Urinary System

Podcast Beta

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is the function of the filtration slit diaphragms in the glomerular filtration barrier?

To regulate the pressure of the blood flow

To produce the filtrate in the corpuscle

To filter small proteins from the blood plasma

To separate the podocyte pedicels from the capillary endothelium (correct)

What is the primary function of the podocytes in the renal corpuscle?

To filter blood in the glomerular capillaries (correct)

To reabsorb nutrients from the filtrate

To regulate blood pressure through vasodilation

To secrete substances into the proximal convoluted tubule

What is the major component of the glomerular filter formed by?

The GBM

The podocyte pedicels

The fenestrated capillary endothelium

Fusion of the basal laminae of a podocyte and a capillary endothelial cell (correct)

What is the structure that drains into an efferent arteriole?

Mass of capillary loops Signup and view all the answers

What is the mechanism of filtrate production in the corpuscle?

Blood plasma is forced under pressure through the capillary fenestrations Signup and view all the answers

What is the term for the secondary processes of the podocytes?

Pedicels Signup and view all the answers

What is the shape of the cells that form the simple squamous layer of Bowman's capsule?

Squamous Signup and view all the answers

What is the function of the capsular space in the glomerulus?

To receive the filtrate Signup and view all the answers

What is the type of epithelium that forms the proximal convoluted tubule?

Simple cuboidal epithelium Signup and view all the answers

What is the structure that surrounds the glomerular capillaries?

Bowman's capsule Signup and view all the answers

What is the region of the renal corpuscle where the afferent arteriole enters and the efferent arteriole leaves?

Vascular pole Signup and view all the answers

What is the type of microscopy used to show the distinctive appearance of podocytes and their pedicel processes?

Scanning electron microscopy Signup and view all the answers

What is the function of the peritubular capillaries?

To reabsorb nutrients from the filtrate Signup and view all the answers

What is the type of epithelium that supports the basal lamina in the outer parietal layer of the glomerular capsule?

Simple squamous epithelium Signup and view all the answers

What is the term for the process of producing filtrate in the corpuscle?

Filtration Signup and view all the answers

What is the structure that branches from the arcuate arteries and radiates out through the cortex?

Small interlobular artery Signup and view all the answers

What is a common cause of inflammation in the urinary tract, besides urinary tract infections?

Immunodeficiency Signup and view all the answers

What is the term for the unique stratified epithelium lining the ureter?

Transitional epithelium Signup and view all the answers

What is the function of the muscularis in the ureter?

To move urine through the ureter by regular waves of peristalsis Signup and view all the answers

What is the term for the benign changes that can occur in the urothelium as a result of chronic cystitis?

Both A and B Signup and view all the answers

What is the type of carcinoma that usually arises from unstable urothelium?

Transitional cell carcinoma Signup and view all the answers

What is the function of the urethra?

To carry urine from the bladder to the exterior Signup and view all the answers

What is the characteristic appearance of the urethral mucosa in cross section?

Folds Signup and view all the answers

In men, where do the ducts for sperm transport during ejaculation join the urethra?

Prostate gland Signup and view all the answers

What is the primary function of the slit diaphragms in the glomerular filtration barrier?

To maintain the integrity of the filtration slit pores Signup and view all the answers

What is the width of the filtration slit pores between the interdigitating pedicels?

25-30 nm Signup and view all the answers

What type of proteins are involved in the formation of the slit diaphragms?

Nephrins, proteoglycans, and glycoproteins Signup and view all the answers

What is the primary component of the glomerular basement membrane?

Fused basal laminae from capillary and podocyte Signup and view all the answers

What is the approximate thickness of the glomerular basement membrane?

300-360 nm Signup and view all the answers

What is the function of the glomerular basement membrane in the filtration barrier?

To restrict the passage of proteins larger than 70 kDa Signup and view all the answers

What is the net charge of the surface of the slit diaphragm?

Negatively charged Signup and view all the answers

What is the fate of smaller proteins that are filtered from plasma?

They are degraded and reabsorbed in the proximal tubule Signup and view all the answers

What is the main function of the collecting system in the nephron?

To reabsorb more water if needed by the body Signup and view all the answers

What type of epithelium is found in the collecting ducts in the cortical medullary rays?

Simple cuboidal Signup and view all the answers

What is the average diameter of the collecting ducts in the cortical medullary rays?

40 μm Signup and view all the answers

What happens to the collecting ducts as they approach the apex of each renal pyramid?

They merge to form larger collecting ducts Signup and view all the answers

What is the function of the JG cells in the nephron?

To regulate blood pressure by secreting renin Signup and view all the answers

What is the shape of the epithelial cells in the collecting ducts of the medulla?

Columnar Signup and view all the answers

What is the diameter of the collecting ducts in the medulla?

200 μm Signup and view all the answers

What is the function of the connecting tubule in the nephron?

To carry the filtrate into a collecting system Signup and view all the answers

What is the location of the proximal convoluted tubule in the kidney?

Cortex Signup and view all the answers

What is the structure that connects the proximal straight tubule to the thin descending limb of the loop of Henle?

Loop of Henle Signup and view all the answers

What is the blood vessel that converges into small stellate veins in the kidney?

Peritubular capillary Signup and view all the answers

What is the number of functional units called nephrons in each kidney?

1-4 million Signup and view all the answers

What is the location of the thin ascending limb of the loop of Henle in the kidney?

Medulla Signup and view all the answers

What is the structure that originates in the cortex of the kidney?

Nephron Signup and view all the answers

What is the fate of the blood that leaves the kidney?

It enters the veins Signup and view all the answers

What is the term for the diseases involving the renal corpuscles?

Glomerular diseases Signup and view all the answers

What is the region where the connecting tubules converge?

Renal papilla Signup and view all the answers

Where does the afferent arteriole enter and the efferent arteriole leave?

Vascular pole Signup and view all the answers

What is the characteristic of juxtamedullary nephrons?

Lie close to the medulla Signup and view all the answers

What is the primary function of the podocytes and capillary endothelial cells?

Filtration Signup and view all the answers

What is the result of polycystic kidney disease?

Loss of renal function and gross kidney enlargement Signup and view all the answers

What is the type of epithelium that continues and forms the proximal convoluted tubule?

Simple cuboidal Signup and view all the answers

What is the structure that drains into an efferent arteriole?

Glomerulus Signup and view all the answers

What is the structure that covers the cortex and hilum?

Fibrous capsule Signup and view all the answers

What is the term for the extensions of the podocyte cell body that curve around the glomerular capillary?

Primary processes Signup and view all the answers

What is the characteristic of the kidney vasculature?

Large and well-organized Signup and view all the answers

How do the segmental arteries arise?

From the renal artery Signup and view all the answers

What is the structure that forms a large, diffuse network throughout the cortex?

Peritubular capillary Signup and view all the answers

What is the shape of the epithelial cells that form the visceral layer of the glomerular capsule?

Stellate Signup and view all the answers

What is the structure that drains into a minor calyx?

Collecting duct Signup and view all the answers

What is the location of the cortical nephrons?

Almost completely in the cortex Signup and view all the answers

What is the term for the small extensions of the primary processes that interdigitate with each other?

Pedicels Signup and view all the answers

What is the primary function of the microvilli in the proximal convoluted tubule?

To facilitate reabsorption of nutrients and ions Signup and view all the answers

What is the characteristic appearance of the lumen in the proximal convoluted tubule in routine histologic preparations?

A fuzzy, filled appearance Signup and view all the answers

What is the purpose of the vesicles in the apical cytoplasm of proximal tubular cells?

To contain reabsorbed proteins for degradation Signup and view all the answers

What is the function of the mitochondria concentrated along the basal invaginations in proximal tubular cells?

To supply ATP for active transport Signup and view all the answers

What is the significance of the interdigitations of the lateral membranes in proximal tubular cells?

To make the discrete limits between cells difficult to see Signup and view all the answers

What is the function of the peritubular capillaries in the proximal convoluted tubule?

To remove reabsorbed proteins from the circulation Signup and view all the answers

What is the characteristic structure of the proximal convoluted tubule in the cortex?

A sparse, surrounding connective tissue Signup and view all the answers

What is the function of the transmembrane proteins in the proximal convoluted tubule?

To mediate tubular reabsorption and secretion Signup and view all the answers

What is the primary role of the urinary system?

To ensure optimal properties of the blood Signup and view all the answers

What is the function of the kidneys in regards to blood pressure regulation?

To regulate blood pressure through the secretion of renin Signup and view all the answers

What is the role of the kidneys in regards to erythrocyte production?

To stimulate erythrocyte production through the production of erythropoietin Signup and view all the answers

What is the role of the kidneys in regards to vitamin D?

To convert vitamin D to its active form Signup and view all the answers

What is the role of the kidneys during starvation or periods of prolonged fasting?

To produce glucose through gluconeogenesis from amino acids Signup and view all the answers

What is the primary function of the kidneys in regards to electrolyte balance?

To regulate electrolyte balance through the excretion of excess electrolytes Signup and view all the answers

What is the role of the kidneys in regards to bioactive substances?

To regulate bioactive substances through the excretion of excess bioactive substances Signup and view all the answers

What is the primary function of the kidneys in regards to acid-base balance?

To regulate acid-base balance through the excretion of excess hydrogen ions Signup and view all the answers

What is the mechanism by which polyanionic GAGs in the glomerular membrane restrict filtration?

Electrostatic repulsion Signup and view all the answers

What is the approximate percentage of blood plasma that is filtered into the capsular space in a normal glomerulus?

20% Signup and view all the answers

What is the function of the internal or visceral layer of the glomerular capsule?

To envelop the glomerular capillaries Signup and view all the answers

What is the composition of the initial glomerular filtrate similar to?

Blood plasma Signup and view all the answers

What is the function of the fenestrations in the capillary endothelium?

To block blood cells and platelets Signup and view all the answers

What is the location of the capsular space?

Between the two capsular layers Signup and view all the answers

What is the function of the thick, combined basal laminae?

To restrict large proteins and some organic anions Signup and view all the answers

What is the structure that receives the fluid filtered through the capillary wall?

Capsular space Signup and view all the answers

What is the type of epithelium that lines the membranous urethra?

Stratified columnar and pseudostratified columnar epithelium Signup and view all the answers

What is the length of the spongy urethra in males?

15 cm Signup and view all the answers

What is the function of the external striated muscle sphincter in both sexes?

To regulate urine flow through the urethra Signup and view all the answers

What is the characteristic feature of the female urethra?

It is exclusively a urinary organ Signup and view all the answers

What is the typical symptom of urethritis?

Pain or difficulty during urination Signup and view all the answers

What is the type of epithelium that lines the distal part of the spongy urethra?

Stratified squamous epithelium Signup and view all the answers

What is the primary cause of urinary tract infections?

Both coliform bacteria and Chlamydia Signup and view all the answers

What is the characteristic feature of the epithelium lining the female urethra?

It is nonkeratinized stratified squamous epithelium Signup and view all the answers

What is the shape of the corpuscles found in the renal cortex?

Round Signup and view all the answers

What is the function of the renal columns?

To separate the renal pyramids Signup and view all the answers

Where do the minor calyces arise from?

From the renal pelvis Signup and view all the answers

What is the approximate length of each kidney in adults?

12 cm Signup and view all the answers

What is the structure that covers the cortex and hilum?

Fibrous capsule Signup and view all the answers

How many conical structures are found in the renal medulla in humans?

8-15 Signup and view all the answers

What is the purpose of the adipose tissue surrounding the renal pelvis and calyces?

To support the structure Signup and view all the answers

What is the structure formed by each pyramid plus the cortical tissue at its base and extending along its sides?

Renal lobe Signup and view all the answers

What is the primary function of the podocytes in the renal corpuscle?

To filter blood through the filtration slits Signup and view all the answers

What is the structure that connects the proximal convoluted tubule to the distal convoluted tubule?

Loop of Henle Signup and view all the answers

What is the primary function of the glomerular capillary endothelium?

To allow for the exchange of substances between the blood and the filtrate Signup and view all the answers

What is the term for the process of producing filtrate in the renal corpuscle?

Ultrafiltration Signup and view all the answers

What is the structure that drains into the minor calyx?

Collecting duct Signup and view all the answers

What is the primary function of the macula densa?

To detect changes in NaCl concentration in the tubular fluid Signup and view all the answers

What is the location of the juxtaglomerular apparatus?

At the vascular pole of the renal corpuscle Signup and view all the answers

What is the primary function of the pedicels?

To increase the surface area for filtration Signup and view all the answers

What is the characteristic of the interstitium as seen in the TEM?

It has a slightly fibrous nature Signup and view all the answers

What is the primary function of the collecting ducts in the nephron?

To reabsorb water and ions if needed by the body Signup and view all the answers

What is the shape of the epithelial cells in the collecting ducts of the medulla?

Columnar Signup and view all the answers

What is the diameter of the collecting ducts in the cortical medullary rays?

40 μm Signup and view all the answers

What is the location of the JG cells that secrete renin?

In the juxtaglomerular apparatus Signup and view all the answers

What is the result of the return of normal blood pressure on the secretion of renin?

It turns off the secretion of renin Signup and view all the answers

What is the structure that forms the last part of each nephron?

Connecting tubule Signup and view all the answers

What is the characteristic of the collecting ducts in the medulla compared to those in the cortical medullary rays?

They are larger and have columnar cells Signup and view all the answers

Study Notes

Renal Vasculature and Filtration

Small interlobular arteries branch from arcuate arteries to supply afferent arterioles to glomerular capillaries.
Each glomerulus contains capillary loops that drain into efferent arterioles, leading to a network of peritubular capillaries throughout the renal cortex.
The renal corpuscle features a vascular pole (afferent and efferent arterioles) and a tubular pole (beginning of proximal convoluted tubule, PCT).
The outer parietal layer of glomerular capsules consists of simple squamous epithelium supported by a basal lamina, transitioning to cuboidal epithelium in the PCT.

Podocytes and Filtration Membrane

Podocytes are stellate epithelial cells forming the visceral layer of the renal corpuscle, crucial for kidney filtration.
Podocytes have primary processes that extend around glomerular capillaries, leading to numerous interdigitating secondary processes called pedicels.
Filtration slits between pedicels, around 25-30 nm wide, are covered by specialized slit diaphragms composed of proteins important for renal function.

Glomerular Filtration Barrier

Composed of three layers: fenestrated capillary endothelium, glomerular basement membrane (GBM), and filtration slit diaphragms.
Fenestrated endothelium blocks blood cells and platelets, while GBM restricts entry of large proteins over 70 kDa.
Negatively charged surfaces of the slit diaphragm and GBM enhance the restriction of organic anions.

Urinary System Functions

The urinary system regulates water and electrolyte balance, blood pressure, and acid-base balance while excreting metabolic waste through urine.
Kidneys secrete renin, erythropoietin, and convert vitamin D into its active form during various physiological states.
Major filtration occurs when approximately 20% of blood plasma entering the glomerulus gets filtered into the capsular space.

Renal Tubules and Collecting Ducts

Proximal convoluted tubule is the main site for reabsorption and features a brush border for increased surface area.
The loop of Henle comprises thin descending and ascending limbs, critical for urine concentration.
Connecting tubules from nephrons converge to form larger collecting ducts before emptying into minor calyces.
Collecting ducts vary in diameter, ranging up to 200 µm in the medulla, adapting epithelium from cuboidal to columnar cells.

Nephrons and Kidney Structure

Each kidney houses 1-4 million nephrons, the functional units of urine formation.
Cortical nephrons reside primarily in the cortex; juxtamedullary nephrons have longer loops reaching into the medulla.
The kidney is approximately 12 cm long and enclosed by a fibrous capsule, with specific structures like the hilum for blood vessels and the ureter.

Pathologies and Medical Applications

Polycystic kidney disease leads to the formation of fluid-filled cysts affecting renal function and structure.
Urinary tract infections commonly produce symptoms like dysuria and frequent urges due to bacterium-induced inflammatory responses.
Cystitis and bladder cancer often arise from chronic inflammation of the urinary tract.

Microscopic and Histological Features

The renal corpuscle features a glomerulus surrounded by a capsular space and includes distinctive podocytes that surround glomerular capillaries.
Histological sections show complex podocyte structures with interdigitating processes, enhancing filtration efficiency.### Renal Histology
Mallory trichrome staining technique helps visualize renal structures.
Transmission Electron Microscopy (TEM) reveals slightly fibrous interstitium.
The simple squamous epithelium of thin limbs is thicker than that of the nearby vasa recta capillaries.

Renal Function

Essential functions of the urinary system: filtration, secretion, and reabsorption.
Juxtaglomerular (JG) cells secrete renin; secretion stops with the return of normal blood pressure.

Collecting Ducts Structure

The connecting tubule is the final segment of each nephron, transporting filtrate to a collecting system.
Collecting ducts consist of simple cuboidal epithelium, with an average diameter of 40 μm.
In the medulla, collecting ducts become larger and straighter, with increasing diameters up to 200 μm and more columnar cell structure.
Medullary collecting ducts converge to form papillary ducts near the apex of renal pyramids.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

Explore the anatomy and function of the renal system, including the role of interlobular arteries, afferent arterioles, and peritubular capillaries in filtration, secretion, and reabsorption. Learn about the structure of the glomerulus and its importance in renal function.