Downing: Urinary System Flashcards
What are the components of the urinary system?
Kidneys
ureters
urinary bladder
urethra
What are the functions of the urinary system?
- Eliminate UREA and NITROGENOUS waste
- Maintain FLUID blance
- Maintain SALT balance
- Control acid-base balance
- ENDOCRINE fxn
How mechanisms does the kidney use to carry out its functions?
- filtration of blood plasma
- passive diffusion
- active secretion
- selective reabsorption
- exchange of hydrogen ions/formation of ammonia through acid-base regulation
What are the three layers of the capsule? What are their characteristics?
Innermost- capsule covers surface of kidney
middle- thick layer of fat
outermost- ct which binds kidney to surface structures
What passes through the hilus?
Renal artery
renal vein
nerves and lymphatics
What does the cortex contain?
renal corpuscles
medullary rays
What does the medulla contain?
6-18 pyramids (base lies adjacent to cortical tissue; tips (renal papillae) point towards minor calyces of renal pelvis
What is the area cribrosa?
Tip of the papilla
Perforated by 10-25 small openings where hte terminal segments of the uriniferous tubules open into the minor calyx
What are the renal columns?
Cortical substance that extends BETWEEN the medullary pyramids
What is the renal sinus?
Cavity/potential space occupied by: Renal pelvis major and minor calyces AVNL LCT/fat
What does a kidney lobe consist of?
Medullary pyramid and surrounding cortical tissue
GROSSLY visible
What does a kidney lobule consist of?
Straight tubules in a medullar ray and the cortical substance immediately surrounding the tubules.
MICROSCOPICALLY visible
What does the parenchyma consist of?
uriniferous tubules and blood vessels
What does a nephron do?
forms urine
What are the two layers of bowmans capsule?
Parietal layer (capsular epithelium) Visceral layer (glomerular epithelium)
Where is the parietal layer in bowmans capsule and what is it composed of?
Simple squamous
Begins where visceral layer is reflected at the vascular pole and is continuous with the proximal convoluted tubule at the urinary pole
What ishte visceral layer composed of?
PODOCYTES that are closely applied to the GLOMERULAR endotehlium (separated only by a thick basal lamina)
What are the two distinct poles of bowmans capsule?
- vascular (eff and aff arterioles enter and exit)
2. Urinary (parietal epith is continuous with cuboidal epith of prox CT)
What is the capsular space in bowmans capsule?
Lumen of hte tubule between the visceral and parietal epithelial layers.
Where does glomerular filtrate originally enter?
Capsular space (continuous with lumen of the proximal convoluted tubule)
What is the glomerulus?
Arterial vascular aparatus
Aff arterioles> fenestrated capillaries> capillaries reunite and form the eff arteriole
What composes the visceral epithelial layer of bowmans capsule?
Podocytes
What are hte components of a podocyte?
- Primary processes
- Secondary processes- interdigitate w/ elements of corresponding processes and surround the basal lamina of capillary endotehlium. Creates slit pores).
What are the components of the filtration apparatus?
- Capillary endotehlium (fenestrated capillaries)
- Basal lamina (find proteins and glycoprotein matrix)
- Slit pores (between adjacent interdigitating foot processes of podocytes)
How do the endothelial pores act as a barrier in the filtration apparatus?
Stop CELLULAR components of blood and large particles of plasma
How does the basal lamina act as a barrier in the filtration apparatus?
- holds back LARGE molecules
2. Hold back some CHARGED molecules
What are mesangial cells?
Similar to a pericyte–occur where adjacent capillaries are close together so that podocytes can’t totally surround them
What do mesangial cells do?
- keep glomerular filter free of debris
- provide support where basement membrane is lacking
- basement membrane turnover
What makes up the bulk of the renal cortex?
Proximal convultuted tubule and proximal straight tubule
What are tubules comprise of?
Simple high cuboidal OR
two columnar epitheliium
How is the cytoplasm of cells comprising the tubules unique?
More acidophilic than other tubules
What is seen on electron microscopy of proximal tubules?
- BRUSH BORDER (closely packed microvilli)- FUZZY
- Apical canaliculi
- Lateral cell membranes are highly folded
- MITOCHONDRIA in basal half of cell
- Basal processes of cells undermine each other and make it look like there is extensive infolding (striations)
What percent of water and NaCL is reabsorbed from the tubule?
65%
Na is ACTIVELY transported out, Cl and water follow