Neuromuscular Physiology of the Longitudinal Muscle of the Earthworm, Lumbricus Terrestris

1974 ◽  
Vol 60 (2) ◽  
pp. 445-452
Author(s):  
C. D. DREWES ◽  
R. A. PAX
Keyword(s):  
Longitudinal Muscle ◽  
Ionic Composition ◽  
Lumbricus Terrestris ◽  
Physiological Saline ◽  
Body Fluids ◽  
Resting Potential ◽  
Muscle Fibres ◽  
The Mean ◽  
Nerve Muscle ◽  
Increased Susceptibility

1. An earthworm saline commonly used in previous investigations of earthworm neuromuscular physiology has been shown to be inappropriate for such studies because the ionic composition of the saline does not correspond to that of earthworm body fluids. 2. Problems encountered when using this saline include: increased excitability of motor axons innervating the longitudinal muscle, a decrease in the amplitude of external electrical responses of the muscle, an increased susceptibility of longitudinal muscle fibres to injury spiking, and a decrease in resting potentials of longitudinal muscle fibres (to a mean of -36.1 mV). 3. Such problems have been overcome by the development of a new physiological saline whose composition closely corresponds to the ionic composition of earthworm body fluids. 4. In the new saline responses of the nerve-muscle preparation remain stable for more than 1 h. 5. Resting potentials of longitudinal muscle fibres are also stable with time, the mean resting potential being -47.9 mV.

Neuromuscular Physiology of the Longitudinal Muscle of the Earthworm, Lumbricus Terrestris

1974 ◽  
Vol 60 (2) ◽  
pp. 453-467
Author(s):  
C. D. DREWES ◽  
R. A. PAX
Keyword(s):  
Time Course ◽  
Longitudinal Muscle ◽  
Lumbricus Terrestris ◽  
Single Pulse ◽  
Repetitive Stimulation ◽  
Muscle Fibres ◽  
Mechanical Responses ◽  
Segmental Nerve ◽  
Earthworm Lumbricus ◽  
Stimulation Of

1. Patterns of innervation of the longitudinal muscle of the earthworm, Lumbricus terrestris, were examined electrophysiologically. 2. The longitudinal musculature of a segment is innervated by relatively few axons, a fast and slow axon being present in segmental nerve I and in the double nerve, segmental nerve II-III. 3. Single-pulse stimulation of the fast axon produces large external muscle potentials and small twitch-like contractions, which with repetitive stimulation are antifacilitating. 4. Repetitive stimulation of the slow axon produces large, slowly developing and sustained mechanical responses, with electrical and mechanical responses showing summation and facilitation. 5. The amplitude and time course of slow mechanical responses are related to the frequency of stimulation. 6. Individual longitudinal muscle fibres are innervated by either the fast or slow axon in a segmental nerve, or by both fast and slow axons. 7. No evidence was found for peripheral inhibitory innervation of the longitudinal muscle.

scholarly journals Activation of Multiply Innervated Fast and Slow Myotomal Muscle Fibres of the Teleost Myoxocephalus Scorpius

1988 ◽  
Vol 140 (1) ◽  
pp. 313-324 ◽  
Author(s):  
J. D. ALTRINGHAM ◽  
I. A. JOHNSTON
Keyword(s):  
Action Potentials ◽  
Spinal Nerve ◽  
Resting Potential ◽  
Muscle Fibres ◽  
Significant Difference ◽  
Slow Muscle Fibres ◽  
Myoxocephalus Scorpius ◽  
Nerve Muscle ◽  
Myotomal Muscle ◽  
Tetanic Tension

A nerve-muscle preparation from the sculpin Myoxocephalus scorpius was used to study the membrane response of fast and slow muscle fibres to stimulation of the spinal nerves. There was no significant difference between resting potential in fast (−81.9mV) and slow fibres (−80.8mV). Fast fibres responded to a suprathreshold stimulus in the spinal nerve with an action potential. Overshoots of up to +32 mV were recorded. Both junction potentials and overshooting action potentials were observed in the slow fibres. The twitch/tetanus characteristics of myotomal muscle were investigated using isolated bundles of ‘live’ fast and slow fibres. Both fibre types responded to a single stimulus with a mechanical twitch. Fused tetani were obtained at around 50Hz in fast fibres and 20 Hz in slow fibres. In the slow fibres, tetanic tension increased with frequency up to around 50Hz. At frequencies giving maximum tetanic tension, the twitch/tetanus ratio was 0.70 for fast fibres and 0.29 for slow ones. These results are discussed with reference to the polyneuronal/multiterminal innervation pattern of the myotomal muscle in teleost fish and its role in locomotion.

scholarly journals THE STRUCTURE OF THE SMOOTH MUSCLE FIBRES IN THE BODY WALL OF THE EARTHWORM

1957 ◽  
Vol 3 (1) ◽  
pp. 111-122 ◽  
Author(s):  
Jean Hanson
Keyword(s):  
Smooth Muscle ◽  
Phase Contrast ◽  
Body Wall ◽  
Longitudinal Muscle ◽  
Lumbricus Terrestris ◽  
Mirror Image ◽  
The Body ◽  
The Other ◽  
Muscle Fibres ◽  
Muscle Coat

1. The structure of the smooth muscle fibres in the longitudinal muscle coat of the body wall of Lumbricus terrestris has been investigated by phase contrast light microscopy and electron microscopy. 2. The muscle fibre is ribbon-shaped, and attached to each of its two surfaces is a set of myofibrils. These are also ribbon-shaped, and they lie with their surfaces perpendicular to the surfaces of the fibre, and their inner edges nearly meeting in the middle of the fibre. These fibrils are oriented at an angle to the fibre axis, and diminish greatly in width as they approach the edge of the fibre. The orientation of the set of fibrils belonging to one surface of the fibre is the mirror image of that of the set belonging to the other surface; thus, when both sets are in view in a fibre lying flat on one face, the fibre exhibits double oblique striation. A comparison of extended and contracted fibres indicates that as the fibre contracts, the angle made between fibre and fibril axes increases (e.g. from 5 to 30°) and so does the angle made between the two sets of fibrils (e.g. from 10 to 60°). 3. The myofibril, throughout its length, contains irregularly packed filaments, commonly 250 A in diameter, which are parallel to its long axis and remain straight in contracted muscles. Between them is material which probably consists of much finer filaments. Thus A and I bands are absent. 4. Bound to one face of each fibril, but not penetrating inside it, is a regularly spaced series of transverse stripes. They are of two kinds, alternating along the length of the fibril, and it is suggested that they are comparable to the Z and M lines of a cross-striated fibril. The spacing of these stripes is about 0.5 µ ("Z" to "Z") in extended muscles, and 0.25 µ in contracted muscles. A bridge extends from each stripe across to the stripeless surface of the next fibril.

Analysis of the rapid responses of Nereis and Harmothoë ( Annelida )

1959 ◽  
Vol 150 (939) ◽  
pp. 245-262 ◽  
Keyword(s):  
Longitudinal Muscle ◽  
Electrical Response ◽  
Low Frequency ◽  
Fast Response ◽  
Motor Neurone ◽  
Muscle Fibres ◽  
Giant Fibre ◽  
Rapid Responses ◽  
Giant Fibres ◽  
Nerve Muscle

The giant-fibre responses of Harmothoë and Nereis have been studied with emphasis on the afferent and efferent path ways and the sites of the rapid accommodation of the fast response. When the bundle of sensory neurones of the anal cirrus is stimulated the giant-fibres respond at the first shock. This terminal junction then rapidly accommodates to further afferent excitation. In Harmothoë the muscles which effect the rapid movements of the giant-fibre response are directly innervated by large axons of unipolar cell bodies in the central nervous system. In each segment one neurone of this type supplies both dorsal and ventral longitudinal muscle fibres. By use of a bridge technique this neurone has been isolated. At the first stimulus above a single sharp threshold the resulting nerve muscle preparation gives a maximum electrical response, which is independent of the stimulus strength. A reduced response persists for many repetitions at low frequency. In addition to this fast motor neurone a slower system in the same muscles is indicated by the muscle-action potentials and by observation of the movements. An axon-axon synapse seen histologically between the lateral giant fibres and the large motor neurone to the longitudinal muscle has been identified with the rapidly accommodating physiological junction between these elements. At this level of analysis the afferent and efferent relations of the giant fibres, and in particular the fast motor innervation, are broadly comparable with those of some arthropods.

Neuromuscular Physiology of the Longitudinal Muscle of the Earthworm, Lumbricus Terrestris

1974 ◽  
Vol 60 (2) ◽  
pp. 469-475
Author(s):  
C. D. DREWES ◽  
R. A. PAX
Keyword(s):  
Longitudinal Muscle ◽  
Lumbricus Terrestris ◽  
Muscle Fibres ◽  
Posterior Pair ◽  
Anterior Pair ◽  
Earthworm Lumbricus

1. The motor fields of individual segmental nerves have been mapped electrophysiologically in the longitudinal muscle of the earthworm, Lumbricus terrestris. 2. The anterior pair of segmental nerves (SNI) innervates approximately the anterior two-thirds of its segment and a small portion of the segment just anterior to it. 3. The posterior pair of segmental nerves (SNII-III) innervates approximately the posterior two-thirds of its segment and a small portion of the segment just posterior to it. 4. Adjacent nerves (both intrasegmental and intersegmental) have partially overlapping motor fields; that is, adjacent segmental nerves innervate some of the same longitudinal muscle fibres.

scholarly journals Ion-Induced Volume Transition in Gels and Its Role in Biology

Gels ◽  
2021 ◽  
Vol 7 (1) ◽  
pp. 20
Author(s):  
Matan Mussel ◽  
Peter J. Basser ◽  
Ferenc Horkay
Keyword(s):  
Nonlinear Response ◽  
Structural Changes ◽  
Ionic Composition ◽  
Biological Systems ◽  
Experimental Results ◽  
Resting Potential ◽  
Cell Secretion ◽  
Solvent Quality ◽  
Volume Transition ◽  
Biological Milieu

Incremental changes in ionic composition, solvent quality, and temperature can lead to reversible and abrupt structural changes in many synthetic and biopolymer systems. In the biological milieu, this nonlinear response is believed to play an important functional role in various biological systems, including DNA condensation, cell secretion, water flow in xylem of plants, cell resting potential, and formation of membraneless organelles. While these systems are markedly different from one another, a physicochemical framework that treats them as polyelectrolytes, provides a means to interpret experimental results and make in silico predictions. This article summarizes experimental results made on ion-induced volume phase transition in a polyelectrolyte model gel (sodium polyacrylate) and observations on the above-mentioned biological systems indicating the existence of a steep response.

CHANGES IN THE RESTING POTENTIAL OF SKELETAL MUSCLE IN RATS WITH COLD ACCLIMATION

1966 ◽  
Vol 44 (5) ◽  
pp. 791-802 ◽  
Author(s):  
M. H. Sherebrin ◽  
A. C. Burton
Keyword(s):  
Skeletal Muscle ◽  
Electrical Properties ◽  
Cold Acclimation ◽  
White Muscle ◽  
Single Cells ◽  
Temperature Gradients ◽  
Resting Potential ◽  
The Mean ◽  
Shivering Thermogenesis ◽  
Main Factor

The resting potential of single cells in the flexor thigh muscles of rats was measured in an attempt to find a change in the electrical properties of the cell membrane with cold acclimation, in order to identify and relate metabolic changes occurring with non-shivering thermogenesis. The mean resting potential of cells in cold-acclimated rats was found to be slightly but significantly higher than in the controls. A larger temperature gradient with depth was measured in the cold-acclimated animals than in the controls. If the Q10 of resting potential with temperature is as great as 1.16, the higher potential in the cold-acclimated rats may be accounted for by this temperature difference. The resting potential was also found to vary with depth in both groups of rats. This could not be attributed to temperature gradients, and change from red to white muscle cells with depth is thought to be the main factor for the increase of potential with depth.

Knowledge Levels of University Students About Sexually Transmitted Diseases

2021 ◽  
Vol 6 (14) ◽  
pp. 8-19
Author(s):  
GAMZE TEMİZ ◽  
Nida GÜNDÜZALP
Keyword(s):  
Nursing Students ◽  
Risk Groups ◽  
Body Fluids ◽  
High Risk Group ◽  
People Who Use Drugs ◽  
Cross Sectional ◽  
Sexually Transmitted ◽  
Bodily Fluids ◽  
Medium Level ◽  
The Mean

Purpose: The aim of the study; To evaluate the knowledge level of nursing students about diseases transmitted by bodily fluids. Materials and Methods: The study is descriptive-cross-sectional. The sample is 352 nursing students studying at a foundation university. The data were evaluated with a questionnaire about diseases transmitted by body fluids. Results: The mean age of nursing students was 20.87±2.14 years and 81.3% of them were girls. Most of the sample consisted of 1st year (26.7%) and 4th year students (31.5%). The mean score of the questionnaire for diseases transmitted by bodily fluids of nursing students was found to be 13.61 ± 2.19. It was determined that 96.9% of the students gave correct answers to the 2nd item of the questionnaire, “Spouses with these diseases should be treated together”. It was determined that 69.3% of the students gave incorrect answers to the 3rd item of the questionnaire, "Untreated, diseases transmitted by body fluids can cause infertility". 62.5% of the students reported that they had received training on the subject before. Of the sample, 97.2% are individuals who have relationships with more than one person, 1.1% are individuals with a single spouse, 38.1% (n=134) are people who use drugs, 31.8% are health professionals. reported that they were in the high-risk group for diseases transmitted by fluids. The results show that nursing students gave insufficient information about the prevention of diseases transmitted by body fluids. Conclusion: In the study, it was determined that the knowledge of nursing students about diseases transmitted by body fluids was above the medium level, and it was noteworthy that they needed training on transmission routes, risk groups and protection from diseases transmitted by body fluids.

Transmembrane Activity Gradients of K and cl in the Muscle Fibres of Osmoconforming Marine Decapod Crustaceans

1978 ◽  
Vol 72 (1) ◽  
pp. 127-140
Author(s):  
ROBERT W. FREEL
Keyword(s):  
Sea Water ◽  
Membrane Potentials ◽  
Resting Potential ◽  
Muscle Fibres ◽  
Salinity Adaptation ◽  
Decapod Crustaceans ◽  
Marine Crustaceans ◽  
Equilibrium Distributions

1. The resting membrane potentials (Em) and the transmembrane activity gradients for K and Cl were measured in the muscle fibres of osmoconforming (Callianassa and Cancer) and weakly osmoregulating (Pachygrapsus) marine crustaceans acclimated to various osmotic conditions. 2. The muscle membranes of sea water acclimated crabs behave as good K electrodes. However, a slight contribution of Na to the resting potential was demonstrated in all species. The ratio PNa/PK was about 0.01. Equilibrium potentials (measured with ion-selective microelectrodes) for Cl were equal to Em, while EK was always more negative than Em as a result of the slight Na contribution. 3. Acclimation to dilute or concentrated sea water had little effect on the K electrode properties or Na permeabilities of these fibres. The muscle fibres were depolarized in crabs acclimated to concentrated sea water and were hyperpolarized in crabs adapted to dilute sea water. These changes resulted solely from alterations in (aK)i/ (aK)O which were in turn brought about by changes in cellular and haemolymph hydration. 4. Since the Na contribution to Em was so small in all conditions, it was concluded that the distributions of K and Cl are best considered in terms of Donnan equilibria, and that the cellular K and Cl adjustments observed during salinity adaptation reflect the passive re-establishment of new equilibrium distributions for these ions.

Magnesium and calcium as regulators of intestinal permeability

1964 ◽  
Vol 206 (1) ◽  
pp. 243-246 ◽  
Author(s):  
C. S. Tidball
Keyword(s):  
Intestinal Permeability ◽  
Calcium Salt ◽  
Ionic Composition ◽  
Intestinal Lumen ◽  
Phenol Red ◽  
Sodium Pentobarbital ◽  
All Solutions ◽  
Physiologic Saline ◽  
The Mean ◽  
And Control

The absorption of phenolsulfonphthalein (phenol red) was used as a measure of intestinal permeability in rats anesthetized with sodium pentobarbital. All solutions placed in the intestinal lumen were adjusted to pH 7.0 and 300 mosmoles/liter. When 5 ml of a 1 mm solution of phenol red were placed in either proximal or distal halves of the small intestine the mean hourly absorption was 1.1%. The presence of 25 mm/liter ethylenediaminetetraacetate (EDTA) as the calcium salt did not alter phenol red absorption. With 25 mm/liter NaEDTA in the lumen, the absorption of phenol red was increased tenfold. After NaEDTA had been present for 1 hr, rinsing the lumen produced results which varied with the ionic composition of the rinsing solution. Balanced physiologic saline did not reverse the increased permeability. A CaCl2 rinse produced a permeability intermediate between NaEDTA and control levels. A MgCI2 rinse reinstated normal permeability. It is concluded that magnesium and calcium, loosely bound in the structure of the membrane, regulate the aqueous permeability of the intestinal epithelium.

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