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Urinalysis Chapter 2
Renal Function
Question | Answer |
---|---|
What are the components of the urinary system? | Kidneys, ureters, urethra, and bladder. |
Name the functions of the kidneys? | Removes waste products from blood, maintains water & electrolyte balance, formation of urine, and elimination of uric acid, urea, and creatinine. |
What are some of the other functions of kidneys? | Regulation of pH, excretion of drugs and toxins, excretion of urobilinogen, excretion of conjugated bilirubin, secretion of hormones: renin, erythropoietin, 1,25-digydoy Vit D3 and prostagladins. |
What is the nephron? | A functional unit of the kidney that forms urine. |
What percentage of nephrons are found in the cortex and what is the name of it? | Cortical nephron and 85% |
What is the responsibility of the cortical nephron? | Primarily for removal of waste products and reabsorption of nutrients. |
What is the function of the Juxamedullary Nephron and where is it located? | Primarily function is concentration of urine and they extend deep into the medulla. |
What are the functions of the nephron? | Renal blood flow, glomerular filtration, tubular reabsorption, and tubular secretion. |
The type of Nephron responsible for renal concentration is the | Juxtaglomerular |
The function of the peritubular capillaries is | Reabsorption and Secretion |
Blood flows through the nephron in the following order: | Afferent arteriole, peritubular capillaries, vasa recta, efferent arteriole |
Filtration of protein is prevented in the glomerulus by: | Capillary pores |
Renin is secreted by the nephron in the response to: | Low systemic blood pressure |
The primary chemical affected by the renin-angiotensin-aldosterone system is: | Sodium |
Secretion of renin is stimulated by: | Macula densa cells |
The hormone aldosterone is responsible for: | Sodium retention |
The fluid leaving the glomerulus has a specific gravity of: | 1.010 |
All of the following are reabsorbed by active transport in the tubules except: | Urea |
Which of the tubules is impermeable to water: | Ascending loop of Henle |
Glucose will appear in the urine when the: | Blood level of glucose is 200 mg/dL, Tm for glucose is reached, Renal threshold for glucose is exceeded |
The countercurrent mechanism takes place in the: | Juxtaglomerular nephrons |
ADH regulates the final urine concentration by controlling: | Tubular permeability |
When the body is dehydrated: | ADH production is increased |
Bicarbonate ions filtered by the glomerulus are returned to the blood: | In the proximal convoluted tubule, Combined with hydrogen ions, and By tubular secretion |
If ammonia is not produced by the distal convoluted tubule, the urine pH will be: | Basic |
The largest source of error in creatinine clearance tests is: | Improperly timed urine specimens |
Values for creatinine clearance tests on children are corrected for: | Body size |
Variables that may be included in estimated creatinine clearance calculations include all of the following except: | Urine creatinine |
An advantage to using cystatin C to monitor GFR is: | It does not require urine collection, It is not secreted by the tubules, and It can be measured by immunoassay |
Solute dissolved in solvent will: | Decrease vapor pressure |
Substances that may interfere with measurement of urine and serum osmolarity include all of the following except: | Sodium |
The normal serum osmolarity is: | 275-300 mOsm |
After controlled flui intake, the urine-to-serum osmolarity ratio should be at least: | 3:1 |
Calculate the free water clearance from the following results: urine volume in 6 hours: 720 mL,urine osmolarity: 225 mOsm, plasma osmolarity: 300 mOsm | +5 |
To provide an accurate measure of renal blood flow, a test substance should be completely: | Cleared on each contact with functional renal tissue |
Given the following data, calculate the effective renal plasma flow: urine volume in 2 hours: 240 mL, urine PAH: 150 mg/dL,Plasma PAH: 0.5 mg/dL | 600 mL/min |
Renal Tubular acidosis can be caused by the: | Inability to produce an acidic urine due to impaired production of ammonia |
Tests performed to detect renal tubular acidosis after administering an ammonium chloride load include all of the following except: | Arterial pH |
What is the approx. total renal blood flow? | 1200 ml/min |
What is the approx. total renal plasma flow? | 600-700 ml/min |
The function of the glomerulus? | Nonselective filtration of substances with MW<70,000, and formation of ultrafiltrate |
The plasma filtrate passes through what 3 cellular layers? | capillary wall membrane, basement membrane, and visceral epithelium of Bowman's capsule. |
What are the effects of low plasma Na? | decrease water retention within circulartory system (dehydration), decreases overall blood volume, and causes a drop in systemic blood pressure. |
What is passive transport? | Movement of molecules across a membrane by diffusion because of a physical gradient. |
What is active transport? | Movement of a substance across cell membranes into the bloodstream by electrochemical energy. |
What must occur for active transport? | the substance to be reabsorbed must combine with a carrier protein contained in the membranes of the renal tubular cells. |
What is active transport responsible for? | reabsorption of glucose, amino acids, and salts in the proximal convoluted tubule, chloride in the ascending loop of Henle, and sodium in the distal convoluted tubule. |
Where does passive transport take place in and what does it reabsorb? | Water is reabsorped and it takes places in all parts of the nephron except the ascending loop of Henle. Urea is also passively reabsorbed in the proximal convoluted tubule and the ascending loop of Henle. |
What is tubular reabsorption? | it reabsorps essential substances and water from filtrate into the blood. |
What is reabsorption of water controlled by? | by the osmotic gradient in medulla and concentration of vasopressin (ADH) |
What does high levels of ADH mean? | retain H2O an increase Specific gravity |
What does low levels of ADH mean? | loss of H2O, an decrease in specific gravity |
What does the Glomerular Filtration Test do? | measures glomerular filtration rate, rate at which the glomerulus is able to remove a substance from the blood. |
What does the GFR determine? | it determines the number of functioning nephrons and the functional capacity of those nephrons. |
What does 125I-iothalamate determine? | determines glomerular filtration through plasma disapperance of the radioactive material and enables visualization of the filtration in one or both kidneys. |
What is Beta2Macroglobulin and what does it do? | molecule formed by dissociation from HLA Ag, sensitive indicator of decrease in filtration rate. |
What is the creatinine clearance test? | measure the rate at which creatinine is filtered by the glomerulus. |
What is the formula for creatinine clearance test? | UC*TV(ml/min)/SC*1.73/SA |
What are the clinical usages for the creatinine clearance test? | evaluate extent of nephron damage in known renal disease, monitor treatment, determine feasibility of administering medications. |