Renal Histology Flashcards
the urinary system consists of
- two kidneys and ureters
- the urinary bladder and urethra
Each kidney has somewhat of an ____ shape with a _____ lateral border and a slightly _____ or_____ medial border through which pass the renal artery, vein, and the ureter
oval shape, convex lateral border, concave or indented medial border.
A sagittal section of the kidney reveals what structures
- an outer capsule surrounding the entire kidney except for the hilum
- an outer cortical area beneath the capsule which has a cup-like form with the open side of the cup facing the hilum
- a juxtamedullary cortex deep to the outer cortical area
- a medullary area made up of triangular-shaped renal pyramids and divided into:
- an outer medullary area deep to the juxtamedullary cortex
- an inner medullary area deep to the outer medullary area
- the renal pelvis into which empty the renal pyramids
Each kidney is fed by a large ______ artery branching directly off the
renal artery branching directly off the abdominal aorta
___ is the functional unit of the kidney
nephron
There are approximately _____ nephrons per kidney
one million
Each nephron consists of
- Renal Corpuscle
- Renal tubule
A renal corpuscle is composed of
- A cup-shaped capsule referred to as Bowman’s capsule
- A glomerulus
- this is a capillary knot situated between two arterioles that lies within the indentation of Bowman’s Capsule
this is a capillary knot situated between two arterioles that lies within the indentation of Bowman’s Capsule
Glomerulus
A renal tubule is a continuation of
bowman’s capsule
nephrons empty into
collecting ducts
Collecting ducts empty into
the renal pelvis
What are the two types of Nephrons
- Cortical
- Juxtamedullary
The renal corpuscles of cortical nephrons are located
The cortex
The glomeruli of cortical nephrons empty into
peritubular capillary networks that surround the proximal and distal convoluted tubules of their own nephrons and those of surrounding nephrons
Structure of cortical nephrons loops of henle
have short loops of henle that do not extend deeply into the medulla
the renal corpuscles of juxtamedullary nephrons are located
in the cortex next to the cortical-medullary junction
The glomeruli of juxtamedullary nephrons empty into
vasa recta consisting of long, straight arterioles and venues that run parallel to the loops of Henle and collecting ducts
The loops of henle in juxtamedullary nephrons
Juxtamedullary nephrons have long loops of Henle that extend deeply into medulla
sequence of branching for the renal artery within the kidney
renal artery—-> Interlobar arteries —-> Arcuate arteries—-> interlobular arteries—-> afferent glomerular arteries————–>glomerular capillary network (glomeruli)——> efferent glomerular arterioles—–> vasa recta (peritubular capillaries) ——> Interlobular veins —–> arcuate veins —–> interlobar veins —–> Renal veins
in general, a capillary network is interposed between
an arteriole and a venule
Explain the arterial portal system in the kidneys
An arteriole is interposed between two capillary networks. An afferent arteriole give rise to a mass of capillaries, the glomerulus. These capillaries coalesce to form an efferent arteriole, which gives rise to capillary networks (peritubular capillary network and the vasa recta) surrounding the nephrons.
Explain Venous portal system in liver and hypophysis
Arteriole to capillary to vein. the veins then feed into an extensive capillary or sinusoid network draining into a vein.
The glomerulus is a ______ inserted between two arterioles
Capillary bed
The glomerulus is a ____ inserted between two ____
Capillary bed inserted between two arterioles (afferent arteriole and efferent arteriole)
A typical capillary bed is inserted between
an arteriole and a venule
The efferent arteriole feeds into either
- a capillary loop, the vasa recta
- a capillary network, the peritubular capillaries
Where are peritubular capillaries found
in cortical nephrons
- efferent arterioles drain into them
Where are vasa recta found
in juxtamedullary nephrons
- efferent arterioles drain into them in juxtamedullary nephrons
Circular smooth muscle cells at the vascular pole
Juxtaglomerular cells
Juxtaglomerular cells are located in
the afferent arteriole of the glomerulus
what cells secrete renin
juxtaglomerular cells
Juxtaglomerular cells secrete
renin (hypertensive factor)
components of the glomerulus
- Afferent arteriole (which houses juxtaglomerular cells)
- Glomerular formation of capillaries
- Efferent Arteriole
This is a double-layered, cup-shaped dilation of the nephron
Bowman’s capsule
What are the two layers of Bowman’s capsule and there stucture
- Parietal layer
- this is an outer layer of simple squamous epithelium
- The squamous epithelium is continuous with the simple cuboidal epithelium of the proximal convoluted tubule
- Visceral layer
- This is the inner layer of podocytes in contact with the endothelium of the glomerular capillaries
_____ is located between the parietal and visceral layers and is continuous with the lumen of the proximal convoluted tubule
Bowman’s space
The renal corpuscle is involved in producing
a filtrate of blood
what parts of the nephron are involved in modifying the nitrate of blood produced by the renal corpuscle
the rest of the nephron, including the convoluted portions and the loop of Henle, as well as the collecting tubules, is involved in modifying the filtrate
The formation of the urine involves three process
- Filtration (occurring in the renal corpuscle)
- Reabsorption (occurring in the renal tubule)
- Secretion (Occurring in the renal tubule)
The Mesangium is part of the
Glomerulus
The mesangium is formed by _____ cells embedded in ______
mesangial cells embedded in a mesangial matrix
Intraglomerular mesangial cells are located between _____ in the _____ and cover ______ not covered by _____
nearby capillaries in the glomerulus and cover endothelium not covered by podocytes
Extraglomerular mesangial cells are located between _______ and _______ at the ______ and are associated with the _________.
afferent and efferent arterioles at the vascular pole and are associated with the juxtaglomerular apparatus
Characteristics and functions of Mesangial cells
- Contractile: utilize cytoskeletal contractile proteins to modify blood flow through glomerular capillaries
- Phagocytic: take up worn out glomerular basal lamina for recycling and also phagocytose immunoglobulins trapped in the basal lamina
- proliferative
- synthesize matrix and collagen
- Secrete prostaglandins and endothelins
- Respond to angiotensin II
- Provide mechanical support and regulate blood flow
what are the three components of the juxtaglomerular apparatus
- macula densa
- Extraglomerular mesangial cells
- Juxtaglomerular cells
The macula densa is formed by
densely packed cells in the wall of the convoluted tubule. . polarity of these cells is reversed
The macula densa responds to changes in
sodium and chloride concentration in the urine or hypotension
The macula densa signals _____ release from juxtaglomerular cells
renin
Macula densa is involved in regulation of _______ and _______
fluid-electrolyte balance and blood pressure
Modified smooth muscle cells associated with macula densa and afferent arteriole
Juxtaglomerular cells
Secrete renin into blood when stimulated by the macula densa
Juxtaglomerular cells
The juxtaglomerular cells are innervated by ______ which increase renin release
sympathetic nerve endings
The simple squamous epithelium of Bowman’s capsule becomes continuous with the simple cuboidal epithelium of the _______.
Proximal convoluted tubule
What is the first part of the renal tubule
Proximal convoluted tubule
What are the parts of the renal tubule
- The proximal convoluted tubule
- The descending limb of Henle (with thick and thin portions)
- The loop of Henle
- The ascending limb of Henle (with thick and thin portions)
- The distal convoluted tubule
The distal convoluted tubule is continuous with the
collecting duct
What are the components of the renal filtration barrier
- Fenestrated endothelium of glomerular capillaries
- Fused basal laminae of endothelial cells and podocytes
- Flitration slits
Filtration slits of the renal filtration barrier are created by? and covered by
-adjacent pedicels of podocytes, covered by filtration slit diaphragm
Pedicels are attached to basal lamina via
alpha3beta1 integrins
The basal lamina of the renal filtration barrier contains
- type IV collagen
- fibronectin
- laminin
- heparin sulphate
Selectivity of the renal filtration barrier
- water, glucose, and most ions pass through filter into Bowman’s space
- Proteins are typically excluded from passing across the filter
- Molecules with a large negative charge are excluded
The proximal convoluted tubule extends from the _____ of the renal corpuscle to the beginning of the loop of henle
urinary pole
The proximal convoluted tubule has what kind of epithelium made up of ________ cells
simple cuboidal epithelium, truncated pyramidal cells
Characteristics of the proximal convoluted tubule
- simple cuboidal epithelium made up of truncated pyramidal cells
- Apical tight junctions and brush border
- Basolateral infolding and interdigitations
- Basal striations with abundant mitochondria (for active transport across basal membrane)
- Large, pale-staining nuclei
- Eosinophilic cytoplasm
What are the functions of the proximal convoluted tubule
- Reabsorbs most of the filtrate, including water
- Removes essentially all the glucose and amino acids form the filtrate
- Reabsorbs most of the sodium and chloride ions
- Characterized by a complex set of transporters, co-transporters, channels, and exchangers
_____ extends form the proximal to distal convoluted tubules
Loop of Henle
The loop of henle is made up of a ____ and ____
ascending limb and descending limb
The descending and ascending limbs of the loop of Henle each have a
thick and thin segments
_____ segments of the loop of Henle are composed of simple low cuboidal epithelium
Thick segments
_____ segments of the loop of Henle are composed of simple squamous epithelium
Thin segments
Cells of the thick ascending limb have no _____ and more ____ than other parts of the loop of Henle
No brush border, more basal vertical striations
The ascending limb is impermeable to
water
The descending limb is permeable to
water and sodium chloride ions
The ascending limb is impermeable to ____ and actively pumps ____ out of the tubule, allowing ____ to follow
Water, actively pumps chloride ion out of the tubule, allowing sodium ions to follow
The major function of the loop of Henle
is to establish the counter-current exchange system which creates the osmotic conditions necessary to pull water out of the distal convoluted tubule and collecting duct in the presence of ADH
The distal convoluted tubule is impermeable to water except in the presence of
ADH
ADH is derived from the
posterior pituitary
What is the function of ADH
Antidiuretic hormone (vasopressin) -fxn- to reduce water loss
The distal convoluted tubule is lined with ____ epithelium with ___ cells than those of the proximal convoluted tubule
simple cuboidal epithelium, smaller
The lumen of the distal convoluted tubule is _____ than that of the proximal convoluted tubule and there is no ______
larger, no brush border
The cytoplasm of the distal convoluted tubule is ____ eosinophilic than that of the proximal convoluted tubule
less
______ has a different embryological origin than that of the nephron
The collecting duct
The wall of the collecting duct consists of
simple cuboidal epithelium
What are the two major specialized cell types associated with the collecting duct
- Principle cells
- Intercalated cells
Function of Principle cells
- Reabsorb sodium ions and water
- Secrete potassium via ATPase pump
Function of Intercalated cells
Secrete either hydrogen ion or bicarbonate ion
what makes up the excretory passages of the kidney
- Renal Pelvis
- Ureter
- Urinary bladder
What are the layers in the excretory passages (renal pelvis, Ureter, and urinary bladder) of the kidney
- Mucosa
- Submucosa (not clearly demarcated)
- Muscularis
- Adventitia (FECT external to muscularis; series over superior surface of bladder)
Characteristics of the mucosa of the excretory passages (renal pelvis, Ureter, and urinary bladder) of the kidney
- Transitional epithelium (urothelium)
- Basement membrane
- Lamina propria of FECT
- some loose lymphoid tissue
- A few smooth muscle cells
Inner longitudinal and outer circular smooth muscle coat in ureter
Muscularis
The _____ ureter has a third external longitudinal smooth muscle coat (muscularis)
Lower third
Layers of smooth muscle in urinary bladder form
detrusor muscle
Section of the urethra passing through prostate gland
prostatic urethra
The mucosa of the prostatic urethra is lined with
transitional epithelium
Vascularization of prostatic urethra
-highly vascularized with veins with abundant elastic tissue
The membranous urethra extends through ________ and receives striated muscle cells forming the ___________ of the _____
urogenital diaphragm, external sphincter of the bladder
The membraneous urethra is composed of _____ cells
tall pseudostratified columnar cells but variable
What are the major components of the male urethra
- Prostatic urethra
- Membraneous urethra
- Cavernous urethra
The cavernous urethra is lined with ________ epithelium with patches of ______ epithelium
pseudostratified epithelium, with patches of stratified squamous epithelium
Glands of the male urethra
- Lucanae of Morgagni
- Glands of Littre
________ are invaginations of mucous membrane containing single or groups of intraepithelial mucous cells in male urethra
Lucanae of Morgagni
______ are branched tubulara glands opening into the lacunae of Morgagni
Glands of Littre
Mucosa of the female urethra is lined primarily with _______ epithelium with intraepithelial nests of ______
pseudostratified columnar epithelium, mucous glands
Vascularization of the lamina propria in the female urethra
highly vascularized with veins with an abundance of elastic tissue
The submucosa of the female urethra is
not discernible
Muscularis of the female urethra has an ________ and ______ but is not
inner longitudinal and outer circular layer of smooth muscle cells but is not well defined
The adventitia of the female urethra is not
discernible
Angiotensin II stimulates secretion of ______ from _____
and ____ from the ____
Aldosterone from adrenal cortex
ADH from the posterior pituitary
Aldosterone acts on the ________ cells of the _______ and the _______
principal cells of the collecting ducts and thick ascending limbs of Henle
Angiotensin I is primarily produced in the
lungs
Angiotensin-converting factor (ACE) is from _______ and ____ and converts
pulmonary and renal endothelium
converts Angiotensin I to Angiotensin II
Renin converts
antiotensinogen to angiotensin I
Angiotensinogen is a circulating blood protein produced by the
liver
Angiotensin II increases the reabsorption of ______ and ____- which increases
sodium ion and water, which increases blood pressure
