urinary

• The urinary system is recognized as an excretory system

  
• General functions of the urinary system

  • Filtration
  • Reabsorption
  • Secretion
  • Excretion

  
• Filtration


  Filtrates body fluids, most abundant being blood
• Reabsorption


  Nutrients absorbed from the digestive system is carried by blood then into the kidney for reabsorption

  
• Secretion


  Secretion of urine
• Excretion


  Also known as urination, voiding, micturition, excretion of urine
• Major parts of the urinary system

  • Right and Left Kidneys
  • Right and Left Ureters
  • Urinary Bladder
  • Urethra

  
• Renal agenesis/Renal Aplasia


  Complete absence of one or both kidneys due to unsuccessful formation of the embryonic kidney

  
• Bilateral renal agenesis/Potter Syndrome

  Rare condition where both kidneys do not develop, incompatible with life and associated with typical facial features and pulmonary hypoplasia

  
• Supernumerary kidney

  Anomaly of renal number where there is an accessory organ (typically one additional kidney)

  
• Kidney functions


  • Regulation of blood ionic composition
  • Regulation of blood pH
  • Regulation of blood volume
  • Regulation of blood pressure
  • Maintenance of blood osmolarity
  • Production of hormones
  • Regulation of blood glucose level
  • Excretion of wastes and foreign substances

  
• Regulation of blood ionic composition

  Kidneys regulate the blood levels of sodium, potassium, calcium, chloride, and phosphate ions

  
• Regulation of blood pH

  Kidneys remove hydrogen ions from the filtered blood to maintain normal blood pH of 7.4

  
• Regulation of blood volume

  Kidneys conserve or eliminate water in urine to increase or decrease blood volume and pressure

  
• Regulation of blood pressure

  Kidneys secrete the enzyme renin which activates the renin-angiotensin-aldosterone pathway to increase blood pressure

  
• Maintenance of blood osmolarity

  Kidneys regulate the loss of water and solutes in urine to maintain blood osmolarity at 300 milliosmoles per liter

  
• Hormones produced by the kidneys

  • Calcitriol (active form of Vitamin D)
  • Erythropoietin (stimulates RBC production)

  
• Regulation of blood glucose level

  Kidneys use amino acid glutamine to perform gluconeogenesis and release glucose into the blood
• Wastes and substances excreted by the kidneys

  • Ammonia and urea
  • Bilirubin
  • Creatinine
  • Uric acid
  • Foreign substances from diet and environment
• Normal location of kidneys

  Lie about halfway between the xiphoid process and iliac crest, with the left kidney slightly higher than the right

  
• Renal hilum


  • Indentation near the center of the concave border where the ureter emerges along with blood vessels, lymphatic vessels, and nerves

  
• Layers of tissue surrounding each kidney

  • Renal fascia (superficial layer)
  • Adipose capsule (middle layer)
  • Renal capsule (deep layer)

  
• Renal fascia


  Thin layer of dense irregular connective tissue that anchors the kidney to surrounding structures and the abdominal wall

  
• Adipose capsule

  Mass of fatty tissue surrounding the renal capsule that protects the kidney from trauma and holds it in place

  
• Renal capsule

  Smooth, transparent sheet of dense irregular connective tissue that serves as a barrier against trauma and helps maintain the kidney's shape

  
• Components of the renal parenchyma

  • Renal cortex
  • Renal medulla

  
• Renal cortex


  Superficial, light red region that extends from the renal capsule to the bases of the renal pyramids and into the spaces between them

  
• Renal medulla


  Deep, darker reddish-brown inner region containing the renal pyramids

  
• Structures within the renal medulla

  • Renal pyramids
  • Renal papilla
  • Base of pyramid

  
• Renal pyramids


  Cone-shaped structures in the renal medulla that consist of a collection of tubules, with 8-18 pyramids per kidney

  
• Renal papilla


  Narrower end, apex of the renal pyramid
• Base of pyramid


  Wider end, adjacent to the cortex
• Renal lobe


  Consists of a renal pyramid, renal cortex, and half of each adjacent renal column

  
• Papillary ducts


  Drain the filtrate (filtered fluid) formed by nephrons, extending through the renal papillae

  
• Minor calyx


  Receives urine from the papillary ducts and delivers it to the major calyx, with 8-18 minor calyces per kidney

  
• Major calyx


  1. 3 minor calyces converge to form the major calyx, with 2 or 3 major calyces per kidney
• Once the filtrate enters the calyces it becomes urine because no further reabsorption can occur
• Renal pelvis


  Receives urine from the major calyces, a large cavity where the major calyces unite

  
• Renal sinus


  Vertical space or cleft of the hilum containing the renal pelvis, calyces, branches of the renal blood vessels, and nerves, with adipose tissue to stabilize these structures

  
• Components of the internal microscopic anatomy of the kidneys

  • Nephron
  • Collecting tubules