ArtsAutosBooksBusinessEducationEntertainmentFamilyFashionFoodGamesGenderHealthHolidaysHomeHubPagesPersonal FinancePetsPoliticsReligionSportsTechnologyTravel

Urinary System Review

Updated on April 30, 2014

How Do Animals Excrete Toxic Wastes from Nitrogen Metabolism?

Animals must eliminate metabolic waste products:

  • Carbohydrates and fat end as water and CO2 and are easily excreted.
  • Proteins and nucleic acids contain nitrogen and also produce nitrogenous waste.

Ammonia (NH3) is the most common and toxic nitrogenous waste.

  • Ammonia is soluble in water; aquatic animals who secrete NH3 through gills are ammonotelic.
  • Terrestrial and other aquatic animals must convert NH3 to urea or uric acid.

Source

Ureotelic vs. Uricotelic

Ureotelic animals mostly excrete urea.

  • Urea is water-soluble but results in a larger water loss.
  • This is how we roll.

Uricotelic animals mostly excrete uric acid.

  • It is insoluble in water and precipitates out of the urine with little water loss.
  • This is the ‘white’ part of bird and reptile droppings

Main Functions of the Kidneys

How Do Vertebrates Maintain Salt and Water Balance?

The kidney:

  • Maintains salt and water balance
  • Removes ammonia from the blood
  • Regulates blood pH
  • Produces bicarbonate.

Urinary System Diagram

Urinary System Diagram
Urinary System Diagram | Source

Basic structure of the kidney and the urinary system

How Does the Mammalian Kidney Produce Concentrated Urine?

The ureter, renal artery, and renal vein enter the kidney on the concave side.

  • The ureter branches and envelops the renal pyramids.
  • Renal pyramids make up the medulla, or internal core.
  • The cortex is the outer layer of the medulla.

Ureter:

  • A duct from the kidney that leads to the urinary bladder.

Urethra:

  • A tube for urine excretion.

The structure of the functional unit of the kidney.

Nephron: the main functional unit of the kidney

The renal tubules

  • Begins with Bowman’s capsule, which encloses the glomerulus.
  • Then the proximal convoluted tubules—the initial, twisted segments of the renal tubule

Loop of Henle (Descending and ascending branches)

  • The ascending limb of the loop of Henle becomes the distal convoluted tubule
  • The distal convoluted tubules join the collecting ducts.
  • Collecting ducts descend through renal pyramids and empty into the pelvis.
  • Pelvic divisions join and leave the kidney as the ureter.

The blood

Afferent arterioles carry blood to the glomeruli.

  • Glomeruli are drained by efferent arterioles that become the peritubular capillaries.
  • The vasa recta is a network of peritubular capillaries parallel to the loops of Henle and the collecting duct.

All peritubular capillaries from a nephron will drain into venules that lead to the renal vein.



Urinary System Audio Review

How ADH, angiotensin, renin and ANP affect kidney function etc....

What Mechanisms Regulate Kidney Function?

A constant glomerular filtration rate (GFR) needs blood supplied to the kidneys under adequate pressure.

  • Autoregulatory mechanisms ensure blood supply and blood pressure:
  • Dilation of afferent renal arterioles— maintains glomerular blood pressure
  • This maintains adequate GFR

Kidney releases hormone renin if GFR still falls, this activates angiotensin:

Angiotensin:

  • Constricts efferent renal arterioles and peripheral blood vessels to raise blood pressure.

The hypothalamus can stimulate release of antidiuretic hormone (ADH) if pressure is too low.

  • ADH increases the permeability of membranes to water.
  • More water = more pressure

Stretch receptors in the aorta and carotid arteries will inhibit ADH if blood pressure increases.

  • Less circulating ADH means less water reabsorbed leading to lower blood volume and pressure.

Atrial muscle fibers release atrial natriuretic peptide (ANP) when blood volume in the atria increases.

  • ANP decreases the reabsorption of Na+ in the kidney.
  • Increased loss of Na+ and water decreases blood volume and pressure.

Comments

    0 of 8192 characters used
    Post Comment

    No comments yet.

    working

    This website uses cookies

    As a user in the EEA, your approval is needed on a few things. To provide a better website experience, hubpages.com uses cookies (and other similar technologies) and may collect, process, and share personal data. Please choose which areas of our service you consent to our doing so.

    For more information on managing or withdrawing consents and how we handle data, visit our Privacy Policy at: https://hubpages.com/privacy-policy#gdpr

    Show Details
    Necessary
    HubPages Device IDThis is used to identify particular browsers or devices when the access the service, and is used for security reasons.
    LoginThis is necessary to sign in to the HubPages Service.
    Google RecaptchaThis is used to prevent bots and spam. (Privacy Policy)
    AkismetThis is used to detect comment spam. (Privacy Policy)
    HubPages Google AnalyticsThis is used to provide data on traffic to our website, all personally identifyable data is anonymized. (Privacy Policy)
    HubPages Traffic PixelThis is used to collect data on traffic to articles and other pages on our site. Unless you are signed in to a HubPages account, all personally identifiable information is anonymized.
    Amazon Web ServicesThis is a cloud services platform that we used to host our service. (Privacy Policy)
    CloudflareThis is a cloud CDN service that we use to efficiently deliver files required for our service to operate such as javascript, cascading style sheets, images, and videos. (Privacy Policy)
    Google Hosted LibrariesJavascript software libraries such as jQuery are loaded at endpoints on the googleapis.com or gstatic.com domains, for performance and efficiency reasons. (Privacy Policy)
    Features
    Google Custom SearchThis is feature allows you to search the site. (Privacy Policy)
    Google MapsSome articles have Google Maps embedded in them. (Privacy Policy)
    Google ChartsThis is used to display charts and graphs on articles and the author center. (Privacy Policy)
    Google AdSense Host APIThis service allows you to sign up for or associate a Google AdSense account with HubPages, so that you can earn money from ads on your articles. No data is shared unless you engage with this feature. (Privacy Policy)
    Google YouTubeSome articles have YouTube videos embedded in them. (Privacy Policy)
    VimeoSome articles have Vimeo videos embedded in them. (Privacy Policy)
    PaypalThis is used for a registered author who enrolls in the HubPages Earnings program and requests to be paid via PayPal. No data is shared with Paypal unless you engage with this feature. (Privacy Policy)
    Facebook LoginYou can use this to streamline signing up for, or signing in to your Hubpages account. No data is shared with Facebook unless you engage with this feature. (Privacy Policy)
    MavenThis supports the Maven widget and search functionality. (Privacy Policy)
    Marketing
    Google AdSenseThis is an ad network. (Privacy Policy)
    Google DoubleClickGoogle provides ad serving technology and runs an ad network. (Privacy Policy)
    Index ExchangeThis is an ad network. (Privacy Policy)
    SovrnThis is an ad network. (Privacy Policy)
    Facebook AdsThis is an ad network. (Privacy Policy)
    Amazon Unified Ad MarketplaceThis is an ad network. (Privacy Policy)
    AppNexusThis is an ad network. (Privacy Policy)
    OpenxThis is an ad network. (Privacy Policy)
    Rubicon ProjectThis is an ad network. (Privacy Policy)
    TripleLiftThis is an ad network. (Privacy Policy)
    Say MediaWe partner with Say Media to deliver ad campaigns on our sites. (Privacy Policy)
    Remarketing PixelsWe may use remarketing pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to advertise the HubPages Service to people that have visited our sites.
    Conversion Tracking PixelsWe may use conversion tracking pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to identify when an advertisement has successfully resulted in the desired action, such as signing up for the HubPages Service or publishing an article on the HubPages Service.
    Statistics
    Author Google AnalyticsThis is used to provide traffic data and reports to the authors of articles on the HubPages Service. (Privacy Policy)
    ComscoreComScore is a media measurement and analytics company providing marketing data and analytics to enterprises, media and advertising agencies, and publishers. Non-consent will result in ComScore only processing obfuscated personal data. (Privacy Policy)
    Amazon Tracking PixelSome articles display amazon products as part of the Amazon Affiliate program, this pixel provides traffic statistics for those products (Privacy Policy)