Histology of the kidney Flashcards
The kidney is organized into many lobes, organized in a pyramidal structure, where the outer portion is made up of_______, and the inner portion is made up of the __________.
The kidney is organized into many lobes, organized in a pyramidal structure, where the outer portion is made up of cortex, and the inner portion is made up of the medulla.
A granular cortex (outer region). It has this appearance because it is full of ovoid filtration units.
And a medullar (inner region) which has a more striated appearance.
The kidney contains about 1 million functional units which are continuous with a system of collecting tubules.
What are the functional units called?
The kidney contains about 1 million functional units called nephrons, which are continuous with a system of collecting tubules.
State the different parts of the nephron and where they are found (cortex or medulla)
The nephron consists of the renal corpuscle and the renal tubule.
This schematic diagram shows where the different parts of the nephron are found in the cortex and medulla of the kidney.
After leaving the renal corpuscle, the filtrate passes through the renal tubule in the following order:
*Proximal convoluted tubule (found in the renal cortex)
*Loop of Henle (mostly in the medulla)
*Distal convoluted tubule (found in the renal cortex)
*Collecting tubule (in the medulla)
*Collecting duct (in the medulla)
*The beginning of the distal convoluted tubule is found close to the renal corpuscle, in a structure known as the juxtaglomerular complex.
What is the secretory units of the kidney called?
The cortex of the kidney is distinguished by characteristic renal corpuscles,
Each renal corpuscles of which consists of an outer envelope of simple squamous epithelium (Bowman’s capsule) surrounding a fluid-filled space (Bowman’s space) within which is suspended a glomerulus.
State the 2 ends of the Bowman’s capsule.
Secretory units of the kidney is the renal corpuscles.
Together, the renal corpuscle and its associated tubule is called a nephron.
The cortex of the kidney is distinguished by characteristic renal corpuscles,
Each renal corpuscles of which consists of an outer envelope of simple squamous epithelium (Bowman’s capsule) surrounding a fluid-filled space (Bowman’s space) within which is suspended a glomerulus.
Bowman’s capsule divided into
*Vascular pole – region closest to where blood vessels enter and exit Bowman’s capsule
*Urinary pole – region between capsule and proximal tubule
Glomerulus supplied by a short, straight afferent glomerulus arteriole and drained by the efferent glomerular arteriole.
Describe the elements that comprises the filtration at the glomerulus.
GLOMERULAR CAPILLARY
*Capillary endothelial cells line the fenestrated glomerular capillaries.
BASEMENT MEMBRANE
The basement membrane is a thin, acellular structure composed of proteins, including collagen and glycoproteins. It has a negatively charged matrix.
INNER LAYER OF THE BPWMAN’S CAPSULE
*The outer layer of the Bowman’s capsule is lined by specialized cells called podocytes, which have finger-like projections known as foot processes (pedicels).
The foot processes interdigitate and form filtration slits, creating an additional layer of filtration control.
Outline all the components that make up the JG apparatus.
T1. he macula densa It may function as a sensor for sodium and/or chloride concentration.
- Juxtaglomerular cells (“J-G cells”) contain secretory granules, the source of the hormone renin.
- 2 Types of mesangial cells
*Extraglomerular-part of the juxtaglomerular apparatus
*Interglomerular – situated within renal corpuscle; probably phagocytic
Describe the epithelium at the different parts of the nephron including the rest of the urinary system.
Proximal tubule: Simple cuboidal epithelium
The descending thick segment is lined by simple cuboidal epithelium that is structurally similar to the proximal convoluted tubule. This segment is essentially a continuation of the proximal tubule (pars recta).
The descending thin segment is lined by simple squamous epithelium.
The ascending thin segment is also lined by simple squamous epithelium.
The ascending thick segment (pars recta of the distal tubule).is lined by simple cuboidal epithelium that is structurally similar to the distal convoluted tubule (pars convolute of the distal tubule).
Distal convoluted tubule: A simple cuboidal epithelium
Collecting ducts: Simple cuboidal/columnar epi.
Renal pelvis: Transitional epithelium
Ureter: Transitional epithelium
Bladder: Transitional epithelium
Urethra:
FEMALES
*Transitional epithelium
*Pseudostratified columnar
*Stratified columnar epithelia
*Stratified squamous cells
MALES
*The proximal epithelium is transitional epithelium(uroepithelium) – periprostatic & prostatic.
*The more distal epithelium is pseudostratified columnar epithelium (Membranous and spongy urethra) except for the terminal portion which is *Stratified squamous epithelium.
