The Sensitivity of the Pedal Ganglion of the Slug to Osmotic Pressure Changes

1956 ◽  
Vol 33 (3) ◽  
pp. 493-501
Author(s):  
G. A. KERKUT ◽  
B. J. R. TAYLOR

1. The effects of different dilutions of Locke solution on the electrical activity of the isolated pedal ganglion of the slug can be reproduced by adding different concentrations of glucose of mannitol to a given concentration of Locke. 2. This indicates that certain cells in the pedal ganglion are sensitive to the osmotic pressure of the solution and not its ionic concentration. 3. The preparation is sensitive to slow changes in the concentration of the bathing medium. The cells increased their activity when the bathing solution was slowly changed from 0.7 Locke to 0.6 Locke, the change taking 43 min. This corresponds approximately to a change of 1% of the body fluid concentration over 4 min. Such rates of change are found in the normal intact animal. 4. The sensitivity of the preparation compares well with that of the mammalian osmoreceptors.

1976 ◽  
Vol 3 (3) ◽  
pp. 311 ◽  
Author(s):  
DL Mcneil

In etiolated sunflower (H. annuus) hypocotyls, the intracellular osmotic pressure was maintained in spite of the dilution caused by growth. The principal osmotic substances present were hexoses (44 � 6 mol m-3 glucose and 40 � 5 mol m-3 fructose) and organic potassium salts (30 mol m-3). , Potassium fluxes in vivo (intact rooted seedlings) and in vitro (1 cm, peeled, cut sections in an aerated bathing solution) were similar, indicating that the sectioning had not affected cell fluxes. The uptake of 3-O-methyl glucose by cut sections from a bathing medium was lower than the uptake estimated using intact tissue (in vitro influx was 5 % of the net accumulation rate of intact tissue). This suggested that some pathway of hexose uptake other than from the extracellular spaces occurred in vivo. To explain this difference in reducing sugar accumulation rates the following pathway is suggested: (1) Transport of sucrose from the cotyledons via the phloem; (2) Direct unloading of the sucrose into the symplast; (3) Transport of the sucrose into the vacuole down a sucrose concentration gradient maintained by hydrolysis of sucrose to glucose and fructose; (4) Low hexose efflux from the vacuole (5 % of in vivo influx), preventing loss from the vacuole.


1978 ◽  
Vol 44 (2) ◽  
pp. 254-257 ◽  
Author(s):  
Y. Kakiuchi ◽  
A. B. DuBois ◽  
D. Gorenberg

Hansen's membrane manometer method for measuring plasma colloid osmotic pressure was used to obtain the osmolality changes of dogs breathing different levels of CO2. Osmotic pressure was converted to osmolality by calibration of the manometer with saline and plasma, using freezing point depression osmometry. The addition of 10 vol% of CO2 to tonometered blood caused about a 2.0 mosmol/kg H2O increase of osmolality, or 1.2% increase of red blood cell volume. The swelling of the red blood cells was probably due to osmosis caused by Cl- exchanged for the HCO3- which was produced rapidly by carbonic anhydrase present in the red blood cells. The change in colloid osmotic pressure accompanying a change in co2 tension was measured on blood obtained from dogs breathing different CO2 mixtures. It was approximately 0.14 mosmol/kg H2O per Torr Pco2. The corresponding change in red cell volume could not be calculated from this because water can exchange between the plasma and tissues.


1967 ◽  
Vol 46 (2) ◽  
pp. 307-315 ◽  
Author(s):  
E. DON STEVENS ◽  
D. J. RANDALL

1. Changes in blood pressure in the dorsal aorta, ventral aorta and subintestinal vein, as well as changes in heart rate and breathing rate during moderate swimming activity in the rainbow trout are reported. 2. Blood pressures both afferent and efferent to the gills increased during swimming and then returned to normal levels within 30 min. after exercise. 3. Venous blood pressure was characterized by periodic increases during swimming. The pressure changes were not in phase with the body movements. 4. Although total venous return to the heart increased during swimming, a decreased blood flow was recorded in the subintestinal vein. 5. Heart rate and breathing rate increased during swimming and then decreased when swimming ceased. 6. Some possible mechanisms regulating heart and breathing rates are discussed.


2020 ◽  
Vol 20 (1) ◽  
pp. 49-55
Author(s):  
Nareerut Jariyapunya ◽  
Blažena Musilová

AbstractBased on the mechanical properties of stretch fabrics and Laplace’s law, the mathematical models have been developed enabling one to determine the values of the relationship between the fabric strain and the circumferential stress depending on pressure and diameter of the body. The results obtained refer to the values of the parameters assessed for the initial phase of their exploitation, which allow us to preliminarily predict the values of these parameters.


2020 ◽  
Vol 11 (4) ◽  
pp. 5315-5320
Author(s):  
Mani Dineshkumar ◽  
Vyshnavi Tallapaneni ◽  
Veera Venkata Satyanarayana Reddy Karri

Eyes are considered as one of the most important organs of the body. The main hurdle for achieving effective ocular treatment is the maintenance of adequate quantity of drug at the site of action within the eye. Maintaining the concentration of drug in the eye is a difficult task as the anatomy and physiology of the eye leads to the draining of the drug from the eye. This leads to poor ocular bio availability and there by poor ocular therapy. The ocular bio availability can be improved by increasing the ocular retention time of the formulation. Insitu gel formation technology is a promising technique to prevent the lacrimal drainage of the drug rapidly from the eyes. Insitu gel preparation will be in liquid from when prepared, they are administered into the Cul-de-sac of the eye. Due to the environmental characteristics of the eye such as temperature, pH, Ionic concentration etc. the liquid formulation changes to gel form. This will increase the residence time and contact time of the drug with the mucosa of the eye. Insitu gels can increase the ocular bioavailability of the drug .The primary requirement of a successful control release product focuses on increasing patient compliance, good stability and bio compatibility. Insitu gels are used now a days as vehicles for both local and systemic drug therapies. This review deals with the study of a novel insitu gel approaches as a means to localize and prolong drug activity at its site of action.


2019 ◽  
pp. 65-75
Author(s):  
R. S. Korytniuk ◽  
L. L. Davtian ◽  
N. I. Hudz ◽  
A. A. Drozdova ◽  
I. О. Vlasenko ◽  
...  

Water is the most common compound of hydrogen and oxygen in the nature. It is a universal solvent of many substances, and therefore chemically pure water does not exist in the nature. The water contained in the body is qualitatively different from ordinary water as it is structured water. Such crystalline structures of water are the matrix of life. Their presence gives possibility of the occurrence of important biophysical processes and biochemical reactions. Insufficient intake of water into the body or its excessive loss leads to dehydration, which is accompanied by thickening of the blood and impairing hemodynamics. Excessive intake of water into the body causes water intoxication. Purpose – to conduct a bibliosemantic analysis of the sources of the literature on the medical and biological functions of water. Research methods – bibliosemantic, analytical, logical methods and generalizion method. Water is the structural basis of cells necessary to maintain their optimal volume. It determines the spatial structure and function of biomolecules. Insufficient intake of water into the body or its excessive loss leads to an impaired hemodynamics. Excessive intake of water into the body causes water intoxication. All disoders of water-salt balance in the body can be divided into two groups: dehydration and hyperhydration. In each group, there are disorders with a decrease, increase, and no change in osmotic pressure (hypotonic, hypertonic, and isotonic disorders, respectively). Water is used in medical and pharmaceutical practice as an excipient, and for the manufacture of allopathic, homeopathic and anthroposophic medicines. The State Pharmacopoeia of Ukraine includes several articles on the use of water depending on the purpose and regulates water quality: 1) highly purified water, water for injections «in bulk» water and sterilised water for injections; 2) purified water: water «in bulk» and water in containers. Cosmetics are presented on the Ukrainian market, the main biologically active compound of which is water, in particular, natural, thermal and micellar. They are widely used in cosmetology. The biomedical function of water in the body is to preserve cell volume, provide turgor to the cells and save the body from temperature fluctuations. Disruption of water-salt balance leads to dehydration or hyperhydration. There are changes with a decrease, increase, and no change in osmotic pressure (hypotonic, hypertonic, and isotonic disorders, respectively). They cause disruption of the life of the whole organism. In pharmaceutical practice, water is widely used for the manufacture of allopathic, homeopathic and anthroposophic medicines. It can be obtained in various ways, but its quality is regulated by the relevant government regulations. In cosmetic practice, water is used not only as a basic solvent, but in the form of natural, micellar and thermal water, where it is a biologically active compound.


1966 ◽  
Vol 45 (2) ◽  
pp. 197-202
Author(s):  
R. A. HAMMOND

1. Two indirect methods for recording changes of hydrostatic pressure within the trunk of Acanthocephalus ranae have been described. 2. Internal pressure has been shown to be lowest when the trunk is fully contracted and the proboscis invaginated, and highest when the trunk is fully elongated. 3. A rapid rise of internal pressure occurs when the circular trunk muscles contract. 4. Overall internal pressure changes of up to 0.5 cm. Hg have been shown to occur in active specimens. 5. The body length when fully extended is only 40-50% greater than when contracted. 6. The correlation between muscular activity, body shape, and internal hydrostatic pressure in A. ranae is discussed


1972 ◽  
Vol 57 (3) ◽  
pp. 821-838
Author(s):  
JOHN P. LEADER

1. The larva of Philanisus plebeius is capable of surviving for at least 10 days in external salt concentrations from 90 mM/l sodium chloride (about 15 % sea water) to 900 mM/l sodium chloride (about 150 % sea water). 2. Over this range the osmotic pressure and the sodium and chloride ion concentrations of the haemolymph are strongly regulated. The osmotic pressure of the midgut fluid and rectal fluid is also strongly regulated. 3. The body surface of the larva is highly permeable to water and sodium ions. 4. In sea water the larva is exposed to a large osmotic flow of water outwards across the body surface. This loss is replaced by drinking the medium. 5. The rectal fluid of larvae in sea water, although hyperosmotic to the haemolymph, is hypo-osmotic to the medium, making it necessary to postulate an extra-renal site of salt excretion. 6. Measurements of electrical potential difference across the body wall of the larva suggest that in sea water this tissue actively transports sodium and chloride ions out of the body.


1985 ◽  
Vol 116 (1) ◽  
pp. 1-25 ◽  
Author(s):  
P. A. Kerfoot ◽  
G. O. Mackie ◽  
R. W. Meech ◽  
A. Roberts ◽  
C. L. Singla

In the jellyfish Aglantha digitale escape swimming is mediated by the nearly synchronous activity of eight giant motor axons which make direct synaptic contact with contractile myoepithelial cells on the under-surface of the body wall. The delay in transmission at these synapses was 0.7 +/− 0.1 ms (+/− S.D.;N = 6) at 12 degrees C as measured from intracellular records. Transmission depended on the presence of Ca2+ in the bathing medium. It was not blocked by increasing the level of Mg2+ to 127 mmol l-1. The myoepithelium is a thin sheet of electrically coupled cells and injection of current at one point was found to depolarize the surrounding cells. The potential change declined with distance from the current source as expected for two-dimensional current spread. The two-dimensional space constant (lambda) was 770 micron for current flow in the circular direction and 177 micron for radial flow. The internal resistance of the epithelium (178–201 omega cm) and the membrane time constant (5–10 ms) were direction independent. No propagated epithelial action potentials were observed. Spontaneous miniature synaptic potentials of similar amplitude and rise-time were recorded intracellularly at distances of up to 1 mm from the motor giant axon. Ultrastructural evidence confirms that neuro-myoepithelial synapses also occur away from the giant axons. It is likely that synaptic sites are widespread in the myoepithelium, probably associated with the lateral motor neurones as well as the giant axons. Local stimulation of lateral motor neurones generally produced contraction in distinct fields. We suppose that stimulation of a single motor giant axon excites a whole population of lateral motor neurones and hence a broad area of the myoepithelium.


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