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Questions and Answers
Which structure in the liver is primarily responsible for detoxification of blood?
Which structure in the liver is primarily responsible for detoxification of blood?
What is the main source of the liver's blood supply?
What is the main source of the liver's blood supply?
What role does the liver serve as an endocrine organ?
What role does the liver serve as an endocrine organ?
Which component is part of the portal triad in the liver?
Which component is part of the portal triad in the liver?
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Which process takes place in the liver that is related to blood?
Which process takes place in the liver that is related to blood?
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What is the primary function of the liver in the context of excretion?
What is the primary function of the liver in the context of excretion?
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Which region of the kidney primarily receives the majority of the renal blood supply?
Which region of the kidney primarily receives the majority of the renal blood supply?
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What structure is responsible for the filtration of fluid from blood into Bowman Capsule?
What structure is responsible for the filtration of fluid from blood into Bowman Capsule?
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Which function is NOT performed by the kidneys?
Which function is NOT performed by the kidneys?
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Which type of nephron is characterized by its loop of Henle extending deep into the medulla?
Which type of nephron is characterized by its loop of Henle extending deep into the medulla?
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Study Notes
Pre-Class Readings: Liver and Renal Physiology Related to Drug Elimination
- Drug elimination involves removal through metabolism (biotransformation) and excretion.
- Liver and kidneys are primary drug-eliminating organs.
- Hydrophilic drugs are excreted by the kidneys.
- Lipophilic drugs are metabolized by the liver into water-soluble forms for kidney excretion or metabolites in bile.
Liver Physiological Functions
- The liver is critical for fat digestion, carbohydrate storage, blood detoxification, and protein production.
- The liver receives dual blood supply:
- 25% from the hepatic artery (oxygenated blood)
- 75% from the portal vein (deoxygenated blood rich in nutrients from digestive tract).
- Blood from both sources flows through hepatic sinusoids, lined by endothelial cells and Kupffer cells (phagocytic macrophages).
- The liver produces bile, which aids in fat digestion.
- Efflux transporters may pump drugs into bile.
- The liver is metabolically active; it functions as digestive, endocrine, hematological, and excretory organ
- Digestive: Bile secretion for fat digestion, Processes carbs & proteins from intestines, stores & Processes vitamins & minerals.
- Endocrine: Metabolism of glucocorticoids, mineralocorticoids, sex hormones, and regulates carbohydrate, fat, and protein metabolism.
- Hematologic: Stores blood, removes bilirubin, produces blood clotting factors.
- Excretory: Excretes bile pigment, cholesterol, urea. Detoxifies drugs and foreign substances.
Drug Elimination and Biotransformation
- Drug metabolism in the liver is site- and flow-dependent.
- Enzymes (e.g., CYP enzymes) are responsible for oxidation/reduction reactions (phase I).
- Phase I reactions introduce or expose a functional group on the drug molecule.
- Phase II reactions involve conjugating the drug with another molecule (glucuronidation, sulfation, etc.) making it more water-soluble to be eliminated in bile or urine.
- First-pass effect describes rapid metabolism of a drug by the liver/intestine before reaching systemic circulation.
- Enterohepatic circulation is a cycle where a drug or its metabolite is excreted into bile, reabsorbed and re-enters the system.
Renal Physiological Functions
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Kidneys are located between the 12th thoracic and 3rd lumbar vertebrae.
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Renal blood supply is significant (approximately 25% of cardiac output).
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The functional unit is the nephron.
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Glomerular filtration rate (GFR) is the rate at which blood is filtered by the glomeruli.
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GFR is influenced by blood volume, pressure, and other factors.
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The nephron regulates fluid and electrolyte balance, and removes waste products.
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Kidneys produce erythropoietin (stimulates red blood cell production) and activate Vitamin D.
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Glomerular Filtration: The first step in urine formation. Blood pressure forces water and small solutes from the glomerulus into Bowman's capsule.
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Tubular Reabsorption: The process whereby essential substances (e.g., water, glucose, amino acids) are reabsorbed back into the bloodstream from the filtrate.
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Tubular Secretion: Substances (e.g., waste products, excess ions) are transported from the blood into the filtrate.
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Age, gender, and race can affect drug metabolism and renal function.
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Description
This quiz covers the essential roles of the liver and kidneys in drug elimination, focusing on the metabolism and excretion processes. It also explores the physiological functions of the liver and its importance in digestion and detoxification. Test your understanding of how these organs contribute to pharmacokinetics.
