Histo Urinary System 1

URINARY SYSTEM
INTRODUCTION
-The urinary system consists of
two kidneys, two ureters that lead
to a single urinary bladder, and a
single urethra.
PAIRED
• Kidneys
• Ureters
UNPAIRED
• Urinary bladder
• Urethra
FUNCTIONS
1. Maintenance of the body’s internal
environment within the normal
limits by the excretion of metabolic
waste products & excess water
through urine (HOMEOSTASIS)
2. Blood filtration
3. Regulation of blood pressure
4. Production of hormones notably
A. Renin
B. Erythropoietin
C. Thrombopoietin
D. other biologically active
substances (kinins and calcitrol)
KIDNEYS
 Perform ALMOST all the functions of the
system
 Located on the posterior abdominal wall
• The kidneys are large, bean-shaped organs
located retroperitoneally adjacent to the
posterior body wall.
• Superior to each kidney is the adrenal
gland embedded in renal fat and connective
tissue.
 Enveloped by a fibrous capsule – easily
stripped off from the organ because very
little connective tissue from the capsule
anchors it to the parenchyma of the organ
• The right kidney is slightly lower than the
left
• Attached to ureters, renal blood vessels,
and nerves at renal hilus
URINIFEROUS TUBULE
 MICROSCOPIC- functional unit of
the kidneys
 Consist of Nephrons and
Collecting ducts.
NEPHRONS
-Tubules in which urine is formed
Has two components
1. Renal corpuscle
2. Renal Tubules
2 TYPES OF NEPHRONS
Cortical nephrons Juxtamedullary nephrons
-located in the cortex of kidney -situated near the junction of the cortex and
medulla of the kidney
2 components of NEPHRON
1. Renal corpuscle (Malpighian
Corpuscle)
– forms proximal end of the nephron
– 2 poles:
 vascular-where afferent arteriole enters &
efferent arteriole leaves the corpuscle and
 urinary-where renal tubule begins
a) Glomerulus — Capillaries forming
glomerulus are fenestrated and their
endothelium rests on a thick basal lamina
b) Bowman’s Capsule(Glomerular )
― double-walled sac that envelops the
glomerulus
―Parietal layer (simple squamous
epithelium) ―visceral layer (podocytes with
pedicels)
2 components of NEPHRON
2. RENAL TUBULES
-Most of the water & solutes are reabsorbed (tubular reabsorption) &
some other solutes are added (tubular secretion)before it becomes
urine
- All walls are made up of Simple Epithelium
- However shape & surface modifications of the epithelial cells vary
from segment to segment
a) Proximal Convoluted Tubule (PCT) ― main function:
reabsorption of water & sodium ions (70-80%) also other
substances, glucose, amino acids, & chloride ions
- Simple Cuboidal Epithelium
- nucleus centrally located
- acidophilic cytoplasm due to presence of numerous mitochondria
- with microvilli in luminal surfaces (brush border)
b) The Loop of Henle
• Descending limb (simple squamous
epithelium)
• Ascending limb (simple cuboidal to low
columnar epithelium)
c) Distal Convoluted Tubule (DCT)
• last segment of the nephron
• reabsorbs little amount of water &
sodium ions, and secretes potassium &
hydrogen ion, from the glomerular
filtrate.
• Simple Cuboidal Epithelium
• cells are shorter & their cell boundaries
are distinct
• do not possess brush borders
• cytoplasm is less eosinophilic
1. JUXTAGLOMERULAR COMPLEX
1. JG CELLS (juxtaglomerular cells)
• Smooth muscle cells are replaced by JG cells
before it enters vascular pole of Renal
Corpuscle
• Larger than ordinary smooth muscle cells
have spherical nucleus contain myofilaments
& numerous secretory granules in their
cytoplasm
• produce renin & thrombopoietin
2. MACULA DENSA
• Nucleus appears more intensely staining
than other epithelial cells
• Cells are sensitive to sodium ion
concentration & water volume of the fluid in
the DCT cells that become columnar & closely
packed
Mesangial Cells
• Found in the glomerulus attached to the
glomerular capillaries
• Extraglomerular cells form part of the
juxtaglomerular apparatus
• Function as macrophages, and regulate blood
pressure as a result of vasoactive receptors and
contractility
URETERs
• Conduct urine from renal pelvis to
the urinary bladder
• 3 walls:
1. Tunica Mucosa -
• Transitional epithelium
- lamina propria mucosae
(connective tissue)
2. Tunica Muscularis - smooth
muscle layer
3. Tunica Adventitia -protective
fibrous CT
URINARY BLADDER
• Temporary storage site for urine;
regulation of micturition
• Distensible organ; changes size and
shape as it fills
• Its wall has 4 tissue layers:
1. Tunica mucosa – transitional
epithelium that rests on lamina
propria of loose C.T
2. Tunica submucosa – fibrous
Connective Tissue
3. Tunica muscularis – has inner, outer
longitudinal & middle layer of smooth
muscles (detrusor muscles)
4. Tunica serosa/ adventitia – loose
Connective Tissue
URETHRA
• Serves as passageway for urine .
In Male Urethra - has 3 segments
1. Prostatic Urethra – transitional epithelium
– Its Lamina propria is poorly Loose C.T that has
many elastic fibers & veins
– External to lamina propria are Smooth muscle
fibers
– External to Smooth muscle is prostatic tissue
2. Membranous Urethra – Pseudostratified
Columnar or Stratified Columnar Epithelium –
surrounded by circularly-arranged skeletal
(voluntary) muscle fibers
3. Spongy Urethra – same lining with
membranous except in certain areas & where
terminally epithelium is Nonkeratinized Stratified
Squamous
URETHRA
In Female Urethra
• Mucosa – Transitional epithelium most of its length,
but becomes Nonkeratinized Stratified Squamous near
the urethral orifice
• Its lamina propria – Loose C.T
• Muscular layer – mostly longitudinally & obliquely
arranged Smooth muscle cells and an outer coat of
circularly-arranged skeletal (voluntary) muscle fibers
• Tunica Adventitia – thin layer of Loose Connective
Tissue.

Histo Urinary System 1

Uploaded by

Copyright:

Available Formats

Histo Urinary System 1

Uploaded by

Document Information

Original Title

Copyright

Available Formats

Share this document

Share or Embed Document

Sharing Options

Did you find this document useful?

Is this content inappropriate?

Copyright:

Available Formats

Histo Urinary System 1

Uploaded by

Copyright:

Available Formats

URINARY SYSTEM

You might also like