General Principles of Renal Physiology

Flashcards about Renal Physiology

Kidney Functions

Maintaining H2O balance, osmolarity of body fluids, ECF ion regulation, plasma volume, acid-base balance, excreting metabolic end products and foreign compounds.

Erythropoietin

Hormone produced by kidneys that stimulates red blood cell production.

Renin

Enzymatic hormone produced by kidneys that triggers a chain reaction important in salt conservation.

Gluconeogenesis

The kidneys synthesize glucose from amino acids and other precursors during prolonged fasting.

Urinary System

Consists of the kidneys and the structures that carry the urine from the kidneys to the outside for elimination from the body

Nephron

Microscopic functional units in the kidneys (approximately 1 million per kidney) that form urine.

Renal Cortex

The outer region of a nephron

Renal Medulla

The inner region of the nephron, made up of striated triangles called renal pyramids.

Glomerular Filtration

The first step in urine formation, where about 20% of the plasma that enters the glomerulus is filtered.

Three Physical Forces in Glomerular Filtration

Glomerular capillary blood pressure, plasma colloid osmotic pressure, and Bowman’s capsule hydrostatic pressure.

GFR

Glomerular filtration rate; normally 125 ml/min.

Tubular Reabsorption

Selective movement of substances from inside the tubule into the blood.

Proximal Tubule Reabsorption

65% of total filtrate is reabsorbed (Water, electrolytes, glucose and aminoacids (100% efficiency)

Glycosuria

Increase blood sugar due to diabetes causes increase glucose in urine.

Descending Loop of Henle

Only permeable to water, leading to increased volume/osmolarity of filtrate.

Aquaporins

Water channels formed by specific plasma membrane proteins in the tubular cells.

Ascending Loop of Henle

Not permeable to water; 25% of ions (Na+, Cl-, K+) are reabsorbed.

RAAS

Renin-angiotensin-aldosterone system regulating Na.

Macula Densa Cells

Renal sensor elements that detect changes in distal tubular fluid composition and transmit signals to the glomerular vascular elements.

Tubular Secretion

Selective transfer of substances from the peritubular capillary blood into the tubular lumen.

Tubular Secretion Substances

Hydrogen ion (H+), potassium (K+), and organic anions and cations

Plasma Clearance

The volume of plasma completely cleared of that substance by the kidneys per minute.

Aldosterone

Hormone that stimulates K+ secretion by the tubular cells.