Kidneys and homestasis The kidneys play many vital roles in homeostasis. They filter all the blood in the body many times each day and produce a total of about 1.5 litres of urine. The kidneys control the amount of water, ions and other substances in the blood by excreting more or less of them in urine. The kidneys also secrete hormones that help maintain homeostasis. The kidneys themselves are also regulated by hormones. For example, antidiuretic hormone from the hypothalamus stimulates the kidneys to produce more concentrated urine when the body is low on water. This process is known as osmoregulation. If you exercise on a hot day, you are likely to lose a lot of water in sweat. Then, for the next several hours, you may notice that you do not pass urine as often as normal and that your urine is darker than usual. This happens because your body is low on water and trying to reduce the amount of water lost in urine. The amount of water the body loses in urine is controlled by the kidneys, the main organs of the excretory system. Excretion is the process of removing waste and excess water from the body. It is one of the major ways the body maintains homeostasis (the process of maintaining a stable internal environment). Although the kidneys are the main organs of excretion, several other organs also excrete waste. They include the large intestine, liver, skin and lungs. All of these organs of excretion, along with the kidneys, make up the excretory system. The focus will be on the role of the kidneys in excretion. The roles of the other excretory organs are summarised below: – The large intestine eliminates solid waste that remains after the digestion of food. – The liver breaks down excess amino acids and toxins in the blood. – The skin eliminates excess water and salts in sweat. – The lungs exhale water vapour and carbon dioxide. The kidneys are part of the urinary system, which is shown above. The main function of the urinary system is to filter waste products and excess water from the blood and excrete them from the body. The kidneys are a pair of bean-shaped organs just above the waist. A cross section of a kidney is shown in the diagram above. The function of the kidney is to filter blood and form urine. Urine is the liquid waste product of the body that is excreted by the urinary system. Nephrons are the structural and functional units of the kidneys. A single kidney may have more than a million nephrons. Each kidney is supplied by a renal artery and a renal vein. As shown in figure above, each nephron is like a tiny filtering plant. It filters blood and forms urine in the following steps: 1. Blood enters the kidney through the renal artery, which branches into capillaries. When blood passes through capillaries of a nephron, blood pressure forces some of the water and dissolved substances in the blood to cross the capillary walls into the Bowman’s capsule. 2. The filtered substances pass to the renal tubule of the nephron. In the renal tubule, some of the filtered substances are reabsorbed and returned to the bloodstream. Other substances are secreted into the fluid. 3. The fluid passes to a collecting duct, which reabsorbs some of the water and returns it to the bloodstream. The fluid that remains in the collecting duct is urine. From the collecting ducts of the kidneys, urine enters the ureters, two muscular tubes that move the urine by peristalsis to the bladder. The bladder is a hollow, sac-like organ that stores urine. When the bladder is about half full, it sends a nerve impulse to a sphincter to relax and let urine flow out of the bladder and into the urethra. The urethra is a muscular tube that carries urine out of the body. Urine leaves the body through another sphincter in the process of urination. This sphincter and the process of urination are normally under conscious control.
Hurricane Irma destroys Barbuda Radical rogues ruining Bahamas tourism reputation Recommended for you Facebook Twitter Google+LinkedInPinterestWhatsApp Facebook Twitter Google+LinkedInPinterestWhatsAppProvidenciales, 24 Feb 2015 – A new Caribbean connection coming for the Turks and Caicos Islands as British Airways has announced that it will be changing its route into Provo. BA will no longer fly to the Providenciales International Airport from Nassau in The Bahamas; but now from Antigua. The flight will remain a once weekly commute, arriving in Provo shortly after 5pm and departing for Antigua two hours later; no day has been specified, but BA currently runs on Sundays. And while the flight will be upgraded from a Boeing 767 to a Boeing 777 which has a longer fuselage and broader wing span; the new route will prove somewhat problematic for the Filipinos who frequent the British Airways flight as now they will have to overnight in Antigua; because the continuing flight to London Gatwick is not until next day. The news has already prompted a visit by a Filipino ambassador of the region and the Filipino community says it will now have to be far more proactive when it comes to travel arrangements which will also now be more expensive. As for what prompted the move, London Air Travel says it is unclear, explaining online that: “It may simply be a more effective use of capacity. BA will continue to offer three classes of service (World Traveller Economy, World Traveller Plus Premium Economy and Club World Business Class) on the route. The new route takes effect March 29th. Reports of damages throughout the Leeward Islands as Hurricane Irma hits Related Items:ANTIGUA, british aIRWAYS, nassau, provo
KUSI Newsroom Categories: Local San Diego News, Trending FacebookTwitter Shark attack victim speaks out for the first time since the attack Posted: November 21, 2018 November 21, 2018 00:00 00:00 spaceplay / pause qunload | stop ffullscreenshift + ←→slower / faster ↑↓volume mmute ←→seek . seek to previous 12… 6 seek to 10%, 20% … 60% XColor SettingsAaAaAaAaTextBackgroundOpacity SettingsTextOpaqueSemi-TransparentBackgroundSemi-TransparentOpaqueTransparentFont SettingsSize||TypeSerif MonospaceSerifSans Serif MonospaceSans SerifCasualCursiveSmallCapsResetSave SettingsSAN DIEGO (KUSI)- The 13-year-old boy who was attacked by a great white shark, while lobster diving in September, is recovering at home with his family.KUSI’s Dani Ruberti spoke with Keane Hayes for his first interview after the vicious attack and why he’s thanking his community. KUSI Newsroom,