Renal system

Cards (24)

    • collecting ducts of kidney converge to the renal papilla and are found in the inner medulla in a region known as the renal pelvis
    • papilla drain urine into the renal pelvis and out of the kidney via the ureter that feeds into bladder
  • kidneys organized into outer layer = cortex, inner layer = medulla
    • Monocalyceal kidney→ one single renal pelvis and set of papillae ex. mouse
    • one single renal pelvis + set of papillae = calyx
  • muticalyceal kidney→ divided into multiple calices ex. other mammals, humans
  • multirenuculated kidney→ separated into distinct lobes each individual lobe called reniculum acts as a separate little kidney having its own cortex and medullar ex. most marine mammals, few land mammals that need to conserve water
  • renal capsule = connective tissue and peritoneum
  • hilus= renal artery enters, rena vein exists, ureter exits
  • renicule = single unit of kidney and each has its own cortex, medulla and pelvis
  • Harbour Seal bladder
    • bladder has very muscular wall, capable of significant expansion
  • Nephrons
    • functional filtration units of the kidney
    • filter blood to remove metabolic wastes and excess minerals and excrete it as urine
    • filter out everything smaller than 68kDa and selectively reabsorb
  • deeper the medulla is relative to the cortex, the more concentrated the urine can become (longer loop of Henle), marine mammals have thicker medulla but no loop of Henle
  • nephrons function and urine concentrating ability is dependent upon the cortico-medullary axis of the kidney which establishes a counter current concentrator to produce urine
    • urine that mammals excrete is dependent upon
    • what is filtered out
    • what is reabsorbed
    • what is actively secreted
    • marine mammals have developed unique strategies to minimize water loss through increased reabsorption of water and increased filtration and secretion of salts and waste
  • Marine Mammals have unique challenges
    • coping with increased salt intake
    • coping with long fasting periods
    • finding fresh water
  • increasing number of reniculi→ Number of reniculi correlates with the salinity of the diet and is associated with an increased capacity to excrete urine
  • Marine mammals in salt water will have high salt intakes and will require more reniculi to remove the saline water it ingests with its food than a manatee or freshwater dolphin who lives in fresh water and has a lower salt content intake
  • Sirenia don’t have a true reniculated kidney, cortex is continuous. Dugong is close to man
    1. drinking fresh water directly → fresh streams or ice
    • some live in freshwater lakes or rivers such as manatee or Amazon river dolphins
    • don’t worry much about removing huge amounts of mineral
    • pinnipeds like the Weddell seal have been seen chewing ice or snow and will drink from hose or trough in captivityDietary water sources→ manatees
    1. H2O in food → most fish and invertebrates consist of 60-80% fresh water
    • West indian manatee maintain in salt water, deprived of fresh water but since they only at leafy green vegetables they still produced a normal urine output
    1. metabolic water→ breakdown of fat or metabolism of protein
    • fatty acid catabolism
    • 1 gram of Palmitate1.07g H20
    • Oxidation of NADH, FADH2
    • proteolysis
    • 1 gram of protein0.4 H2O
    • sources of dietary fat and proteins as well as stored fat and protein will contain water
  • Mariposa→ intentional ingestion of sea water
    • may be beneficial to marine mammals who have high protein diets, as sea water can provide urinary osmotic space for urea, minimizes water loss
    • sea otter freely swallow seawater to help excrete high amount of urea it forms
    • northern fur seal, harbour seal and common dolphins also consume large amounts of sea water
    • non renal adaptions
    • pinnipeds have few sweat glands
    • cetaceans have NO sweat glands
    • water loss from breathing is reduced by conserving breaths and cooling expelled air (countercurrent exchanges)