Nephron Function and Structure

Nephron Function

• The nephron is the functional unit of the kidney, responsible for filtering waste and excess fluids from the blood.
• Each nephron consists of:
  • Renal corpuscle (glomerulus and Bowman's capsule)
  • Proximal convoluted tubule (PCT)
  • Loop of Henle
  • Distal convoluted tubule (DCT)
  • Collecting duct
• The nephron's main function is to:
  • Filter blood to remove waste and excess ions, water, and nutrients
  • Regulate electrolyte and water balance
  • Maintain acid-base balance

Tubular Reabsorption

• Tubular reabsorption is the process by which the kidney reabsorbs water and solutes from the filtrate back into the bloodstream.
• Types of reabsorption:
  • Passive reabsorption: occurs through diffusion and osmosis
  • Active reabsorption: requires energy and involves transport proteins
• Reabsorption occurs in different segments of the nephron, including:
  • PCT: reabsorbs majority of glucose, amino acids, and other nutrients
  • Loop of Henle: reabsorbs sodium, chloride, and potassium
  • DCT: reabsorbs sodium and water

Renal Blood Flow

• Renal blood flow is the amount of blood that flows through the kidneys per minute.
• The kidneys receive approximately 20-25% of the total cardiac output.
• Regulation of renal blood flow is critical for maintaining blood pressure and kidney function.
• Factors that influence renal blood flow:
  • Sympathetic nervous system activity
  • Renal artery pressure
  • Hormonal regulation (e.g., vasopressin)

Urine Concentration

• Urine concentration is the process by which the kidneys regulate the amount of water in the urine.
• The kidneys can concentrate or dilute the urine depending on the body's needs.
• Mechanisms of urine concentration:
  • Antidiuretic hormone (ADH) regulates water reabsorption in the collecting duct
  • Osmotic gradient in the medulla of the kidney
  • Urea recycling

Glomerular Filtration

• Glomerular filtration is the process by which the kidneys filter the blood to remove waste and excess fluids.
• The glomerular filtration rate (GFR) is the rate at which the kidneys filter the blood.
• Factors that influence GFR:
  • Blood pressure
  • Renal blood flow
  • Glomerular capillary permeability
  • Bowman's capsule pressure
• The glomerular filtration barrier consists of:
  • Glomerular endothelial cells
  • Glomerular basement membrane
  • Podocytes

Nephron Function

• Nephron is the functional unit of the kidney, responsible for filtering waste and excess fluids from the blood.
• Each nephron consists of renal corpuscle, proximal convoluted tubule, loop of Henle, distal convoluted tubule, and collecting duct.

Nephron's Main Function

• Filter blood to remove waste and excess ions, water, and nutrients.
• Regulate electrolyte and water balance.
• Maintain acid-base balance.

Tubular Reabsorption

• Process by which the kidney reabsorbs water and solutes from the filtrate back into the bloodstream.
• Types of reabsorption: passive reabsorption (occurs through diffusion and osmosis) and active reabsorption (requires energy and involves transport proteins).
• Reabsorption occurs in different segments of the nephron.
• PCT reabsorbs majority of glucose, amino acids, and other nutrients.
• Loop of Henle reabsorbs sodium, chloride, and potassium.
• DCT reabsorbs sodium and water.

Renal Blood Flow

• Amount of blood that flows through the kidneys per minute.
• Kidneys receive approximately 20-25% of the total cardiac output.
• Regulation of renal blood flow is critical for maintaining blood pressure and kidney function.
• Factors that influence renal blood flow: sympathetic nervous system activity, renal artery pressure, and hormonal regulation (e.g., vasopressin).

Urine Concentration

• Process by which the kidneys regulate the amount of water in the urine.
• Kidneys can concentrate or dilute the urine depending on the body's needs.
• Mechanisms of urine concentration: antidiuretic hormone (ADH) regulates water reabsorption in the collecting duct, osmotic gradient in the medulla of the kidney, and urea recycling.

Glomerular Filtration

• Process by which the kidneys filter the blood to remove waste and excess fluids.
• Glomerular filtration rate (GFR) is the rate at which the kidneys filter the blood.
• Factors that influence GFR: blood pressure, renal blood flow, glomerular capillary permeability, and Bowman's capsule pressure.
• Glomerular filtration barrier consists of glomerular endothelial cells, glomerular basement membrane, and podocytes.