2 - Urinay System Histology Flashcards
What are the components of the kidney?
- Hilum
- Renal Sinus
- Capsule
- Cortex
- Medulla
- Minor Calyx
- Major Calyx
- Kidney Lobe
- Kidney Lobule
- Uriniferous Tubule
- Juxtaglomerular (JG) Apparatus
- Renal Interstitium
- Blood Supply
Describe the hilum of the kidney
- depression in the kidney’s concave surface
- Opens into the renal sinus
- Is the site where vessels and nerves pass into or leave the kidney
- Where ureter exits kidney
What is the renal pelvis?
Renal pelvis - is the funnel-shaped, expanded, proximal end of the ureter
Describe the renal sinus
Is a fat-filled cavity enclosing the following:
- Branches of the renal artery and vein, lymph vessels
Ureter and nerve fibers
Describe the capsule of the kidney
Two layers:
- Its outer layer has collagen and fibroblasts
- Its inner layer has collagen and myofibroblasts
Describe the cortex of the kidney
- Is the outer region of the kidney
- The cortical tissue overlying the base of a pyramid is the cortical arch
- The cortex consists of alternating regions, the cortical labyrinth and medullary rays
Describe the cortical labyrinth of the cortex of the kidney
Consists of the regions between the medullary rays. It contains the following structures:
- Renal corpuscles
- Convoluted tubules
- Connecting tubules
Describe the meduallary rays of the cortex of the kidney
They consist of medullary tissue that extends from the base of the pyramids into the
cortex. Each medullary ray consists of:
- Straight tubules
- Collecting ducts
Describe the blood flow in the cortex of the kidney
90 - 95% of blood flowing through the kidney is in the cortex where it will be filtered through the glomeruli
Describe the medulla of the kidney
Is the inner region of the kidney. Contains the following:
- Renal pyramids (apex and base)
- Renal columns (of Bertin)
Describe the renal pyramids of the medulla
There are 8 - 18 per kidney
Apex
- AKA “renal paiplla” has an area cribrosa which consists of 20 openings of papillary ducts (of Bellini)
- The apex projects and drains/empties into a minor calyx
Base
- Found at the corticomedullary border
Describe the renal columns (of Bertin) of the medulla
- Consisting of cortical tissue
- Project between the medullary pyramids
- THEY RESIDE WITHIN AND ARE PART OF THE MEDULLA ***
Renal columns include the following:
- straight tubules (of the nephrons)
- collecting ducts
What are the vascular components of the medulla?
- Vasa recta (straight vessels)
- 5 - 10% of blood flowing through the kidney is in the medulla
Describe the minor calyx of the kidney
- Cup-like, funnel-shaped
- Receives apex of one pyramid
Describe the major calyx of the kidney
- Several minor calyces converge and open (and drain) into a major calyx
Describe the kidney lobe components
- A renal pyramid (the number of lobes = the number of pyramids)
- Associated cortical tissue at the base of the pyramid
- Associated cortical columns (of Bertin) (one half of each adjacent renal column)
- The human kidney is multilobar (has multiple lobes)
Describe the kidney lobule
consists of a central medullary ray and surrounding cortical tissue
- A collecting ducts
- All nephrons that empty into the collecting duct
What does the uriniferous tubule consist of?
Nephron + Collecting Duct
Describe the uniferous tubule
- It consists of epithelium and is covered by a basal lamina on its exterior
- Contains both the nephron and collecting duct
What is the structural and functional unit of the kidney?
NEPHRON ***
What are the components of the nephron?
- Renal Corpuscle
- Proximal tubule
- Thin limbs of Henle
- Distal dubule
What are the components of the first part of the nephron, the renal corpuscle?
- Glomerulus
- Bowman’s Capsule
- Bowman’s space (urinary space)
- Vascular Pole
- Urinary Pole
- Filtration Barrier
Describe the glomerulus of the renal corpuscle
- is a cluster of fenestrated capillaries
- is an arterio-capillary bed
- glomerular ultrafiltrate oozes out of glomerulus by passing through the filtration barrier
Describe Bowman’s capsule of the renal corpuscle
Bowman’s capsule
- is the proximal end of the nephron
- visceral layer of Bowman’s capsule (cover glomerulus with a cluster of capillaries and is composed of podocytes)
- ** Filtration slits are present here and have a slit diaphragm (nephrin) ***
- parietal layer of Bowman’s capsule (simple squamous epithelium that is covered by a basal lamina)
Describe Bowman’s space of the renal corpuscle
- is the space between the visceral and parietal layers of Bowman’s capsule
- contains ultrafiltrate
Describe the vascular poles of the renal corpuscle
Vascular poles is the site where…
- Afferent glomerular arterioles enter the renal corpuscle (mesangial cells)
- Efferent glomerular arteriol leaves the renal corpuscle (greater resistance to blood flow)
Describe the urinary poles of the renal corpuscle
Contains the initial part of the proximal convoluted tubule (PCT)
Describe the filtration barrier of the renal corpuscle
From inside outward, it consists of:
- endothelial surface layer of glomerular capillarie (glycocalyx glycoproteins)
- fenestrated endothelium of glomerular capillary (NO diaphragms over fenistrations)
- basal lamina (produced by endothelium and podocytes)
- subpodocyte space
- visceral layer of Bowman’s capsule (podocytes)
The filtration barrier ahs 2 discontinuous layer of all the components listed above
What is the next part of the nephron we will cover?
Proximal tubule
What are the parts of the proximal tubule?
- Proximal convoluted tubule (PCT)
- Proximal straight tubule
Describe the proximal convoluted tubule of the proximal tubule
- simple cuboidal epithelium
- striking eosinophilic, granular cytoplasm
- microvilli (“striated border”)
- basement membrane (PAS+)
Describe the proximal straight tubule of the proximal tubule
Proximal Straight Tubule (THICK Descending Limb of the Loop of Henle) – similar structure as PCT