The Structure and Function of the Alimentary Canal of Aplysia Punctata

1942 ◽  
Vol s2-83 (331) ◽  
pp. 357-397 ◽  
Author(s):  
H. H. HOWELLS
Keyword(s):  
Alimentary Canal ◽  
Buccal Cavity ◽  
Muscular Activity ◽  
Mantle Cavity ◽  
Ion Concentration ◽  
Forward Movement ◽  
Hydrogen Ion Concentration ◽  
Anterior Intestine ◽  
Storage Cells ◽  
And Function

1. The anatomy and histology of the alimentary canal, process of feeding, and physiology of digestion in Aplysia punctata have been investigated. 2. The food undergoes little trituration in the buccal cavity. The mode of action of the jaws and odontophore is adapted to the rapid intake of vegetable food. 3. The oesophagus and crop together form an anatomical and physiological unit. 4. Trituration occurs in the gizzard. The teeth are adapted to the trituration of plant material; this is of particular importance owing to the weak action of the cellulase. 5. Coarser particles of weed are retained by the teeth of the filter chamber and returned to the gizzard during the forward movement of the gut fluid. 6. The ciliary currents in the anterior intestine ensure that only food in a finely divided or fluid state is admitted to the stomach. Medium and larger sized particles are carried straight into the intestine. 7. Ciliary currents in the stomach are concerned with the removal of material rejected from the tubules of the digestive diverticula. This material is consolidated, cemented, and moulded into a faecal rod within the caecum, and conveyed by ciliary action to the intestine. 8. The intestine is concerned with the further consolidation and moulding of the complete faecal mass, and its propulsion (by combined ciliary and muscular action) to the rectum. 9. Mucus is secreted throughout the gut with the exception of the regions of the jaws, gizzard, and filter chamber. Enzymes are secreted in the salivary glands (amylase and protease) and in the digestive diverticula (carbohydrases, lipase, and proteases). Glands probably secreting a lubricant (other than mucus) occur in the epithelium of the lateral walls of the buccal cavity, and others, secreting a cementing substance, in the caecum and intestine. 10. Absorptive cells occupy the greater part of the epithelium of the digestive diverticula. They occur together with secretory, excretory, and storage cells. 11. Digestion occurs within the oesophagus and crop, gizzard, filter chamber, anterior intestine, stomach, and tubules of the digestive diverticula. The hydrogen ion concentration is here suitable for the action of the enzymes, and the gut fluid is kept in motion by the muscular activity of the walls. 12. A high pH exists in the lumen of the caecum, posterior intestine, and rectum, probably assisting in the consolidation of the faecal mass by increasing the viscosity of the mucus. 13. The presence of a highly efficient mechanism for the formation of the faeces is probably correlated with the poorly developed cleansing mechanism in the mantle cavity.

A Note on the Habits and Nutrition of Solemya parkinsoni (Protobranchia: Bivalvia)

1961 ◽  
Vol s3-102 (57) ◽  
pp. 15-21
Author(s):  
G. OWEN
Keyword(s):  
Organic Material ◽  
Alimentary Canal ◽  
Spring Tide ◽  
Muscular Activity ◽  
Mantle Cavity ◽  
Animal Burrows ◽  
Water Spring

Adult specimens of Solemya parkinsoni Smith, embedded in mud at a depth of 50 cm or more, were collected near low water (spring tide). The animal burrows with the anterior end downwards and does not maintain an opening to the surface. An inhalant current is drawn into the mantle cavity anteriorly on each side of the foot, while an exhalant current leaves by the single, posteriorly situated aperture. This is probably a respiratory current, bottom material entering the mantle cavity as a result of the muscular activity of the mantle and foot. The course of the alimentary canal is described, and the problem of feeding and nutrition correlated with the extreme reduction of the gut exhibited by S.parkinsoni discussed. It is suggested that an initial breakdown of organic material may take place in the mantle cavity.

scholarly journals The Hydrogen Ion Concentration in the Gut of certain Lamellibranchs and Gastropods

1925 ◽  
Vol 13 (4) ◽  
pp. 938-952 ◽  
Author(s):  
O. M. Yonge
Keyword(s):  
Mantle Cavity ◽  
Mya Arenaria ◽  
Hydrogen Ion ◽  
Ion Concentration ◽  
Pecten Maximus ◽  
Hydrogen Ions ◽  
Acid Media ◽  
Hydrogen Ion Concentration ◽  
Acid Reaction ◽  
Acid Region

1. In the Lamellibranchs, as typified by Pecten maximus, Mya arenaria and Ensis siliqua, the entire, gut has an acid reaction, the stomach being the most acid region and the pH rising along the mid-gut and rectum.2. The origin of the acidity of the gut lies in the style. This has a low pH (5·4 in Pecten and Mytilus, 4·6 in Ensis and 4·45 in Mya), and, after it has been artificially extracted from Mya or induced to disappear, by keeping the animals under abnormal conditions, in Mytilus, Tapes and Pecten, the pH of the stomach invariably rises (by as much as 0·825 in Mya and 0·72 in Tapes), although the pH in the mantle cavity has fallen.3. The style, which dissolves rapidly in alkaline or weakly acid media, is not dissolved in fluids below a certain pH—4·4 for Ensis, 4·2 for Mya, 3·6 for Pecten and Mytilus.4. The style is never absent, even though animals are starved, so long as they are kept under otherwise healthy conditions. The disappearance of the style under abnormal conditions is probably due to a lowering of the vital activities, which include the secretion of the style substance, and the consequent dissolution of the style by the less acid contents of the stomach.5. The style is only maintained as a result of a balance between the rate of its secretion and the rate of its dissolution.6. There is a well-marked correlation between the tolerance of the presence of hydrogen ions possessed by the cilia from the various regions of the gut and the degree of acidity of the fluid with which they are normally surrounded.7. The pH of the gut in five Gastropods has been investigated. The fore-gut and stomach have invariably the lowest pH.8. This acidity may be caused by the salivary glands (Patella and Buccinum), the digestive gland (Doris and Aplysia), or the style (Crepidula).9. The mid-gut and rectum have a high pH, except in Doris, where there is little secretion of mucus, the gut being free and muscular.10. The style of Orepidula has similar properties to those of the Lamellibranchs. It has a pH of 5·8, and is not dissolved in fluid of pH 3·6 or lower.11. The cilia from the gut of Buccinum and Doris can function in a pH of 5·0, but there is little difference in the toleration of the various cilia to the presence of hydrogen ions.

scholarly journals The Hydrogen Ion Concentration in the Alimentary Canal of Larval and Adult Lepidoptera

1949 ◽  
Vol 2 (4) ◽  
pp. 428 ◽  
Author(s):  
DF Waterhouse
Keyword(s):  
Alimentary Canal ◽  
Feeding Habits ◽  
Hydrogen Ion ◽  
Ion Concentration ◽  
Hydrogen Ion Concentration

The pH of the midgut digestive juices of two species of carnivorous lepidopterous larvae and of 40 species of adult Lepidoptera belonging to 16 families was determined. In all species it was alkaline. From these records, and from those available from the literature for phytophagous, wool-eating, and wax-eating lepidopterous larvae, it is possible to generalize that midgut alkalinity is characteristic of the order Lepidoptera and that it is not dependent upon feeding habits.

Memoirs: The Spermatheca of Loligo Vulgaris. I. Structure of the Spermatheca and Function of its Unicellular Glands

1938 ◽  
Vol s2-80 (320) ◽  
pp. 593-599
Author(s):  
G. J. van OORDT
Keyword(s):  
Sea Water ◽  
Goblet Cells ◽  
Hydrogen Ion ◽  
Ion Concentration ◽  
Hydrogen Ions ◽  
Hydrogen Ion Concentration ◽  
Loligo Vulgaris ◽  
And Function

The structure of the spermatheca of Loligo vulgaris is described; it lies on the inner wall of the buccal membrane and within it large quantities of inactive spermatozoa are stored. This inactivity of the spermatozoa within the spermatheea is attributed to the effect of the secretion of the goblet-cells, situated as unicellular glands on the inner wall of the spermatheca. Inactive spermatozoa from the spermatheca become very active in sea-water, but are immobilized again after a few moments' contact with the pulp of the spermatheca contents. The hydrogen-ion concentration of the spermatheca contents is approximately 6.06; and, since spermatozoa become inactive in sea-water, the hydrogen-ion concentration of which is increased to this level, it seems probable that the inactivity of the spermatozoa within the spermatheca is due to the presence of hydrogen-ions. The spermatheca is functionally comparable to the mammalian epididymis.

Changes in pH, Carbonate and Lactate of the Blood of Yearling Kamloops Trout, Salmo gairdneri, During and Following Severe Muscular Activity

1959 ◽  
Vol 16 (4) ◽  
pp. 391-402 ◽  
Author(s):  
Edgar C. Black ◽  
Wing-gay Chiu ◽  
Francis D. Forbes ◽  
Arthur Hanslip
Keyword(s):  
Marked Decrease ◽  
Initial Level ◽  
Muscular Activity ◽  
Hydrogen Ion ◽  
Ion Concentration ◽  
Salmo Gairdneri ◽  
Blood Levels ◽  
Hydrogen Ion Concentration ◽  
Initial Rise ◽  
Initial Figure

Alterations in the blood levels of lactate, carbonate, hydrogen ion and hemoglobin following vigorous muscular exercise were studied in yearling Kamloops trout, Salmo gairdneri, over four years.Lactate increased during exercise and during the first 2 hours of rest, returning to the initial level after 6 to 8 hours. Carbonate increased to a maximum during the first 3 minutes of exercise, then dropped precipitously to a minimum far below the initial level after [Formula: see text] hour of rest, later rose to near the initial level at the 4th hour of recovery, maintained this until the 12th hour, but it had decreased again at the 24th hour. Hydrogen ion concentration rose sharply during the first 3 minutes of activity, then fell off to a stable level a little above the initial figure until the end of exercise, after which it fell substantially below initial level and had not completely recovered after 24 hours of rest. A marked decrease in swimming rate occurred after 3 minutes exercise, following the initial rise of carbonate and hydrogen ion concentration.

scholarly journals FORWARD MOVEMENT OF PARAMECIUM AS A FUNCTION OF THE HYDROGEN ION CONCENTRATION

1930 ◽  
Vol 13 (6) ◽  
pp. 627-636 ◽  
Author(s):  
Aurin M. Chase ◽  
Otto Glaser
Keyword(s):  
Prolonged Exposure ◽  
Carbonic Acid ◽  
External Medium ◽  
Ion Concentration ◽  
Forward Movement ◽  
Hydrogen Ion Concentration ◽  
Physiological Limits ◽  
Inorganic Acids ◽  
Fixed Quantity ◽  
Final Speed

1. At constant temperatures, and within physiological limits, changes of pH in either direction from the neutral point result in immediate increases in speed of movement of Paramecium. 2. These increases are temporary. In 30 to 45 minutes a minimum of speed is reached. This is followed by a period of recovery lasting about an hour. Finally an equilibrium is found. With inorganic acids (HCl or H2SO4) the final speed after 3 or 4 hours is that characteristic of prolonged exposure to pH 7.0; on the other hand, 3 or 4 hours after the application of either valeric or carbonic acid, speed is proportional to the [H^prime;] of the external and, probably, of the internal medium. 3. These facts become explicable if we assume that the ionization of an ampholyte superficially localized is essential for the execution of the ciliary stroke. Valeric and carbonic acid, in time, demonstrably penetrate the cell. As a working hypothesis we postulate that internal increase of the [H'] accelerates the rate at which this ampholyte is synthetized; but without actually penetrating the cell, hydrogen or hydroxyl ions in the external medium could also increase the degree to which this ampholyte dissociates. 4. Increased ionization of a fixed quantity of ampholyte and an increase in the rate of its production are in these experiments practically indistinguishable. Hence we assume that immediate and temporary increases of speed resulting from any change of pH, as well as final and permanently higher speed levels manifest only after prolonged exposures to organic acids, involve essentially the same mechanism.

Hydrogen-ion Concentrations in Alimentary Canals of Third-instar Larvae of Three Species of Hylemya

1958 ◽  
Vol 90 (5) ◽  
pp. 303-305 ◽  
Author(s):  
E. H. Salkeld ◽  
W. G. Friend
Keyword(s):  
Alimentary Canal ◽  
Accurate Method ◽  
Hydrogen Ion ◽  
Ion Concentration ◽  
Hydrogen Ion Concentration ◽  
Ion Concentrations ◽  
Ph Indicators ◽  
Gut Ph ◽  
Third Instar Larvae

The hydrogen-ion concentration of the alimentary canal of insects has been studied by many workers. In their review of this subject, Day and Waterhouse (1953) conclude that the pH of the foregut is often the same as that of the food, that of the midgut varies in different species from 3 to 10, but that of the hindgut rarely varies far from neutrality. Various methods of determining pH and their relative merits have been discussed by Waterhouse (1940). He considers that incorporating pH indicators into the food is the most accurate method with insects that are too small to enable their gut pH to be measured electrometrically.

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