Renal Histology Flashcards
Gross Anatomy of the Urinary System
- organs included
- Kidneys (right lower than the left- because of the liver)
- drain filterate (urine) in the ureters
- drain into the bladder
- bladder drains the urine to the urethra & excretion occurs
Vasculature
- Renal arteries - supply blood
- renal veins: drain blood Left renal vein is longer –> needs to cross over the aorta to drain into the IVC on the right side
Gross and Internal anatomy of the Kidney
Kidney parachyma: divided into the renal cortex (outtermost portion) and the medulla (the meduall is in individual renal medullary pyramids)
- drainage into the renal minor calyx into major calyx into the renal pelvis & then into the ureter
the area of the cortex which outlines and lies between each meduallary pyramid is called renal column
Basics of the Nephron
- number
- components
- basic function
- location within the kidney (cortex or medulla)
approx. 1 million nephrons per kidney
components + function
- renal corpuscle (glomerulus + bowman’s capsulre) = responsible for filteration of the blood
- Proximal Convoluted Tubules = selevtive reabsorbtion of the substances needed & secretion of unneeded substances that will become urine
- Loop of Henle = reabsorb and secrete
- Distal Convoluted Tubule = reabsorb & secrete
- Collecting Tubule/Duct = reabosrb & secrete
Locations
- within the Cortex: Renal Corpuscle, Proximial Tubule, Distal Tubule
- within the Medullar: Loop of Henle, Collecting Duct
Two types of Nephrons
- specifics of each
Juxtamedullary Nephrons
- think “jutxamedullary” becuase they’re deep in the cortex NEXT TO the medulla
- strat DEEP in the cortex: & long and thin Loop Of Henle travel the depth of the medullar
- 15% of nephrons: but account for majority of the urine concentration
Cortical Nephrons
- think cortical becuase they arise in the superfiscial cortex
- contain a short and thick Loop of Henle which doesnt travel deep into the medulla
The Renal Corpuscule
- contents (2)
- function
- layers of each contents
Renal Corpuscule: Glomerulus (capillary) & Bowman’s Capsule
function: sight of filteration from the blood
Layers of the Structures
Bowmans Capusule
- parietal cells line the outermost layer = simple squamous epithelium (these are continuous with the proximal tubule)
- visceral cells line the capillary (glomerulus): “hug” the capillary as podocytes (specialized epithelial cells)
- Bowman’s Space (urinary space): the space between the parietal and visceral cells: point where the filtrate passes from golmerulus to the PCT
- Urinary pole: where the PCT attaches to the renal corpusule attaches
- vascular pole: where the efferent and afferent arterioles enter
Glomerular Structure
- capillary endothelial layer: a fenestrated capillary layer
- basement membrane: the shared layer between the podocytes and the capillary endothelial cells
- podocytes: hug the capillaries (part of bowmans capsule)
Function of the glomerular structure: filteration (Selective)
- permit water and small molecules through
- does NOT allow large moecules, cells and proteins to pass (remain within the blood)
Mesangium: mesanigial cells & the mesangial matrix
= responsible for structual support, phagocytosis (immune) & maintain the basement membrane
exact structure of the podocyte
what stains under microscope show basement membrane
Podocyte
- the body of the podocyte hovers above the basement membrane it shares with the glomerulus
- its foot processes are projections from the body which project downward and touch the basement membrane
- contina filteration slit: the spaces between foot processes & the foot process of th enext podocyte
- the slit diaphragm is the area of the basement membrane: a specialized cell junction which sits in between each foot process
when looking at histology:
- the PAS and Silver stain: will show the basement membrane
- the H&E will not
Proximal Convoluted Tubule Histology
- function
- cells have abundant what & why
- specific cellular components of the PCT cells
Function: reabsorb approx. 60% of what was filterated in the glomerulus
the cells of the PCT
- contain LOTS of mitochondria: because they need energy to help pump and push ions against their concentartion graidents to reabsorb them
cells will have abundant PINK showing cytoplasm on H&E stain
- contain a brush border: (microvilli) to INCREASE surface area and accomodate more membrane channels to reabosrb more
Loop Of Henle Histology
- function
- type of cells
- specific things within these cells
Loop of Henle
- responsible for Cl- and H20 reabsorbtion
Cells = simple squamous epithelium
- they continan nuceli which protrude into the lumen
Distal Convoluted Tubule Histology
- function
- cell type
- specifics of these cells
DCT: a part of the juxtaglomerular apparatus!
cells = simple cuboidal epithelium
- less volume and pale cytoplasm when compared to the PCT
- these cells have NO brush border
Collecting Duct Histology
- function
- type of cell
- specifics
Function : collect urine from the distal tubules of various nephrons
- ADH acts here and within the DCT to increase permiability of H2O = increased water absorbtion (from urine into blood)
Cells = simple cuboidal epithelium
- have a prominent lateral border between them
Juxtaglomerular Apparatus
- function
- types of cells within the JGA (3) & their hsitology, and specific function
Function
- a collection of specialized cells within the DCT and the glomerular afferent arteriole
- they regulate the blood pressure & filteration rate of the glomerulus
Cells
Macula Densa Cells: detect the change in sodium concentration
- these are densely packed epithelial cells in the DCT and the LOH
- when they detect a drop in sodium –> trigger the release of renin to occur
Granular (JG cells): secrete renin
- smooth muscle cells in the afferent arteriole
- secrete renin from their granules –> which regulated the BP
Extraglomerular Mesangial Cells
- structural support cells to the juxtaglomerular apparatus
Renal Vasculature
- flow of blood & why there is two arterioles in the glomerulus
- what is the vasa recta
Renal Artey –> segmental artery –> interlobar artery –> arcuate artey –> cortical radiate artery –> afferent arteriole –> glomerulus –> efferent arteriole –> peritub/vasa recta capillaries –> cortical radiate vein –> arcuate vein –> renal vein
**arteriole in and out of the capillary allows for the back flow of nutrientes and solutes back to the arterial system to get distributed to the body still
Glomeruluar capillary
- inital filteration occurs here
Peritubular Capillaries
- feed the cells of the PCT& DCT as tehy do the absorption and filteration
Vasa Recta: the blood which runs parallel to the LOH
Path of Urine Drainage from the Kidney
- Cell types in the calyces, renal pelivs, ureter, bladder and proximal urethra
- and their function
transitional epithelium (urothelium)
- the cells which line the calcyes (minor and major)
- the cells taht line the renal pelvis
- the cells whcih line the urters, bladder & proximal urethra
Cell Specifics
- 5-7 layers of cells with the superfisical umbrella layer
- contain an IMPERMIABLE TIGHT JUNCTIONS so that the urine cannot pass
- have the ability to accomodate for distension (think bladder)
when streched: look flat
when relaxed: looked cube-like/dome shaped
