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21 Cards in this Set
- Front
- Back
what is the main function of the urinary system [5]
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1. conserve H20, produce & excrete urine
2. Regulate blood volume & body fluids [Regulate Na+,K+,Ca2+,HPO42-,Cl-] [Regulate blood pH: excrete H+, conserve HCO3-] 3. Secrete erythropoietin for erythropoiesis 4. 1,25-hydroxycholecalciferol: synthesize vit D & Ca2+ metabolism 5. Renin secretion for angiotensin I, cleaving angiotensinogen & BP regulation |
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what to observe in urine production/secretion? [4]
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1. volume (normal 1.25 l/day with 75% water)
• polyuria, oligouria, incontinence, retention 2. Colour 3. Clarity (levels of cells, proteins, crystal/salt) 4. Smell/odour • urea breakdown • sweet & fruity (diabetes, ketones) • unpleasant (bacterial infection) • maple syrup (metabolic disorder) |
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clinical conditions of urinary system (5)
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1. PCKD
2. UTI, kidney infections 3. Frequent micturition (aged patients) 4. DM: hyperglycemia, polyruria, polydipsia 5. Diabetes insipidus: • lack of ADH or response → lose ability to reabsorb water from DCT & CD, leading to large volume of urine production (up to 22 l/day) • excessive thirst/excrete much severely diluted urine |
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Morphology of PCT (7)
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• simple cuboidal epithelium
• apical (faces filtrate) surface: many microvilli (luminal brush border) • basal (faces interstitial fluid) interdigitations • lateral surface between cells • strongly eosinophilic cytoplasma • no distinctive cell border • substances pass through cell wall |
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1. function of PCT (2)
2. how is this changed in DM? (2) |
1.
• Na+ & substances (amino acid, proteins & sugars) are removed. • Water follows passively 2. • conc. of glucose in filtrate exceeds rate of transport • high conc. of glucose in plasma, thus filtrate, reflected in glucose in urine |
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describe the histology of loop of Henle
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• initial part of desc. limb: simple cuboidal epithelium
• latter part: simple squamous epithelium • initial part of asc. limb: simple squamous epithelium • distal part: simple cuboidal epithelium |
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function of loop of Henle
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descending thin segment
• highly permeable to water: water moves into interstitial fluid then vasa recta • moderately permeable to urea, sodium, other ions ascending thin segment • not permeable to water • permeable to solutes. solutes diffuse out into more diluted interstitial fluid as ascending limb projects toward cortex |
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describe the histology of distal convoluted tubule (4)
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• simple, pale stain cuboidal epithelial cells,
• appear less in one section since shorter • few microvilli, less brush border on luminal surface, more distinctive border • smaller cell size |
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what are the common features between PCT and DCT (3)
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• found in cortex
• basolateral membrane interdigitation • numerous mitochondria |
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what is differential features between PCT and DCT (8)
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• PCT thicker wall, DCT thinner wall
• PCT smaller lumen, DCT larger lumen • PCT numerous microvilli, DCT no brush border • PCT indistinct cell boundary, DCT distinct cell boundary • PCT acidophilic cytoplasma, DCT less acidophilic • PCT fewer nuclei/XS, DCT more nuclei/XS • DCT stain darker than PCT |
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describe function of DCT (5)
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response to renin/angiotensin/aldosterone
• aldosterone fits into aldosterone receptor in DCT (which is behind basal & apical membrane) • ↑ synthesis of transport protein • countertransport of Na+ and H+ • active transport of Na+ and K+ • Cl- reabsorbed |
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morphology of collecting tubule (4)
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• similar to DCT, with larger lumen
• found in cortex, medulla, w. many in medullary rays • cells pale staining cytoplasm • tubules join to collecting ducts |
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what is the function of medullary CT? (3)
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• ↑permeability of CT to water in response to ADH [which is synthesized by hypothalamus & released by posterior lobe of pituitary]
• if ADH absent, water not reabsorbed. Urine is dilute • if ADH present, water moves OUT. Urine is conc. |
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describe histo (3) and function (1) of collecting duct
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• Large diameter w. simple pale staining cuboidal epithelium
• CD forms from many distal tubules • form medullary rays & lead to papillary ducts (ducts of Bellini) • reabsorb water |
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transitional epithelium:
• structure • function |
• S: epithelial cells change shape depending on amount of distention of organ
• F: accommodates fluctuations in volume of fluid in tube; protects against hypertonic urine |
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describe urine movement (4)
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• hydrostatic pressure forces urine through nephron
• peristalsis moves urine through ureters from renal pelvis to urinary bladder (from every few secs, to every 2-3 min) • PSNS ↑ frequency of peristalsis, SNS ↓ frequency • ureters enter bladder obliquely through trigone: pressure in bladder compresses ureter, preventing backflow |
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contrast male and female bladder/urethra (4)
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Female:
• 4 cm • opens into vestibule ant. to vaginal openine Male • 11cm • extends from inferior part of urinary bladder through penis |
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histology of female urethra (3)
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• pseudostratified columnar epithelium
• muscular walled tube w. transitional ep. near bladder • non-keratinized strat. squamous epithelium close to skin |
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histology of male urethra (4)
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urinary & reproductive function
• prostatic (transitional) • membraneous & cavernous (spongy) • penile (pseudo or stratified columnar epi) • non-keratinized strat. squamous epithelium in spongy urethra |
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structure (2) and function (4) of inferior urethra
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structure: (multiple layers of cells)
• cuboidal in basal layer, • progressively flattening towards surface (nucleus & cytoplasm still rained) Functions • protect against abrasion • protect vs caustic (silver nitrate, H2SO4) chemicals • protect vs water loss • protect vs infection |
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3 major cell types present in the JG apparatus, and outline the functions of each of these cell types
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JG cells:
- secrets renin which converts angiotensinogen (circulating in the plasma) to angiotensin I then cleave to form angiotensin II by angiotensin converting enzyme (ACE) Macula densa cells: Modified DCT cells - sensitive to osmolarity & volume of filtrate - regulates GFR [increase NaCl uptake → increase ATP to adenosine → increase vasoconstriction → GFR increase] - Detects the GFR & secretes prostaglandins which act on their receptors on the juxtaglomerular cells to regulate the renin secretion from the JG cells Lacis cells: - like mesangial cells with gap junction among them and juxtaglomerular cells → functional link between these cells |