QUIZ 3 Flashcards
(43 cards)
The quantity of glomerular filtrate formed each minute in all the nephrons of both kidneys per kilogram of body weight. In humans, it is about 125 mL/min, with a total daily formation of 180 L.
Glomerular Filtration Rate (GFR)
The volume of blood delivered to the kidneys per unit time, playing a crucial role in maintaining GFR and kidney function.
Renal Blood Flow (RBF)
The percentage of renal plasma flow that becomes glomerular filtrate. Normally, about 19% of plasma flow (650 mL/min) is filtered into the nephrons (125 mL/min).
Filtration Fraction
A high plasma flow into the glomerulus maintains filtration by counteracting the increase in plasma colloidal osmotic pressure (COP), ensuring a steady filtration rate.
Effect of Renal Blood Flow on GFR
Constriction of the afferent arteriole decreases blood flow into the glomerulus, reducing GFR. Dilation of the arteriole increases glomerular pressure and GFR.
Effect of Afferent Arteriolar Constriction on GFR
Constriction of the efferent arteriole initially increases glomerular pressure and GFR. However, prolonged constriction raises plasma COP, leading to a slight decrease in GFR.
Effect of Efferent Arteriolar Constriction on GFR
Mild to moderate sympathetic stimulation constricts afferent arterioles, reducing GFR. Strong stimulation significantly decreases glomerular blood flow, potentially reducing GFR to zero.
Effect of Sympathetic Stimulation on GFR
A rise in arterial pressure (from 100 to 200 mmHg) leads to afferent arteriole constriction via autoregulation, preventing a major increase in glomerular pressure and limiting GFR increase to only 15-20%.
Effect of Arterial Pressure on GFR
The ability of renal blood flow (RBF) and glomerular filtration rate (GFR) to remain relatively constant despite changes in systemic arterial pressure (75-160 mmHg), maintained by intrinsic mechanisms independent of nerve supply.
Autoregulation of GFR & RBF in Animals
A mechanism that adjusts GFR based on changes in tubular flow rate, mediated by macula densa cells of the juxtaglomerular apparatus.
Tubuloglomerular Feedback (TGF)
The process by which plasma is filtered through the glomerular capillary membrane into Bowman’s capsule, forming the glomerular filtrate.
Glomerular Filtration
The net pressure forcing the fluid through the glomerular membrane, calculated as glomerular pressure minus the sum of glomerular colloidal osmotic pressure and capsular pressure.
Filtration Pressure
The movement of fluid from Bowman’s capsule to the renal pelvis, driven by hydrostatic pressure differences.
Tubular Transport
The process of transporting water and solutes from the tubular fluid to the peritubular capillaries.
Tubular Reabsorption
The movement of solutes from the peritubular capillaries into the tubular fluid.
Tubular Secretion
About 65% of sodium is reabsorbed in the proximal tubule, driven by the sodium-potassium ATPase pump.
Sodium Reabsorption
Water follows osmotic gradients created by sodium and solute reabsorption, with about 65% of water being reabsorbed in the proximal tubule.
Passive Transport of Water and Solutes
Proteins with molecular weight below 69,000 are reabsorbed in the proximal tubule by endocytosis and degraded into amino acids.
Reabsorption of Proteins and Peptides
The active or passive movement of ions from peritubular capillaries into the tubular fluid for excretion.
Tubular Secretion of Ions
The process by which hormones regulate kidney function, including fluid balance and electrolyte homeostasis.
Hormonal Regulation of Renal Function
The regulation of hydrogen ion concentration to maintain normal blood pH.
Acid-Base Balance
The lungs regulate pH by adjusting CO₂ levels through ventilation.
Respiratory Regulation of Acid-Base Balance
The kidneys regulate pH by excreting hydrogen ions and reabsorbing bicarbonate.
Renal Control of Acid-Base Balance
The regulation of body fluids and ions to maintain homeostasis.
Fluid and Electrolyte Balance
