Urinary System II Flashcards
Fluid filtered from the capillary blood into the bowman’s space and forms the primary urine
Filtrate
3 layers of the glomerular flitration membrane capillary wall
1) endothelium - with fenestrae
2) basement membrane
3) epithelial podocytes
Allows the fast movement of water through the epithelium of endothelial cells in the glomerular capillaries
Aquaporin 1 water channel
Principal component of filtration barrier - acts as a physical barrier and ion selective barrier
Glomerular Basement Membrane
Glomerular basement layers
Footlike extensions with filtration slits between extensions
specialized epithelium of visceral layer
Podocytes
composed of proteins: nephrin, CD2-associated protein, and podocin
Mutations in the glomerular podocytes can cause
Nephrotic syndrome
Glomerular Filtration Membrane:
(1) prevents the passage of large protein molecules
(2) prevents the passage of RBCs & WBCs
(3) prevents the passage of medium sized proteins
(1) glomerular basement membrane
(2) endothelium of glomerulus
(3) podocytes
Acts as the physical filter of the glomerular basement membrane
lamina densa
Act as the charge barrier of the glomerular basement membrane
via anionic sites
laminae rarae
Fate of filtration
Flat cells with fine cytoplasmic processes - controls glomerular blood flow
forms part of the juxtaglomerular apparatus
mesangial cells
Mesangial cells with their extracellular matrix
also attached to the capillaries and glomerulus
Mesangium
Mesangial cells located outside the corpuscle along the vascular pole
Lacis cells
3 cellular components of the Juxtaglomerular Apparatus
1) macula densa
2) extraglomerular mesangial cells
3) juxtaglomerular cells or granular cells
Specialized smooth muscle cells of afferent arteriole which contains renin in secretory granules
Juxtaglomerular cells
Location of the macula densa
terminal distal straight tubule adjacent to renal corpuscle
Site of blood pressure regulation via renin-angiotensin-aldosterone (RAA) system
Located at the vascular pole of Bowman’s capsule
Juxtaglomerular apparatus
Cells act as baroreceptors and chemoreceptors
(1) Has chemical composition similar to that of blood plasma but contains almost no proteins
(2) contains water, electrolytes as well as waste products (urea, uric acid, creatinine) and breakdown products of various substances
(1) primary urine - ultrafiltrate
(2) final urine
Determine which kidney tubule, given the function
1) reabsorbs solutes and water from the filtrate
2) reabsorbs Na and Cl from the filtrate into the interstitial fluid
3) filters small solutes from the blood
4) selectively secretes and absorbs different ions to maintain blood pH and electrolyte balance
5) aquaporins allow water to pass from the filtrate into the interstitial fluid
6) reabsorbs ions, water and nutrients; removes toxins and adjusts filtrate pH
1) collecting duct
2) ascending loop of Henle
3) glomerulus
4) distal convoluted tubule
5) descending loop of Henle
6) proximal convoluted tubule
Urine formation process
1) filtration
2) reabsorption
3) secretion
Cells of the proximal convoluted tubule
simple cuboidal epithelium w/ eosinophilic granular cytoplasm
Have microvilli on their luminal surface
actively reabsorbs from the filtrate, reabsorption of 60-65% of the water via osmosis
Initial and major site of reabsorption
- reabsorbs nearly all glucose, amino acids, and polypeptides
- proteins and polypeptides are endocytosed
- recovers most of the fluid from the ultrafiltrate of blood
Proximal convoluted tubule
Maintains the adhesion between neighboring cells at the proximal convoluted tubules
tight narrow junctions and zona adherens
