THE URINARY SYSYEM

1
THE URINARY SYSYEM
2
THE URINARY SYSTEM

• Paired kidneys
• form the urine from the blood
• Ureters
• that convey the urine from the kidneys to the
  bladder
• The bladder
• where urine is stored until it can be discharged
• The urethra
• through which urine finally passes to the
  exterior.

3
(No Transcript)
4
The kidney functions

• 1- Maintenance of the internal environment.
• They do this by filtering the plasma
• initially extracting an enormous volume of fluid
  
• subjecting the ultra filtrate to further
  processing in which
• useful substances selectively reabsorbed
• waste substances are concentrated for elimination
• the volume is adjusted by the conservation of
  sufficient water to maintain the composition of
  the plasma

5
The kidney functions

• In large dogs and animals of similar size 1000 to
  2000 L of blood perfuse the kidneys daily
• the 200 to 300 L of fluid that are filtered from
  this volume are later reduced by reabsorption
  until only 1 or 2 L of urine remain to be
  discharged

6
The kidney functions

• 2- The endocrine function
• consists of the production and release of two
  hormones
• Renin, which plays a vital role in the regulation
  of systemic blood pressure
• Erythropoietin, which influences erythropoiesis.

7
General morphology
The kidneys are firm, reddish-brown glands whose
appearance varies The most familiar
kidney-shaped to the common vocabulary, is
encountered in the dog, cat, and small ruminants.
The kidneys of the pig are a much flattened
version, whereas those of the horse are more
heart-shaped . In contrast, the bovine kidneys
are deeply fissured to outline many lobes
8
General morphology

• The kidneys are usually found pressed against the
  abdominal roof
• one to each side of the vertebral column, and
  mostly in the lumbar region

9
General morphology

• They are rarely symmetrical
• the right one is about half a kidney-length in
  advance of its fellow
• The cranial extremity of the right kidney
  commonly fits into a fossa of the liver, which
  helps fix its position
• The left one, lacking this lodgment, is more
  mobile and is more likely to sag within the
  abdomen (pendulous left kidney)

10
(No Transcript)
11
L
R
12
(No Transcript)
13
General morphology

• The surface of a kidney is generally smoothly
  convex except for an indentation of the medial
  border
• This indentation leads to a concealed space
  occupied by the dilated origin of the ureter
  (renal pelvis)
• The vessels and nerves passing to and from the
  renal hilus

14
(No Transcript)
15
The internal organization of the kidney

• Longitudinal section will divide the organ into
  dorsal and ventral halves.
• Such a section shows that the parenchyma is
  enclosed within a tough fibrous capsule.
• The capsule restricts the kidneys ability to
  expand
• the swelling that occurs in certain disease
  conditions
• tends to compress the tissue and narrow the
  internal passages.

16
The internal organization of the kidney

• The parenchyma is visibly divided into an outer
  cortex and an inner medulla.
• The cortex is distinguished by its reddish-brown
  color and finely granular appearance.
• The medulla consists of
• a dark, purplish outer zone
• a paler, grayish-red inner zone

17
(No Transcript)
18
The internal organization of the kidney

• In many species the medulla is arranged as
  several discrete masses, each roughly pyramidal
  in form.

19
The functional units of the kidney

• The functional units are known as renal tubules
  or nephrons.
• These epithelial tubules are supported by a
  connective tissue interstitium
• estimated number several hundred thousand or
  even a million in canine kidneys.
• Each nephron begins with a blind expansion that
  is invaginated by a cluster of capillaries known
  as a glomerulus
• The glomerulus and its epithelial covering
  together constitute renal corpuscle.

20
The functional units are known as renal tubules
or nephrons.
Estimated number several hundred thousand or even
a million in canine kidneys. Each nephron
begins with a blind expansion that is invaginated
by a cluster of capillaries known as a glomerulus
21
The general organization of the kidney

• The remaining part of the nephron forms a long
  tubules differentiated into several successive
  segments
• 1- Proximal convoluted tubule
• 2- A long hairpin loop
• 3- Distal convoluted part that.
• 4- Collecting tubule within the medullary ray.
• Each collecting tubule, which serves many
  nephrons, runs through the medulla before opening
  into a larger vessel,
• 5- A papillary duct

22
Blood supply

• Each kidney is supplied by a renal artery
• The renal artery divides into several interlobar
  arteries
• They give rise to branches known as Arcuate
  arteries

23
Blood supply

• Arcuate arteries in turn give origin to numerous
  interlobular arteries that supply the units or
  lobules (cortex)
• Each interlobular artery gives rise to many
  branches that supply individual glomeruli
• The glomerular capillaries rejoin in one emissary
  vessel at the distal pole of the glomerulus

24
Renal Pelvis and Ureter

• In most domestic species the ureter begins in a
  common expansion, the renal pelvis
• All the papillary ducts open
• The ureter penetrates the bladder wall very
  obliquely.
• The length of the intramural course guards
  against reflux of urine into the ureter when the
  pressure is raised within the bladder.
• It does not prevent further filling of the
  bladder since the resistance is overcome by
  peristaltic contractions of the ureter wall.

25
(No Transcript)
26
The Urinary Bladder

• The bladder is a distensible storage organ and
  thus can have no constant size, position, or
  relationships.
• The contracted bladder rests on the pubic bones
• in the larger species it is confined to the
  pelvic cavity
• in carnivores extends into the abdomen

27
The Urinary Bladder

• In the larger species the contracted bladder is
  largely retroperitoneal
• but most of the surface becomes intraperitoneal
  when the organ is even moderately expanded.

28
The Urinary Bladder

• Three folds continue from the serosal covering
  onto the abdominal and pelvic walls.
• Paired lateral vesical folds convey the round
  ligaments of the bladder
• these vestiges of the umbilical arteries
• The third, median vesical fold
• is empty in the adult, but in the fetus it
  supports the urachus,

29
(No Transcript)
30
The Female Urethra

• The female urethra runs caudally on the pelvic
  floor below the reproductive tract.
• It passes obliquely through the vaginal wall to
  open ventrally at the junction of vagina and
  vestibule.

31
(No Transcript)
32
(No Transcript)