Excretory Sentence Examples
These vessels are the nitrogenous excretory organs.
The excretory system is epiblastic in its origin.
The excretory system is highly developed and opens at the posterior extremity by a paired muscular bladder.
The excretory tubes, the nervous system, and the parenchyma and integument are continuous from one end of the worm to the other.
The excretory system consists of peculiar cells, each of which bears several"flames" or bunches of synchronously vibrating cilia.Advertisement
It seems likely that the coelomic pore-canals were originally excretory organs, but in the existing Enteropneusta the pore-canals (especially the collar canals) have, as we have seen, acquired new functions or become vestigial, and the function of excretion is now mainly accomplished by a structure peculiar to the Enteropneusta called the glomerulus, a vascular complex placed on either side of the anterior portion of the stomochord, projecting into the proboscis-coelom.
Further, it is pointed out by Korschelt and Heider that the hinder portion of the gut frequently acts in Arthropoda as an organ of nitrogenous excretion in the absence of any special excretory tubules, and that the production of such caeca from its surface in separate lines of descent does not involve any elaborate or unlikely process of growth.
The excretory system is highly developed; the larger collecting ducts are elaborately looped and open posteriorly by a single terminal aperture.
There are only six or eight Malpighian tubes - contrasting with the large number of these excretory organs found in the Orthoptera and Plecoptera.
These ducts, however, as well as the coelomic epithelium, may assume excretory functions.Advertisement
There is usually one pair of coelomic ducts leading from the pericardium to the exterior, and these are the excretory organs or kidneys, formerly known as the organs of Bojanus.
The walls of the pericardium are also excretory in parts, these parts forming the pericardial glands.
These protonephridia are the excretory organs.
Alimentary, Respiratory and Excretory Systems. - Although the function of the two latter systems of organs is the purification of the blood, they are not usually considered together, and it is therefore the more remarkable that their close association in Amphioxus renders it necessary to treat them in common.
While it is not improbable that the collar-pores and the proboscispores may evacuate excretory substances, there can be little doubt that their primary function is to regulate the turgidity of the segment to which they respectively belong.Advertisement
It is therefore by no means certain that so profound a difference embryologically can be asserted to exist between the excretory nephridia and the ducts leading from the coelom to the exterior, which are usually associated with the extrusion of the genital products among the Chaetopoda.
The Monozoa are unsegmented; the Ligulidce have segmented gonads and gonopores without any trace of somatic metamerization except secondary excretory pores in addition to the usual terminal one; the remaining Cestodes are unisegmental only in their larval stage, and all of them show in their later stages repetition of the reproductive organs and of the musculature.
In addition, some show duplication of the gonads and of their ducts, so that we find both transverse and longitudinal repetition of these organs, without corresponding multiplication of the nervous ganglia mesenchyma, or excretory opening.
A, a segment of Bothriocephalus latus, showing the generative organs from the ventral surface; ex., excretory vessels; c., cirrus; c.p., cirrus pouch; v.d., vas deferens; v.o., vaginal opening; v., vagina; sh.g., shell-gland; od., oviduct; ov., ovary; y.g., yolk-gland; y.d., its duct; ut., uterus; u.o., uterine opening; the testes are not visible from this side; X 23 (from Sommer and Landois).
B, portion of the bladder (hind-body and tail), showing the invaginated portion (scolex) and traces of the excretory system.Advertisement
It is important to emphasize the fact that in Amphioxus the excretory tubules are co-extensive with the gill-clefts.
Several herbs, including chamomile (Matricaria recutita), dandelion (Taraxacum mongolicum), and burdock (Arctium lappa), act as bitters, stimulating the movement of the digestive and excretory systems.
As mentioned previously, laxatives and diuretics can damage the body's digestive and excretory functions, and they can be addictive.
This at first is an important excretory organ, but during development becomes used for other purposes.
In the larvae of several Gastropoda and Lamellibranchia occur excretory organs which have the characters of true nephridia.Advertisement
They invariably disappear before the adult stage is reached, but their presence in the larva is evidence that the ancestral mollusc possessed a pair of true nephridia quite distinct from the coelomic excretory organs, which are so characteristic of existing forms in the adult condition.
These tubules are the excretory tubules or nephridia.
There are reasons for supposing that these funnels are vestiges of an ancient excretory system, which has given way by substitution to the excretory tubules described above.
The most important excretory or renal organs of the Crustacea are two pairs of glands lying at the base of the antennae and of the second maxillae respectively.
Thus, in the Phyllopoda, the antennal gland develops early and is functional during a great part of the larval life, but it ultimately atrophies, and in the adult (as in most Entomostraca) the maxillary gland is the functional excretory organ.
In addition to these two pairs of glands, which are in all probability the survivors of a series of segmentally arranged coelomoducts present in the primitive Arthropoda, other excretory organs have been described in various Crustacea.
Although the excretory function of these has been demonstrated by physiological methods, however, their morphological relations are not clear.
In some cases they consist of masses of mesodermal cells, within which the excretory products appear to be stored up instead of being expelled from the body.
In addition to the digestive and excretory glands already mentioned, various glandular structures occur in the different groups of Crustacea.
Into this same cloacal chamber open ventrally a pair of ciliated tubes communicating by funnels with the coelom (Nansen and Wheeler); these are possibly nephridia, and excretory in function.
As a rule there is no other opening to the body except the mouth, but in some cases excretory pores are known to occur in the foot, and pores may occur at the tips of the tentacles.
Tubes of renal excretory function in a like position occur in most terrestrial Arthropoda - viz.
Renal excretory caeca (Malpighian tubes) are developed from the proctodaeum (not from mesenteron as in scorpion and Amphipoda).
It contains two tufts of peculiar excretory cells, described by Goodrich (5) as " solenocytes," which surround the blind ends of a pair of nephridia.
They enlarge and diminish, and are possibly excretory like the " contractile vacuoles " of other Protista; though it has been suggested that by their communication with the medium they subserve nutrition.
When taken internally it is both a secretory and an excretory cholagogue, but so irritant and powerful that its use in cases of jaundice is generally undesirable.
In some Leptomedusae excretory " marginal tubercles " are developed on the ring-canal.
In the Disconectae the coenosarc forms a spongy mass, the " centradenia," which is partly hepatic in function, forming the socalled liver, and partly excretory.
If a distal pore or aperture is present, it is excretory in function; suck varieties have been termed " cystons " by Haeckel.
The excretory (malpighian) tubes are few in number, either four or six.
The coelom is lined throughout by cells, which upon the intestine become large and loaded with excretory granules, and are known as chloragogen cells.
Ray Lankester to the members of a series of tubes, proved in some cases to be excretory in nature, which exist typically to the number of a single pair in most of the segments of the Chaetopod body, and open each by a ciliated orifice into the coelom on the one hand, and by a pore on to the exterior of the body on the other.
The Polychaeta, however, present us with another form of nephridium seen, for example, in Arenicola, where a large funnel leads into a short and wide excretory tube whose lumen is intercellular.
It is not clear, for example, to which category it is necessary to refer the excretory organs of Arenicola, or Polynoe.
Thus Nereis among the latter worms, from the resemblance which its excretory system bears to that of the Oligochaeta, may be made the starting-point of a series.
It has been ascertained that the nephridia of Oligochaeta are preceded in the embryo by a pair of delicate and sinuous tubes, also found in the Hirudinea and Polychaeta, which are larval excretory organs.
It is not quite certain whether these are to be regarded as the remnant of an earlier excretory system, replaced among the Oligochaeta by the subsequently developed paired structures, or whether these "head kidneys" are the first pair of nephridia precociously developed.
Among the Megascolicidae, however, which in number of genera and species nearly equals the remaining families taken together, another form of the excretory system occurs.
The tips of these tufts enclose a flamecell similar to those found in Platyhelminths, &c., and these probably function as excretory organs.
The y are really excretory glands, and communicate with the exterior by a very minute aperture on the posterior face of the coxa of the fifth limb on each side.
Scorpio is here provided with a single or double pair of renal excretory tubes, which have been identified by earlier authors with the Malpighian tubes of the Hexapod and Myriapod insects.
Limulus agrees with the majority of the Crustacea in being destitute of renal excretory caeca or tubes opening into the hinder part of the gut.
It must be pointed out that the presence or absence of such renal excretory tubes opening into the intestine appears to be a question FIG.
These cells are f - - imbedded in the peri pheral parenchyma, E"- and lead into convo luted excretory tubes _ that form an anasto- - mosis opening to the exterior by a pore at the " hinder " end of the body.
A well-developed cellular parenchyma forms a matrix in which the muscular, excretory and generative organs are imbedded.
In the remainder the segmentation involves primarily the genitalia and includes the integument, muscles and part of the excretory system.
The nervous system is, however, not segmented, and the excretory system is continuous throughout the worm.
B, head showing the suckers, proboscides and excretory canals; X 25.
The mass of the body consists of richly branched stellate cells - the mesenchyma - and imbedded in this plasmic tissue are the nervous, excretory, muscular and generative organs.
Each cansists of an eversible hollow tentacle provided with hooklets and capable of introversion within a mem The excretory organs consist of flame-cells, richly convoluted canaliculi, and a pair of longitudinal canals leading to the exterior by one or more pores.
An excretory system develops, opening at FIG.
The terminal or first-formed proglottis is sterile, and contains the primitive and (except in a few genera) the only excretory pore.
A, Fasciola hepatica, from the ventral surface (X 2); the alimentary and nervous systems only shown on the left side of the figure, the excretory only on the right; a, right main branch of the intestine; c, a diverticulum; g, lateral ganglion; n, lateral nerve; o, mouth; p, pharynx; s, ventral sucker; cs, cirrus sac; d, left anterior dorsal excretory vessel; m, main vessel; v, left anterior ventral trunk; x, excretory pore.
D, a flame-cell from the excretory apparatus, highly magnified (from Fraipont).
The excretory system opens to the exterior by a pair of dorsal pores at the level of the pharynx.
A, Dorsal view showing the nervous system and digestive system; a, mouth; b, pharynx; c, d, e, gut; E, post-genital union of two limbs of gut; f, excretory pore; g, vaginal pore; h, j, k, brain and nerves; 1, dorsal nerves; m, ventral nerves; n, adoral sucker; o, posterior sucker; p, hooks on posterior sucker; r, vitello-intestinal duct.
The periodical histolysis may be partly due to the absence of specific excretory organs and to the accumulation of pigmented excretory substances in the wall of the alimentary canal.
It is terminated by a well-developed structure (fg) corresponding with the apical sense-organ of ordinary Trochospheres, and an excretory organ (nph) of the type familiar in these larvae occurs on the ventral side of the stomach.
The principal differences are the complication of the ciliated band, the absence of the excretory organ, the great lateral compression of the body, the possession of a pair of shells protecting the sides, the presence of an organ known as the "pyriform organ," and the occurrence of a sucker in a position corresponding with the depression seen between (m) and (a) in fig.
Usually there are four excretory (Malpighian) tubes; but there are only two in the Coccidae and none in the Aphidae.
The stone-flies further resemble the Orthoptera in their numerous Malpighian excretory tubes, which vary in number from twenty to sixty.
In effect, therefore, Mayow - who also gives a remarkably correct anatomical description of the mechanism of respiration - preceded Priestley and Lavoisier by a century in recognizing the existence of oxygen, under the guise of his spiritus nitro-aereus, as a separate entity distinct from the general mass of the air; he perceived the part it plays in combustion and in increasing the weight of the calces of metals as compared with metals themselves; and, rejecting the common notions of his time that the use of breathing is to cool the heart, or assist the passage of the blood from the right to the left side of the heart, or merely to agitate it, he saw in inspiration a mechanism for introducing oxygen into the body, where it is consumed for the production of heat and muscular activity, and even vaguely conceived of expiration as an excretory process.
The grounds for this view are the radial symmetry of several Polyclads and the supposed origin of gonads and excretory flame-cells from the walls of gut, the occurrence of nematocysts in Anonymus, one of the most radially constructed Polyclads, and lastly the presence of two peculiar animals Ctenoplana and Coeloplana, which suggests a transition from Ctenophora to Polyclads.
The careful study of the development of one Acoelous form and of certain Rhabdocoels has strengthened this hypothesis by showing that no definite enteron or gut is at first laid down, but that certain embryonic syncytial tracts become digestive tracts, others excretory, others again muscular.
There are no specialized circulatory, respiratory or excretory organs.
These excretory products have usually an acid nature and hence are generally known as lichen-acids.
The excretory organs are coelomoducts with an internal ciliated opening into the pericardium and an opening to the exterior.
The ectoderm is in some genera modified to form certain excretory glands, which usually take the form of papillae with an apical opening.
The excretory organs are typical nephridia, with an internal ciliated opening into the body-cavity, and an external pore.
One surface of the tube is prolonged into a large sac lined with glandular excretory cells.
This, when garlic has been eaten, is evolved by the excretory organs, the activity of which it promotes.
They are lined by cells charged with a yellow or brown pigment, and besides their excretory functions they act as ducts through which the reproductive cells leave the body.
In fact it is not possible to maintain that the renal excretory tubes of the gut are of one common origin in the Arthropoda.
Pectinibranchia.-In this order there is no longer any trace of bilateral symmetry in the circulatory, respiratory and excretory organs, the topographically right half of the pallial complex having completely disappeared, except the right kidney, which is FIG.
The possession of a variable number of excretory tubes (Malpighian tubes), which are developed as outgrowths of the hind-gut and pour their excretion into the intestine,is also a distinctive character of the Hexapoda.