Ch. 25 Review Flashcards
Identify the structures of the kidneys
- Cortex
- Medulla
- Pyramids
- Columns
- Pelvis
- Calyces (Calyx)
- Hilium
- Fibrous capsule
What are the structures of a nephron?
- Glomerulus (incl. glomerular capsule, afferent & efferent arterioles)
- Proximal convoluted tubule
- Nephron loop
- Distal convoluted tubule
- Collecting duct
Cortical nephrons are found mainly in the ____ of the kidney
cortex
Juxtamedullary nephrons extend far into the ____
medulla
Where are the peritubular capillaries or Vasa Recta found?
Surrounding the renal tubules
What is the juxtaglomerular complex?
The region where the most distal portion of the ascending limb of the nephron loop lies against the afferent arteriole
What are the three populations of cells in the juxtaglomerular complex?
- Macula densa cells
- Granular cells
- Extraglomerular mesangial cells
What is the function of macula densa cells?
Chemoreceptors that monitor the NaCl content of the filtrate
What do granular cells do?
Sense blood pressure in the afferent arteriole and secrete renin
What is the filtration membrane?
A porous membrane allowing free passage of water and solutes smaller than plasma proteins
What are the components of the filtration membrane?
- Fenestrated endothelium of glomerular capillaries
- Visceral membrane of the glomerular capsule (podocytes)
- Basement membrane
List the three steps of urine formation
- Glomerular filtration
- Tubular reabsorption
- Tubular secretion
What is glomerular filtration?
A passive process where hydrostatic pressure forces fluids and solutes through the filtration membrane
What is net filtration pressure (NFP)?
The positive pressure due to forces pushing fluids out of the capillaries being greater than forces pushing fluids back in
How is glomerular filtration rate (GFR defined)?
The volume of filtrate formed each minute by all glomeruli in the kidneys
What regulates GFR?
- Intrinsic controls
- Extrinsic controls
What are intrinsic controls of GFR?
- Myogenic (stretch)
- Renal autoregulation/tubuloglomerular mechanism
What role does the sympathetic nervous system play in GFR?
It releases norepinephrine & epinephrine to constrict afferent arterioles, lowering GFR
What are the roles of the kidneys in maintaining body homeostasis?
- Control the excretion of ions
- Monitor blood pH
- Maintain osmotic balance
- Monitor blood pressure
What is tubular reabsorption?
The movement of molecules from renal tubules back into the blood
Where does tubular reabsorption primarily occur?
Proximal convoluted tubule (PCT)
What substances are reabsorbed during tubular reabsorption?
- Glucose
- Amino acids
- Water
- Electrolytes (Na+, K+, Cl-, Ca2+)
What features facilitate mass reabsorption in proximal convoluted tubule cells?
- Microvilli increasing surface area
- Large number of mitochondria
- Permeable tight junctions
What is tubular secretion?
The movement of substances from blood into the filtrate
