renal 1-6 Flashcards
What are the eight basic functions of the renal system?
Hint - 1 metabolism, 1 count, 1 detoxify, 1 homeostasis, 3 regulation, 1 gluco-related
- remove waste products of metabolism
- RBC count
- detoxify free radicals + some drugs
- calcium homeostasis
- body fluid pH regulation
- fluid balance and BP regulation
- electrolyte regulation
- gluconeogenesis during starvation
What are the six organs of the renal system?
Hint - 1K and 3Us
- kidneys (L+R)
- ureters (L+R)
- urinary bladder
- urethra
What is the location of the kidneys?
Hint - faces the spine and poles LT 36
- between peritoneum + posterior abdominal wall → concave medial border faces vertebral column
- upper pole T12 and lower pole L3
- protected by R11-12 with R kidney lower than L (liver)
What are the vital statistics of one kidney in terms of how heavy, long, wide and thick?
(Hint - comes up to around 150cm squared)
- 130-160g
- 10-12 cm long
- 5-7 cm wide
- 3 cm thick
(about the size of a bar of soap)
What are the names of the deep, middle and superficial layers of the kidney and what are their structures and functions?
(Hint - RAR → deep and middle layer have very similar structure)
- renal capsule → smooth, trauma barrier made of dense, irregular CT to maintain kidney shape - continuous with outer ureter layer (deep)
- adipose capsule → fatty tissue, trauma barrier which maintains kidney position (middle)
- renal fascia → dense, irregular CT which anchors kidney to abdominal wall and structures (superficial)
What is the renal cortex, renal medulla, renal parenchyma, renal sinus and renal lobe?
(HInt - parenchyma is basically the whole kidney, renal sinus is the leftovers the day after, renal lobe is that small Egyptian section)
- renal cortex: (= bark) → superficial layer, smooth and brownish
- renal medulla: (= inner portion) → deep, striated and reddish
- renal parenchyma: renal cortex + medulla
- renal sinus: remaining structures → fat, pelvis, calyces, blood vessels, nerves
- renal lobe: renal pyramid, overlying renal cortex area and ½ adjacent renal column
How much blood supply do the kidneys obtain relative to their size?
low body mass but receive ¼ of CO via L+R renal arteries (from ABD aorta)
What is the complex blood pathway through the kidneys?
HInt - rita skeeter is an ignorant, angry grasshopper endof - also segarc
renal artery → segmental arteries → interlobar arteries → arcuate arteries → interlobular arteries → afferent arterioles → glomerular capillaries → efferent arterioles
What is the pathway of blood through the kidneys from an efferent arteriole (a type of portal vessel)?
(Hint - E-V-I/A)
efferent arteriole → vasa recta (medullary capillaries) → interlobular/arcuate veins
What is a nephron?
- blind-ended tube which is the functional unit of kidney supplied by an afferent arteriole
- made of renal corpuscle (glomerulus + bowman’s capsule) and renal tubule
What are the glomerulus, bowman’s capsule and podocytes?
Hint - bc → where filtrate gathers + continuous
- ball of capillaries inserted into Bowman’s capsule → initial site of urine production (supplied by AA + drained EA)
- site of blind-end of nephron which is capsular space where filtrate collects
- inner visceral layer which envelope glomerular capillaries
What is a renal tubule composed of?
Hint - P + D, L, C
- PCT, distal tubule (2 tubular segments)
- Loop of Henle
- collecting duct
What are the two types of nephrons and what are their relative proportions?
(Hint - CJ)
- cortical (85%) → glomeruli in outer 2/3 of cortex and short loops of Henle
- juxtamedullary (15%) → glomeruli in inner 1/3 of cortex and long loops of Henle
What is the structure of the proximal tubule?
(Hint - two types of c epithelia, has beginning + end which start out dodgy and then straighten themselves out in the end)
- cuboidal/columnar epithelium
- early part (pars convolute) → convoluted
- late part (pars recta) → straight
What is the loop of Henle?
Hint - very basic - the shape and the two types of limbs
U-shaped loop with descending and descending limbs
What are the structures of the thin and thick segments of the loop of Henle?
(Hint - epithelia, which parts of limbs, metabolic activity and water permeability for thin)
- thin segments: simple squamous epithelium, lower part of descending limb + sometimes ascending, low metabolic activity and high water permeability
- thick segments: simple cuboidal epithelium, initial part of descending + ascending limb, metabolically active (mitochondria)
What is the structure of the juxtaglomerular apparatus?
Hint - where does the LoH start + return, MD, j cells
- final part of ascending loop of Henle returns to afferent/efferent arterioles of same nephron
- macula densa (thick ascending limb columnar cells)
- juxtaglomerular cells (afferent arteriole SM cells)
Which epithelium is found in the early and late parts of the distal convoluted tubule?
cuboidal
Which two types of cells are found in the late part of the distal convoluted tubule and what do they regulate?
(Hint - π - acidity and urine hormones/enzymes - calate = anhydrase)
- principal cells (ADH + aldosterone receptors)
2. intercalated cells (carbonic anhydrase activity, pH)
What is the structure of the collecting duct?
(Hint - cells like distal C tubules, receives fluid from, in internal region Bellisimo ducts which drain into a part of the internal kidneys)
- cells similar to late DCT
- receives fluid from 6 distal tubules
- in the medulla, pair up to form ducts of Bellini which drain into minor calyces
What is nephroptosis?
Hint - ghost kidney from L3 to L5
when kidney descends more than 2 vertebral bodies (‘floating kidney’)
What are peritubular capillaries and what are they called when they surround the PCT, DCT and loop of Henle?
(Hint - clue is in the name and used to suck things up and release them, name is the synonym for “straight arteries”)
- tiny blood vessels alongside nephrons → allow reabsorption + secretion
- ‘vasa recta’
What is the lymphatic drainage of the kidneys?
(Hint - bloodstream fluid to cells by c. action, bathes tissues with new name IS, collects rubbish and drains into lymph vasculature)
- fluid from circulating blood leaks into body tissues by capillary action → carrying nutrients to cells
- fluid bathes tissues as interstitial fluid
- collects waste products, thendrainsaslymphinto lymphaticvessels + capillaries
What is a UTI, where is it more common and why?
- infection that can affect bladder, kidneys and tubes connected to them
- more common in women as they have shorter urethra than men
- often caused by catheters becoming infected w/ bacteria etc…
Where do the three renal systems develop from and how are they deposited? See notes for diagram.
(Hint - in the middle layer, deposited around middle during gi system development between P + L meso)
- develop from intermediate mesoderm
- deposited either side of midline during gastrulation → between paraxial + lateral plate mesoderm
Which three structures develop craniocaudally to form the renal system?
(Hint - pro-mes-met)
- pronephros (cervical nephrotomes)
- mesonephros
- metanephros
Describe the formation of the pronephros (cervical nephrotomes) including time-scales.
(Hint - 5-7 neck segments of middle meso produces tomes/vesicles which then disappear)
- 5-7 paired cervical segments of intermediate mesoderm produce nephric vesicles
- nephric vesicles/nephrotomes (hollow epithelial balls which are vestigial remnants) are formed early week 4 and disappear by the end of it
How does the mesonephros form during week 4 and why do we end up with 30 pairs of mesonephric tubules in the end rather than 40? see notes for diagrams.
(Hint - TC region form msnprhic tubes either end, due to the dropping of tubules)
- in the thoracolumbar region during early week 4 mesonephric tubules form from mesonephric ridges either side of intermediate mesoderm
- 40 pairs of mesonephric tubules produced craniocaudally → 30 pairs in total due to cranial regression
How does the formation of the mesonephros occur during weeks 5-6?
(Hint - number of L. mesonephric tubulesreduced again by falling process, then the ball of capillaries and its lid created from differentiation of the L. mesonephric tubules)
- massive cranial regression so 20 pairs of lumbar mesonephric tubules
- mesonephric tubules differentiate into abbreviated excretory units → bowman’s capsule and glomerulus (the renal corpsucle) from dorsal aorta
What is a MEU and what is it made up of?
mesonephric excretory unit → renal corpuscle + mesonephric tubule
Describe the formation of mesonephric (Wolffian) ducts during week 4.
(Hint - originate in T spinal region and grow c, longitudinal middle rods condense to tubules, diverge into L spinal region, fuse ventrally with cloac. and then cavitate to produce inner region)
- originate in thoracic region + grow caudally
- longitudinal intermediate mesoderm rods that condense dorsolaterally to mesonephric tubules
- diverge from intermediate mesoderm in lumbar region
- fuse with ventrolateral walls of cloaca (bladder) by day 26 → cavitate at distal end to produce lumen
State the roles of MEUs in the formation of the mesonephros during weeks 5-10.
(Hint - passage to the embryological bladder, urine-production then stopped at week 10, then how it remains after in males and females)
- lateral tips of MEUs fuse with mesonephric duct to allow their passage to the cloaca
- MEUs functional in week 6 and 10 → produce small amounts of urine and regress after week 10
- in males, mesonephric duct becomes part of the genital system (SEED) and in regress in females remnants may persist (i.e. epoophoron)
Describe the metanephros including time-scales.
(Hint - formed in S region, penetrate sacral middle derm encouraging joining of u-bud, u-tip called ampulla which causes aggregation and lobe formation and separation via sulcus, lots of even lobes formed by week 16 and then filled so smoother appearance)
- formed in sacral region by pair of ureteric buds from distal mesonephric duct (sprout end of week 4)
- penetrate sacral intermediate mesoderm region called metanephric blastema → encourages bifurcation of ureteric bud
- ureteric growing tip is called ampulla → cap-like aggregation near this structure causes lobe formation separated by sulcus
- 14-16 lobes formed by week 16 → sulci eventually filled so lobulated appearance obscured
What is reciprocal interaction?
(Hint - differentiation of U + CDs depending on meta-b → give rise to renal organs, differentiation of n depending on UBs)
- differentiation of ureters + collecting ducts dependent on metanephric blastema giving rise to kidneys
- differentiation of nephrons dependent on ureteric bud
When do the sulcus and the lobe of a kidney form?
- sulcus → at 6 weeks
- lobes → at 16 weeks
Describe the formation of the nephrons and collecting system of the kidneys (see notes for help).
(Hint - week 6 caps around ampullae of CDs, CD distinct from nephron, DTs + CTs connect → functional MEUs in week 10)
- during week 6, metanephric tissue caps form around ampullae of bifurcating collecting ducts
- collecting duct embryologically distinct from the nephron
- distal tubules connect fully with collecting tubules in week 10 and become functional MEUs
What is the main function of fetal urine in embryological development?
to assist in production of amniotic fluid
When is normal ascent (rise) of the kidneys complete and what is the abnormal ascent of the kidneys?
- by week 9
- transient inferior arteries fail to regress causing accessory renal arteries to form
State two kidney abnormalities due to the abnormal ascent of the kidneys.
- pelvic kidney
- horseshoe kidney
How does the urinary tract develop as part of the renal system and how does this differ between males and females?
(Hint - c split by us to form pus and r, s + a → bladder, c → F urethra, m + p urethra → M urethra, distal PUS → vv (F) + PU (M))
(see notes for diagram)
• cloaca split by urorectal septum in weeks 4-6to form primitive urogenital sinus (PUS) and rectum
- superior PUS + allantois → bladder
- constricted pelvic urethra → urethra (F)
- membranous and prostatic urethra → urethra (M)
• distal part of PUS (urogenital sinus) expands and becomes:
→ vaginal vestibule (F)
→ penile urethra (M)
How does the bladder develop as part of the renal system from week 6-12?
(Hint - week 6 root of m. duct turns inside out into b. wall, pushes origin of u. buds into it creating ureter holes, meso. duct pushed inferiorly to pelvic urethra, extros. wall of m. duct joined with b. wall → forming that SM part)
(see notes for diagram)
- week 6 → root of mesonephric duct exstrophies (turns inside out) into bladder wall
- pushes origin of ureteric buds into bladder wall, creating ureteric openings
- causes opening of mesonephric duct to be pushed inferiorly to level of pelvic urethra
- exstrophied wall of mesonephric duct incorporated into bladder wall, forming smooth trigone of bladder
- process complete by week 12
What are each of the following common renal developmental abnormalities:
a) unilateral/bilateral renal agenesis
b) multicystic dysplastic kidney
c) autosomal recessive polycystic kidney (Hint - PCOS)
d) branchiootorenal syndrome
e) duplication (bifid pelvis)
f) megaureter
g) ureteral-pelvic junction obstruction
h) calyceal cyst or diverticulum (Hint - to with just cysts)
i) calyectasis (Hint - to with fluid + cysts)
a) absence of one/two kidney(s)
b) a collection of largerenal cysts
c) cysts causing kidney enlargement → may lead to pulmonary and renal complications
d) can result in malformation of kidneys (disruption of reciprocal induction of epithelialureteric budand mesenchymal metanephricblastemain developing embryonic kidney)
e) absence of ureter
f) abnormally-dilated ureter
g) part of kidney blocked so urine can’t move through
h) cystic activity within kidney/s
i) calyces of kidney dilated and swollen with excess fluid
How does body water (BW) compare in males and females?
- standard physiological male → has 10% more BW is water than the standard female
- higher adipose tissue content + lower BW in females (responsible for TBW variation too)
What is a compartment and why is this used?
- compartment: a small space or subdivision for storage (not always the same)
- “virtual” compartment = made up of multiple cells/compartments
- used for convenience to allow meaningful discussion
Describe the distribution of TBW in percentages.
Hint - first at a cellular level with the more extra one having a pit of fluid
Body fluid (100%) • extracellular fluid (35%) - interstitial fluid (25%) - plasma (8%) - transcellular fluid (2%) • intracellular fluid (65%)
