Renal Flashcards
(29 cards)
What are the primary functions of the urinary tract system?
→ Filters blood excretes metabolic waste
What happens in acidosis in terms of cardiac and respiratory effects?
→ Bradycardia and hyperventilation.
How does the kidney influence drug therapy?
→ It is the site of drug excretion requiring dose adjustments in renal impairment.
Where are the kidneys located?
→ In the abdominal cavity—left kidney inferior to the spleen right inferior to the liver.
Name 5 key functions of the kidney.
→ 1. Blood pressure & volume regulation 2. Electrolyte & pH balance 3. Nutrient reabsorption 4. RBC production via erythropoietin 5. Toxin & drug excretion
What is found in the cortex vs. the juxtamedullary region?
→ Cortex: Bowman’s capsule short loop of Henle. Juxtamedullary: Long loop of Henle
Why is renal blood flow important?
→ Ensures filtration efficiency and delivery of oxygen/nutrients.
Trace the path of filtrate through the nephron.
→ Afferent arteriole → Glomerulus → Efferent arteriole → PCT → Loop of Henle → DCT → Collecting duct
What are the functions of each nephron segment?
→ Glomerulus: Filtration. PCT: Reabsorption & secretion. LOH: Electrolyte & water reabsorption. DCT: Na+ reabsorption K+/H+ secretion. CD: ADH-dependent water reabsorption.
How is net filtration pressure calculated?
→ BHP (55 mmHg) - CHP (15 mmHg) - OP (30 mmHg) = 10 mmHg
Net Filtration Pressure =
Pressure pushing fluid out (BHP)
– Pressure pushing fluid back in (CHP)
– Pressure pulling fluid back in (OP)
= 55 mmHg – 15 mmHg – 30 mmHg
= 10 mmHg
What is the normal GFR?
→ 90–120 mL/min/1.73m²
How is MAP calculated?
→ MAP = Diastolic + 1/3(Systolic - Diastolic)
What are the two intrinsic regulation mechanisms?
→ 1. Myogenic: Stretch → Na+ influx → Vasoconstriction 2. Tubuloglomerular feedback: High NaCl → ATP → Adenosine → A1 receptor → Ca²⁺ → Vasoconstriction
What are the two extrinsic mechanisms regulating GFR?
→ Neural: Sympathetic NS → Noradrenaline → Vasoconstriction. Hormonal: RAAS (vasoconstriction) & ANP (vasodilation).
Describe the stages of urine formation.
Glomerular Filtration (Out)
In the renal corpuscle
Filters unbound small molecules (electrolytes, amino acids, glucose, metabolic waste, drugs)
Determined by GFR
2. Tubular Reabsorption
Na+ Reabsorption:
Against concentration gradient via Na+/K+ pump
Water Reabsorption:
Through aquaporins & osmosis
Nutrient & Ion Reabsorption:
Coupled with Na+ transport via luminal membrane transporters
3. Tubular Secretion
Removes protein-bound drugs, metabolites, toxins, & waste products
Excretes nitrogenous compounds: urea, creatinine, ammonia, uric acid
Secretes organic acids (acidic drugs) & organic bases (alkaline drugs)
What drives water reabsorption in the collecting duct?
→ ADH → Aquaporin-2 expression
What is normal 24-hr urine osmolarity?
After 12-14 hrs water restriction? → 500–800 mOsm/kg; ~850 mOsm/kg
What causes high vs low urine osmolarity?
→ High: Dehydration SIADH
What is the normal range of urine specific gravity?
→ 1.005–1.03
What does increased vs decreased specific gravity indicate?
→ ↑ = dehydration ↓ = overhydration
What is the countercurrent multiplier system?
→ Loop of Henle + vasa recta create osmotic gradient for water reabsorption.
How does ADH affect urine concentration?
→ ↑ADH: Water reabsorption → Concentrated urine. ↓ADH: Less reabsorption → Dilute urine.
What role does urea play in urine concentration?
→ Recycled in medulla via UT-A1/3 → raises medullary osmolality → promotes water reabsorption
