The liver is a critical organ responsible for numerous physiological processes, including macronutrient metabolism, blood volume regulation, immune support, endocrine control, lipid and cholesterol homeostasis, and xenobiotic compound breakdown. Its functions are supported by a variety of cell types, such as hepatocytes, cholangiocytes, stellate cells, Kupffer cells, and liver sinusoidal endothelial cells, each with unique roles. The liver's structure, organized into lobules, facilitates the exchange of nutrients and waste products through a sinusoidal network. Developmentally, the liver arises from a complex differentiation program involving signal gradients, cellular localization cues, and transcription factors. Liver failure can result from various causes, emphasizing the importance of understanding its development and physiology for therapeutic interventions. Key aspects of liver function include: 1. **Macronutrient Metabolism**: The liver processes and stores glucose, oxidizes lipids, and handles protein and amino acid metabolism. 2. **Developmental Pathways**: Hepatic development involves signals from the definitive endoderm, ectoderm, and mesoderm, leading to the formation of hepatocytes and cholangiocytes. 3. **Cell Patterning and Maturation**: Hepatoblasts differentiate into hepatocytes and cholangiocytes, influenced by signals like TGF-β and transcription factors. 4. **Perinatal Metabolic Programming**: The liver transitions from glucose consumption to storage and production during the final stages of gestation. 5. **Glucose Metabolism**: The liver regulates glucose output and uptake, crucial for postnatal metabolic transitions and maintaining blood glucose levels. 6. **Lipid and Cholesterol Metabolism**: The liver handles lipid absorption, synthesis, and secretion, maintaining cholesterol homeostasis. 7. **Protein and Amino Acid Metabolism**: The liver synthesizes and breaks down proteins, disposing of nitrogenous wastes and providing energy. Understanding these functions and their regulation is essential for addressing liver pathologies and developing effective treatments.The liver is a critical organ responsible for numerous physiological processes, including macronutrient metabolism, blood volume regulation, immune support, endocrine control, lipid and cholesterol homeostasis, and xenobiotic compound breakdown. Its functions are supported by a variety of cell types, such as hepatocytes, cholangiocytes, stellate cells, Kupffer cells, and liver sinusoidal endothelial cells, each with unique roles. The liver's structure, organized into lobules, facilitates the exchange of nutrients and waste products through a sinusoidal network. Developmentally, the liver arises from a complex differentiation program involving signal gradients, cellular localization cues, and transcription factors. Liver failure can result from various causes, emphasizing the importance of understanding its development and physiology for therapeutic interventions. Key aspects of liver function include: 1. **Macronutrient Metabolism**: The liver processes and stores glucose, oxidizes lipids, and handles protein and amino acid metabolism. 2. **Developmental Pathways**: Hepatic development involves signals from the definitive endoderm, ectoderm, and mesoderm, leading to the formation of hepatocytes and cholangiocytes. 3. **Cell Patterning and Maturation**: Hepatoblasts differentiate into hepatocytes and cholangiocytes, influenced by signals like TGF-β and transcription factors. 4. **Perinatal Metabolic Programming**: The liver transitions from glucose consumption to storage and production during the final stages of gestation. 5. **Glucose Metabolism**: The liver regulates glucose output and uptake, crucial for postnatal metabolic transitions and maintaining blood glucose levels. 6. **Lipid and Cholesterol Metabolism**: The liver handles lipid absorption, synthesis, and secretion, maintaining cholesterol homeostasis. 7. **Protein and Amino Acid Metabolism**: The liver synthesizes and breaks down proteins, disposing of nitrogenous wastes and providing energy. Understanding these functions and their regulation is essential for addressing liver pathologies and developing effective treatments.