Lecture 15: Urinary System Flashcards

1
Q

Kidney structure

A

Several lobes w/ cortex + medulla. Each lobe = multiple lobules

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2
Q

Hilum

A

Aka hilar region/hilus. Region where renal artery, vein, and ureter enter the kidney.

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3
Q

Renal sinus

A

CT space between lobes continuous with the hilus. Contains first major vessel branches and distal ureter branches (aka major/minor calyces)

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4
Q

Medullary pyramid

A

Structure shaped by epithelia-lined minor calyces. Separates renal sinus from medullae of lobes

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5
Q

Collecting ducts

A

Series of tubes extending into medulla; extension of calyx lumen. Each drains several nephrons via short tangential collecting tubules.

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6
Q

Ducts of Bellini

A

Area of collecting ducts opening up to minor calyx.

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7
Q

Medullary ray

A

Collection of collecting ducts in medulla, defines center of corticle lobule

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8
Q

Nephron

A

Basic functional unit of kidney. Contains 1 highly folded tubule and a capillary bed.

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9
Q

Glomerulus

A

Encapsulated capillary bed at distal end of nephron. Located in cortex; tube descends and returns through the medulla.

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10
Q

Juxtaglomerular apparatus (JGA)

A

Returning DCT comes in close approximation to the originating glomerulus. Set of structures for signaling filtration efficiency

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11
Q

JGA structures

A
  1. Macula densa
  2. Extraglomerular mesangial cells (lacis cells)
  3. Juxtaglomerular cells
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12
Q

Macula densa (JGA)

A

Concentrated nuclei of JGA on side of glomerulus. Senses filtrate salt balance at apical surface. Communicates with other JGA cells via paracrine signals.

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13
Q

Extraglomerular mesangial cells

A

Aka lacis cells. Nearby CT cells sitting between the other structures. Forms cap over glomerulus vascular pole.

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14
Q

Juxtaglomerular cells

A

First and last sm. muscle cells in a/efferent arterioles to/from glomerular capillaries. Controls GFR by vessel diameter and renin secretion.

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15
Q

Nephric tubule

A

From distal to prox (rel. to kidney): PCT -> prox. straight -> thick descend. -> thin descend./ascend. -> thick ascend. -> dist. straight -> DCT

Prox./dist. in terms is relative to glomerulus

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16
Q

Nephric tubule morphologies

A

PCT + thick descend. = large cells w/ apical brush border + basal enfoldings (ion pumps/pore proteins)
Thin tubule = near-squamous
Thick ascend. + DCT = basal strations, smaller cells vs PCT
Collecting duct = (major.) principal cells + (minor.) intercalated cells (more mito.)

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17
Q

Bowman’s capsule

A

Epithelial-lined space by which nephric tubule encapsulates its associated glomerulus. Has inner visceral and outer parietal epithelia.

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18
Q

Inner visceral epithelium of Bowman’s capsule

A

Part of glomerulus; podocytes w/ interdigitating pedicels.

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19
Q

Podocytes

A

Form filtration slits through interdigitating pedicels, spanned by filtration diaphragm

20
Q

Filtration diaphragm

A

Spans filtration slits between pedicels, made of transmembrane nephrin

21
Q

Outer parietal epithelium of Bowman’s capsule

A

Simple squamous cells

22
Q

Bowman’s space

A

Aka urinary space. Space between inner/outer visceral/parietal epithelia of Bowman’s capsule. Filtrate drains into here toward urinary pole.

23
Q

Intraglomerular mesangial cells

A

Major element of glomerulus CT space, between podocytes and endothelium. Similar to JGA lacis cells. Phagocytic, contractile, CT matrix production, growth factor release.

24
Q

Glomerulus

A

Highly convoluted capillary bed under visceral epithelium and basal CTs (minimal CT space). Forms arterial portal system between afferent/efferent arterioles.

25
Q

Minimum kidney filtration barrier

A
  1. Fenestrated endothelium + basement
  2. Podocyte basement + filtration slit
    Selects substances by size + charge.
26
Q

Renal corpuscle

A

Glomerulus + encapsulating nephric tubule (parietal Bowman’s capsule layer)

27
Q

Vascular pole of renal corpuscle

A

Afferent/efferent arteriole regions

28
Q

Urinary pole of renal corpuscle

A

Origin of PCT

29
Q

Renal artery branching (afferent)

A

Enters at hilum -> 5 branches in renal sinus -> segmental -> interlobar -> arcuate (entering lobe, cortico-medullary) -> interlobular -> afferent arterioles

30
Q

Renal vein branching (efferent and out)

A

Efferent arterioles -> 2nd cap. bed of portal system (peritubular cap. plexus/vasa recta) -> interlobular veins -> arcuate -> interlobar -> renal vein
All run parallel to homonymous arteries

31
Q

Peritubular capillary plexus

A

Capillary blood supply for cortical layers

32
Q

Vasa recta

A

Capillary blood supply for medullary layers

33
Q

Erythropoietin production

A

Produced by cortical interstitum, controls marrow RBC production. Secretion triggered by low kidney O2

34
Q

Prostaglandin production

A

Producing cells found in medullary interstitum

35
Q

Kidney functional compartments

A
  1. Superficial renal cortex
  2. Medulla
36
Q

Columns of Bertin

A

Cortical tissue separating renal pyramids (medullary tissue)

37
Q

Filtrate path

A

Cortex -> through pyramids -> renal papilla -> minor calyx -> major calyx -> renal pelvis -> ureter

38
Q

Blood path

A

Renal artery -> hilus -> renal pelvis, calyces, sinus -> cortical branching -> renal vein draining

39
Q

Nephron types

A
  1. Cortical (shorter tubule, higher in cortex)
  2. Juxtamedullary (much longer loop of Henle, important for urine concentration)
40
Q

Loop of Henle

A

Thick/thin descending/ascending tubules

41
Q

Relative tubule permeability

A

PCT: glucose, ions, H2O, AAs
Thick/thin descend.: H2O
Thick/thin ascend.: Na+, Cl-
DCT: Ca++, Na+, Cl-
Collecting duct: H2O, Ca++, Na+, Cl-

42
Q

Hormonal system control of tubules

A

Nephron/collect. duct system has different localized aquaporin channels. Hormones like ADH control aquaporin activation and H2O resorption

43
Q

Medullary osmolarity

A

Deeper into the medulla osmolarity increases, up to 1200 mOsm near the renal papilla. Allows more efficient H2O resorption.

44
Q

Nephric tubule functional roles

A

PCT: Active H2O/Na+ adjustment, large molecule/nutrient resorption
Thin descend. loop of Henle: Passive H2O diffusion only
Thick ascend./DCT: active ion transport, H2O impermeable
Collecting duct: H2O, Na+ resorption; active HCO3-/H+ acid/base transport by intercalated A+B cells.

45
Q

Prostaglandins + angiotensin II

A

Both increase GFR. Prostaglandins increase afferent arteriole diameter, angiotensin increase efferent arteriole diameter

46
Q

RAAS activation by JGA

A
  1. Macula densa cells sense low Na+ in DCT indicating low GFR
  2. Macula densa signals JG cells to release renin
  3. Renin increases angiotensin II which increases Na+ resorption
47
Q

COX-1/-2

A

Macula densa signals for prostaglandin increase via COX1/2