Unit 16 The Urinary System PDF

Unit 16: The Urinary System Excretory Organs Skin (Integumentary System): o Function: Waste excretion via sweat, involved in thermoregulation, and water balance. Lungs (Respiratory System): o Function: Excretion of carbon dioxide as a waste product of cel...

Unit 16: The Urinary System Excretory Organs Skin (Integumentary System): o Function: Waste excretion via sweat, involved in thermoregulation, and water balance. Lungs (Respiratory System): o Function: Excretion of carbon dioxide as a waste product of cellular respiration through breathing; vital for maintaining acid-base balance. Kidneys (Urinary System): o Function: Main organ for waste elimination and regulation of blood volume, pressure, and solute balance. Functions of the Urinary System Regulation of Blood Composition: o Maintains blood water, ion levels (sodium, potassium, calcium), and balances electrolytes. Waste Excretion: o Eliminates metabolic waste products such as urea, creatinine, and excess salts from the bloodstream. Blood Pressure Regulation: o Kidneys regulate blood volume and pressure through the production of renin and adjusting fluid levels. pH Regulation: o Excretes excess hydrogen ions and bicarbonate to maintain acid-base homeostasis in the body. Hormones Released: o Calcitriol: Active form of vitamin D, essential for calcium absorption in the gut. o Erythropoietin (EPO): Stimulates production of red blood cells in response to low oxygen levels in tissues. Organs of the Urinary System Kidneys: regulate blood volume and composition, help regulate blood pressure and pH, produce two hormones, and excrete wastes Ureters: transport urine from the kidneys to the urinary bladder  Urinary bladder: stores urine and expels it into the urethra Urethra: discharges urine from the body Anatomy of the Kidneys Each kidney is approximately 3 inches long Blood Supply: o Each kidney receives over 20% of the heart's output through renal arteries, critical for filtering blood Location of kidneys: o Retroperitoneal o Between T12 and L3 o The right kidney is slightly lower than the left Major Components: o Renal Capsule: Protective outer covering. o Medulla: Contains renal pyramids and is involved in urine concentration. o Cortex: Contains glomeruli and proximal tubules (important for filtration). o Nephron: Functional unit responsible for urine formation. The Nephron Structure: o Functional unit of the kidney; each kidney has over 1 million nephrons. 2 Parts: o The renal corpuscle (filters blood) o The renal tubule (processes filtrate into urine) Renal Tubule Structure Composed of: o Proximal Convoluted Tubule: Reabsorption of water, ions, and nutrients. o Nephron Loop: Plays a role in concentrating urine (includes descending and ascending limbs). o Distal Convoluted Tubule: Fine-tunes reabsorption based on body needs. o Collecting Duct: Final adjustments of urine composition and water reabsorption before exiting to the bladder. Nephron Functions Overview Key Functions: through this processes is how urine is produces o Filtration: Initial filtering of blood through glomeruli into Bowman’s capsule. o Reabsorption: Nutrients and ions reclaimed from filtrate back into the bloodstream, balancing body's needs. o Secretion: Active transport of wastes, toxins, and excess ions from blood into the nephron for excretion. Filtration Process in the Nephron 2 Capillary Types: o Glomerular capillaries have specialized pores for enhanced filtration capabilities.  o Peritubular High Blood Pressure: o Required to ensure efficient solute movement into Bowman’s capsule, promoting effective filtration. Hydrostatic pressure force the fluids and solute through a membrane and into the Bowman’s Capsule. Efficient Filtration Passive Filtration: o Utilizes hydrostatic pressure to move fluids across membranes without the need for energy expenditure. High Output: o Kidneys process significant volumes of fluid daily (approximately 180 L), emphasizing their importance in fluid balance. Importance of Plasma Proteins During filtration it is important that the plasma proteins stay in the plasma to maintain osmotic pressure Proteinuria: Presence of blood cells/proteins in urine o indicates potential filtration membrane damage, signifying underlying health concerns that may require intervention o common during diabetes and hypertension Glomerular Filtration Rate (GFR) Healthy kidneys filter about: o 125 mL/min, a critical indicator of kidney health and function. Tubular Reabsorption in the Nephron Mechanism: o Movement of nutrients (like glucose, amino acids) and water back into the blood, primarily occurring in the proximal tubule and loop of Henle, ensuring essential substances are not lost in urine. Sodium and Water Reabsorption Active Processes: o Sodium reabsorption is active and drives passive water reabsorption, aiding in maintaining fluid balance; aquaporin channels facilitate water movement, regulated by Antidiuretic Hormone (ADH). o 2/3 of water & ions are reabsorbed in the proximal tubule and the loop of Henle Reabsorption Rates in Proximal Tubule Percentages of Substances Reabsorbed: o Water 65%, Glucose 100%, Sodium ions 65%, reflecting the nephron's efficiency in reclaiming essential nutrients. Secretion Mechanisms Active Transport: o Wastes and excess ions (like H+) are actively transported from the capillaries into the nephron, crucial for maintaining stable blood pH through acid-base balance. Summary of Nephron Processes Collective Functions: o Filtration, reabsorption, and secretion work together to ensure efficient urine formation and excretion, playing a vital role in homeostasis. Nitrogenous Wastes Metabolic Waste Products: o Includes urea (from ammonia breakdown), creatinine (muscle metabolism), and uric acid (purine metabolism), all assessed through urine testing for kidney functionality. The urethra Internal Urethral Sphincter:  o Involuntary control; helps maintain continence. External Urethral Sphincter: o Voluntary control from skeletal muscle, critical for the conscious management of urination. Regulation of Urinary System Diuretics: o Medications that induce sodium (Na+) and water loss; can include substances like alcohol and caffeine that affect kidney function. Diuretic Medications: o Target various renal processes to manage conditions like hypertension or fluid overload. Hormonal Regulation of Urine Volume Key Hormones: o Antidiuretic Hormone (ADH): Increases water reabsorption in nephron. o Aldosterone: Promotes sodium reabsorption; retains water indirectly. o Atrial Natriuretic Hormone (ANH): Acts to reduce blood volume and pressure by inhibiting renin and aldosterone secretion. Chronic Kidney Disease (CKD) Overview Primary Causes: o Commonly results from hypertension and diabetes, both of which lead to progressive loss of kidney function; early detection is critical for management. Kidney Stones Prevalence and Causes: o Results from excess uric acid and calcium precipitation; factors include dehydration and dietary composition Uric acid is a waste product produced from the breakdown of the purine nucleotides. Buildup: o in the joints causes gout o in the kidneys causes stones  This disease is highly linked to metabolic syndrome and also has a strong genetic component. Polycystic Kidney Disease Overview Hereditary Disorder: o Causes cyst formation in the kidneys, leading to obstruction of tubules and impaired kidney function over time