Role of the Kidney (pH, BP, fluid balance) Flashcards
What is the primary role of the kidney in fluid balance?
The kidney regulates the volume and composition of body fluids by adjusting the amount of water excreted in urine.
Which hormone helps the kidneys regulate water reabsorption?
Antidiuretic hormone (ADH).
How do the kidneys respond to dehydration?
They conserve water by increasing water reabsorption, producing concentrated urine.
Which part of the nephron is mainly responsible for sodium reabsorption?
The proximal tubule and the ascending limb of the loop of Henle.
What hormone promotes sodium reabsorption in the distal nephron?
Aldosterone.
How do the kidneys help maintain electrolyte balance?
By selectively reabsorbing or excreting ions such as Na⁺, K⁺, Ca²⁺, Cl⁻, and phosphate.
How do the kidneys regulate blood pH?
By excreting hydrogen ions (H⁺) and reabsorbing bicarbonate (HCO₃⁻).
What happens to H⁺ and HCO₃⁻ when the blood is too acidic?
The kidneys excrete more H⁺ and reabsorb more HCO₃⁻ to increase blood pH.
What happens when the blood is too alkaline?
The kidneys retain H⁺ and excrete more HCO₃⁻ to decrease blood pH.
Which part of the nephron is most important in acid-base regulation?
The distal tubule and collecting duct.
How do the kidneys contribute to blood pressure regulation?
By controlling blood volume and releasing renin, which starts the RAAS (Renin-Angiotensin-Aldosterone System).
What does renin do?
Renin catalyzes the formation of angiotensin I, which is converted to angiotensin II—a vasoconstrictor that raises blood pressure.
How does aldosterone affect blood pressure?
It increases sodium and water reabsorption, which raises blood volume and pressure.
What is the effect of angiotensin II on blood vessels?
It causes vasoconstriction, increasing systemic vascular resistance and blood pressure.
What role does the kidney play in long-term blood pressure regulation?
It adjusts extracellular fluid volume and systemic vascular resistance through water and sodium balance and RAAS activation.
