A norepinephrine causes vasoconstriction through the

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a. Norepinephrine causes vasoconstriction through the activation of a1 receptors, which are particularly plentiful in the smooth muscle fibers of afferent arterioles. 3. Hormonal Regulation : two hormones contribute to regulation of GFR a. Angiotensin II: reduces GFR i. Decrease blood volume or blood pressure stimulates production of angiotensin II. b. Atrial natriuretic peptide ANP: increases GFR i. Stretching of atria of heart stimulates secretion of ANP Formation of Dilute Urine o We have two nephron: cortical nephron which is the majority and then juxtamedullary nephron that involves in concentration of urine. o When ADH levels is low, urine is dilute and has an osmolarity less than the osmolarity blood. o Filtration is going to accumulate in the Capsule. Then go through the tubules, flash through the PCT. Then its going to go through the loop of descending and then ascending, in ascending limb the water is impermeable therefore at this point the concentration is going to change where we will lose ions. The descending limb is permeable to water therefore the concentration number will be higher than the
ascending limb. In ascending limb the concentration will decrease through the collecting duct. Mechanism of Urine concentration in Long-loop in Juxtamedullary nephrons
o The formation of concentrated urine depends on high concentrations of solutes in interstitial fluid in the renal medulla. o The green lines indicate the presence of Na+-K+-2Cl- symporters that simultaneously reabsorb these ions into the interstitial fluid of the renal medulla, o This portion of the nephron is also relatively impermeable to water and urea. o All concentrations are in milliosmoles per liter. Evaluation of the Kidney Function
o Normal volume of urine per day is 1-2L o Routine urinalysis primarily evaluates for the presence of abnormalities in the urine Albumin - presence of excessive albumin in urine- albuminuria indicates increase in permeability of filtration membranes due to injury or disease, increased blood pressure, or irritation of kidney cells by substances such as bacterial toxins, either, or heavy metals. Glucose - presence of glucose in urine- glucosuria, usually indicates diabetes mellitus. Red Blood Cells (Erythrocytes)= presence of red blood cells in urine hematuria, generally indicates pathological condition Ketone Bodies - high levels of ketone bodies in urine ketonuria, may indicate diabetes mellitus, anorexia, starvation, or too little carbohydrate in diet. Bilirubin - when RBC are destroyed by macrophages, above normal level of bilirubin in urine is called bilirubinuria. Microbes- number and type of bacteria vary with specific urinary tact infections.
Chapter 27 Fluid, Electrolyte, and Acid Base Homeostasis Fluid Compartments and Fluid Homeostasis o Female contains 55% of body fluids o Male contains 60% of body fluids in which 2/3 is intracellular fluid and 1/3 is extracellular fluid. In ECF 80% is interstitial fluid and remaining 20% is blood plasma.

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