9.5 The Excretory System individual cells cannot eflectively secrete wastes o th
ID: 215140 • Letter: 9
Question
9.5 The Excretory System individual cells cannot eflectively secrete wastes o th t One of the main functions of the excretory sye laided of the excretory system is to regulare fluids and water within the bodh waste peodes external osmoregulation) is to concentrate wastes and espel them from the body. The ncond Most metabolic wastes and toxins are dissolved in the body's internal maintenance of the body Buids is essencial for keeping the body free of and enabling it to function properly. In this section, you will earn ao tions of the excretory sytem and examine how the excretory system works in oeganisms and in more complex organisms, such as humans and other mamma Excretion in Invertebrates and Non-mammalian Vertebrates and simple multicellular organisms produce the same meta bolic wastes and toxic compounds as more complex organisms. These waste producta must be excreted to maintain homeostasis: Simple organisms have an adrantage isms because their cells are in constant contact with the extemal more complex environment. Wastes are excreted directly from their cells, and the water cu Figure 1 Some single-celled organisms, i in the external environment carry the wastes away. A greater challenge for simle such as the parameclm, excrete material directly into the external organisms is maintaining Buid balance with the external enviromment. Fre envwronment via contractile vaculessingle-celled organisms, such as the paramecium, have an internal evicnme is hyperosmotic to their surroundings (Figure 1). If they were not able to maintain fluid balance, they would continaously absorb water from the environment and contractile vacuole a structure ina single-celled organism that maintains osmotic equilbrium by pumping excess tually burst. To expel excess water, these protozoans have contractile vacuoles ich pump out water to maintain osmotic balance. In more complex organisms, the excretory system must take on different formso meet different challenges. Some invertebrate animals, such as the earthworm, hane excretory organs called metanephridia (singular: metanephridium) that expel wastes from the body (Figure 2). In each segment of the earthworm, hemolyph (a fuid fluid out of the cell metanephridium an excretory organ in some invertebrates that is used to reabsorb and eliminate wastes that serves as both interstitial fluid and blood) flows into a pair of which are twisted into convoluted shapes to maximize their surface area lons ad wastes are reabsorbed from the hemolymph and secreted (along with water) into a saclike organ called a bladder. From there, the excess water and waste products an secreted to the external environment through a pore in the side of the wornls body network melanephridiun in red) hemolymph urine is released enters through through pore openings at ends opening to exterio of metanephridia in a different in each segment segment Figure 2 A metanephridium of an earthwormExplanation / Answer
Excretion in Invertebrates and Non-mammalian vertebrates
The same metabolic waste is produced by both single and multi-celled organism. The cells of single cell organisms are connected to external environment and as the waste is excreted out from cells where the water current outside carry the waste away. The internal environment of free living organism is hyper-osmotic to the surrounding and in case they are not able to maintain fluid balance, it burst by continuous absorption of water. The osmotic balance in protozoans is maintained by expelling water through contractile vacuole.
In case of earthworm, it has excretory organs called metanephridia which expels waste from body. Hemolymph is a fluid which flows though each segment of metanephridia that have large surface area due to its twisted convoluted shape. The ions and water are reabsorbed in hemolymph and secreted in the bladder where the excess ions and water is secreted out in environment through a pore.
The insects have slightly different mechanism and excrete through malphighian tubules. The closed ends are immersed in hemolymph and the open ends empty in stomach. The tubules excrete many substances like uric acid, potassium, sodium etc ions. The water moves osmotically from hemolymph into tubule to form dilute waste solution which moves through intestine and cell reabsorb Na and K back in hemolymph and allows water to be move from intentine into hemolymph by osmosis. This is how it expels out the waste.
The reptiles and birds do so by expelling nitrogenous waste in water less form in form of uric acid crystals. It is removed from cloaca and removed from body with digestive wastes and the white dropping is uric acid. The ones that live around salt water excrete excess salt through salt glands located in head. It is via active transport that the salt is removed and salts are removed to environment as water solution which is highly concentrated.
Related Questions
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.