Urinary System Overview

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Questions and Answers

What is the function of the lamina densa of the basement membrane in the glomerular capillary loop?

To retain albumin and larger molecules (correct)

To produce ultrafiltrate

To secrete potassium and hydrogen

To reabsorb glucose and amino acids

What is the width of the filtration slits in the glomerular capillary loop?

10-20 nm

25-60 nm (correct)

200-250 nm

100-150 nm

What percentage of the ultrafiltrate is reabsorbed in the renal tubules?

50%

98% (correct)

75%

100%

What is the main function of the mesangial cells in the glomerulus?

To support the glomerular capillary loop Signup and view all the answers

What type of cells are mesangial cells?

Macrophages Signup and view all the answers

Do fish have a glomerulus?

No Signup and view all the answers

What is the name of the structure that contains the mesangial cells and matrix?

Mesangium Signup and view all the answers

What type of cells line the proximal convoluted tubule?

Cuboidal epithelial cells Signup and view all the answers

What is the location of the proximal convoluted tubule?

Cortex Signup and view all the answers

What is the correct order of the urinary system?

Kidney → ureters → urinary bladder → urethra Signup and view all the answers

What is the primary function of the ureters in the urinary system?

To convey urine to the bladder Signup and view all the answers

Which of the following is NOT a function of the kidney?

Digestion of nutrients Signup and view all the answers

What is unique about the appearance of cat kidneys?

They appear on the paler side due to high lipid concentration Signup and view all the answers

Which of the following is a type of kidney structure?

Multilobular Signup and view all the answers

What is the primary component of the nephron?

Renal corpuscles and convoluted tubules Signup and view all the answers

What is the function of the juxtaglomerular apparatus in the kidney?

Regulation of blood pressure Signup and view all the answers

What is the function of the renal corpuscles in the kidney?

To filter waste and excess water Signup and view all the answers

Which of the following is a function of the kidney in terms of electrolyte homeostasis?

All of the above Signup and view all the answers

What type of epithelium is present in the thin segment of the Loop of Henle?

Squamous Signup and view all the answers

Where does the Loop of Henle exclusively reside?

Medulla Signup and view all the answers

What is the function of the principal cells in the collecting ducts?

Reabsorb sodium and water Signup and view all the answers

What is the site of action of antidiuretic hormone (ADH)?

Collecting ducts Signup and view all the answers

What is reabsorbed in the proximal convoluted tubule?

Glucose, Na+/H2O, and low molecular weight proteins Signup and view all the answers

What type of epithelial cells line the distal convoluted tubule?

Cuboidal with basal striations Signup and view all the answers

What is the function of the intercalated cells in the collecting ducts?

Regulate acid-base balance Signup and view all the answers

What percentage of cardiac output is allocated to the kidneys?

25% Signup and view all the answers

What is the terminal portion of the inner medulla that extends into the renal pelvis or calices?

Renal papilla Signup and view all the answers

What is the primary function of the glomerulus?

To filter blood plasma and form a filtrate Signup and view all the answers

What is the main function of the renal corpuscle?

To filter blood plasma and form a filtrate Signup and view all the answers

What is the location of the proximal tubules in the kidney?

In the cortex Signup and view all the answers

What is the function of the mesangial cells in the glomerulus?

To support the glomerular capillaries Signup and view all the answers

What is the term for the process of filtering blood plasma to form a filtrate?

Ultrafiltration Signup and view all the answers

What is the name of the membrane that forms part of the filtration barrier?

Glomerular basement membrane Signup and view all the answers

What is the significance of protein in the urine?

It is a sign of kidney disease Signup and view all the answers

What is the function of the peritubular capillary plexuses?

To supply oxygen to the kidney cells Signup and view all the answers

What is the direction of blood flow in the glomerulus?

From the afferent arteriole to the efferent arteriole Signup and view all the answers

What is the function of the middle circular layer in the urinary bladder?

Regulating peristalsis Signup and view all the answers

What is the lining of the urethra in its initial segment?

Transitional epithelium Signup and view all the answers

What is the origin of the kidneys?

Intermediate mesoderm Signup and view all the answers

What is the fate of the pronephros in mammals?

It regresses Signup and view all the answers

What is the origin of the ureteric bud?

Mesonephric duct Signup and view all the answers

What is the function of the detrusor muscle?

To contract and relax the urinary bladder Signup and view all the answers

What is the characteristic of the female urethra?

It is shorter than the male urethra Signup and view all the answers

What is the derivative of the metanephros?

Kidney and nephrons Signup and view all the answers

What is the characteristic of the tunica mucosa in the urinary bladder?

It is lined with transitional epithelium Signup and view all the answers

Study Notes

Overview of the Urinary System

The urinary system consists of the kidney, ureters, urinary bladder, and urethra.
The kidney's functions include excreting nitrogenous waste, conserving body fluids and electrolytes, reabsorbing solutes and water, and regulating electrolyte homeostasis and acid-base balance.

Functions of the Kidney

The kidney regulates water and electrolyte homeostasis through filtration, selective reabsorption, and regulation of fluid balance.
It excretes metabolic waste products, bioactive substances, and excess water.
The kidney also produces hormones such as renin and erythropoietin, regulates blood pressure, and activates vitamin D.

Structure of the Kidney

The kidney is located retroperitoneally and has a unique structure depending on the species.
The kidney has lobes, which are unilobular in carnivores, multilobular with deep grooves in large ruminants, and multilobar with smooth surfaces in pigs.

Important Tissues of the Kidney

The kidney has a capsule made of collagen fibers, smooth muscle, and blood vessels.
The cortex contains renal corpuscles, convoluted tubules, and peritubular capillary plexuses.
The medulla has loops of Henle, collecting ducts, and vasa recta.

Nephron

The nephron is the functional unit of the kidney and is responsible for osmoregulation.
It consists of renal corpuscles, convoluted tubules, and loops of Henle.
The nephron regulates water and electrolyte balance through filtration and selective reabsorption.

Renal Corpuscle

The renal corpuscle is composed of the glomerulus and Bowman's capsule.
The glomerulus is a tuft of capillaries with fenestrated endothelium within the Bowman's capsule.
The Bowman's capsule has a visceral epithelium, glomerular basement membrane, urinary space, and parietal epithelium.

Ultrafiltration

Ultrafiltration occurs at the glomerulus, where blood is pushed through a filtration barrier to produce an ultrafiltrate.
The filtration barrier consists of the endothelium, glomerular basement membrane, and podocyte foot processes.

Formation of Urine

The primary/glomerular filtrate is produced by ultrafiltration of blood in the renal corpuscle.
The composition of the ultrafiltrate is similar to blood plasma, but without most proteins.
Reabsorption of most substances occurs, and waste molecules and some water remain in the tubular system to form urine.

Renal Tubules

The renal tubules consist of the proximal convoluted tubule, loop of Henle, and distal convoluted tubule.
The proximal convoluted tubule is highly metabolically active, reabsorbs glucose, Na+/H2O, and amino acids, and has microvilli and a brush border.
The loop of Henle is U-shaped, has thick descending and thin segments, and is located in the medulla.
The distal convoluted tubule is involved in the regulation of sodium and water reabsorption.

Collecting Ducts

The collecting ducts connect the distal convoluted tubule to the renal papillae and contain primitive urine.
They are lined with cuboidal to low columnar epithelium and have site-specific functions, such as the regulation of sodium and water reabsorption.

Renal Papilla and Vasculature

The renal papilla is the terminal portion of the inner medulla and contains papillary ducts.
The vasculature of the kidney is a high blood supply, with a terminal artery system, renal artery, and interlobar artery.

Urinary Bladder and Urethra

The urinary bladder stores urine and has a tunica mucosa, tunica submucosa, and tunica muscularis.
The urethra is lined with transitional epithelium, has a similar structure to the ureters and urinary bladder, and has accessory sex glands.

Development of the Kidney

The kidney develops from intermediate mesoderm.
The pronephros regresses in mammals, while the mesonephros forms nephros that secrete fluid into the amnion.
The metanephros develops from the ureteric bud, and the collecting tubules form, bifurcate, and lead to lobular architecture.

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Description

Learn about the components and functions of the urinary system, including the kidney, ureters, urinary bladder, and urethra.