29 Renal Physiology Flashcards

Flashcards covering the key concepts of renal physiology, including glomerular filtration, tubular reabsorption, and tubular secretion.

Glomerular Filtration

The process by which blood is filtered as it passes through glomerular capillaries in the kidneys.

Tubular Reabsorption

The process where fluid and solutes are reabsorbed from the filtrate and returned to the blood, mainly in the proximal tubules and nephron loops.

Tubular Secretion

The process where substances are secreted from the blood into the filtrate along the tubules.

Filtration

The separation of molecules by size, crucial in glomerular filtration.

Filtration Membrane Layers

Composed of: 1. Capillary endothelial cells. 2. Basal lamina. 3. Podocytes.

Glomerular Filtration Rate (GFR)

The amount of filtrate formed by both kidneys in 1 minute, normally around 125 ml/min.

Glomerular Hydrostatic Pressure (GHP)

The force of fluid on the wall of a container, equal to blood pressure (50 mm Hg), pushing H2O out of the capillary into the interstitial space.

Glomerular Colloid Osmotic Pressure (GCOP)

The pressure created by proteins in plasma (about 30 mm Hg), pulling H2O into capillaries by osmosis and opposing filtration.

Capsular Hydrostatic Pressure (CHP)

The pressure of filtrate inside the capsular space, about 10 mm Hg, opposing filtration.

Net Filtration Pressure (NFP)

Calculated as NFP = GHP - (GCOP + CHP), normally around 10 mm Hg.

Autoregulation of GFR

Maintaining a constant GFR through local responses, involving the myogenic mechanism and tubuloglomerular feedback.

Myogenic Mechanism

Vasoconstriction of blood vessels following stretch of smooth muscle in response to changes in blood pressure affecting GFR.

Tubuloglomerular Feedback

A process related to [NaCl] in the filtrate, where increased filtrate volume leads to macula densa releasing ATP, constricting the afferent arteriole, and decreasing GFR.

Angiotensin II

Preserves GFR, triggered by sympathetic stimulation, low GHP, and macula densa stimulation. Part of the renin-angiotensin-aldosterone system.

Atrial Natriuretic Peptide (ANP)

Produced by atrial cells in response to increased atrial volume. It decreases blood volume and pressure by dilating the afferent arteriole and constricting the efferent arteriole, increasing GFR.

Paracellular Route

A route of transport across epithelia where substances pass between adjacent tubule cells due to leaky tight junctions, especially in the proximal tubule.

Transcellular Route

A route of transport across epithelia where substances move through tubule cells involving carrier-mediated transport (facilitated diffusion, primary/secondary active transport).

Transport Maximum (TM)

The limit on the amount of a substance carrier proteins can transport. Once sites are filled, carrier proteins are saturated.

Obligatory Water Reabsorption

Water reabsorption that follows solute movement, primarily in the proximal tubule, facilitated by aquaporin channels.

Aldosterone Effect

Increases reabsorption of Na+ and secretion of K+, increases the number of Na+/K+ pumps, and affects H2O and Cl- reabsorption if ADH is present.

Antidiuretic Hormone (ADH) Effect

Causes a decrease in urine volume and an increase in H2O retention due to increased aquaporins and H2O reabsorption.

Atrial Natriuretic Peptide (ANP) Effect

Causes an increase in Na+ and H2O in urine, inhibiting ADH and aldosterone release, leading to less Na+ and H2O reabsorption.