Flame cells contain cilia that direct water and metabolic wastes to enter the cells and pass into excretory canals. The excretory canals join with other canals to form excretory tubules. Fluid from the excretory tubules leaves the body through pores.
In earthworms, members of the phylum Annelida, the excretory system consists of structural units called nephridia the singular is nephridium. Each nephridium contains a ciliated tunnel that leads to a long, coiled tubule, which leads to a bladderlike sac a primitive bladder. Fluid moves from the internal environment into the funnel. As fluid passes through the tubule, cells in the tubular lining absorb useful compounds such as glucose, amino acids, and salts.
The remaining materials constitute metabolic waste, and they are passed into the bladderlike sac. The extent of blood volume and blood pressure regulation facilitated by the kidneys is a complex process. Besides ADH secretion, the renin-angiotensin feedback system is critically important to maintain blood volume and blood pressure homeostasis. Learning Objectives Review the urinary system. Key Points The renal system eliminate wastes from the body, controls levels of electrolytes and metabolites, controls the osmoregulation of blood volume and pressure, and regulates blood pH.
The renal system organs include the kidneys, ureter, bladder, and urethra. Nephrons are the main functional component of the kidneys. The respiratory and cardiovascular systems have certain functions that overlap with renal system functions.
Metabolic wastes and excess ions are filtered out of the blood, combined with water, and leave the body in the form of urine. A complex network of hormones controls the renal system to maintain homeostasis. Key Terms ureter : These are two long, narrow ducts that carry urine from the kidneys to the urinary bladder. The Renal System The renal system, which is also called the urinary system, is a group of organs in the body that filters out excess fluid and other substances from the bloodstream.
Renal System Functions The renal system has many functions. Removal of metabolic waste products from the body mainly urea and uric acid. Regulation of electrolyte balance e.
Osmoregulation controls the blood volume and body water contents. Blood pressure homeostasis: The renal system alters water retention and thirst to slowly change blood volume and keep blood pressure in a normal range. Recall that enzymes lose their three-dimensional conformation and, therefore, their function if the pH is too acidic or basic. This loss of conformation may be a consequence of the breaking of hydrogen bonds.
Move the pH away from the optimum for a specific enzyme and you may severely hamper its function throughout the body, including hormone binding, central nervous system signaling, or myocardial contraction. Proper kidney function is essential for pH homeostasis. Stem cells are unspecialized cells that can reproduce themselves via cell division, sometimes after years of inactivity. Under certain conditions, they may differentiate into tissue-specific or organ-specific cells with special functions.
In some cases, stem cells may continually divide to produce a mature cell and to replace themselves. Stem cell therapy has an enormous potential to improve the quality of life or save the lives of people suffering from debilitating or life-threatening diseases. There have been several studies in animals, but since stem cell therapy is still in its infancy, there have been limited experiments in humans.
Acute kidney injury can be caused by a number of factors, including transplants and other surgeries. It affects 7—10 percent of all hospitalized patients, resulting in the deaths of 35—40 percent of inpatients. In limited studies using mesenchymal stem cells, there have been fewer instances of kidney damage after surgery, the length of hospital stays has been reduced, and there have been fewer readmissions after release. How do these stem cells work to protect or repair the kidney?
Scientists are unsure at this point, but some evidence has shown that these stem cells release several growth factors in endocrine and paracrine ways.
As further studies are conducted to assess the safety and effectiveness of stem cell therapy, we will move closer to a day when kidney injury is rare, and curative treatments are routine. The effects of failure of parts of the urinary system may range from inconvenient incontinence to fatal loss of filtration and many others.
The kidney hormone EPO stimulates erythrocyte development and promotes adequate O 2 transport. The kidneys work with the adrenal cortex, lungs, and liver in the renin—angiotensin—aldosterone system to regulate blood pressure.
They regulate osmolarity of the blood by regulating both solutes and water. The kidneys share pH regulation with the lungs and plasma buffers, so that proteins can preserve their three-dimensional conformation and thus their function. Answer the question s below to see how well you understand the topics covered in the previous section. Stem cells and their role in renal ischaemia reperfusion injury. Am J Nephrol [Internet].
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