Renal Histology Flashcards
Three functions of the kidney
Excretory
homeostatic
endocrine
How does the kidney participate in excretory functions
makes an ultra filtrate; extra water, ions, drugs and metabolic breakdown products get excreted in the urine
How does the kidney participate in endocrine fnxs?
Monitoring the O2 carrying capacity of the blood via erythropoietin, regulating blood pressure through the renin-angiotensin system
What is the apperance of the cortex?
What are the linear arrays of tubles that extend into the cortex?
granular in appearance and homogeneous in consistency.
Medullary Rays.
has a striated appearance and consists of 6-18 Renal Pyramids.
Medulla
The apex or tip of a renal pyramid is called a
Renal Papilla
a macroscopic subdivision consisting of a renal pyramid and its surrounding cortex.
A Kidney Lobe
a microscopic subdivision consisting of a medullary ray and the cortical tissue (primarily nephrons) on either side.
A Kidney Lobule
The Capsule consists mainly of
fibrous connective tissue and surrounds the kidney.
*The parenchyma is not subdivided by septa.
The kidneys receive _____ of the total cardiac output/minute. The total blood volume of
the body passes through the kidneys every_____ minutes
20-25%
4-5
_____ ml of fluid is extracted from the blood each minute as filtrate [180 L/day].
•_____ ml is reabsorbed in the kidney tubules
• ___ml is excreted as urine
125 extracted
124 reabsorbed
1 ml excreated
The order of arterial supply to the kidney
Renal a.–> Lobar a.–>Interlobar a.–> arcuate a. –> Interlobular a. –> Afferent arteriole
- supplies tubules of the cortical nephrons
- long capillary loops supplying tubules of juxtamedullary nephrons
- Tubular Plexus
* Vasa Recta
Glomerulus is a two capillary system consisting of:
Tubular plexus and Vasa recta
Components of the Nephron
Renal Corpuscle
Renal Tubule
- an epithelial-lined Tubule that varies in size, shape and function along its length
Renal tubule (part of nephron)
• The kidney produces an_________ of the blood, but
it recycles many components that are in the filtrate.
Other compounds are added to the filtrate as it goes
through the tubular system
ultrafiltrate
If primarily from a Developmental Viewpoint, a nephron consists of
Renal Corpuscle, Proximal Tubule, Loop of Henle, Distal Tubule [collecting ducts not included]
If primarily from a Functional Viewpoint, a nephron consists of:
Renal Corpuscle, Proximal Tubule, Loop of Henle, Distal Tubule & Collecting Duct
Renal Corpuscle has Four Components
Glomerulus
Visceral Layer of the Renal Capsule (Bowman’s)
Parietal Layer of the Renal Capsule
Mesangium
is a spherical, double-layered sac (Renal Capsule) that surrounds a network of capillaries (Glomerulus -ball of thread).
The renal corpuscle
_____ where the arterioles enter and exit and a _______ that is continuous with the proximal convoluted tubule.
Vascular Pole
Urinary Pole
a network of capillary loops supplied and drained
by an arteriole.
Glomerulus
The Afferent (supplying) Arteriole is larger in diameter than Efferent (draining) Arteriole. Why?
This size difference creates a pressure differential that
drives glomerular filtration.
a double-layered epithelial sac surrounding the glomerulus.
Bowmans capsule
The outer or Parietal Layer is a _______epithelium.
• The Visceral Layer is also ______epithelium composed of cells called Podocytes.
simple squamous
a simple squamous
The space between the two epithelial layers is called the ________ and is continuous with the proximal tubule. The glomerular filtrate enters this space.
Urinary Space
Capillary Endothelium is discontinuous, containing numerous 70-100 nm pores . The pores are freely
permeable to
water and solutes ≤ 6-8 kD and moderately permeable to molecules 8-16kD.
The luminal
surface of the capillary endothelium has a negative charge because it is coated with a
glycocalyx consisting of negatively charged proteoglycan molecules.
is the primary barrier that prevents protein from entering the glomerular filtrate.
Basement Membrane
consists of epithelial cells called Podocytes because of their 1o and 2o foot processes (pedicles).
The Visceral Layer of Bowman’s Capsule
The space between pedicles is called the_____ and is bridged by an electron dense Filtration Slit Diaphragm, a modified ______ consisting of the protein _____
Filtration Slit
adherens junction
Nephrin.
Four functions of the mesangium
Functions:
• physical support
• regulation of glomerular blood flow
• turnover of glomerular basement membrane
• cells and ECM that abut the inner surface of the glomerular basement membrane
Glomerular Mesangium
ECM contains
fibronectin and collagen
specialized pericyte/smooth muscle cells:
• contain receptors for
• secrete
(ANP) and antiotensin II
endothelin, cytokines and PGEs
Location of convoluted portion of proximal tubule
begins at the urinary pole
and located in cortex
convoluted portion of proximal tubule
Fnx:
Cell Type:
Mitochondria?
substantial reabsorption
cuboidal/columnar cells with granular cytoplasm and basal nuclei
Numerous mitochondria at base of cell
provide energy for transport
Straight Portion: also Thick Descending Limb of
Henle has what cell type?
• cuboidal epithelium
Loop of Henle: Length is determined by the location of its renal corpuscle with respect to the:
corticomedullary junction
_________located external to the juxtamedullary zone, have short loops that have only
a Descending Thin Limb
Cortical Nephrons
_______ are long looped and
have Ascending and Descending Thin Limbs
Juxtamedullary Nephrons
thick portions of the loop are lined with _______, but the thin segments are lined with simple ______
cuboidal epithelium
squamous epithelium
cell membranes in the ascending thin limb between
epithelial cells are interdigitated, resulting in
water impermeability
Straight portion: Thick Ascending • lined with • scant microvilli,\_\_\_\_\_\_junctions • Lateral & basal membane interdigitations •\_\_\_\_\_\_ mitochondria
cuboidal epithelium
efficient tight
abundant
Straight portion: thick ascending
- What’s reabsorbed?
- relationship with water
- What’s secreted?
- Impermeable to water
- Na2+, Cl-, and water reabsorbed
- glucose, amino acids, proteins reabsorbed through facilitated transport
- H+ions secreted
Convoluted Portion (Early Distal Tubule) • lined with •\_\_\_\_\_ microvilli •\_\_\_\_\_ basal interdigitations •\_\_\_\_\_\_ mitochondria
cuboidal epithelium
scant
fewer
fewer
Convoluted Portion: early distal tubule:
What is reabsorbed?
What is secreted>
- Na2+ (Aldosterone responsive), Cl-, K+, HCO3 reabsorbed
* K+, urate, H+ions, N3H secreted
Contains Cuboidal cells (Principal [light] &
Intercalated [dark] cells) with Distinct cell borders
Collecting Tubules (Late Distal Tubule) & Collecting Ducts
transition segment between the nephron and the collecting duct
Collecting Tubules (Late Distal Tubule)
epithelium contains principal cells
Collecting tubules: late distal tubules
Collecting tubules: late distal tubules Antidiuretic Hormone (ADH) dependent segment where:
Na2+ is reaborbed and K+
is secreted
Renal Tubular Disease:
Caused by:
How reabsorptive secreatory functions affected:
- Caused by toxins, drugs, infections, metabolic disturbances, ischemia
- Affects reabsorptive and secretory functions resulting in either polyuria or oligo/anuria
Acidosis in renal failure results because of failure of
H ion excretion
Collecting ducts are lined with
Lined with cuboidal to columnar epithelium
have one primary cilium and Antidiuretic Hormone (ADH) sensitive AQP-2 water channels.
Principal (light) Cells in collecting ducts
In the presence of
ADH, urea and water diffuse out of the collecting duct and into the renal interstitium.
What is the result?
This increases urine tonicity
in the absence of ADH, water is
excreted from the collecting ducts leading to
Polyuria and hypotonic urine (Diabetes Insipidus).
acts as a flow sensor in collecting ducts. This function is mediated by two
proteins Polycystin 1 & 2.
The single, nonmotile Primary Cilium
– Defects in these proteins result in polycystic kidney disease.
Polycystin 1 & 2.
the Space Between the Tubules
Renal Interstitium
• interstitial (stromal) tissue is
found in the
renal cortex & medulla
Renal interstitium components has what 2 componements?
- interstitial CT
* interstitial cells (fibroblasts) in cortex & medulla
Tubular-Interstitium-Vascular Interaction provides a mechanism for modifying and concentrating urine and as what three components?
- Collecting ducts
- Loops of Henle
- Vasa Recta
________- urine concentration
_________- protects ion gradient
Countercurrent Multiplier
Countercurrent Exchanger
three components of JG apparatus
Renin producing
Extraglomerular mesangial cells
Macula densa
Renin producing JG cells are what type of cell and located where?
special smooth muscle cells
in wall of afferent arteriole
Extraglomerular mesangial (lactis) cells are connected to JG cells via _________
gap junctions
Macula Densa
– _____ of the distal convoluted tubule.
– detects ____ and _____concentration for JG cells resulting in alterations of the
filtration rate and auto-regulation of blood volume
columnar cells
Na2+ and Cl-
JG apparatus components can increase systemic blood pressure (BP) & blood volume
(BV) through the
angiotensin system
_____ stimulates angiotensin
conversion/increase in aldosterone secretion/increased Na and water reabsorption
Renin
Function of erythropoietin
- increase mitosis of red blood cell precursors
* increase release of red cells from marrow
Erythropoietin is mostly likely made by _______ and transported to __________
- Probably produced by cortical interstitial cells
* Transported to bone marrow
What stimulates production of Erythropoietin?
• Production stimulated by
- high altitude
- hemorrhage
- impaired pulmonary function
What are clinical indications for acute kidney fail?
oligouria <400ml/day, unexpected weight gain or
edema, increased toxins in blood
*Prognosis depends on cause, severity, treatment, age
Progression of End Stage renal disease
Irreversible injury–>ESRD–> uremia + hematuria
Nephrons are connected to a collecting duct system found mostly in the
medulla
collect urine and transport it to the urinary bladder
hollow organs with lumen and wall with several layers
Calyces, Pelvis, Ureters
Mucosa in calyces,pelvis, ureters
• _____ (uro)epithelium
• lamina propria contains
transitional
abundant elastic tissue
Muscular organization of Calyces, Pelvis, Ureters
• smooth muscle
• in ureter -2 layers in the upper 2/3 of the ureter;
3 layers lower 1/3 of the ureter
Urinary Bladder
•______ epithelium
• ____layers of smooth muscle
Transitional
3
Male Vs female urethra
Male: 15-20 cm; 3 parts
(prostatic, membranous, penile)
• Transitional – pseudostratified sq. and Shared urinary &
reproductive systems
Female:
3-5 cm
• Transitional – pseudostratified sq. and Urinary system only
Benign Prostatic Hypertropyhy
also known as nodular hyperplasia seen in:
- Older males >45 years
* Can cause urethral obstruction
Common in USA (7-21/1000), Increased in men, sedintary individual
• Hereditary disposition
• Hypercalcemia, pH change, supersaturation of ions encourage it
Kidney stones
Bladder Cancer
• Associated with_____
• Majority in US involve the ______
smoking
uroepithelium
