Renal System / Urinary System

• located in paired elevations called urogenital ridges
• Three pairs of kidneys: pronephros, the mesonephros, and the metanephros
• Pronephros is the most superior of the three and has an associated pronephric duct
• Pronephric duct empties into  the cloaca, expanded terminal part of the hindgut, which functions as a common outlet for the urinary, digestive, and reproductive ducts.
• pronephros begins to degenerate during the fourth week and is completely gone by the sixth week
• Mesonephors replaces the pronephros
• The retained portion of the pronephric duct, which connects to the mesonephros, develops into the mesonephric duct.
• Mesonephros begins to degenerate by the sixth week and is almost gone by the eighth week.
• At about the fifth week, a mesodermal outgrowth, called a ureteric bud, develops from the distal portion of the mesonephric duct near the cloaca
• Metanephros or ultimate kidney, develops from the ureteric bud and metanephric mesoderm.
• Ureteric bud forms the collecting ducts, calyces, renal pelvis, and ureter.
• Metanephric mesoderm forms the nephrons of the kidneys
• By the third month, the foetal kidneys begin excreting urine into the surrounding amniotic fluid
• kidneys do the major work of the urinary system
• The kidneys help regulate the blood levels of several ions, most importantly sodium ions (Na1), potassium ions (K1), calcium ions (Ca21), chloride ions (Cl2), and phosphate ions (HPO4 22).
• The kidneys adjust blood volume by conserving or eliminating water in the urine
• kidneys also help regulate blood pressure by secreting the enzyme renin, which activates the renin–angiotensin–aldosterone pathway. Increased renin causes an increase in blood pressure
• Kidneys maintain a relatively constant blood osmolarity close to 300 milliosmoles per litre
• Kidneys produce two hormones: Calcitriol & Erythropoietin
• kidneys can use the amino acid glutamine in gluconeogenesis, the synthesis of new glucose molecules.
• kidneys are reddish, kidney bean–shaped organs
• Kidneys are located just above the waist between the peritoneum and the posterior wall of the abdomen
• Kidneys are located between the levels of the last thoracic and third lumbar vertebrae, a position where they are partially protected by ribs 11 and 12
• A typical adult kidney is 10–12 cm (4–5 in.) long, 5–7 cm (2–3 in.) wide, and 3 cm (1 in.) thick
• Three layers of tissue surround each kidney: Renal capsule, Adipose capsule, Renal fascia
• Renal hilum is Near the centre of the concave border is an indentation
• Renal hilum which the ureter emerges from the kidney along with blood vessels, lymphatic vessels, and nerves
• Renal capsule, is a smooth, transparent sheet of dense irregular connective tissue that is continuous with the outer coat of the ureter.
• Renal capsule serves as a barrier against trauma and helps maintain the shape of the kidney
• Adipose capsule is a mass of fatty tissue surrounding the renal capsule
• Adipose capsule also protects the kidney from trauma and holds it firmly in place within the abdominal cavity.
• Renal fascia thin layer of dense irregular connective tissue
• Renal fascia anchors the kidney to the surrounding structures and to the abdominal wall.
• Position and coverings of the kidneys

  A) Large intestine

  B) Abdominal aorta

  C) Renal artery and vein

  D) RENAL HILUM

  E) LEFT KIDNEY

  F) Spleen

  G) Rib

  H) Quadratus lumborum muscle

  I) Inferior vena cava

  J) Peritoneum

  K) RENAL FASCIA

  L) ADIPOSE CAPSULE

  M) RENAL CAPSULE

  N) RIGHT KIDNEY

  O) Stomach

  P) Pancreas

  Q) Liver

  R) Body of L2

  
• A frontal section through the kidney reveals two distinct regions: Renal Cortex & Renal Medulla
• Renal Cortex is a superficial, light red region of the kidney
• Renal Cortex is a smooth-textured area extending from the renal capsule to the bases of the renal pyramid
• Renal Cortex is divided into: outer cortical zone and an inner juxtamedullary zone
• Those portions of the renal cortex that extend between renal pyramids are called renal columns
• Renal Medulla d a deep, darker reddish-brown inner region