module 8 review
What are the 3 processes involved in urine formation? Describe where they occur.
(1) filtration (2) reabsorption and (3) secretion. Filtration takes place in the renal corpuscle; reabsorption and secretion occur in the renal tubules.
What are the 3 categories of acute renal failure?
(1) prerenal, (2) postrenal, and (3) intrarenal.
List the 3 regulatory mechanisms of the GFR.
(1) renal autoregulation, (2) nervous system control, and (3) hormonal control.
List the 4 segments of the nephron tubule.
(1) the proximal convoluted tubule (highly coiled) which drains Bowman capsule; (2) the loop of Henle; (3) the distal convoluted tubule; and (4) the collecting tubule which joins with other nephron tubules to collect the filtrate.
List 3 ways that the kidney acts as an endocrine organ.
(1) through the renin-angiotensin-aldosterone system (RAA) (2) through the regulation of red blood cell production through the formation of erythropoietin, and (3) through calcium metabolism by the activation of vitamin D.
Describe the action of ADH.
ADH acts on the collecting tubule to increase water absorption. ADH inhibits urine output by increasing the number of water channels in the cell membrane of the collecting ducts.
What is the norm value for the GFR? Discuss why maintenance of this value is important.
A normal glomerular filtration rate (GFR) is 120-125 ml/min or 180 L/day. Maintenance of a relatively constant GFR is important for adequate reabsorption of water and other needed nutrients from the filtrate.
What are the common causes of acute postinfectious glomerulonephritis?
Acute Postinfectious Glomerulonephritis occurs as the result of another infection including streptococcus and staphylococcus bacterial infections, viral infections such as hepatitis, and even parasitic infections.
Describe the action of Aldosterone.
Aldosterone acts to place several types of ion channels inside the cells of the collecting ducts. One type of ion channel is a sodium-hydrogen ion channel. Aldosterone increases Na+ reabsorption through the excretion of H+ ions. Na+ ions are pumped out of the filtrate while hydrogen ions are pumped inside and then excreted. Because water follows salt, Na+ reabsorption will cause water reabsorption. Aldosterone will also increase K+ secretion through Na+/K+ pumps. Na+ is pumped out of the filtrate to be returned to the blood while potassium (K+) is excreted in urine. The main action of aldosterone is to increase the blood volume and, therefore, blood pressure when needed.
What blood values are closely monitored in renal failure?
BUN and creatinine levels
What are the 3 mechanisms of control for blood pH.
Blood pH is controlled by three main methods in the body: (1) the chemical buffer systems, (2) the brainstem respiratory center, and (3) the renal system.
Be able to list and describe the 4 types of kidney stones.
Calcium stones are a result of increased concentrations of calcium in the blood and urine. This can occur secondary to increased bone resorption, typically associated with immobility, bone disease, or hyperparathyroidism. Magnesium ammonium phosphate stones form in urine that is alkaline (pH>7.) This increase in pH is the result of a UTI caused by bacteria possessing an enzyme called urease. Urease will break urea into ammonia and carbon dioxide. The ammonia will form an ammonium ion which increases the pH of the urine. The resulting stones increase in size as the levels of bacteria rise. These types of stones account for approximately 15% of all kidney stones. Uric acid stones typically coincide with gout. These stones form when the pH of urine is more acidic. Unlike calcium stones, uric acid stones are not visible on x-ray films. They account for approximately 7% of kidney stones. Cystine stones are rare, making up approximately 1-3% of all kidney stones. However, they are the most common cause of stones among children. They are a result of cystinuria. Cystinuria occurs when there is a decrease in tubular absorption of cystine, a result of a genetic defect in renal transport.
Explain the difference between cortical nephrons and juxtamedullary nephrons.
Cortical nephrons make up 85% of all nephrons. They originate superficially in the cortex and have shorter loops of Henle that extend only a short distance into the medulla. Juxtamedullary nephrons make up the remaining 15% of all nephrons. They originate deeper in the cortex, and their loops of Henle are thinner and extend into the medulla entirely.
What are the 2 types of ATN?
Ischemic and Nephrotoxic
Name the structures of the nephron and describe their individual functions.
Each nephron consists of two parts, the glomerular capsule (renal corpuscle) and the renal tubule. These two structures are connected (through the tubule) to the associated collecting ducts. The glomerular capsule (renal corpuscle) filters the blood, while the renal tubule reabsorbs needed materials, and the collecting ducts carry the remaining material away as urine to be excreted.
Name two specialized structures of the glomerular capillaries that contribute to the filtration of blood.
Fenestrations and podocytes
Describe the process of Hemodialysis.
Hemodialysis utilizes an "artificial kidney" or hemodialysis system to filter the blood. It is composed of 3 parts: (1) a blood delivery system, (2) a dialyzer, and (3) a dialysis fluid delivery system. Blood circulates through the hollow dialyzer composed of bundles of capillary tubes. Dialysate (dialysis fluid) moves on the outside of the tubes. The walls of these capillary tubes are composed of semipermeable material which allows all molecules (except blood cells and plasma proteins) to move in both directions (from the blood into the dialysate and from the dialysate into the blood.) Waste products will diffuse into the dialysate. During dialysis treatments blood will flow from the patient's artery through the blood chamber in the dialysis machine (where it is filtered) and back into the patient's body through a vein. Vascular access is achieved via a shunt (implantation of tubing into an artery and a vein) or more commonly through an arteriovenous fistula (anastomosis of an artery to a vein.) Patients are put on blood thinners such as heparin to prevent blood clotting during treatment. Common symptoms that accompany dialysis treatment include nausea, vomiting, muscle cramps, headache, chest pain, and vertigo. Treatments are usually done 3 times each week and last 3-4 hours.
Define hypercalcemia using blood values.
Hypercalcemia occurs when plasma Ca2+ levels are greater than 10.5 mg/dL.
Define hyperkalemia using blood values.
Hyperkalemia occurs when plasma K+ levels rise above 5 mEq/L.
Define hypermagnesemia using blood values.
Hypermagnesemia is the result of blood Mg2+ levels rising above 3.0 mg/dL.
Define hypernatremia using blood values.
Hypernatremia occurs when plasma Na+ levels rise above 145 mEq/L with a serum osmolality greater than 295 mOsm/kg.
Define hypocalcemia using blood values.
Hypocalcemia is the result of Ca2+ levels falling below 8.5 mg/dL.
Define hypokalemia using blood values.
Hypokalemia occurs when plasma K+ levels fall below 3.5 mEq/L.
Define hypomagnesemia using blood values.
Hypomagnesemia occurs when plasma Mg2+ concentration is less than 1.8 mg/dL.
Define hyponatremia using blood values.
Hyponatremia occurs when plasma concentration falls below 135 mEq/L.
What are the 3 phases of ATN?
Initiating, maintenance, and recovery
Explain the differences in the two systems providing the blood supply to the nephron. How does their structure determine their role?
Nephrons receive their blood supply from 2 systems known as the glomerulus and peritubular capillary network. The glomerulus is a unique system in that it is located between 2 arterioles, afferent and efferent. Arterioles are high resistance vessels resulting in an extremely high-pressure system which can easily force fluid and solutes out of the blood into the glomerular capillary along its entire length. The peritubular capillaries are low-pressure vessels better suited for reabsorption as opposed to filtration. These capillaries surround the tubules in their entirety allowing rapid movement of solutes and water.
Describe the process of peritoneal dialysis.
Peritoneal dialysis utilizes the same principles of hemodialysis; however, the serous membrane of the peritoneal cavity serves as the dialyzing membrane. A catheter is surgically placed in the peritoneal cavity and is tunneled through subcutaneous tissue to its exit on the side of the abdomen. A sterile dialyzing solution is run through the catheter over a period of 10 minutes. The fluid will remain in the peritoneal cavity for a prescribed amount of time allowing metabolic waste products to diffuse into the solution. At the end of this time, the fluid is drained from the peritoneal cavity into a sterile bag. This type of dialysis can be done in a dialysis clinic or at home by the patient or caregiver. One of the major concerns with peritoneal dialysis is the risk for infection at the catheter exit site.
Be familiar with various diagnostic tests and treatments for renal Calculi.
Refer to section of the module on Renal Calculi: Diagnosis and Treatment
Describe the differences between renal-colic pain and non-colicky pain.
Renal colic pain is described as "colicky" pain brought on by the stretching of the collecting ducts or the ureter. This type of pain occurs as stones that are 1-5 mm in diameter move through the ureter and block flow. It is an acute, sharp pain that comes in waves and is felt in the upper, lateral quadrant of the abdomen and/or the back of the affected side. This is termed "flank pain." Pain can radiate to the lower abdominal region, bladder area, perineum, or the male scrotum. It can be accompanied by clammy, cool skin as well as nausea and vomiting. Non-colicky pain is caused by stones that distend the renal pelvis or renal calyces. It can be described as a deep, dull ache in the flank area. It varies in intensity from mild to severe.
Describe the functions of the nephron.
The function of the nephron is to control the concentration of water and soluble materials by filtering the blood, reabsorbing needed materials and excreting waste products as urine. The nephron thereby eliminates wastes from the body, regulates blood volume, pH and pressure, and controls the levels of electrolytes.
Describe the location of the hilus and its significance.
The hilus is a concave cleft, and it is at this point where the ureters, blood vessels, and nerves enter the kidney.
Discuss risk factors for the formation of renal calculi.
The levels of stone components in the blood and urine, anatomical changes of the urinary tract structures, metabolic and endocrine function, dietary and intestinal absorption, past history of UTIs, and supersaturated urine.
Compare and contrast the renal cortex and renal medulla. Discuss the structures found in each.
The outer cortex houses the glomeruli and convoluted tubules (proximal and distal) of the nephron as well as blood vessels. The inner medulla is comprised of the Loop of Henle of the nephron and cone-shaped masses also known as the renal pyramids.
What are the determinants of transplantation success?
The overall health of the recipient, the degree of compatibility between the donor and the recipient, and the management of recipient immunosuppression.
