CC 2 NPNS

• The loop of Henle is divided into three segments: descending limb, thick ascending limb, and thin ascending limb
• Each segment of the loop of Henle has its own unique function
• The loop of Henle uses a counter-current multiplier system to elevate the concentration of solutes and ions
• The ions involved in this process include sodium, potassium, chloride, magnesium, and other ions present in the body
• The counter-current multiplier system in the loop of Henle helps the nephron to reabsorb more water and concentrate urine using minimal energy
• The Proximal Convoluted Tubule (PCT) reabsorbs substances such as Na+, chloride, bicarbonate, glucose, amino acids, urea, and uric acid
• The PCT is responsible for delivering about 25 liters of dilute urine to the ascending limb of Henle
• The Distal Convoluted Tubule (DCT) decreases osmolality progressively to about 60-80 mOsmol/liter
• The collecting duct is the final site for either concentrating or diluting urine
• Plasma Non-Protein Nitrogen (PNP) levels include urea (45%), amino acids (20%), uric acid (20%), creatinine (5%), creatine (1-2%), and ammonia (0.2%)
• The collecting ducts serve as the final site for either concentrating or diluting urine
• The collecting duct is the final site for either concentrating or diluting the urine
• The blood, specifically the plasma, contains about 20-35 mg/dL of NPN (Non-Protein Nitrogen)
• Urea has the highest concentration in the blood
• The primary function of the kidneys is to regulate the extracellular environment of the body
• Functions of the kidneys:

  • Elimination of waste products
  • Maintenance of the blood volume
  • Maintenance of electrolyte balance
  • Endocrine function
• When the kidneys are not functioning properly, harmful toxins and excess fluids start to build up in the body
• The kidneys can filter about 200 L of water every day
• The kidneys have the ability to regulate the blood plasma volume and the concentration of waste products
• The kidneys can regulate pH, electrolyte balance (especially sodium and potassium), and have an endocrine function
• The extracellular fluid (ECF) outside the cells of the body needs to have a stable composition of salts (sodium chloride, sodium potassium) and pH maintained by the kidneys
• The kidneys play a crucial role in maintaining the correct balances of pH, electrolytes, and other components for the proper functioning of cells in the body
• Endocrine function - The kidneys secrete hormones that are important for the normal functioning of the body
• An example of a hormone secreted by the kidneys is Renin
• Renin is a hormone secreted from the kidneys to regulate blood pressure
• Renin is important to keep our blood pressure within the normal level
• If blood pressure is decreasing or falling below the normal level, renin is secreted by the kidneys
• Renin stimulates the constriction of small vessels, leading to an increase in blood pressure
• If the kidneys are not working correctly, there will be too much secretion of renin
• Functions of the kidneys:

  • Endocrine function
  • Renin, EPO
  • Function of renin:
  • If the blood pressure of the patient/individual is decreased, the kidneys will release renin and the renin will stimulate to constrict/lessen the small blood vessels to increase the blood pressure
• If the amount of renin secreted is more than needed by the body, too much production of renin will increase blood pressure, leading to hypertension/high blood pressure
• EPO/Erythropoietin is another hormone secreted by the kidneys
• EPO stimulates the bone marrow to produce red blood cells and promote erythropoiesis/production of red blood cells
• People with kidney failure may have lower hemoglobin, hematocrit, and RBC count due to insufficient secretion of EPO
• Nonprotein Nitrogen (NPN):

  • Urea, creatinine, creatine, uric acid, ammonia, and amino acids
  • Assesses the levels of nitrogenous wastes in the blood
• Measuring total NPN helps assess/determine the levels of nitrogenous wastes in the blood
• By measuring the level of NPNs in the body, it will help us to assess/determine the levels of nitrogenous wastes in the blood
• The three major/principal compounds routinely measured in the laboratory are urea, uric acid, and creatinine
• Kidney function tests include:

  • Tests for Renal Blood Flow
  • Tests for the Glomerular Filtration
  • Tests Measuring Tubular Function
• Tests for renal blood flow, glomerular filtration, and measuring tubular function are used to assess whether kidneys are functioning well or not