Urinary Tract Anatomy and Function

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Questions and Answers

What type of gland is the kidney?

Simple cuboidal gland

Simple tubular gland

Compound tubular gland (correct)

Compound acinar gland

What is the outer layer of the kidney cortex?

Cortex proper (correct)

Labyrinth

Medullary pyramids

Columns of Bertini

What are the collecting tubules in the medulla part of?

Straight blood vessels

Loops of Henle

Medullary pyramids

Medullary rays (correct)

What is the function of the kidney?

To filter blood and produce urine Signup and view all the answers

What is the characteristic of the outer cortex?

Reddish and granular Signup and view all the answers

How many medullary pyramids are present in the kidney?

Up to 18 Signup and view all the answers

What is the functional part of the uriniferous tubules?

Nephrons Signup and view all the answers

What is the main difference between cortical and juxta-medullary nephrons?

Length of the loop of Henle Signup and view all the answers

What is the approximate diameter of the Malpighian Renal Corpuscle?

200 µm Signup and view all the answers

What is the function of the efferent arteriole in the Malpighian Renal Corpuscle?

It carries blood away from the glomerulus Signup and view all the answers

What is the name of the space between the outer parietal layer and the inner visceral layer of Bowman's capsule?

Capsular space Signup and view all the answers

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

They provide structural support to the glomerulus Signup and view all the answers

What is the primary function of the glomerular endothelium?

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

What is the main component of the glomerular basement membrane?

Fused basement membranes of glomerular endothelium and podocytes Signup and view all the answers

What is the purpose of the slit diaphragms in the renal blood barrier?

To form a barrier between the feet processes of podocytes Signup and view all the answers

What is the characteristic of the glomerular endothelium in the renal blood barrier?

It is not closed by diaphragms Signup and view all the answers

What is the function of the mesangial cells in the renal blood barrier?

To continuously renew the basement membrane Signup and view all the answers

What is the location of the glomerular basement membrane in the renal blood barrier?

Between the glomerular endothelium and podocytes Signup and view all the answers

What is the size of the pores in the glomerular endothelium?

100 nm Signup and view all the answers

What is the main component of the slit diaphragms in the renal blood barrier?

Nephrins and other proteins Signup and view all the answers

What is the function of the filtration slits?

To filter the glomerular filtrate Signup and view all the answers

What is the main function of mesangial cells?

To support and secrete collagen and matrix Signup and view all the answers

What is the function of the slit diaphragm?

To close the filtration slits Signup and view all the answers

What is the function of the podocyte?

To filter the glomerular filtrate Signup and view all the answers

What is the function of the glomerular endothelium?

To allow the passage of substances through fenestrae Signup and view all the answers

What is the function of the Bowman's capsule?

To surround the glomerulus Signup and view all the answers

What is the function of the glomerular basement membrane?

To form a barrier between the glomerular endothelium and podocytes Signup and view all the answers

What is the renal blood barrier?

The barrier between the blood in the glomerular capillaries and the glomerular filtrate Signup and view all the answers

Study Notes

Urinary System

The kidney is a compound tubular gland that performs many functions.
The kidney is composed of stroma and parenchyma, with the stroma consisting of a fibrous capsule and interstitial connective tissue.

Histology of Kidney

The kidney has an outer cortex and an inner medulla.
The outer cortex is reddish and granular, and is subdivided into three regions: cortex proper, columns of Bertini, and labyrinth.
The inner medulla is greyish and contains medullary pyramids and medullary rays.
A renal lobe consists of a medullary pyramid and the overlying cortex proper.
A renal lobule is a medullary ray and the corresponding cortical tissue.

Uriniferous Tubules

The uriniferous tubules are composed of nephrons and collecting tubules.
There are approximately 1-4 million nephrons in each kidney.
Nephrons are of two types: cortical nephrons with short loops of Henle and juxtamedullary nephrons with long loops of Henle.

The Nephron

A nephron is formed of four components: Malpighian renal corpuscle, proximal convoluted tubule, loop of Henle, and distal convoluted tubule.
The Malpighian renal corpuscle is a rounded body in the cortex, approximately 200 µm in diameter, with two poles: urinary pole and vascular pole.

Malpighian Renal Corpuscle

The Malpighian renal corpuscle is formed of three components: Bowman's capsule, glomerular capillaries, and mesangial cells.
Bowman's capsule is a double-walled cup-shaped epithelial capsule, formed of outer parietal layer and inner visceral layer (podocytes).
The capsular space is between the two layers.
Podocytes are modified squamous cells in the visceral layer of Bowman's capsule, separated from glomerular capillaries by subpodocytic space.

Podocytes

Podocytes are formed of a cell body and major cytoplasmic processes that give rise to minor processes and terminate by feet processes firmly implanted on the basement membrane of capillaries.
The gaps between the implanted feet are called filtration slits (40 nm) and are closed by slit diaphragms.
The functions of podocytes are filtration and formation of the renal blood barrier, and renewal of the glomerular basement membrane.

Glomerulus

The glomerulus is formed of 50 tufts of blood capillaries that arise from the afferent arteriole and drain into the efferent arteriole.
The glomerular endothelium is fenestrated, and the glomerular basement membrane is thick.

Mesangial Cells

Mesangial cells are branched cells between glomerular capillaries, attached to their walls by processes.
The functions of mesangial cells are support, renewal of glomerular basement membrane, and change to macrophages to phagocytose foreign bodies and old basement membrane.

Renal Blood Barrier

The renal blood barrier is a barrier between blood in glomerular capillaries and glomerular filtrate in the capsular space.
The renal blood barrier has three components: glomerular endothelium, fused basement membrane of glomerular endothelium and podocytes, and filtration slit diaphragms.
The ultrastructure of the renal blood barrier shows feet processes of podocytes, glomerular basement membrane, and slit diaphragms.

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Description

Test your knowledge of the urinary tract, including the kidney's anatomical structure, nephrons, and podocytes, as well as their role in forming the renal blood barrier.