Kidney Structure and Glomerular Filtration Flashcards
(25 cards)
What are the main functions of the kidneys?
Excretion, regulation of blood pressure and volume, electrolyte balance, pH balance, and hormone production.
What is the functional unit of the kidney?
The nephron.
What are the two main regions of the kidney?
Cortex and medulla.
What is the pathway of urine flow from the nephron?
Nephron → collecting duct → renal pelvis → ureter → bladder → urethra.
What vessels supply blood to and from the glomerulus?
Afferent arteriole (in), efferent arteriole (out).
What are the components of a nephron?
Bowman’s capsule, proximal tubule, loop of Henle, distal tubule, collecting duct.
Where does filtration occur in the nephron?
In the glomerulus within Bowman’s capsule.
What is the glomerular filtration barrier composed of?
Fenestrated endothelium, basement membrane, and podocyte filtration slits.
What are podocytes and their role?
Specialized epithelial cells in Bowman’s capsule that form filtration slits.
What is the glomerular filtration rate (GFR)?
The rate at which plasma is filtered across the glomeruli (≈ 125 mL/min).
What factors influence GFR?
Hydrostatic pressure, oncotic pressure, and capsular pressure.
What is the role of hydrostatic pressure in GFR?
Drives fluid from capillaries into the nephron.
What is autoregulation of GFR?
Maintains stable GFR despite fluctuations in blood pressure.
How does myogenic regulation work in the kidney?
Smooth muscle contraction in afferent arterioles in response to stretch.
What is tubuloglomerular feedback?
Feedback from macula densa cells adjusting afferent arteriole tone.
What is the juxtaglomerular apparatus?
Structure where distal tubule contacts the glomerulus; regulates GFR and renin release.
What is the macula densa and what does it detect?
Cells in the distal tubule that sense NaCl concentration.
How does low NaCl at the macula densa affect GFR?
It stimulates renin release and dilates afferent arteriole to increase GFR.
What is the role of renin in kidney function?
Converts angiotensinogen to angiotensin I → angiotensin II → stimulates aldosterone.
How does the renin-angiotensin-aldosterone system (RAAS) affect blood pressure?
Increases sodium reabsorption, vasoconstriction, and water retention to raise BP.
What is filtered load?
GFR × plasma concentration of a substance.
What is net filtration pressure (NFP)?
Pressure driving filtration = glomerular hydrostatic − Bowman’s hydrostatic − oncotic.
What substances are freely filtered by the glomerulus?
Water, glucose, amino acids, small ions.
What does not normally pass through the filtration barrier?
Large proteins (e.g., albumin) and blood cells.
