Renal System Flashcards
What are the functions of the kidney?
Filter metabolic products and toxins from the blood and excrete them as urine
Regulate the body fluid status, electrolytes, and acid-base balance
Humoral regulation of blood pressure and flow
What does the cortex of the kidney have?
Glomeruli and highly convoluted epithelial structures in the form of tubules
What does the medulla of the kidney have?
Parallel arranged tubules and small blood vessels
What is the nephron?
The basic structural and functional unit of the kidney
What makes up the renal corpuscle?
The glomerulus, Bowman’s space, and Bowman’s capsule
What are filtration slits?
Interdigitations connected by the slit diaphragm
Where is the largest portion of the glomerular filtrate retreived?
The proximal tubule
What are the main functions of the loop of henle?
Assisting in the formation of concentrated or dilute urine, increasing osmolarity of the interstitial space
What is the main function of the distal tubule and collecting duct?
Performing fine control of electrolyte and water excretion
What is the juxtaglomerular apparatus?
The region where the glomerulus makes contact with the thick ascending limb of the loop of henle
What does sympathetic stimulation of the kidney do?
Causes vasoconstriction, sodium reabsorption in the proximal tubules, and renin secretion
What are the three processes of the kidney?
Glomerular filtration, tubule reabsorption, and secretion
What is renal clearance?
The virtual volume of plasma that would be totally cleared of a solute in a given time
Why isn’t inulin used to determine GFR?
It has to be given intravenously and is difficult to measure
What endogenous metabolite is often used to measure GFR?
Creatine phosphate
Why is a high glomerular filtration rate essential?
To maintain stable and optimal extracellular levels of solutes and water
What are the four elements of a glomerular filtration barrier?
Endothelial cells, glycocalyx on the endothelial cells, glomerular basement membrane, and epithelial podocytes
What are the three determinants of the filterability of solutes across the glomerular filtration barrier?
Molecular size, electrical charge, and molecule shape
What determines fluid movement across the capillary wall?
Capillary hydrostatic pressure difference and colloid osmotic pressure difference
Why does the glomerulus filtration rate exceed other regions of the body?
Greater starling forces and higher capillary permeability
Which two forces favour ultrafiltration?
Hydrostatic pressure in the glomerular capillary and oncotic pressure in the Bowman’s space
Which two forces oppose ultrafiltration?
Hydrostatic pressure in the Bowman’s space and oncotic pressure in the glomeruli
What are the two unique features of the renal microvasculature?
Two major sites of resistance (afferent and efferent arterioles) and the two capillary beds in series
Which capillary bed favours filtration and which favours reasorption?
The glomeruli favours filtration and the peritubular capillaries favours reabsoption
What is the myogenic response?
Afferent arterioles have the ability to respond to changes in vessel circumference by contracting or relaxing
What is tubuloglomerular feedback?
Macula densa cells sense increase in GFR which translates into contraction of afferent arterioles and decreases GFR
What kind of transport drives the movement of solutes and water across different sections of the nephron?
Transepithelial transport
What is one of the main jobs of epithelial cells?
To work against the laws of thermodynamics to impact the movement of substances
What is an important feature of epithelial cells that helps mediate movement of ions?
Two membranes with asymmetrical distribution of transporters
What do membrane bound carriers rely on to move solutes?
The cumulative thermodynamic gradient of the substances being moved
Where are the three membrane potentials in an epithelial cell?
The entire endothelial cell, the basolateral membrane, and the apical membrane
What causes paracellular electrical coupling to occur?
Large shunts which allow a lot of current movement through the paracellular space
How does water move through a cell?
It moves from regions of low solute to high solute. It can not be actively transported
What is osmolarity?
A measure of the solute concentration
This is the number of osmoles per liter
Where does reabsorption in the kidney occur and in what quantities?
The proximal tubule (67%)
Loop of Henle (25%)
Convoluted tubule, connecting tubule, initial collecting duct, and cortical collecting tubule (5%)
Medullary collecting ducts (3%)
How is sodium transported across the apical membrane of the proximal tubule?
Cotransporters (glucose, amino acids, etc.) and Na-H exchanger
How is sodium transported across the basolateral membrane of the proximal tubule?
Na-K pump and Na-HCO3 co-transporter
Backleak through the paracellular pathway