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28 Cards in this Set
- Front
- Back
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What are the functions of the urinary system?
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1. filtration and excretion
2. Balance body fluid 3. reabsorption of small molecules (AA, glucose), ions (Na+, Ca2+, Cl- etc.) and water in order to maintain homeostasis 4. Regulate blood pressure by producing enzyme renin 5. produces erythropoietin (EPO) |
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Describe features of the kidney
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encapsulated by dense CT and retroperitoneally located; contains the following:
1. Renal sinus-medial concavity; contains renal pelvis and nerves 2. Renal hilum- contains renal sinus 3. Cortex-outer region that underlies the capsule; contains renal corpuscles, proximal and distal tubules, peritubular capillaries and medullary rays 4. Medulla-surrounds renal sinus; consists of medullary pyramids 5. Medullary pyramids-base at cortex and apex (renal papillae) pointed toward the renal sinus; contains collecting ducts, loops of Henle, vasa recta 6. Medullary rays-Straight portion of the nephrons together with the single collecting ducts. 7. Renal lobes-consist of medullary pyramid with associated cortical region; lateral boundaries are the renal columns. 8. Renal lobules-cortical structure; medullary rays in the center of renal lobes that empty into its collecting tubules and are surrounded by interlobular arteries and veins 9. Minor calyx-cup shaped wall surround each papilla 10. Major calyx-convergence of 2-3 minor calyxes 11. Renal Pelvis-convergence of major calyces which is continued into the ureters |
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describe the vasa recta
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formed by efferent arterioles, associated with Juxta Meduallary (JM) Nephrons; provides O2 and nourishment to medulla
thin, straight vessels go into the medulla and then loop back into the corticomedullary junction descending vessel-continuous type capillary ascending vessel-fenestrated endothelium |
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What's the renal interstitium?
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the space between uriniferous tubules and blood and lymph vessels; contains connective tissue with fibroblasts amd collagen fibers
medulla renal interstitium-also contains a highly hydrated ground substance rich in proteoglycan |
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What are interstitial cells?
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contain cytoplasmic lipid droplets and are implicated in synthesis of EPO, prostaglandins, and prostacyclin
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Describe the anatomy of the uriniferous tubules
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Uriniferous tubules-contain Nephron and collecting duct
1. Nephron-Consist of Renal corpuscle and renal tubule a. Renal tubules- Consist of Proximal convoluted tubule (PCT); Loop of Henle (LoH); Distal convoluted tubule (DCT) b. renal corpuscle: Cortical nephron-short LoH; Juxtamedullary nephron-long LoH 2. Collecting duct a. Cortical collecting tubule (CCT) b. Outer medullary collecting tubule (OMCT) c. Inner medullary collecting tubule (IMCT) |
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Describe the PCT
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Lined by cuboidal epithelium w/ basolateral infolding and interdigitation
acidophilic cytoplasm due to numerous mitochondria abundant lysosomes and vesicles; cell apex has abundant microvilli forms a brush border surrounded by peritubular capillaries |
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Describe the LoH
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U-shaped structure consisting of descending and ascending limbs, each has thick and thin segments
Thick segment lined by low cuboidal, while thin segment lined by squamous epithelial cells Thin descending limb (tDLH) freely permeable to water; the entire ascending limb is impermeable to water |
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Describe the DCT
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lined w/ shorter cuboidal epithelial cell and lack brush border
connects w/ vascular pole of renal corpuscle of its parent Nephrons, where it is modified; cells become columnar, nuclei closely packed together and apically located (called MACULA DENSA) ion exchange in DCT if aldosterone is present; Na is absorbed and K ions secreted also secretes H+ and NH4- ions into tubular urine to regulate acid-base balance. |
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Describe the macula densa
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Cells of macula densa are sensitive to ionic content and water volume of tubular fluid, producing molecular signals that promote liberation of enzyme RENIN from the smooth muscle of afferent arteriole into the circulation
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Describe the collecting duct
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large straight duct which widens on approach to tip of medullary pyramids
lined by 2 types of cuboidal epithelial cells-Principal and Intercalated cells principle cell-basal infolding; acts as mechanosensor; absorbs Na and water and secretes K intercalated cells-apical microvilli; secrete H+ and HCO3- |
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Describe the path of urine
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urine leaves collecting duct at the area cribrosa and enters the minor calyces then into the major calyces; after that the urine leaves the kidney passing through the renal pelvis and the ureter into the urinary bladder where it is stored
urine will be excreted outside the body by the urethra. All the passages contain the same structures-mucosa, muscularis and adventitia/serosa |
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Describe the transitional epithelium (TE)
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stratified epithelium that is impermeable to H2O and salts
Started w/ 2 layers at the calyces and increased to 4-5 layers in the ureter and many more in the bladder cells of this epithelium have the capability to accommodate distension by unfolding and flattened the underlining cell, reduced the number of layers and increase the surface area individual cells are cuboidal in shape; those on the surface are dome shaped surface TE apical plasma membranes exhibit “plaques” that can adjust to large changes in the surface area TE covers mucosa of all excretory passages up to the first part of male urethra |
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describe the ureter
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conducts urine from renal pelvis to urinary bladder
TE lines luminal surface; wall composed of smooth muscles and CT smooth muscles are arranged into three layers: a. Inner longitudinal b. Middle circular c. Outer longitudinal outer longitudinallayer-present only at the distal end of the ureter ureter is embedded in the retroperitoneal adipose tissue. When the bladder is distended the ureters are compressed, reducing of reflux of urine into the ureters |
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describe the urinary bladder
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distensible reservoir for the urine; located in the pelvis posterior to the pubic symphysis
contains three openings; two for ureter and one for urethra defining a smooth triangular region called Trigone;rest of the wall of the bladder is folded and thick trigone-originated from the mesonephric duct rest of the wall-originated from the cloaca wall is lined by several layers TE when empty, and 3 layers when distended muscular coat of the bladder is made up of smooth muscles that are not regularly organized into distinct layers; At the opening of urethra, the smooth muscle forms sphincter bladder supplied by sympathetic and parasympathetic nerves; sensory fibers to sacral portion of the spinal cord are afferent fibers of micturition reflex |
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Describe general characteristics of the urethra
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fibromuscular tube that conveys urine from the bladder to exterior through external urethral orifice; lining epithelium changes throughout its length
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Describe the male urethra
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serves as terminal duct for urine and genital system
1. Prostatic urethra-lined by TE; many prostatic ducts empty into this segment 2. Membranous urethra-Lined by stratified or pseudostratified columnar epithelium 3. Penile urethra-opens at glans penis; surrounded by corpus spongiosum throughout its length; Lined w/ pseudostratified columnar epithelium that becomes stratified squamous epithelium toward the distal end where it continues w/ skin of the penis |
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Describe the female urethra
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short (3-5 cm); runs from urinary bladder to vestibule of the vagina; lined with stratified squamous epithelium which becomes keratinized near the urethral meatus; Lamina propria is highly vascularized and has inner smooth muscle and outer striated muscle
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Describe the renal corpuscle
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located in cortex; 2 kinds of renal corpuscles
1.Subcapsular/Cortical 2. Juxtamedullary renal corpuscle is spherical in shape and contains filtration apparatus which consists of glomerular endothelium, basement membrane and the parietal layer of Bowman’s capsule Each corpuscle has one afferent arteriole which breaks down into a capillary tuft (glomerulus) which eventually forms efferent arteriole leaving the corpuscle; afferent and efferent arterioles form the vascular pole |
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Describe Bowman's capsule
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surrounds the glomerulus; consists of parietal and visceral layers
Parietal layer-simple squamous epithelium; continues into the PCT where it changes into cuboidal or low columnar epithelium to form the renal pole; supported by a basal lamina and thin layer of reticular fibers; not involved in the filtration process of the renal corpuscle Visceral layer-contains Podocyte (visceral epithelial) cells which extend their processes around the capillaries, and develop numerous secondary pedicles which interdigitate with the foot process of the neighboring cells both layers create renal space between them which is continued into the PCT |
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Describe the filtration apparatus
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separates urinary space from the blood in the capillaries
contains podocytes, basement membrane, and filtration slits |
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describe podocytes
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contain bundles of actin microfilaments in their cytoplasm, giving them contractile capacity
cell body contains secondary processes called PEDICELS that embrace capillaries of glomerulus pedicels directly contact the basal lamina; podocytes don't touch basement membrane |
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describe the basement membrane
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located b/t fenestrated endothelial cells of the capillaries and podocytes
made up of lamina densa sandwiched by lamina rara; fibronectin binds them to the cells Lamina densa-composed of type IV collagen and laminin w/ proteoglycan heparan sulfate; restricts passage of cationic molecules Glomerular basement membrane is a selective macromolecular filter 1. lamina densa-physical filter 2. lamina rara-charge barrier |
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describe filtration slits
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formed by interdigitation between secondary processes of podocytes (pedicels); bridged by diaphragm
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What does the juxtaglomerular apparatus contain?
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mesangial cells
macula densa juxtaglomerular cells |
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describe mesangial cells
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contractile cells that adhere to glomerular capillary walls
contain receptors for angiotensin II; upon activation, glomerular flow is reduced also contain receptors for Natriuretic factor; upon activation, relaxes mesangial cells, causing vasodilation and increased blood flow other mesangial cells functions: 1. provide structural support to glomerulus 2. synthesize Extracellular matrix 3. endocytose and dispose of immune-complex molecules trapped by glomerular basement membrane 4. produce chemical mediators such as cytokines and prostaglandins extraglomerular mesangial cells-mesangial cells that are located in the vascular pole |
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describe macula densa
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Lay adjacent to the Afferent and efferent arterioles and mesangial cell; line the straight distal convoluted tubules; become tall and closely packed w/ an apical nuclei
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describe juxtaglomerular cells
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constitute smooth muscle of the wall of the afferent and sometimes efferent arterioles; contain spherical nucleus
cytoplasm contains secretory granules that secrete “renin”. |
