30 Questions
What is the primary function of the principal cells in the collecting duct?
To regulate water permeability through ADH-regulated water channels
What is the histological characteristic of the cells lining the collecting ducts as they descend from the cortex to the medulla?
They change from squamous to cuboidal to columnar
What is the primary function of the intercalated cells in the collecting duct?
To secrete hydrogen ions or bicarbonate ions
What is the function of the collecting ducts in the kidney?
To drain urine from the nephron to the renal pelvis
What is the characteristic of the epithelium lining the collecting tubules and ducts?
Simple cuboidal/columnar epithelium
What is the location of the collecting ducts in the kidney?
In the medullary ray within the cortex
What is the function of aldosterone in the collecting duct?
To stimulate the reabsorption of sodium ions
What is the primary function of the glomerular filtration barrier?
To prevent some large molecules from entering the capsular space
What type of epithelium forms the outer or parietal layer of Bowman's capsule?
Simple squamous epithelium
What is the function of the mesangial cells in the glomerulus?
To give structural support to podocytes and vessels
What is the name of the network of blood capillaries surrounded by Bowman's capsule?
Glomerulus
What is the name of the thin membrane that spans the filtration slits?
Filtration slit membrane
What is the name of the cells that form the inner layer of Bowman's capsule?
Podocytes
What is the name of the space between the outer and inner epithelial layers of Bowman's capsule?
Capsular space
What is the primary function of the proximal convoluted tubule in the nephron?
Transport of majority of recovered water, ions, and glucose from the filtrate
What is the effect of antidiuretic hormone (ADH) on the collecting ducts?
Makes collecting ducts more permeable to water and increases the rate of water reabsorption
What is the histological characteristic of the epithelial cells lining the proximal convoluted tubule?
Simple cuboidal with microvilli
Which segment of the nephron is responsible for ion exchange and regulation of Na+ and K+ concentration?
Distal convoluted tubule
What is the function of the juxtaglomerular apparatus?
Regulation of blood pressure
What is the histological characteristic of the epithelial cells lining the descending limb of the loop of Henle?
Simple squamous
What is the primary function of the ascending limb of the loop of Henle?
Concentration of the filtrate through osmotic gradient
What is the main function of the filtration membrane in the renal corpuscle?
To filter waste and excess substances from the blood
Which structure is responsible for influencing the resorption of sodium ions in the nephron?
Macula densa
What is the primary function of the juxtaglomerular apparatus in the nephron?
To regulate blood pressure
What is the term for the specialized smooth muscle cells in the afferent arteriole that contain renin in secretory granules?
Juxtaglomerular cells
What is the function of the podocyte filtration slits in the glomerulus?
To filter waste and excess substances from the blood
Which structure is responsible for producing renin in response to falling blood pressure?
Juxtaglomerular cells
What is the term for the portion of the terminal distal straight tubule adjacent to the renal corpuscle?
Macula densa
What is the primary component of the filtration barrier in the glomerulus?
All of the above
What is the function of the mesangial cells in the glomerulus?
To phagocytose and remove waste from the glomerular capillaries
Study Notes
Collecting System
- The collecting system starts in the cortex as a continuation of the distal convoluted tubules and descends through the medulla
- The ducts coalesce and increase in size, with cells changing from squamous to cuboidal to columnar and becoming increasingly stratified
- The ducts terminate at the tip of the renal pyramid as the papillary ducts
Collecting Ducts
- Function: resorb Na+, H2O, transfer K+, regulated by aldosterone and ADH
- Simple cuboidal/columnar epithelium
- Two types of cells: Light cells (Principal cells) and Dark cells (Intercalated cells)
Light Cells
- Also known as Collecting Duct or CD cells
- Principal cells of the system
- Pale staining cells
- Basal infoldings present
- Single primary cilium
- Few short microvilli
- Small, spherical mitochondria
- Possess abundance of ADH-regulated water channels AQP-2, responsible for water permeability of collecting duct
Dark Cells
- Also known as Intercalated cells or IC cells
- Less in number
- Cytoplasm is denser
- Many mitochondria
- No basal infoldings
- Basally located interdigitations with neighboring cells
- Numerous vesicles present in apical cytoplasm
- Secrete Hydrogen (H+) or Bicarbonate (HCO3-) ions
Renal Papilla and Renal Calyx
- Renal papilla: area where collecting ducts terminate
- Renal calyx: funnel-shaped structure that collects urine from the renal papilla
Ureter
- 3 layers in wall:
- Tunica mucosa: transitional epithelium and lamina propria
- Also attached to capillaries
- Supports contraction, phagocytosis, and secretion
Histology of Renal Tubule and Collecting Duct
- Proximal convoluted tubule: simple cuboidal with brush border of microvilli
- Descending limb of Loop of Henle: simple squamous
- Ascending limb of Loop of Henle: simple cuboidal to low columnar
- Distal convoluted tubule and collecting ducts: simple cuboidal composed of principal and intercalated cells with microvilli
Functions of Renal Tubule Segments
- Proximal convoluted tubule: transports majority of recovered water, ions, and glucose from filtrate back to blood
- Loop of Henle: regulates sodium and potassium concentration in response to aldosterone secretion
- Distal convoluted tubule: regulates sodium and potassium concentration in response to aldosterone secretion
Renal Corpuscle
- Glomerulus: network of blood capillaries surrounded by Bowman's capsule
- Bowman's capsule: capsule that surrounds the glomerulus
- Podocytes: complex cells with small foot-like processes (pedicles) that form a fenestrated epithelium around the fenestrated capillaries of the glomerulus
Blood-Urine Barrier
- Filtration membrane composed of:
- Fenestrated endothelium of the glomerulus
- Glomerular basement membrane (GBM)
- Filtration slits of the podocyte
This quiz covers the structure and function of the renal corpuscle and glomerulus, including the podocytes, filtration membrane, and blood-urine barrier. It's a great resource for students studying nephrology and renal physiology.
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