PPA Renal


Lecture Series Topics

  1. Anatomy of Kidney and Nephron with Emphasis on Glomerular Filtration

  2. Nephron Segments: Mechanisms of Water and Sodium Reabsorption

  3. Assessment of Renal Function, Osmotic Pressure, and Body Water Distribution

  4. Endocrine Systems Regulating Water and Sodium Homeostasis

  5. Disorders of Water and Sodium Homeostasis: Hyponatremia, Hypernatremia, Polyuria

  6. Renal Regulation of Potassium

  7. Renal Regulation of Acid-Base Physiology: Metabolic Alkalosis and Acidosis

  8. Renal Pathophysiology: Acute and Chronic Kidney Failure

Learning Objectives

  • List basic renal functions and structures

  • Describe the gross anatomy of the kidney

  • Identify the nephron segments

  • Explain the three primary renal processes:

    • Glomerular filtration

    • Tubular secretion

    • Tubular reabsorption

  • Discuss glomerulus components in filtration

  • Describe autoregulation of renal function

Renal Functions

  • Removal of metabolic waste products (urea, uric acid, creatinine)

  • Regulation of water and electrolyte balance (osmolarity, blood pressure, pH)

  • Blood pressure regulation through volume and resistance management

Hormonal Functions

  • Erythropoietin: Stimulates red blood cell production

  • Renin: Key enzyme for Angiotensin II production

  • 1,25-dihydroxyvitamin D (Calcitriol): Active form for calcium absorption

Basic Anatomy of the Kidney

  • Bean-shaped, located behind peritoneum (from T12 to L3)

  • Average weight: 125-170g (male), 115-155g (female)

  • Each kidney covered by a fibrous capsule; hilus is point of entry/exit for blood vessels and ureters

Kidney Layers

  1. Cortex: Outer layer with glomeruli and tubules

  2. Medulla: Inner layer with renal pyramids containing urine-collecting spaces (calices, pelvis)

Blood Flow and Filtration

  • Renal circulation has high blood flow (20% of cardiac output)

  • Glomerular capillaries: Undergo filtration, surrounded by afferent and efferent arterioles

Nephron Structure

  • Functional unit of the kidney

  • Contains 800,000 to 1,200,000 nephrons per kidney

  • Major components: Glomerulus, tubules (Bowman's capsule, proximal tubule, loop of Henle, distal convoluted tubule, collecting ducts)

Basic Renal Processes

  1. Glomerular Filtration: ~20% of plasma filters into Bowman’s space

  2. Tubular Secretion: Movement of substances from peritubular capillaries into tubule lumen

  3. Tubular Reabsorption: Movement from tubular lumen back into peritubular capillaries

Glomerulus

  • Composed of glomerular capillaries and Bowman’s capsule

  • Important structures: Afferent arteriole, efferent arteriole, podocytes, glomerular basement membrane (GBM)

Filtration Barrier

  • Composed of:

    • Capillary endothelium

    • GBM

    • Podocyte foot processes

  • Selectivity based on size and charge (negatively charged favors positive molecules)

Autoregulation of GFR

  • Regulation through myogenic response and tubuloglomerular feedback

  • Sympathetic innervation can stimulate renin release for blood pressure control

Nephron Segments and Solute Transport

  • Study of each nephron segment: proximal tubule, loop of Henle, distal convoluted tubule, collecting tubule

  • Mechanisms include: active transport, co-transport, counter-current mechanisms, hormonal control (ADH, aldosterone)

Renal Pathophysiology

  • Acute Kidney Injury (AKI): Sudden decrease in kidney function

  • Chronic Kidney Disease (CKD): Progressive decline in function, often leads to end-stage renal disease (ESRD)

Key Assessments

  • GFR assessment through creatinine clearance, blood tests, urine tests

  • Urinalysis for proteinuria, hematuria, and specific gravity

Conclusion

  • Understanding renal function and regulation is critical for managing diseases affecting kidney health and related systemic impacts.