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41 Cards in this Set
- Front
- Back
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Cortical Nephrons |
FOund in the cortex where they remove waste a reabsorb nutrients. |
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What blood vesile supplies the kidney? |
Affrent Arteriol |
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Where dose the Glomerulus recive it's blood from? |
The Affrent Arteriol |
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Efferent Arteriole |
From which blood leaves the glomerulus. |
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Vasa Recta |
Adjacent to the Loop of Henle
Most water and salt exchange
Maintains medulla osmotic gradient. |
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Blood flow order through nephron |
Renal Artery --> Afferent Arteriole --> Glomerulus --> Efferent Arteriole --> Proximal Convoluted Tubules --> Vasa Recta --> Distal Convuluted Tubules --> Renal Vein |
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Renal blood flow: |
~1200mL/min |
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Renal Plasma flow: |
~600-700mL/min |
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What is the size limit on glomerular filtration? |
Must be an MW of 70,000 or less |
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What are the cells layers of the glomerulus? |
Capillary Wall Membrane: Contain pores to increase permiability.
Basal Lamina (Basement Membrane): Restricts the passage of large molecules
Bowman's Capsule Inner Layer: "podocytes" Membrane covered filtration slits. |
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What is the charge of the glomerula? |
It is negative to repel proteins.
Albumin is positive, but is to large to pass through. |
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What are the impacts of high/low blood pressure on the glomerula? |
High: Smaller Afferent Arteriole to prevent over filtration and collarteral damage.
Low: Smaller Afferent and Efferent Arteriole to prevent a decrease in flow |
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Renin-Angiotensin-Aldosterone System |
Controla the flow of blood through the glomerulus.
Triggered by Low plasma sodium and decreased water retention: Renin from Juxtaglomerular cells --> Angiotensinogin --> Angiotensin 1 --> Angiotensin Converting Enzyme --> Angiotensin 2 --> Aldosterone |
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Angiotensin 2 |
Dialates afferent arteriole and constricts efferent arteriole.
Stimulates sodium reabsorbtion in proximal convuluted tubule
Triggers the release of aldosterone and antidiuretic hormone (ADH) |
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Aldosterone: |
Causes the reabsorbtion of sodium in the distal convuluted tubule and collecting duct. Also increases potasium excretion.
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ADH |
Stimulates water reabsorption on Collection duct. |
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Glomerular filtrate stats |
120mL/min of filtrate, most of this water is reabosrbed.
Made up of plasma without cells or protein
Has a specific gravity of 1.010 |
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Active reabsorbtion mechanim |
Substances must combine with a carrier protein from the renal tube membrane. They are then moved into the blood via elctrochemical energy.
Applies to the reabsorbtion of glucose, amino acids, and salts in the proximal convoluted tubule. Cholride in the in the ascending loop of henle, and sodium in the distel convuluted tubule |
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Passive reabsorbtion mechanisms |
Work off concentration gradients.
Applies to water in all parts of nephron except the ascending loop of henle; urea in the proximal convuluted tuble and ascending loop of henle and sodium in the ascending loop of henle |
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Maximum reabsorption capacity (Tm) |
Occurs when a substance that is typically fully absorbed reaches abnormally high levels. They will not be absorbed and show up in the urine. |
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Renal Threshold |
The plasma concentration where at which active transport stops.
Glucose: 160-180mg/dL |
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Tubular Concentration of Filtrate |
Begins in the descending and ascending loop of henle.
Water removed via osmosis in the descending loop of henle
Sodium and Chloride are reabosobed in the ascending loop which cannot absorb water.
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Concentration of filtration in the collecting duct |
Depends on the osmotic gradient and presence of ADH.
More ADH = More water absorbed
No ADH = very dilute urine |
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Tubular secretion |
The passage of substances from the blood to the in the peritubular capillaries to the tubular filtrate |
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Acid-Base Balance |
Blood buffered by Bicabonate ion(HCO3-), whic are regulary filtered and reabsorbed to retain proper pH
Bicarbonate is protonated to prevent it's filtration, and the un-protonated to return to the blood as bicarbonate thanks to carbonic anhydrase. |
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How is excess hydrogen excreted? |
Combine with phosphate ion instead of bicarbonate.
Reacting with ammonia to for ammonium |
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What substances can test glomular filtration rates? |
Creatinine, Cystine C, Beta2-microglobulin |
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What is the most common clearance rate test? |
Creatinine is the most commonly used in clinical labs to measure GFR.
Since creatinine is naturally produced by the body there are many factors that can raise or lower it. It is also broken down by bacteria in the urine if samples area allowed to sit. |
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GFR formula |
C = (urine creatin mg/dL) (Urine Volume mL/min) / Plasma creatin mg/dL
Normal range = 107-139 mL/min (men) 87-107 mL/min (women) |
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Modification of Diet in Renal Disease Study Formula |
GFR = (175)(Serum Creatinine^-1.154)(Age^-.203)(.742 if female)(1.212 if Black) |
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Advantages of Cystatin test |
Readily filtered and reabsorbed
Broken down by the tubules, not secreted
Levels not impacted by muscle mass |
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Beta2-microglobulin test |
This is an enzyme assay
Rise a in plasma levels are the best indicator of a lowered filtration rate.
unrelaiable if patient has immune disorders or cancer |
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Freezing Point Osmometry |
A small amount of urine is super cooled, so that a slight shock causes it's temeprature to instantly rise to the freezing, which the machine measures.
A lower freezing point means more solutes. |
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Renal Concentrating Ability Test |
Perfomed after fluid deprevation, measures urine and serum osmolaity
After 12 hour deprevation take a sample and test if it is an osmolarity greater than or equal to 800
if not, deprive for 2 more hours then recollect urine and serum samples. If urine to serum is not 1:3 or if osmolarity is not greater than or equal to 800, something is wrong
Inject with ADH and take samples again after 2-4 hours. If results are normal, they cannot produce ADH, if not they do not react to ADH at all. |
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Vapor Pressure Osmometer |
Measures the urines dew point using a thermocupler. This is compared to an NaCl standard.
Reported in miliosmoles |
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Osmometry interference |
Lipemic samples are very disruptive, as is lactic acid.
Volantile substances have normal readings in the vapor pressure test, but elevated results in freezing test |
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Normal urine Osmolarity |
Serum = 275-300 mOsm
Urine = 50-1400 mOsm |
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Free water clearance test |
Cosm = (Uosm x Vol) / Posm |
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P-Amminohippuric acid test |
Used to test renal blood flow, secreated by proximal convuluted tubules
Loosly bound to proteins and removed when it comes into contact with renal tissue. |
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PAH test |
C-PAH = (U-PAHmg/dL x V mL/min) / P-PAHmg/dL
8% never contacts renal tissue and is peed out.
On average this is 1200mL/min |
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Titratable Urine Acidity/Ammonia |
Measures H+ and NH4+in the urine
70 mEq/day is normal
Alkaline Tide: lowest pH at night.
Renal tubular acidosis means there is a metabolic acidosis.
Total acidity - Tirtatable acidity = ammonia
PCT = H+
DCT = NH3 |
