditions, amiloride reduced the current and conductance at half-maximal concentrations of 3.6 and 2.0 μmol l–1, respectively. At outside-positive voltages, but not under short-circuit conditions, external amiloride induced Lorentzian components in the power density spectra. The amiloride-dependent changes in the corner frequency (linear) and of the low-frequency plateau (‘bell-shaped’) were as expected for channel blockade by amiloride with pseudo-first-order kinetics. With an outside-positive clamp voltage of 50 mV across isolated cuticles, a positive cuticular current (Icut) of 25 188±3791 μA cm–2 and a cuticular conductance (Gcut) of 547±76 mS cm–2 were measured. External amiloride reduced Icut and Gcut at half-maximal concentrations of 0.7 and 0.6 μmol l–1, respectively. Amiloride-induced current-noise analysis gave similar results to those observed with split gill lamellae. Ion-substitution experiments with isolated cuticles further support inhibition by external amiloride of the cuticular Na+ conductance of shore crab gills and not amiloride-sensitive transporters (Na+ channels or Na+/H+ antiports) in the apical membrane.

Heart Rate Signal Decomposition

2000 ◽  
Vol 39 (02) ◽  
pp. 200-203
Author(s):  
H. Mizuta ◽  
K. Yana
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Pressure Change ◽  
Normal Subjects ◽  
Signal Decomposition ◽  
Large Individual ◽  
Heart Rate Fluctuations ◽  
Type Pattern ◽  
Signal Cancellation ◽  
Pressure Changes

Abstract:This paper proposes a method for decomposing heart rate fluctuations into background, respiratory and blood pressure oriented fluctuations. A signal cancellation scheme using the adaptive RLS algorithm has been introduced for canceling respiration and blood pressure oriented changes in the heart rate fluctuations. The computer simulation confirmed the validity of the proposed method. Then, heart rate fluctuations, instantaneous lung volume and blood pressure changes are simultaneously recorded from eight normal subjects aged 20-24 years. It was shown that after signal decomposition, the power spectrum of the heart rate showed a consistent monotonic 1/fa type pattern. The proposed method enables a clear interpretation of heart rate spectrum removing uncertain large individual variations due to the respiration and blood pressure change.

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