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What is the name of the structure that surrounds the glomerulus?
What is the function of the afferent arteriole?
What is the name of the tubule that collects waste from the nephron?
What is the name of the structure that contains the glomerulus and the glomerular capsule?
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What is the name of the part of the nephron that begins at the urinary pole?
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What is the name of the structure that is divided into medullary pyramids and renal columns?
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What is the name of the structure that connects the renal corpuscle to the proximal convoluted tubule?
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What is the name of the structure that contains the cortical labyrinth and the medullary rays?
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What type of cells are found in the thin segment?
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What is the main function of the distal tubule?
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What is the primary function of aldosterone in the distal tubule?
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What type of process is involved in the absorption of glucose and amino acids?
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What is the approximate length of the thin segment?
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What is excreted in the excretion process?
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What is the characteristic of the opening of the fenestrated variety of capillaries of the glomerulus?
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What is the function of mesangial cells in the capillary network of the glomerulus?
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What is the characteristic of the parietal layer of the glomerular capsule?
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What is the function of the filtration slits in the podocyte?
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What is the composition of the basal lamina in the glomerulus?
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What is the characteristic of the primary urine formed by the glomerular filter?
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What is the characteristic of the proximal tubule?
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What is the function of the proximal tubule?
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What is the function of the collecting tubule in the kidney?
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What is the effect of excreting hydrogen and ammonium ions?
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What is the function of the juxtaglomerular cells?
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What is the structure of the cells in the collecting tubule?
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What is the function of the macula densa?
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What is the location of the extraglomerular mesangial cell?
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What is the effect of the arginine vasopressin (ADH) on the collecting tubule?
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What is the structure of the juxtaglomerular cells?
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Study Notes
Urinary System Components
- The urinary system consists of the kidney, ureters, bladder, and urethra.
Kidney Structure
- The kidney has two main parts: the parenchyma and the medulla.
- The medulla has 10-18 medullary pyramids, and the renal column is located between them.
- The cortex has medullary rays and cortical labyrinth.
Renal Lobe and Renal Lobule
- A renal lobe is a medullary pyramid and the associated cortical tissue.
- A renal lobule is a medullary ray and the surrounding cortical labyrinth.
Renal Corpuscle (Nephron)
- The renal corpuscle is spherical, approximately 200mm in diameter.
- It has a glomerulus (a tuft of capillaries) and a glomerular capsule (a double-walled epithelial capsule).
- The renal corpuscle has two poles: the vascular pole (where the afferent arteriole enters and the efferent arteriole leaves) and the urinary pole (where the proximal convoluted tubule begins).
Glomerulus
- The glomerulus is a fenestrated capillary and arterial capillary.
- Blood flow through the glomerulus is very fast (1.2-1.3L/min) with high hydrostatic pressure (about 45mmHg).
Capillaries of Glomerulus
- The capillaries are fenestrated, with openings of about 70-90 nm in diameter.
- The cell coat contains negatively charged proteoglycan.
Glomerular Capsule
- The glomerular capsule is a double-walled epithelial chamber.
- It has a parietal layer (simple squamous epithelium) and a visceral layer (podocytes).
Podocyte
- Podocytes have secondary processes that interdigitate with each other and embrace the capillaries.
- The filtration slits are narrow spaces between the secondary processes, approximately 25nm wide.
Filtration Barrier
- The filtration barrier consists of fenestrated endothelial cells, a fused basal lamina, and slit membrane.
Basal Lamina
- The basal lamina has two electron-lucent layers (laminae rara) and a central electron-dense layer (laminae densa).
- The central electron-dense layer is a meshwork of type IV collagen and laminin.
Filtration Membrane
- The filtration membrane is a selective macromolecular filter.
- It has a physical filter, allowing molecules less than 10nm in diameter to pass through.
- It also has a charge barrier, allowing negatively charged proteins with a molecular mass of less than 69kD to pass through sparingly.
Renal Tubule
- The renal tubule is simple epithelium.
- It has proximal convoluted tubule, proximal straight tubule, thin segment, distal convoluted tubule, distal straight tubule, and collecting tubule.
Proximal Convoluted Tubule
- The proximal convoluted tubule is approximately 14 mm long and 50-60um in diameter.
- It has a cuboidal shape with a round nucleus, a small lumen, and a brush-like border.
Function of Proximal Tubule
- The proximal tubule absorbs 85% of sodium chloride, phosphate, and calcium, as well as all of glucose, amino acid, polypeptide, proteins, and vitamins.
- It excretes creatinine and foreign substances.
Thin Segment
- The thin segment is 10-15 um in diameter, with a simple squamous epithelium.
- It absorbs sodium and chloride and 5% of water.
Distal Convoluted Tubule
- The distal convoluted tubule has a lumen that is larger than the proximal convoluted tubule.
- It has a cuboidal shape with a round nucleus, and no brush-like border.
Function of Distal Tubule
- The distal tubule is regulated by aldosterone (adrenal gland).
- It absorbs sodium and secretes potassium ions, influencing the total salt and water content of the body.
- It maintains the acid-base balance in the blood.
Collecting Tubule and Duct
- The collecting tubule and duct have a simple epithelium with cuboidal to columnar cells.
- They are controlled by arginine vasopressin (ADH) or antidiuretic hormone.
Function of Collecting Tubule
- The collecting tubule absorbs sodium and water and secretes potassium ions.
- It is controlled by the arginine vasopressin (ADH) or antidiuretic hormone.
Juxtaglomerular Complex
- The juxtaglomerular complex consists of juxtaglomerular cells (JG cells) and macula densa cells.
Juxtaglomerular Cells (JG Cells)
- JG cells are modified smooth muscle cells of afferent arterioles.
- They have a larger, cuboidal shape with round nuclei and contain secretory granules.
- They secrete renin, which increases blood pressure.
Macula Densa
- Macula densa cells are derived from the epithelium of the distal tubule.
- They have a taller, narrower shape with round nuclei and apical processes connecting with other cells.
- They are chemoreceptors, sensing the sodium concentration.
Extraglomerular Mesangial Cell
- Extraglomerular mesangial cells are located between the macula densa and Bowman's capsule at the entry of the afferent arteriole.
- They produce ground substance, endocytose normal and pathologic molecules, give structural support to the glomerulus, and secrete chemical mediators.
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Description
This quiz assesses knowledge of the urinary system's components, including the kidney, ureters, bladder, and urethra. It covers the internal structures of the kidney, such as the parenchyma, medulla, cortex, and renal corpuscle.
