renal final - Sheet1 Flashcards
What is the function of the glomerulus?
The glomerulus is a group of capillaries that filter blood. It allows small solutes like glucose, sodium, and urea to pass into Bowman’s capsule while blocking large solutes like RBCs, platelets, and proteins.
What is the Glomerular Filtration Rate (GFR)?
GFR is the amount of plasma filtered by the glomerulus per minute. Normal GFR is 125 mL/min.
How is GFR related to renal blood flow?
GFR is directly related to perfusion pressure in the capillaries. If mean arterial pressure decreases or vascular resistance increases, GFR decreases.
What are the 3 processes that regulate renal blood flow?
- Autoregulation, 2. Neural regulation, 3. Hormonal regulation (RAAS).
How does autoregulation maintain GFR?
Autoregulation keeps GFR consistent by adjusting afferent arterioles. When systemic BP increases, afferent arterioles constrict to maintain GFR; when BP decreases, they dilate to increase GFR.
What is the role of the sympathetic nervous system in renal regulation?
When BP drops (e.g., in shock), the SNS causes vasoconstriction in the kidneys, reducing renal blood flow and GFR to help conserve blood volume and maintain BP.
What does RAAS regulate?
RAAS regulates blood volume, electrolyte balance, and systemic vascular resistance. It increases BP by stimulating the release of aldosterone, which promotes salt and water retention.
What is the role of aldosterone?
Aldosterone increases BP by promoting sodium and water reabsorption in the kidneys, which increases blood volume and systemic vascular resistance.
How does antidiuretic hormone (ADH) affect the kidneys?
ADH increases blood pressure by promoting water reabsorption in the distal tubules and collecting ducts of the kidneys.
What is the function of natriuretic peptides?
Natriuretic peptides inhibit sodium and water reabsorption in the kidneys, vasodilate arterioles, and increase urine production, helping to reduce pressure on the heart.
What hormones are activated or synthesized by the kidneys?
Vitamin D (activated in the kidneys for calcium absorption) and erythropoietin (stimulates RBC production in response to low oxygen levels).
How is vitamin D activated in the kidneys?
Vitamin D is activated in two steps: first in the liver, then in the kidneys by the action of parathyroid hormone. The activated form helps with calcium absorption in the intestines.
What is the role of erythropoietin?
Erythropoietin is secreted by the kidneys in response to low oxygen levels and stimulates the bone marrow to produce RBCs.
What are renal clearance tests?
Renal clearance tests measure how much of a substance is cleared from the blood by the kidneys per unit of time, providing information on kidney function and GFR.
What is the normal range for blood urea nitrogen (BUN)?
The normal range for BUN is 10-20 mg/dL. It is a waste product from protein breakdown.
