renal system Flashcards
(20 cards)
What do the components of the functional kidney test (ELE table) mean?
Electrolytes (e.g., Na⁺, K⁺, Cl⁻): Assess ion balance and kidney filtration efficiency.
Urea and Creatinine: Indicators of kidney function; high levels may indicate reduced GFR.
GFR (Glomerular Filtration Rate): Measures the filtering capacity of the kidneys.
Urinalysis (pH, protein, glucose): Detects abnormalities in kidney excretion processes.
How do the results of someone with typical working kidneys differ from someone with kidney problems in a functional kidney test?
Healthy kidneys: Balanced electrolytes, low urea/creatinine, normal GFR (~90+ mL/min/1.73m²).
Kidney dysfunction: Electrolyte imbalances, high urea/creatinine, low GFR.
What are the different types of nephrons?
Cortical nephrons: Located in the cortex, short loop of Henle, less concentrated urine.
Juxtamedullary nephrons: Located near medulla, long loop of Henle, concentrates urine effectively.
What is the counter-current system in the loop of Henle?
The counter-current multiplier mechanism allows urine concentration:
Descending loop: Water is reabsorbed.
Ascending loop: Ions (Na⁺, Cl⁻) are reabsorbed.
Opposing flows maintain an osmotic gradient for efficient water reabsorption.
What are the structural differences between cortical and juxtamedullary nephrons?
Cortical: Short loops, mainly filter blood, located in the cortex.
Juxtamedullary: Long loops into the medulla, critical for concentrating urine.
Outline the path of blood flow from the renal artery to the renal vein.
Renal artery → Segmental artery → Interlobar artery → Arcuate artery → Cortical radiate artery → Afferent arteriole → Glomerulus → Efferent arteriole → Peritubular capillaries/vasa recta → Cortical radiate vein → Arcuate vein → Interlobar vein → Renal vein.
Why is kidney blood flow unique compared to other organs?
It has two capillary beds (glomerular and peritubular/vasa recta) linked by efferent arterioles, allowing for both filtration and reabsorption.
What is the relationship between renin and blood pressure?
Renin converts angiotensinogen to angiotensin I, which is converted to angiotensin II, leading to vasoconstriction and aldosterone release, increasing blood pressure.
How does the sympathetic nervous system impact renin secretion?
The SNS activates β1-adrenergic receptors in the juxtaglomerular apparatus, stimulating renin release.
What is the purpose of the RAAS system?
To regulate blood pressure and fluid balance by promoting vasoconstriction (angiotensin II) and sodium reabsorption (aldosterone).
What hormones are involved in fluid homeostasis and their functions?
ADH: Promotes water reabsorption in collecting ducts.
Aldosterone: Increases sodium reabsorption, indirectly conserving water.
ANP: Reduces sodium reabsorption, promoting fluid excretion.
What is the purpose of vasoconstriction in fluid homeostasis?
To maintain blood pressure and ensure adequate organ perfusion during low fluid volume.
How do osmotic diuretics work?
They prevent water reabsorption by increasing solute concentration in the nephron, promoting water excretion.
What are angiotensin receptors, and how are they influenced by kidney hormones?
Angiotensin receptors bind angiotensin II, mediating vasoconstriction and aldosterone release. Blockers (ARBs) inhibit these effects, reducing blood pressure.
What is the role of the kidney in acid-base balance?
The kidney reabsorbs bicarbonate (HCO₃⁻) and excretes hydrogen ions (H⁺) to maintain blood pH.
How does the renal system compensate for metabolic acidosis (e.g., diabetic ketoacidosis)?
The kidneys increase H⁺ excretion and reabsorb more HCO₃⁻ to buffer the blood.
What is the significance of renal ammonium (NH₄⁺) excretion in acid-base balance?
NH₄⁺ excretion provides a buffer for H⁺ ions, crucial for acid-base regulation in chronic acidosis.
How does the sympathetic nervous system influence sodium reabsorption in the kidney?
The SNS activates α-adrenergic receptors, increasing sodium reabsorption in the proximal tubule.
What is the purpose of sodium (Na⁺) and electrolytes like phosphate (PO₄³⁻) in active reabsorption?
Na⁺ drives water reabsorption via osmotic gradients, and PO₄³⁻ aids in pH buffering and metabolic functions.
What are the primary waste products excreted by the kidney?
Urea, creatinine, ammonia, uric acid, excess electrolytes, and drug metabolites.
