Module 1: Understanding Chronic Kidney Disease (ckd)

Glomerulus

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• The Nephron

• Glomerulus
• Proximal tubule
• Loop of Henle
• Distal tubule
• Collecting duct

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• Each kidney has about 1 million nephrons; slow loss may not be noticeable

• Healthy people have a large physiologic reserve.
• Slow, progressive loss of functioning nephrons may not be noticeable.
• Often, there are no symptoms until more than three-quarters of kidney function is lost.

The functions include:

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• The functions include:
• Filtration
• Glomeruli generate ultrafiltrate of the plasma.
• Reabsorption
• Tubules selectively reabsorb substances from the ultrafiltrate.
• Secretion
• Tubules secrete substances into the urine.

• Nephrons maintain homeostatic balance

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• Ultrafiltration of plasma is the main
• function of the glomerulus

• Volume of ultrafiltrate = 135–180 liters(L)/day
• 99% water reabsorbed  1–1.5 L urine excreted
• Filtration of solutes is based on size and charge
• Small solutes cross readily.
• Larger substances are generally restricted.

The ultrafiltrate is modified by the tubules

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• Reabsorption and secretion of substances occurs within the tubules.
• Examples:
• Potassium is reabsorbed from and secreted into the urine by the tubules.
• Sodium and glucose are reabsorbed by the tubules.
• Organic acids are secreted into the urine.

The kidneys have many functions

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• Regulatory function
• Control composition and volume of blood
• Maintain stable concentrations of inorganic anions such as sodium (Na), potassium (K), and calcium (Ca)
• Maintain acid-base balance
• Excretory function
• Produce urine
• Remove metabolic wastes
• Including nitrogenous waste