Urogenital Module BMS305: Kidney Histology

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Questions and Answers

What is the structure of the kidney?

Compound cuboidal gland

Compound tubular gland (correct)

Simple tubular gland

Simple cuboidal gland

What is the outer layer of the kidney cortex composed of?

Fatty tissue

Granular tissue (correct)

Fibrous tissue

Muscular tissue

What are the columns of Bertini?

Blood vessels in the kidney

Nerve endings in the kidney

Extensions of the medulla

Extensions of the cortex (correct)

What is the labyrinth region of the kidney cortex?

Region surrounding the medullary pyramids Signup and view all the answers

What is the color of the inner medulla?

Greyish Signup and view all the answers

What are medullary pyramids composed of?

Collecting tubules, loops of Henle, and straight blood vessels Signup and view all the answers

What are medullary rays?

Collecting tubules that extend to the cortex Signup and view all the answers

How many medullary pyramids are present in each kidney?

Up to 18 Signup and view all the answers

What is the outer layer of Bowman's capsule composed of?

Simple squamous epithelium Signup and view all the answers

What is the function of podocytes in the visceral layer of Bowman's capsule?

Filtration and formation of the renal blood barrier Signup and view all the answers

What is the structure that separates the glomerular capillaries from the visceral layer of Bowman's capsule?

Subpodocytic space Signup and view all the answers

What is the function of mesangial cells in the glomerulus?

Support and renewal of glomerular basement membrane Signup and view all the answers

What is the renal blood barrier composed of?

Fenestrated glomerular endothelium and podocytes Signup and view all the answers

What is the structure that connects the glomerulus to the efferent arteriole?

Efferent arteriole Signup and view all the answers

What is the functional part of uriniferous tubules?

Nephron Signup and view all the answers

What is the diameter of the Malpighian Renal Corpuscle?

200 µm Signup and view all the answers

How many poles does the Malpighian Renal Corpuscle have?

2 Signup and view all the answers

What is the function of the vascular pole of the Malpighian Renal Corpuscle?

Where afferent arteriole enters and efferent arteriole leaves Signup and view all the answers

How many types of nephrons are mentioned in the text?

2 Signup and view all the answers

What is the characteristic of a cortical nephron?

Short loop of Henle Signup and view all the answers

What is the term for a medullary pyramid and its overlying cortex?

Renal lobe Signup and view all the answers

What demarcates renal lobules?

Interlobular arteries 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 slit diaphragms?

Nephrins and other proteins Signup and view all the answers

What is the purpose of the fused basement membrane in glomerular filtration?

To block large proteins and cells Signup and view all the answers

What is the function of the podocytes' foot processes?

To form a gap for the slit diaphragms Signup and view all the answers

What is continuously renewed by mesangial cells?

Basement membrane Signup and view all the answers

What is the primary function of the slit diaphragms?

To block small proteins and organic anions Signup and view all the answers

What is the main function of the glomerular filtration barrier?

To filter small molecules and block large proteins and cells Signup and view all the answers

What is unique about the glomerular endothelium?

It has pores that allow for filtration Signup and view all the answers

Study Notes

Kidney Structure

The kidney is a compound tubular gland that performs many functions (see physiology).

Outer Cortex

Reddish and granular in appearance
Subdivided into three regions:
- Cortex proper: Just under the capsule
- Columns of Bertini: Extensions of the cortex between medullary pyramids
- Labyrinth: Around medullary rays

Inner Medulla

Greyish in appearance
Contains medullary pyramids (up to 18) and medullary rays (represent collecting tubules)
Medullary pyramids are formed of collecting tubules, loops of Henle, and straight blood vessels (vasa recta)

Renal Lobe and Lobule

Renal lobe: Medullary pyramid + overlying cortex proper
Renal lobule: Medullary ray + corresponding cortical tissue (cortical labyrinth)
Lobules are demarcated by interlobular arteries

The Nephron

Functional part of uriniferous tubules
1-4 million per kidney
Types: cortical nephron (short loop of Henle) and juxta-medullary nephron (long loop of Henle)

Components of the Nephron

Malpighian renal corpuscle
Proximal convoluted tubule
Loop of Henle
Distal convoluted tubule

Malpighian Renal Corpuscle

Rounded body in the cortex, 200 µm in diameter
Has two poles: urinary pole (continuous with proximal convoluted tubule) and vascular pole (through which afferent arteriole enters and efferent arteriole leaves)

Components of the Malpighian Corpuscle

Bowman's capsule
Glomerulus (glomerular capillaries)
Mesangial cells

Bowman's Capsule

Double-walled cup-shaped epithelial capsule
Formed of outer parietal layer and inner visceral layer (podocytes) adherent to capillaries
Capsular space between the two layers

Podocytes

Modified squamous cells in the visceral layer of Bowman's capsule
Separated from glomerular capillaries by subpodocytic space containing glomerular filtrate
Formed of cell body, major cytoplasmic processes, and minor processes that terminate in feet processes firmly implanted on the basement membrane of glomerular capillaries
Filtration slits (40 nm in diameter) are closed by slit diaphragms
Functions: filtration, formation of renal blood barrier, and renewal of glomerular basement membrane

Glomerulus (Glomerular Capillaries)

50 tufts of blood capillaries arising from the afferent arteriole and draining to the efferent arteriole
Electron microscopy shows fenestrated glomerular endothelium and thick glomerular basement membrane

Mesangial Cells

Branched cells between glomerular capillaries and attached to their walls by processes
Functions: support (secrete collagen and matrix), renewal of glomerular basement membrane, and change to macrophages to phagocytose foreign bodies and old basement membrane

Renal Blood Barrier (RBB)

Barrier between blood in glomerular capillaries and glomerular filtrate in capsular space
Components:
- Glomerular endothelium with pores (100 nm)
- Fused basement membranes of glomerular endothelium and podocytes (most effective component)
- Slit diaphragms between feet processes of podocytes
Functions: blocks blood cells and platelets, blocks plasma proteins (mainly albumin), and blocks small proteins and organic anions

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Description

Study guide for the urogenital module, covering the histology of the kidney, including its structure and functions.