Notes on Renal System and Renal Failure Effects on Cardiopulmonary System

Urinary System Overview

  • Urine is formed by the kidneys and flows via the ureters to the bladder, then eliminated through the urethra.

  • Key organs/vessels: kidneys (right and left), renal arteries/veins, adrenal glands, ureters, bladder, urethra.

Kidney Anatomy and Pathways

  • Cross-section features: renal cortex, medulla, renal papillae, renal pyramids, minor and major calyces, renal pelvis, hilus, renal sinus with fat.

  • Internal flow: cortex and medulla house nephrons; minor/major calyces collect urine; renal pelvis funnels to ureter.

Nephron Structure and Function

  • Nephron filters waste from blood.

  • Main components:

    • Afferent arteriole → Renal corpuscle (Glomerulus + Bowman's capsule)

    • Proximal convoluted tubule

    • Loop of Henle (descending and ascending limbs)

    • Distal convoluted tubule

    • Collecting duct

    • Peritubular capillaries

  • Blood vessels: interlobular arteries/veins, arcuate arteries, interlobar arteries, renal artery/vein, efferent arteriole, afferent arteriole.

Renal Blood Vessels (Pathway Summary)

  • Renal artery → segmental arteries → interlobar arteries → arcuate arteries → interlobular arteries/veins → afferent arterioles → glomerulus → efferent arteriole → peritubular capillaries → venous drainage via interlobular/arcute/interlobar veins → renal vein.

  • Note: renal arteriogram can show overlying intestine in studies.

Acid-Base Balance by the Kidneys

  • All renal tubules can secrete hydrogen ions.

  • Rate of H⁺ secretion ∝ [H⁺] in blood; when fluids are acidic, kidneys excrete H⁺ into urine.

  • When fluids are alkaline, kidneys excrete basic substances, primarily ext{NaHCO}_3 into urine.

  • Thus, kidneys help restore acid-base balance by adjusting acid excretion and bicarbonate handling.

Blood Volume Regulation

  • Normal adult blood volume ≈ 5\ \text{L}.

  • Blood volume remains constant due to two major mechanisms: 2 major processes (capillary fluid shift system and renal system).

Renal Failure: Common Causes

  • Congenital disorders

  • Infections

  • Obstructive disorders

  • Inflammation and immune responses

  • Neoplasm

Prerenal Abnormalities (Causes of Reduced Renal Function)

  • Hypovolemia

  • Decrease of gastrointestinal tract fluids

  • Hemorrhage

  • Fluid sequestration (e.g., burns)

  • Septicemia

  • Heart failure

  • Renal artery atherosclerosis

Cardiopulmonary Disorders Caused by Renal Failure

  • Hypertension and edema

  • Anemia

  • Metabolic acidosis

  • Electrolyte abnormalities: ext{chloride},\; \text{potassium}

  • Bleeding tendencies

  • Cardiovascular problems