Nephron Function and Hormonal Regulation

• The urinary system consists of the kidneys and other structures.
• The intended learning outcomes are to label diagrams, describe function, explain blood flow, explain nephron function, and describe homeostasis of the kidney system.

GDC Learning Outcomes

• Describe dental, oral, craniofacial, and general anatomy and their patient management applications.
• Describe relevant physiology and its patient management applications.

Assessing Knowledge

• Start by assessing current knowledge of the urinary system function on a scale of 1-5 before continuing.
• It is best to reassess it at the end

Anatomy and Physiology

• Anatomy focuses on the physical structures.
• Physiology focuses on how these structures function.
• Watch linked YouTube videos to learn about the anatomy and physiology of the kidney and urinary system.

Key Functions of the Kidney

• Excretory: Waste removal.
• Regulatory: Maintains balance.
• Endocrine: Hormone production.
• Metabolic: Various metabolic processes

Renal Function

• Renal function maintains normal body fluid volume and composition.
• It is also essential for waste product and drug excretion

Anatomy Practice

• Practice labeling diagrams of the urinary system, kidney sections, and nephrons.
• Explain the direction of flow in the diagrams.

Urine Formation

• Urine formation involves three processes: filtration, selective reabsorption, and tubular secretion.
• Filtration occurs in the glomerulus capsule, where water and small molecules pass through semipermeable walls.
• The larger molecules and blood cells remain in the capillaries

Selective Reabsorption

• Constituents needed by the body are put back into the blood capillary.
• This happens at carrier sites in the epithelial membrane
• Active transport occurs at carrier sites in the epithelial membrane, requiring energy against concentration gradients.
• Exceeding the renal threshold leads to substances appearing in urine such as glucose.

Hormonal Regulation of Reabsorption

• Parathormone and calcitonin regulate calcium and phosphate reabsorption.
• Antidiuretic hormone increases water reabsorption by increasing the permeability of convoluted tubules.
• Aldosterone increases sodium reabsorption and potassium excretion and Angiotensin II is a vasoconstricting hormone.

Tubular Secretion

• Substances that remain in the blood after filtration may be secreted into the convoluted tubules such as hydrogen ions and drugs.
• The process requires energy.

Water Balance

• Kidneys regulate water balance through the management of water gain, urine, feces, perspiration and expired air.
• Water regulation is controlled by antidiuretic hormone.

Electrolyte Balance

• Sodium and potassium are taken in through food, with excess excreted in urine, and sodium excretion regulated by aldosterone.
• Parathyroid and calcitonin hormones coordinate calcium balance, PTH reabsorbs calcium, and calcitonin absorbs less calcium in tubules.