52. Histology - Microanatomy of the Urinary System

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Questions and Answers

What is the primary function of the nephron in the kidney?

Production of hormones.

Storage of urine before excretion.

Filtration of blood and formation of urine. (correct)

Regulation of blood pressure.

Which of the following structures is NOT found in the renal sinus?

Fatty connective tissue.

Renal pelvis.

Medullary pyramids. (correct)

Major calyx.

What is the role of the ureter in the urinary system?

Stores urine.

Filters blood.

Produces hormones.

Carries urine from the kidney to the bladder. (correct)

What characterizes the renal corpuscle?

It includes Bowman’s capsule and glomerular capillaries. Signup and view all the answers

How many nephron units does each kidney approximately contain?

1 million. Signup and view all the answers

Which part of the kidney is primarily involved in urine concentration?

Medulla. Signup and view all the answers

What is the shape of the nephron's Bowman’s capsule?

Spherical. Signup and view all the answers

What does the term 'lobule' refer to in the kidney's anatomy?

Medullary ray and associated cortical tissue. Signup and view all the answers

What is the primary function of the renal corpuscle?

Filtration of plasma Signup and view all the answers

Which component of Bowman’s capsule contains podocytes?

Visceral layer Signup and view all the answers

What type of epithelium is found in the parietal layer of Bowman’s capsule?

Simple squamous epithelium Signup and view all the answers

What anatomical feature distinguishes juxtamedullary glomeruli from other types of glomeruli?

Efferent arterioles forming vasae rectae Signup and view all the answers

What aspect of the filtration barrier is primarily formed by fenestrated endothelium?

Selective filtration of small molecules Signup and view all the answers

Which layer of the renal corpuscle is continuous with the proximal convoluted tubule?

Parietal layer of Bowman’s capsule Signup and view all the answers

Which vessels are responsible for the counter-current exchange system in the medulla?

Vasae rectae Signup and view all the answers

What type of structure do podocytes form in relation to the glomerular capillaries?

Slit membranes Signup and view all the answers

What type of muscle forms the internal sphincter around the origin of the urethra from the bladder?

Smooth muscle Signup and view all the answers

What is the role of hairpin turns in the vasa rectae arteries?

Facilitate counter-current exchange Signup and view all the answers

Which structure is involved in the initial filtration of blood plasma?

Glomerular capillary Signup and view all the answers

What is a notable structural difference between the female and male urethra?

The male urethra is significantly longer. Signup and view all the answers

What type of epithelium transitions near the bladder to stratified squamous epithelium?

Transitional epithelium Signup and view all the answers

Which type of muscle arises from the urogenital diaphragm in the male urethra?

Skeletal muscle Signup and view all the answers

What is the primary purpose of the mucous glands of Litttré?

To lubricate the urethra Signup and view all the answers

What is the primary function of intraglomerular mesangial cells?

Regulating blood flow through the glomerulus Signup and view all the answers

Which type of cells are described as not being derived from monocytes?

Mesangial cells Signup and view all the answers

What aids the absorption of substances in the proximal tubule?

Aquaporin-1 channels Signup and view all the answers

Which substances are primarily recovered by the proximal tubule?

Electrolytes and water Signup and view all the answers

What is one notable secretion from mesangial cells?

Interleukin 1 (IL-1) Signup and view all the answers

Which process is NOT a function of the proximal tubule?

Filtration of blood Signup and view all the answers

How does water follow the absorbed ions in the proximal tubule?

Osmosis and diffusion Signup and view all the answers

What significant role do mesangial cells play in renal function?

Maintenance of basement membrane Signup and view all the answers

Which ion is actively transported in the proximal tubule?

Sodium Signup and view all the answers

What is a key difference between mesangial cells and typical phagocytic cells?

Mesangial cells originate from smooth muscle cells Signup and view all the answers

Which characteristic is NOT associated with simple cuboidal epithelium in the proximal tubule?

Abundant cilia Signup and view all the answers

What is the primary function of the Na+, K+, ATPase pump in the ascending thin limb of the loop of Henle?

Increases osmotic gradient in the interstitium Signup and view all the answers

What type of capillaries are found in close proximity to the proximal tubule?

Fenestrated capillaries with diaphragms Signup and view all the answers

What effect do diuretics have on the Na+, K+, ATPase pump in the ascending limb?

Inhibit its uptake of NaCl Signup and view all the answers

Which cellular structure is primarily involved in intracellular degradation in the proximal tubule epithelium?

Endocytotic apparatus Signup and view all the answers

Which type of epithelium lines the thin limb of the loop of Henle?

Simple squamous epithelium Signup and view all the answers

What aspect of the proximal tubule enhances its role in reabsorption?

Prominent brush border with microvilli Signup and view all the answers

What is a key feature of the ascending portion of the thin limb?

Impaired NaCl permeability Signup and view all the answers

How does the morphological structure of the proximal tubule contribute to its function?

High surface area increases reabsorption Signup and view all the answers

Which of the following functions is NOT directly attributed to the proximal tubule?

Concentration of urine Signup and view all the answers

Study Notes

Kidney Structure

The kidney has an outer cortex and an inner medulla
The cortex is composed of renal corpuscles and tubules
The medulla contains tubules and collecting ducts grouped into pyramids
The pyramids converge to form a papilla which projects into a minor calyx
The renal sinus contains the renal pelvis, major and minor calyces, blood vessels and nerves

Nephron Structure

The functional unit of the kidney is the nephron
Each kidney contains approximately 1 million nephrons
The nephron is composed of a renal corpuscle and a tubule
The renal corpuscle is composed of Bowman's capsule and a glomerulus

Glomerulus

The glomerulus is a branched fenestrated capillary
The glomerular capillary endothelium has open fenestrae
The glomerular capillary is surrounded by Bowman's capsule

Bowman's Capsule

Bowman's capsule encloses the urinary space which contains provisional urine
The parietal layer of Bowman's capsule is made of simple squamous epithelium
The visceral layer of Bowman's capsule is made of podocytes with interdigitating pedicels, separated by slit pores spanned by slit membranes

Filtration Barrier

The filtration barrier is composed of the glomerular capillary endothelium, the basement membrane and podocyte pedicels with slit pores
The filtration barrier prevents the passage of large molecules from the blood into the urine

Mesangial Cells

Mesangial cells are specialized contractile cells located within the glomerulus
Mesangial cells participate in the maintenance of the basement membrane, provide structural support and regulate blood flow through the glomerulus

Proximal Tubule (PT)

The proximal tubule is responsible for the reabsorption of about 2/3 of the glomerular filtrate
The proximal tubule reabsorbs water, ions, glucose, amino acids and small proteins and secretes creatinine, some dyes and drugs
The proximal tubule is lined by simple cuboidal epithelium with a brush border and basal striations
The brush border contains peptidases which aid in the digestion of proteins
The basal striations are folds in the plasma membrane which increase the surface area for reabsorption

Loop of Henle

The loop of Henle is a U-shaped structure that extends from the proximal tubule into the medulla
The loop of Henle is divided into a descending limb, a thin limb and an ascending limb
The descending limb of the loop of Henle is permeable to water but impermeable to solutes
The thin limb of the loop of Henle is permeable to both water and solutes
The ascending limb of the loop of Henle is impermeable to water but permeable to solutes, including sodium and chloride
The ascending limb of the loop of Henle contains a Na+, K+, ATPase pump which helps to create the osmotic gradient necessary for the concentration of urine

Distal Tubule (DT)

The distal tubule is responsible for the reabsorption of sodium chloride and water
The distal tubule is lined by simple cuboidal epithelium
The distal tubule also plays a role in the regulation of potassium and calcium levels in the blood

Collecting Duct

The collecting duct is responsible for the final concentration of urine
The collecting duct is lined by simple cuboidal epithelium
The collecting duct is permeable to water but impermeable to solutes
The wall of the collecting duct contains aquaporins which allow water to pass from the tubule into the interstitial fluid, resulting in a concentrated urine.

Urethra Structure

The male urethra is about 20 cm long and is part of the urinary and genital systems
The female urethra is about 3-5 cm long and is part of the urinary system
The female urethra is lined by stratified squamous epithelium and has patches of stratified or pseudostratified columnar epithelium
The female urethra has mucous glands of Littre
The male urethra will be examined later together with the Male Reproductive System

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Description

Test your knowledge on the intricate structures of the kidney and nephron, including their key components such as the renal corpuscle, medulla, and glomerulus. This quiz covers essential details about how these structures function together in the urinary system.