it enables the students to know about excretory system:kidneys,urteres,urethra and urinary bladder and function of excretory system ,RAS

1. `
JASLEEN
KAUR
MSC(N)

2. Excretion: It is removal of the waste products
of metabolism,toxic material and substances
from the body.
Micturition: Micturition or urination is the
process of expelling urine from the
bladder.This act is also known as voiding of
bladder.
Nephrology:Nephrology is the scientific study
of anatomy , physiology and pathology of the
kidneys.

3.  KIDNEYS-These are the primary excretory
organs throwing out excretory products in the
form of urine.
 LARGE INTESTINE-Undigested food is
removed from large intestine and thrown out of
body through anus.
 SKIN-It eliminate excess of water,urea,salts and
other metabolic waste in the form of
sweat.Sweat is secreted from sweat gland.

4.  The urinary system is the main excretory system
and consists of the following structures-
 2 kidneys,which secrete urine
 2 ureters, which conveys the urine from the
kidneys to the urinary bladder.
 The urinary bladder, where urine collects and is
temporarily stored
 The urethra through which the urine passes from
urinary bladder to the exterior.

5. .

6. FUNCTIONS OF KIDNEYS-
The main functions of kidneys are-
• Formation and excretion of urine,which regulates total body
water,electrolytes and acid base balance and enables excretion of waste
products.
• Production and secretion of ERYTHROPOIETIN, the harmone that
stimulates formation of red blood cells.
• Production and secretion of RENIN, an important enzyme in the control of
blood pressure.
• Activation of VITAMIN D.
• Regulation of BLOOD GLUCOSE LEVEL.

7. -
WHERE ARE THE
KIDNEYS SITUATED IN
THE HUMAN BODY?
 The kidneys lie on the posterior
abdominal wall,one each side of the
vertebral column,behind the peritoneum
and below the diaphragm.They extend
from the level of the 12th thoracic
vertebra to the 3rd lumbar vertebra.

8.  The right kidney is usually slightly lower
than the left kidney, probably because of
the space occupied by liver`

9. SHAPE- Kidneys are bean shaped
organ.
SIZE- About 11cm long,6cm wide and 3
cm thick and weigh 150gms each
Kidneys are held in position by a mass
of fat. A Sheath of fibrous connective
tissue,also known as renal
fascia,encloses the kidneys and renal
Fat.

10. SURFACE ANATOMY-
Each kidney is surrounded by three layers-
 Renal fascia- fibrous tissues which mainly provides
support to the kidneys
 Adipose tissues- Protects kidney
 Renal capsule –it anchors kidney to body wall
continuous with peritoneum.

11. 3 layers of connective
tissue:
Inner layer- Renal
capsule
Middle layer- Adipose
capsule
Outer layer-Renal fascia
Renal cortex
Retroperitoneal space

12. There are three areas of tissues that can be
distinguished when distinguished when a longitudinal
section of the kidney is viewed with a naked eye-
An outer fibrous capsule, surrounding the kidney
The cortex, a reddish brown layer of tissue immediately
below the capsule
The medulla, the innermost layer, consisting of pale
conical shaped striations, the renal pyramids.
The hilum is the concave medial border of the kidney
where the renal blood and lymph vessels, the ureters
and nerve enters.

13. .

14. A longitudinal section of right
kidney


15.  What volume of blood enters the renal arteries
per minute?
The renal arteries deliver 20-25% 0f the resting
cardiac output to the kidneys.
Hence in adult,renal blood flow through both
kidneys,is about 1000-1200ml per minute.
NOTE-The blood vessels of kidney are supplied by
both sympathetic and parasympathetic nerves.

16. MICROSCOPIC
STRUCTURE OF THE
KIDNEY- The kidney is composed of about 1-2 million
functional units, The Nephrons and a smaller
number of collecting ducts.
 The collecting ducts transport urine through the
pyramids to the calyces and renal pelvis,giving the
pyramids their striped appearance.
 These collecting ducts are suported by a small
amount of connective tissue,containing blood
vessels,nerve and lymph vessels.

17. The Nephron:


18.  The nephron consists of:
1)Renal corpuscles-The head of nephron.
 The renal corpuscles is composed of bowman’s
capsule-
 Bowman’s capsule is the cover of corpuscles that
surrounds the glomerulus
 The glomerulus is the network of cappillaries found
inside the corpuscles
Blood enters at glomurules by the way of
affarent arteriole and leaves in an
efferent arterioles.

19. 2)Renal Tubule-the tubular passageway
of nephrons.It cosists of-
*PROXIMAL CONVOLUTED
TUBULE(PCT)
*LOOP OF HENLE
*DISTAL CONVOLUTED TUBULE

20.  There are two types of
Nephrons:
 1)Cortical Nephrons:85% of
the nephrons located in the
cortex
 2)Juxtamedullary
Nephrons:closer to renal
medulla and extends deep into
renal pyramids

21. =
Blood enters the
kidney through the
renal artery at the
site of the hilum
The renal artery
divides in to ever
smaller arteries and
arterioles
Afferent arterioles take
blood to the glomerulus to
be filtered
Once blood is filtered
efferent arterioles take
blood away from the
glomerulus
The glomerulus is a
network of capillaries
which filters the
blood
Products which are filtered
out: water, mineral salts,
amino acids, glucose,
hormones, urea, toxins
Products which do not
filter and remain in the
blood: Leukocytes,
erythrocytes, platelets,
plasma proteins
The filtered
substances move into
the proximal
convoluted tubule
The PCT is concerned with
reabsorption- organic
nutrients are reabsorbed and
water follows because there
is a concentration gradient
The remaining filtrate moves
into the descending loop of
henle. This is lined with thin
cells so water moves out
Because water has
been reabsorbed the
concentration of the
filtrate is not very high
The walls of the ascending
loop of henle are lined with
thicker cells, so water can’t
pass in or out. Instead
sodium and chloride is
pumped out actively The filtrate now enters
the distal convoluted
tubule- is it now only
20% of what it originally
was.
In the DCT the volume
and composition of the
filtrate can be adjusted
but this is controlled by
hormones
From the DCT the filtrate
now passes into the
collecting duct.
A number of other nephrons
join up to the cleectig duct
which travels through the
medulla to the renal papilla
wher the filtrate is emptied in
the minor calyx
4-5 minor calyces join
up to make a major
calyx
2-3 major calyces
join up to form the
renal pelvis
The renal pelvis joins
the ureter at the hilum
The ureter transport the
filtrate/urine from the
kidney to the bladder

22. THE FORMATION OF
URINE:3 processes involved in the
formation of urine.

23.  It takes place through the semipermeable
walls of glomerulus and glomerular
capsule.
 Water and other small molecules pass
through while blood cells,plasma proteins
and other large molecules are too large to
filter though and therefore remain in the
capillaries.

24. FILTERATION
TAKES PLACE
BECAUSE THERE
IS A DIFFERENCE
BETWEEN THE
BLOOD PRESSURE
IN THE
GLOMERULUS
AND THE
FILTERATE IN THE
GLOMERULAR

25.  NET FILTERATION PRESSURE=Glomerular
hydrostatic pressure-(blood osmotic
pressure+capsular hydrostatic pressure
 NFP=55-(30+15)
 =10mmHG

27. FACTORS AFFECTING
GFR: Renal Blood flow
 Environmental conditions
 Constriction of afferent and efferent
arteriole
 Disease condition e.g ureteral
stricture,dehydration
 Biochemical changes under the influence
of sympathetic nd parasympathetic
stimulation

28.  Selective reabsorption is the process by which certain molecules e.g.
ions,glucose and amino acid after being filterd out of the capillaries
along with nitrogeneous waste products i.e. urea and water in the
glomerulus,are reabsorbed back into the blood circulation from the
filtrate as they pass through the nephron.
 Only 60-70% filtrate reaches the loop of nephron.much of this is
reabsorbed in the loop of henle. So only 15-20% of the original filtrate
reaches the DCT.
 Now the composition of filtrate is very different from its starting values.

30. Hormones that influence
Selective Reabsorption:
 PARATHYROID HORMONE
 ANTIDIURETIC HORMONE
 ALDOSTERONE HORMONE
 ATRIAL NATRIURETIC PEPTIDE

31. RAAS MECHANISM

32.  Substances not required and foreign material .e.g.
drugs including penicillin and aspirin, may not be
cleared from the body by filtration because of short
time it remain in the glomerulus. Such substances are
cleared by secretion from the peritubular capillaries
into the convoluted tubules and excreted from blood in
the urine.
 Tubular secretion of hydrogen ion is important in
maintaining normal blood pH.

33. COMPOSITION OF URINE:
Urine is clear and amber in colour due to presence of urobilin,a bile pigment
.
 Water-96% specific gravity of urine=1.020-1.030
 Urea-2%
 Uric acid urine output/day=1000-1500ml/day
 Creatinine
 Ammonia pH=4.5-8
 sodium
 Potassium 2%
 Chlorides
 Phosphates
 Sulphates
 Oxolates

34. ureters

35. DIMENSIONS:

37. BLOOD SUPPLY

38. Position of ureters:

40.  The urinary blader is reservoir for
urine..it lies in the pelvic cavity
and its size and position
vary,depending on the volume of
urine it contains.when
distended,the bladder rises into
the abdominal cavity.

41.  The appearance of bladder varies depending on the
amount of urine stored.when full,it exhibits an
, and when empty it is flattened and pear
shaped.
 The external features of bladder are:
1.APEX-IS LOCATED SUPERIORLY,POINTING TOWARDS THE
SYMPHYSIS PUBIS.
2.BODY-MAIN PART OF BLADDER,LOCATED BETWEEN THE
APEX AND FUNDUS.
3.FUNDUS (BASE)-LOCATED POSTERIORLY.IT IS TRIANGULAR
SHAPED,WITH THE TIP OF TRIANGLE POINTING BACKWARDS.
4.NECK-IT IS CONTINUOUS WITH THE URETHRA.

42. The bladder wall is composed of
three main layers:
* Outer loose connective tissues
* The middle layer consisting of interlacing smooth
muscle fibres and elastic tissues loosely arranged in
three layers .this is called detrusor muscle and when it
contracts , it empties the bladder.
* The mucosa,composed
that readily permits distension of bladder as it fills with
urine.

43.  When the bladder is empty the
inner lining is arranged in folds or
rugae which gradually disappear
as it fills.
 Bladder capacity-250-300ml
Filling upto 500ml may be tolerated
,but beyond this it becomes painful.

44.  The urethra is a tube that connects the urinary bladder to
the urinary meatus for the removal of urine from the body
of both male and female.it is longer in male than in female.
Length of urethra in male and female:
male-16-18cm long
Female- 3-4cm long
Diameter-5-6mm respectively

45.  The male urethra is generally associated with urinary
and reproductive system
 The female urethra is associated with urinary system
only.it runs downwards and forwards behind the
symphysis pubis and opens at external uretheral
sphincter just in front of the vagina.
 The internal uretheral sphincter , a thickening of
uretheral smooth muscles and is under involuntary
control
 The external urethral orifice is guarded by the external
urethral sphincter,which is under voluntary control.

47.  Micturition reflex is the neurological
pathways involved in urination. When
your bladder fills, the detrusor
muscles expand and proprioceptors
within the walls of the muscle
activate. It sends signals (afferent
nerves) that go to your medulla and
also to the parasympathetic system
in the sacral spinal cord.