Anatomy WK 10 (4/10) | Nephron, Kidneys, UTIs

Key Structures of the Nephron

• Nephron: The functional unit of the kidney, consisting of various components such as the glomerulus, proximal and distal tubules, loop of Henle, and collecting duct.

Capillaries

• Capillaries: Present throughout the nephron, essential for the filtration and collection of blood, but shown variably across nephron types (juxtamedullary vs. cortical nephrons).

Kidney Functions

• Kidney Functions: Critical for filtering blood and producing urine. The processes that occur here are vital for maintaining body homeostasis.
• Three Main Processes: Filtration, reabsorption, secretion.
  • Filtration: Occurs in the glomerulus, where blood enters the nephron, becoming filtrate (rejected larger molecules like proteins).
  • Reabsorption: Essential nutrients and water are reabsorbed from the nephron back into the bloodstream, primarily in the proximal convoluted tubule.
  • Secretion: Further removal of wastes and excess ions happens in the distal convoluted tubule.

Cells of the Nephron

• Macula Densa: Senses changes in urine concentration to regulate blood flow and filtration.
• Juxtaglomerular (Granular) Cells: Secrete renin, manipulating blood pressure and urine output.
• Extraglomerular Mesangial Cells: Help with structural support and contractility regarding blood flow.

Urea and Blood Chemistry

• Urea: Critical waste product that indicates kidney function; high levels in blood (> 25 grams) signal renal failure leading to toxicity affecting the brain and heart function.

Diabetes and Its Impact on Kidneys

• Diabetes: Characterized by chronically elevated blood sugar levels, leading to inflammation and complications in blood processing through the kidneys.
  • Inflammation: Increases blood pressure, affecting capillary dynamics, especially in the kidneys.
  • Leaky Capillaries: High pressure leads to leakage of unwanted molecules like protein and glucose into urine.
  • Kidney Damage: Long-term increased leakiness results in scarring of the capillaries, limiting filtration capacity.

Histological Changes in Diabetes

• Healthy Glomerulus: Shows normal capillary architecture and functionality.
• Diabetic Kidney: Features glomeruli replaced with scar tissue, impairing filtration efficacy, leading to accumulation of waste products in blood.

Dialysis and Kidney Transplantation

• Dialysis: A process where a machine filters blood outside the body; necessary when kidneys fail.
  • Procedure: Blood is drawn, cleaned through a dialyzer, and returned to the body. Treatment typically occurs several times a week, making it inconvenient yet life-saving.
• Kidney Transplantation: A permanent solution when kidneys fail, but carries risks of rejection or complications from chronic diseases (e.g., autoimmune).

Urinary Pathologies: Kidney Stones

• Kidney Stones: Solid accumulations formed from excess electrolytes (e.g., calcium, potassium) can obstruct urinary pathways.
  • Complications: Can block urine flow, elevate internal kidney pressure, and result in severe pain and further filtration issues.
  • Surgical and Non-Surgical Treatments: Options include traditional surgery or non-invasive shockwave lithotripsy that breaks up stones to facilitate easier passage.

Ureters and Bladder Anatomy

• Ureters: Tubes that transport urine from the kidneys to the bladder, featuring transitional epithelium to accommodate stretching.
  • Histological Layers: Include transitional epithelium, lamina propria, and smooth muscular layers.
• Bladder: Functions as a temporary urine storage facility, featuring a muscular wall (detrusor muscle) for contraction during urination.
  • Sphincters: Control urine release; the internal sphincter is involuntary, and the external sphincter is under conscious control.

Urinary Tract Infections (UTIs)

• Commonality: More prevalent in women due to anatomical proximity between urethra and vagina.
  • Hygiene Practices: Urinating after sexual activity can help clear out invading bacteria from the urethra.

Conclusion

• Final Thoughts: Understanding kidney function and urinary pathways is vital for recognizing health issues and managing conditions effectively. Keeping hydrated can reduce risks associated with kidney stones and UTIs while monitoring blood components is key in diabetes management.