Mastery: Nephron Physiology, Glomerular Filtration
Rate (GFR), BUN & Creatinine Interpretation, RAAS
Regulation, Acid–Base Balance, Electrolyte & Fluid
Management, Urinalysis & Creatinine Clearance,
Acute & Chronic Renal Failure, Glomerulonephritis
& Nephrotic Syndrome, Pyelonephritis & Cystitis,
Urolithiasis, Urinary Incontinence Types, Renal
Cancer & Bladder Cancer, Dialysis Indicators,
Diuretic Pharmacology, Diagnostic Imaging (KUB,
IVP), and Post-Operative Nursing Care Exam
Questions Verified and Provided with A+ Graded
Rationales Latest Updated 2026
Nephron
The functional unit of the kidney
consists of the glomerulus, afferent and efferent arterioles, the Bowman's capsule, the proximal
tubule, the distal tubule, the Loop of Henle, collecting ducts (which converge open directly into
the renal pelvis which narrows to become the ureter).
Folly bag
Urometer to measure hour to hour intake and output.
Your patient is doing well if they are putting out what they are taking in hour per hour.
urometer where in the ICU we often monitor hour per hour intake and output. We like that
urine. Our patient is doing well. So, if you’re not putting out urine you are not doing well.
Blood Supply: Renal Artery
a major branch of the abdominal aorta.
It receives 20-25% of the cardiac output, or 1,200 ml/min.
Each afferent arteriole supplies a glomerulus.
Blood Supply: The glomerulus
,is composed of three filtering layers—the capillary endothelium, the base membrane, and the
epithelium. The glomerular membrane allows filtration of fluid and small particles. It limits the
passage of large molecules such as blood cells and albumin. The filtrate then moves into the
Bowman's capsule
Blood supply: Bowman's capsule.
Blood leaves the glomerulus via the efferent artery.
It subdivides into the peritubular capillaries and the vasa recta. These capillaries are extensive
and intimately associated with the tubules, allowing the movement of solutes and water
between the tubules and capillaries—where reabsorption and secretion occur
Urine Formation: nephrons
Urine is formed in the nephrons.
It is a complex process of glomerular filtration and tubular reabsorption and secretion.
Urine Formation: Glomerular filtration
·depends on adequate blood flow.
Factors that can alter blood flow, alter glomerular filtration rate.
These factors can be hypotension, decrease oncotic pressure.
And you remember that albumin is responsible for our oncotic pressure, increased pressure in
the tubules from obstruction
Damage to the glomerulus
Periodically small amounts of protein may be excrete, in less than 150 milligrams per deciliter,
persistence protein urea,
Urine formation: Filter fluid
enters the proximal tubal, about 180 liters per day.
It consists of water, electrolytes and other small particles.
Protein is generally not found in the urine.
Periodically small amounts may be excrete, in less than 150 milligrams per deciliter,
Urine Formation: Tubular reabsorption
o substance moves from the filtrate back into the paratubular capillaries
o of the 180 liters of filtrate 99% is reabsorbed,
o resulting in 1000 to 1500 ml of urine per day.
o Almost all reabsorption occurs in the proximal tubule.
o Glucose is completely reabsorbed and does not normally appear in the urine.
,Glycouria appears in the urine if
the amount of glucose in the blood and glomerular filtration exceeds the amount, the tubules
able to reabsorb
Urine Formation: Tubular secretion
o substance move from the para tubular capillaries into the tubulars filtrate
o Filtrate becomes concentrated in the distal to bowl and collection ducks under the influence
of anti-diuretic hormone and aldosterone.
Function of the Kidneys
· The kidneys regulate fluid and electrolyte balance,
· three parameters can be buried in order to maintain body fluids.
Urine volume.
Urine concentration. Urine content.
Function of the kidney: Urine volume
§ In a healthy person, the volume of urine produced each day can vary from as little as 300 ml a
day if no water is ingested or there is excessive loss.
§ Up to a maximum of 23 liters can be eliminated if excessive fluid is ingested, or there is lack of
anti diuretic hormones, such as in diabetes insipidus.
§ Healthy urine output cannot drop below 300mL a day, this is the absolute minimal water
volume required to excrete daily toxic load.
§ If the amount of waste product rises, the minimal urine volume must also arise.
§ Average urine output is 1500 ml for 24 hours.
§ The kidneys ability to vary urine volume is essential if body fluid is to maintain constant in face
of adverse factors such as:
§ excessive heat, sweating, diarrhea, or excessive ingestion.
Function of the Kidney: Urine content
§ Urine content range of substances in the urine varies.
§ It includes ions such as:
· sodium, potassium, calcium, magnesium, chloride, bicarbonate.
§ It includes waste,
, · urea, creatine, uric acid, bilirubin and metabolic acid,
§ Drug metabolites.
· Most drugs are toxified by the liver and excreted by the kidneys,
§ hormones.
· it degrades hormones, such as insulin.
· So therefore, when your kidneys start to fail, you start to have even more episodes of
hypoglycemia.
Function of the kidneys:
Urine concentration
§ Normal urine is clear
§ color varies depending on the concentration.
§ it can vary in color from pale straw.
·---If it's diluted
§ To dark amber
· ---if it's concentrated,
§ normal pH of the urine is 6
· but it can vary from 4 to 8 in cases of acidosis or alkalosis.
§ Although the volume of urine can vary, the amount of solids to be
§ excluded is less variable.
§ Healthy kidneys have the ability to excrete a fairly fixed volume of excess solutes in varying
amounts of water by concentrating or diluting urine.
§ Essential for maintaining a constant body osmolarity
§ Early in renal disease, the mechanism that controls concentration or dilution is lost.
§ Unable to control body, fluid volume and osmolarity and responses to changes fluids, intakes
and outputs, results in the individual tipping back and forth between states of dehydration to
fluid overload.
Normal urine specific gravity is
1.010 to 1.022