Renal Anatomy and Histology Flashcards
what are the organs of the urinary system
kidneys, ureters, urinary bladder, and the urethra
Anterior aspect of the kidney
Retroeritoneal lying about T12-L3 level
-lower on the right due to the liver
Suprarenal gland above the zidney
size is about 10cm long, 5 cm wide, and 2 cm thick
Renal hilum: entrance to the renal sinus (area in kidney where BV, renal pelvis, and nerves, locafte
Posterior aspect of the kidney
Left hilum runs through the transpyloric plane (transverse plane)
Transpyloric plane runs through superior pole of right kidney
-2.5 cm lower than left
superior parts lie deep to 11th and 12th ribs
Inferior pole or right kidney is approximately index fingers breath superior to iliac crest
hilum of each kidney is about 5cm (2 in) from the midline
What are the two types of renal fat and what divides them
Perinephric fat: adjacent to the kidney capule and extends into renal hilum and pelvis
renal fascia: covers the fat enveloping kidney and suprarenal gland
-superiorly continuous with inferior diaphragmatic fascia
Paranephric fat: external to renal fascia
what composes the gross internal anatomy of the kidney (9 things)
Capsule: dense irregular CT on surface with inner layer of myofibroblasts
Renal cortex: outer portion containing renal corpuscles
Renal medulla: collection of renal pyramids and columns
renal pyramids: cone shaped masses in the medulla projecting into the calyx
renal columns: tissue lying between pyramids running from cortex to the calyx
renal lobes: single pyramids plus surrounding adjacent cortex
renal pelvis: collecting funnel for urine
renal calyxes: out pocketing of the renal pelvis
-major and minor
renal papillae: projections of medullary pyramids apices into calyxes
where does the ureter travel in regards to the arterial supply
water flows under the bridge
ureter is underneath the arterial bridge
order of flow of the renal arteries and veins
Segmental Interlobar Arcuate Interlobular Afferent arteriole Glomerulus Efferent arteriole Peritubular capillaries (Vasa recta)
Cortical radiate vein Arcuate vein interlobar vein Renal vein Inferior vena cava
where does the Ureter get its blood supply
bunch of different arteries as it descends
- Renal branches
- gonadal branches
- Abdominal aorta branches
- Iliac branches
- Superior vesicular branches
- Pelvic branches
NutCracker syndrome
Traction of the superior mesenteric artery compression on the left renal vein
leads to hematuria, proteinuria, flank pain, nausea, vomitting, and left sided variocele
what is the Renal nerve Plexus and where does it get its nerve supply from the Autonomic Nervous system
the nerve supply to the renal system
Sympathetic:
- Lesser splanchnic (T10-11)
- Least splanchnic (T12) both synapsing in the aorticorenal ganglia
- lumbar splanchnic (L1-L2)
Parasympathetic:
Vagus N via the posterior vagal trunk
all nerves will follow arteries to get to specific location
what is the urine forming and carrying units made of
Nephron (urine forming unit)
- consists of renal corpuscle and renal tubules)
- juxtamedullary and cortical nephrons
Cortical and medullary collecting ducts
-final concentration of urine
what is the type of capillary bed for the Glomerulus
tuft of capillaries
- Fenestrated endothelium
- fed by afferent and drained by efferent arterioles
what is the peritubular capillaries composed of
Cortical: in the cortex
- surround the proximal and distal convoluted tubules
- Fenestrated endothelium
Long Medullary (vasa recta): In the medulla
- surround the loop of henle
- Ascending portion: Fenestrated endothelium
- Descending portion: Continuous endothelium
why are some sections of peritubular capillaries fenestrated endothelium and others continuous
Corresponds with what molecules are being reabsorbed or secreted in that section of the nephron
what makes up the renal corpuscle
Glomerulus
-capillary system, fenestrated endothelium
and the Glomerular capsule (Bowmans)
what makes up the layers of the Glomerular (bowmans) capsule
Visceral layer: consist of podocytes
Glomerular space: contains primary filtrate (early urine)
Parietal layer: simple squamous epithelium
what are the poles of the renal corpuscles
Vascular pole: vessels are Endothelium (not continuous with outside world)
- Afferent arteriole
- Efferent arteriole
Urinary pole or Tubular pole: tubules with epithelium (continuous with external environment. i.e GI tract)
-Origin of proximal convoluted tubule
what are Mesangial cells
structural support cells for glomerular loops and the extracellular matrix of the podocytes
also are phagocytic cells
prevents glomerular distension (contraction) due to high glomerular blood pressure
secrete growth factors and cytokines in response to injury
what are the layers of the Glomerulus endotheilum
Open fenestrations
Thick luminal glycocalyx
Posses large number of aquaporin water channels
can generate nitric oxide and PGE2 for vasodilation
what is the significance of the Glomerular Basement membrane
contains type IV and XVIII collagens, laminin, entactin, and proteoglycans
restricts particles larger than 70kD which would be blood cells
chemical barrier is strong and anti-anionic (repels negative charge)
-good since proteins are negative (albumin)
what is the significance of the Podocytes
makes up the visceral layer of the bowmans capsule (glomerular capsule)
helps make the filtration barrier
has feet like connections that serve as filtration like slits that are critical in regulating size, patency, and selectivity of filtration
what is the significance of the Filtration membrane
Lies between the blood and capsular space
composed of:
-Fenestrated endothelium, basement membrane, and podocytes
restricts passage of blood cells, Ig, and large proteins
allows passage of water, ions, glucose, amino acids, and urea
-makes urine
what kind of cells make up the parietal layer of the Bowmans Capsule
Simple squamous empithelium
Functions and locations of the Proximal Convoluted Tubule
Only found in the renal cortex
It is the most active tubule in resorption and secretion
- simple cuboidal to columnar epithelium
- abundant microvilli
- abundant mitochondria
- basal and lateral cell membranes are highly folded to increase surface area
- lumen is star shaped and jagged
contains lots of transporters
- Na,K-ATPase
- aquaporins
- glucose transporters sGLT2
- amino acid transporters
end is the proximal straight tubule:
- not as tall as PCT with less developed brush border
- equipped with high affinity sodium glucose co-transporters (sGLT1)
function and parts of the Loop of Henle
Loops down into the medulla and then back up into the cortex and terminates near the vascular pole
Thin limb segment: thin permeable simple squamous epithelial lacking a brush border
Thick ascending segment: simple cuboidal epithelium with numerous microvilli but no visible brush border
sets up the hyperosmotic gradient
Function and location of the Distal convoluted tubule
only found in the cortex
Lined with simple cuboidal epithelium with sparse microvilli, luminal surface is much smoother and open compared to PCT
Segment begins a variable distance from the Macula Densa of the thick ascending loop of henle portion
Angiotensin II influences Na+ resorption here!
what is the function of the juxtaglomerular apparatus and how does the Macula densa interact with it?
Juxtagomerular cells:
-Mechanosensory cells in afferent arterioles and they secrete renin if BP is too low
Macula densa:
- tight nuclei at distal end of thick ascending loop of henle
- signals release of renin (from juxtaglomerular cells) if low Na+
cell types found in the Collecting tubules/ducts
Final urine osmolality is determined by reabsorbing water
Target of both ADH and aldosterone therby increasing Na+ reabsorption and water retention
Two basic mechanosensory cell types:
- Principal cells (light cells), target of aldosterone
- Intercalated cells (dark cells) - involved in H+ and bicarbonate transport
Function of the collecting ducts
Lined with simple cuboidal epithelium but are simple columnar at their ends
Primary function is water reabsorption
runs straight through cortex into deep medulla
several join together to form larger papillary ducts that then drain into renal minor calyx
what are the cortical medullary rays
aggregation of collecting ducts and straight tubules running between the renal corpuscles and convoluted tubules within the cortex
what does the renal interstitum do?
special fibroblasts that produce erythropoietin depending on O2 levels
where is transitional epithelium located?
aka Urothelium
found in Calyces, ureters, bladder and portions of the urethra
this epithelium has a relaxed and stretched state
what are the three layers that make up the transitional epithelium
deepest single layer of basal cells on basement membrane
Intermediate region of cuboidal/columnar cells in several layers (sliding layer)
Superficial: binucleated umbrella cells (where the stretch and relax happens)
-Urothelial plaques form impermeable barrier on membrane. this is made with Uroplakin proteins that protect the cells from urine when stretched and then stored when not needed in fusiform vesicles
What are the three layers of the Ureters
Transitional epithelium
Muscularis
- three distinct layers
- moves with waves of peristalsis
- folds form when empty
- enters bladder obliquely to prevent retrograde flow
Adventitia
-typical connective tissue
Significance of the bladder
Detrusor muscle is a smooth muscular sac that encloses the bladder
can hold up to a liter of urine but normally 400-600ml
anterior to the uterus and rectum and sits within the pelvis so that when really full can expand up in the abdomen
Pregnant women can run into problems with this
what are the components of the Urinary bladder
Trigone
- location where the ureters and urethra open
- inferior/posterior wall of bladder
Bladder wall
- urothelium
- 3 layers of smooth muuscle tissue (detrusor m)
- Fibrous adventitia
Components of the Female Urethra and how does the epithelium change through the urethra
the length of the female urethra is only 3-5 cm long so it is at high risk for UTI
connects bladder to the external urethral orifice
Epithelium changes through the urethra:
- Transitional near the bladder
- Majority of urethra is pseudostratified columnar
- distal end stratified squamous epithelium
Membranous urethra through the urogenital diaphragm
Internal urethral sphincter: involuntary smooth muscle
External urethral sphincter: skeletal muscle so control is voluntary
Components of the Male urethra and how does the epithelium change through the urethra
20 cm in length
Epithelium changes through the urethra:
- transitional near the bladder
- Majority of urethra: pseudostratified columnar
- distal end: stratified squamous epithelium
Three named regions
- prostatic urethra
- Membranous urethra (through the urogenital diaphragm)
- spongy (penile) urethra
Internal sphincter: involuntary smooth muscle
external sphincter: skeletal muscle and is voluntary
Polycystic Kidney Disease
Autosomal Dominant
-appears in 4th decade
PKD1 or PKD2 mutations
- cysts form that crush tissue that impede drainage
- leads to kidney failure
hypertension, renal hemorrhage, calculi or UTI
Dialysis and kidney transplant is the treatment
Urinary Incontinence
can be a lot of different causes, and types but affects more females than males
Urinary tract infections
Women at higher risk
normally E.coli
catheters are a risk to cause these
dysuria, pelvic pain, fever
lead to pyelonephritis, cystitis, urethritis
treat with antibiotics
Schistosoma Hematobium
Parasitic blood flukes
GU tract disease
passed via a snail species
Chronic infection can cause fibrosis and calcification of the bladder
risk of bladder cancer
