Term
What is the basic functional unit of the kidney? How many are there in each kidney? |
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Definition
nephron about one million |
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Term
| What are the two main activities of the nephron? |
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Definition
selective reabsorption & secretion of the ions mechanical filtration of fluids, wastes, electrolytes, and acids & bases |
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Term
Components of the nephron (6) |
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Definition
glomerulus bowman's capsule proximal convoluted tubule loop of henle distal convoluted tubule collecting tubule/duct |
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Term
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Definition
beginning of the nephron; a tuft of capillaries branching off the afferent arteriole; the blood is filtered by the glomerulus & this ultrafiltrate enters Bowman's capsule **more permeable than any other body membrane |
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Term
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Definition
layer of epithelial cells surrounding the glomerular capillaries; it collects newly formed untrafiltrate that is passed to tubules connects with the first portion of the proximal tubule into which the filtrate flows |
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Term
| Proximal convoluted tubule |
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Definition
- located in the cortex of the kidney; filtrate flows into the proximal tubule from Bowman's capsule & then passes into the Loop of Henle
- site of reabsorption of glucose, amino acids, metabolites & electrolytes form filtrate; reabsorbed substances return to circulation
- 80% of filtrate reabsorbed here
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Term
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Definition
- U-shaped nephron tubule lecated in the medulla & extending from the proximal convoluted tubule to the distal convoluted tubule; site for further conc of filtrate through reabsorption
- water & Na ions continue to be reabsorbed here
- descending: not permeable to electrolyes; only water
- ascending: 10-30% Na absorbed here
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Term
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Definition
- site from which filtrateenters the collecting tubule
- Further absorption as needed:
- if the pt is hypovolemic, ADH will cause more water to be reabsorbed back into circ
- renin system activated
- (5-10% Na reabsorbed here)
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Term
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Definition
flitrate flows into the collecting duct from the distal tubule & then empties into the calyx into the renal pelvis & to the ureter releases urine (3-5% Na reabsorbed here) |
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Term
Types of nephrons (not clinically important) |
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Definition
Cortical Juxtamedullary (this is where meds work) |
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Term
| about 20% of the blood plasma entering the kidneys is filtered from the ____ into _____ |
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Definition
glomerular capillaries Bowman's capsule |
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Term
| In a 70kg person, the avg vol of fluid filtered from the plasma into Bowman's capsule is ____ L/day. thus, the entire plasma volume is filtered by the kidney 60x/day! |
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Definition
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Term
| describe the filtrate in the Bowman's capsule |
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Definition
- free of proteins & blood cells but contains most LMW plasma components in about the same conc as are found in the plasma
- these include: glucose, sodium bicarbonate, amino acids, other organic solute, electrolytes (such as Na, K, Cl)
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Term
| Kidney regulates the ionic composition & vol of urine by the reabsorption or secretion of ions and/or water at five functional zones along the nephron: |
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Definition
Proximal convoluted tubule Descending loop of Henle Ascending loop of Henle Distal convoluted tubule Collecting duct |
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Term
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Definition
| act by diminishing NaCl reabsorbtion at different sites in the nephron, thereby increasing urinary sodium choloride and water losses |
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Term
| Diuretic drugs are ion transport inhibitors that decrease the reabsorption of Na at different sites in the nephron, as a result, Na & other ions such as Cl enter the urine..... |
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Definition
| at greater amts than normal along with water, which is carried passively to maintain osmotic equilibrium |
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Term
| Diuretic drugs ___ the volume of urine, change it's pH & change ionic composition of the urine & blood. |
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Definition
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Term
| major clinical uses of Diuretic drugs: |
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Definition
| managing disorders involving abnormal fluid retention (edema) or in treating HTN in which their diuretic action causes a decrease blood vol, leading to a reduction in blood pressure |
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Term
| Diuretics are classifed according to: (4) |
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Definition
chemical structure pharmacologic activity mechanism primary site of action within the nephron |
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Term
| what is a major determinant of diuretic potency? |
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Definition
| site of action within the nephron |
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Term
| Carbonic Anhydrase (CAH) Inhibitors |
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Definition
inhibit the action of CAH enzyme which decreases reabsorption of water, Na, K & HCO3 also, raise the seizure threshold and decrease the formation of aqueous humor in the eye by inhibiting CAH enzyme in the CNS |
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Term
Enzyme CAH is found primarily in _______. CAH catalyzes the formation of: |
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Definition
the proximal convoluted tubular epithelium CO2 and H20 from H2CO3; absence of CAH leads to H & HCO3; the result is increased urinary excretion of HCO3 & Na, leading to diuresis |
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Term
| CAH inhibitors are more often used for their _____ rather than for their ____ effect; they are much less efficacious than other ____. |
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Definition
other pharmacologic actions diuretic effect diuretics |
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Term
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Definition
acetazolamind (Diamox) (memorize both names) |
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Term
| CAH Inhibitors are derivatives of ___. Acetazolamide is a ___ w/o antibacterial activity. |
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Definition
sulfonamide abx sulfonamide |
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Term
| Pharmacotherapeutics of CAH Inhibitors |
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Definition
- treatment of glaucoma (open-angle) is the most common use; useful in chronic tx but should not be used in acute attack (decreases prod. of fluid)
- Mountain sickness: prophylaxis/tx of mountain sickness, in which individuals rapidly ascend above 10,000ft elevation
- given nightly for 5 days before ascent prevents the symptoms of the syndrome (weakness, breathlessness, dizziness, nausea, cerebral/pulmonary edema)
- tx of edema: rarely used b/c mainly excretes Na2CO3, not NaCl & edema fluid is not mobilized unless Cl ions are excreted w/ Na ions
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Term
| Pharmacokinetics of CAH inhibitors |
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Definition
PO, IM, IV, ophthalmic drops well distributed int he tissue, crosses the placenta & passes into breast milk excreted in urine (PCT) |
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Term
| contraindications of CAH inhibitors: |
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Definition
- sulfonamide hypersensitivity
- electrolyte imbalances (pH) **most important thing to monitor
- long term use in glaucoma (b/c used "in btwn" laser tx)
- severe renal & hepatic disease (b/c metabolized 50%, excreted 50%)
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Term
| Adverse effects of CAH inhibitors |
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Definition
- metabolic acidosis (mild) - b/c lose HCO3
- potassium depletion (hypokalemia) in circ --> all diuretics cause this!
- renal stone formation
- drowsiness
- paresthesia (tingling due to decreased Ca) b/c Na, Ca, Mg not reabs. so excreted in urine
- hyperglycemia (b/c some channels for glucose reabsorb. are taken up)
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Term
| Nursing management for CAH inhibitors |
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Definition
assess for allergy to sulfonamides monitor I & O admin. PO doses w/ food monitor BP for postural hypotension montior blood glucose if pt has DM (most diurectis cause hyperglycemia) teach pt not to double a dose if one is missed |
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Term
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Definition
increase the osmotic pressure of the glomerular filtrate (in lumen & circ) by remaining highly concentrated in the renal tubule,causing water tobe dreawn into the blood stream from the extracellular fluid compartment only a small amt of Na is excreted, thus not useful in tx conditions on which Na rentention occurs cause diuresis even when renal circ & glomerular filtration are impaired as in shock or dehydration freely filtered but not reabs & not metabolized so no direct effect on the body; do not significantly affect electrolytes (so amt injected will be same as amt excreted) |
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Term
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Definition
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Term
| pharmacotherapeutics of osmotic diuretics: |
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Definition
reduction of ICP & IOP; mainstay of tx of increased ICP caused by cerebral edema (b/c will dehydrate the area quickly) tx of acute chemical poisoning by increasing excretion of toxic substances prevention of acute renal failure (oliguria-low urine output) due to shock or trauma (increases blood supply to kidney to improve function) |
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Term
| pharmacokinetics of osmotic diuretics |
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Definition
not absorbed orally; can be administered only IV excreted unchanged in the urine |
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Term
| contraindications of osmotic diuretics: |
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Definition
anuric renal failure (kidney is not producing urine) - b/c fluid & mannitol would never be excreted & would build up acute intracranial hemorrhage CHF & pulmonary edema (b/c will just worsen it) |
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Term
| adverse effects of osmotic diuretics |
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Definition
- increased blood vol caused by mannitol can recipitate/worsen CHF (pump may fail due to circ. overload)
- HAs, blurred vision (b/c increased circ vol)
- n/v/d
- marked diuresis
- electrolyte imbalances
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Term
| nursing management for osmotic diuretics |
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Definition
| ensure infusion is given through a filter (can cause precipitate otherwise) |
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Term
| Loop (high-ceiling) Diuretics |
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Definition
- peak effect is much greater than that of other diuretics
- most potent diuretics, producind the greatest vol of diuresis (urine prod) & the highest efficacy in mobilizing Na & Cl from the body
- act primarily on thin ascending loop of Henle (the part of the nephron responsible for concentration urine)
- increase water excretion by blocking reabs. of Na & Cl in loop of Henle; resulting in decreased osmolarity of the interstitial fluid surrounding the collecting ducts, which impedes the ability of the kidneys to concentrate urine; excretion of large amts of urine w/ high levels of NaCl result; increased secretion of K, Mg, Ca also
- systemic heodynamic effects; by increasing venous capacitance, they reduce L Vent. filling pressure & relieve pulmonary edema if present
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Term
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Definition
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Term
| pharmacotherapeutics of loop diuretics |
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Definition
pulmonary edema or CHF (drug of choice) systemic edema drug of choice (edema associated w/ nephritic syndrome), liver disease HTN (possible, not ideal drug) tx of hypercalcemia (in circ) - increases Ca in urine which decreases amt in body |
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Term
| pharmacokinetics of loop diuretics |
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Definition
admin. PO, IM, IV duration of action 1-4 hrs (IV = 2 hrs) |
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Term
| contraindications of loop diuretics |
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Definition
- caution w/ concurrent use w/ other ototoxic drugs
- infants/elderly
- contraindicated in: allergy to sulfonamides, anuria, severe electrolyte depletion (esp K) - b/c the channel we're modifying is very potent, dehydration, lactation, hepatic coma
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Term
| drug interactions with loop diuretics |
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Definition
- digitalis: increased risk of digitalis toxicity; increased risk of electrolyte imbalances that can trigger arrhythmias (b/c hypokalemia)
- Lithium: excretion reduced, increased tox. risk
- reduction of the hypoglycemic effect of oral antidiabetic drugs (which reduce sugar levels), possible result in hyperglycemia
- antihypertensive agents: potentiate action
- Salicilates:decreased elimination of salicilates, increased risk for toxicty (b/c takes excratory sites)
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Term
| adverse effects of loop diuretics |
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Definition
- ototoxicity (transient w/ furosemide) - sign = ringing in ears
- hyperuricemia/gout exacerbation: competes w/ uric acid for the renal & hepatic secretory systems, thus blocking its secretion from the body
- acute hypovolemia/orthostatic hypotension
- electrolyte depletion (hypocalcemia, hypomagnesemia, hypokalemia, hyponatramia, hypocholoremia)
- photosensitivity (always w/ sulfa drugs!!)
- neg. effect on lipid profile (decrease HDL, increase LDL)
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Term
| Nursing management for loop diuretics |
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Definition
- admin in AM to avoid voiding at noc
- recommend diet high in K (bananas, orange juice)
- take w/ food
- avoid sun exposure
- report ototoxicity
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Term
| Thiazides & related agents |
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Definition
- most widely used diuretic drug (weak)
- sulfonamide derivatives, related in structure to CAH inhibitors
- work by preventing Na from being reabsorbed in the kidney; as Na is excreted, it pulls water along with it
- also, excretion of Cl, K, Mg, HCO is increased
- work in distal convoluted tubules (cortical diluting tubule)
- They also:
- augment Ca absorption in distal tubule
- relax arterial smooth muscle & reduce PVR
- interfere w/ insulin release (dose dependent, but my actualy create diabetics due to increased glucose levels)
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Term
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Definition
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Term
| pharmacotherapeutics of thiazides |
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Definition
- first line tx in HTN; take 1-3 wks to produce stable reduction in BP
- used in tx of edema (extracellular fluid) in CHF & renal impairment
- may be useful in tx of hypercalcuria (inhibit urinary Ca excretion, improve Ca metabolism) & tx of calcium oxalate stones in the urinary tract
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Term
| contraindications of thiazides |
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Definition
hypersensitivity to sulfa anuria (b/c drug is excreted in urine) renal insufficiancy (IF SEVERE!) pregnancy (all diuretics harmful to fetus) |
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Term
| drug interactions with thiazides |
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Definition
- may increase blood glucose levels requiring higher doses of insulin & oral antidiabetic drugs
- antihypertensive agents: potentiateaction of other antihypertensive drugs (synergistic) - good
- digitalis: potentiate digitalis toxicity by inducing hypokalemia
- lithium: increased serum lithium levels by redcing ints renal excretion (b/c use same channel)
- anticoagulants (oral): decreased effect
- ETOH & CNS depressants: increased sedation
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Term
| adverse effects of thiazides |
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Definition
electrolyte imbalances dehydration increased LDLs, TC, TGs hyperglycemia hyperuricemia photosensitivity |
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Term
| Potassium-sparing Diuretics |
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Definition
act in the distal tubule to inhibit Na absorption & K secretion - aldosterone antagonists: counteract effects of aldosterone by competing for aldosterone receptor sites in distal tubules; as a result, Na & water are excreted & K is retained
- nonaldosterone antagonists directly inhibit the exchange of Na & K in tubule; Na is eliminated & K is retained
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Term
Common potassium-sparing diuretics 2 subcategories |
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Definition
aldosterone antagonists spironolactone (Alton) nonaldosterone antagonists amyloidal (Marimar) |
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Term
| pharmacodynamics of potassium sparing diuretics |
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Definition
- have weaker diuretic & hypertensive effects than others, but have the advantage of conserving K
- most often used in combo w/ thiazides or loop diuretics to counteract excessive K loss
- extremely important that pts treated w/ any K-sparing diuretics be closely monitored for K levels
- exogenous K supplementation is usually stopped when K-sparing diuretic therapy is instituted
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Term
| pharmacotherapeutics of potassium-sparing diuretics |
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Definition
adjunctive therapy w/ other diuretics to minimize K loss edema associated w/ CHF, cirrhosis of the liver & nephritic syndrome only PO |
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Term
| contraindications of potassium-sparing diuretics |
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Definition
- hyperkalemia, especially if used w/ a K supplementation or high K diet
- hypersensitivity
- caution in infants/elderly
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Term
| drug interactions w/ k-sparing diuretics |
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Definition
- ACE inhibitors: may cause hyperkalemia
- Digitalis: decreased effect
- lithium: reduce renal clearance of lithium
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Term
| Adverse effects of potassium-sparing diuretics |
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Definition
spironolactone: - gynecomastia in males, hirsutism, mentrual irregular bleeding, deepening of voice
- sexual dysfunction
- hyperkalemia
nonaldosterone antagonists: - n/v, leg cramps, dizziness, hyperkalemia
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Term
| nursing implications with K-sparing diuretics |
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Definition
counsel pt to avoid large amts of K-rich food warn pt not to use salt substitutes avoid tasks that require alertness/coordination until response to drug is known use sun protection |
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