It passes through the penis in males, and opens in front of the vagina in females. Nephrons as kidney processing units Each kidney contains about a million very fine tubes called nephrons. Each has its own blood supply, so the "dirty" blood is divided between them, and each nephron processes the blood and returns it in a "cleaned" state, so urine is produced as a result of their combined effect. There are 2 stages to this processing:
Pedicellaria and papulae of Asterias forbesi The body wall consists of a thin cuticle, an epidermis consisting of a single layer of cells, a thick dermis formed of connective tissue and a thin coelomic myoepithelial layer, which provides the longitudinal and circular musculature.
The dermis contains an endoskeleton of calcium carbonate components known as ossicles.
These are honeycombed structures composed of calcite microcrystals arranged in a lattice. They remove debris from the body surface and wave around on flexible stalks in response to physical or chemical stimuli while continually making biting movements.
They often form clusters surrounding spines. The edges of adjacent paxillae meet to form a false cuticle with a water cavity beneath in which the madreporite and delicate gill structures are protected. All the ossicles, including those projecting externally, are covered by the epidermal layer. These serve a respiratory function.
This arrangement enables both easy flexion of the arms by the starfish and the rapid onset of stiffness and rigidity required for actions performed under stress.
Water enters the system through the madreporitea porous, often conspicuous, sieve-like ossicle on the aboral surface. It is linked through a stone canal, often lined with calcareous material, to a ring canal around the mouth opening. A set of radial canals leads off this; one radial canal runs along the ambulacral groove in each arm.
There are short lateral canals branching off alternately to either side of the radial canal, each ending in an ampulla.
These bulb-shaped organs are joined to tube feet podia on the exterior of the animal by short linking canals that pass through ossicles in the ambulacral groove. There are usually two rows of tube feet but in some species, the lateral canals are alternately long and short and there appear to be four rows.
The interior of the whole canal system is lined with cilia. These extend to contact the substrate. Although the tube feet resemble suction cups in appearance, the gripping action is a function of adhesive chemicals rather than suction.
The tube feet latch on to surfaces and move in a wave, with one arm section attaching to the surface as another releases. When crawling, some arms act as the leading arms, while others trail behind. The sand star Luidia foliolata can travel at a speed of 2.
The water vascular system serves to transport oxygen from, and carbon dioxide to, the tube feet and also nutrients from the gut to the muscles involved in locomotion. Fluid movement is bidirectional and initiated by cilia.
Oxygen is transferred from these to the coelomic fluidwhich acts as the transport medium for gasses. Oxygen dissolved in the water is distributed through the body mainly by the fluid in the main body cavity; the circulatory system may also play a minor role.
Intestine and anus, 3. Ambulacral ridge The gut of a starfish occupies most of the disc and extends into the arms. The mouth is located in the centre of the oral surface, where it is surrounded by a tough peristomial membrane and closed with a sphincter.
The mouth opens through a short oesophagus into a stomach divided by a constriction into a larger, eversible cardiac portion and a smaller pyloric portion. The cardiac stomach is glandular and pouched, and is supported by ligaments attached to ossicles in the arms so it can be pulled back into position after it has been everted.
The pyloric stomach has two extensions into each arm: These are elongated, branched hollow tubes that are lined by a series of glands, which secrete digestive enzymes and absorb nutrients from the food. A short intestine and rectum run from the pyloric stomach to open at a small anus at the apex of the aboral surface of the disc.
Shell valves and other inedible materials are ejected through their mouths. The semi-digested fluid is passed into their pyloric stomachs and caeca where digestion continues and absorption ensues.Fasciolahepatica is a common fluke found in the liver and bile ducts of cattle, sheep, goat, pig, rabbit, dog etc.
It causes damage to the liver tissues producing liver rot in all sheep breeding areas of the world. Its life cycle is completed in two hosts, a vertebrate, the sheep and an invertebrate host, which is the snail of the genera Planorbis, . INTRODUCTION.
Hypernatremia is most often due to unreplaced water that is lost from the gastrointestinal tract (vomiting or osmotic diarrhea), skin (sweat), or the urine (diabetes insipidus or an osmotic diuresis due to glycosuria in uncontrolled diabetes mellitus or increased urea excretion resulting from catabolism or recovery from renal failure) .
Osmoregulation is the active regulation of the osmotic pressure of an organism's body fluids, detected by osmoreceptors, to maintain the homeostasis of the organism's water content; that is, it maintains the fluid balance and the concentration of electrolytes (salts in solution) to keep the fluids from becoming too diluted or concentrated.
Below is a list of chapters from the Campbell's Biology, 8th Editon textbook that we have slides for. These slides will cover all of the key points of the chapter and will be useful when studying for the AP Biology exam or any other Biology test.
Excretion and Osmoregulation The process of elimination or removal of harmful substances from the body is known as excretion. The organs associated with the removal of harmful substances known as excretory system.
Osmoregulation means the physiological processes that an organism uses to maintain water balance; that is, to compensate for water loss, avoid excess water gain, and maintain the proper osmotic concentration (osmolarity) of the body fluids.