The Excretory system is responsible for the elimination of wastes produced by homeostasis. There are several parts of the body that are involved in this process, such as sweat glands, the liver, the lungs and the kidney system. ... From there, urine is expelled through the urethra and out of the body.

1. EXCRETORY SYSTEM
MOHANRAJ.S-B.PHARM
KMCH college of pharmacy
Coimbatore-48

2. Excretory
System

3. Why excretion is necessary?
• Cells to stay alive, they must continually intake water and other molecules.
• The cells would continue to get bigger and bigger if they only took in
molecules
• They must also excrete molecules
– such as hormones, or glucose, or they may be waste products like
Carbon dioxide or Ammonia.
Role of Kidneys
• They are responsible for cleaning the blood by removing metabolic wastes,
excess solutes, and excess water and excreting them as urine
• Besides removing urea, it also removes excess salts or glucose, the
remnants of drugs (reason for urine tests), and excess water.

4. Why excretion is necessary?
• During metabolism cells produce wastes
– waste - any substance acquired or produced
in excess with no function in body
– e.g. - CO2, H2O, heat
• All wastes must be eliminated, or at least
maintained at low concentrations
• Additionally, protein breakdown leaves
nitrogenous wastes
• Excess sodium (Na+
), (Cl-
), (K+
), sulfate (SO4
2-
),

5. Functions of Urinary System
1. Filter Blood and Removes waste products from the blood
2. Regulation of Blood Volume/Pressure [renin]
3. Regulation of the solute concentration of the Blood: Na+
, Cl-
, K+
, Ca+2
, HPO4
-2
pH regulation of extracellular fluid
5. Regulation of RBC synthesis [erythropoietin]
6. Vitamin D activation
7. Produces and eliminates urine
8. Kidneys produce the hormone Erythropoietin (EPO)
Stimulates the production of red blood cells within the bone marrow
8. Kidneys produce the enzyme Renin
• Aids in the raising of the blood pressure

6. Anatomy of the
Urinary System
 Two kidneys
Two ureters
One bladder
One urethra

7. Anatomy of the Urinary System
KIDNEYS
Primary organs of the urinary system
• Reddish-brown, bean-shaped organs located on either
side of the vertebral column at back of upper
abdominal cavity
• Located between the 12th
thoracic and 3rd
lumbar
vertebrae.
• partially protected by 11th, 12th ribs
• Right kidney sits lower than the left kidney
• Receive 20-25% of the resting cardiac output
• Each kidney is approx. 3 cm thick, 6 cm wide and 12 cm
long
Lie in shallow depressions against the posterior abdominal
wall and behind the parietal peritoneum – retroperitoneal

8. KidneysCortex -Outer layer of kidney
Contains millions of nephrons
Medulla-Inner layer of kidney
Consist of triangular tissue-
renal pyramids- loops and collecting
tubules of nephron located here
Pyramids extend into a cuplike urine
collection cavity called the minor
calyx
Minor calyces merge to form major
calyx
Major calyces merge to form the
renal pelvis

9. 9

10. 10
• Ureters
– Muscular tubes lined with mucous
membrane about 25 cm long
– Urine is propelled from renal pelvis
through ureters by peristalsis
• Bladder
– Hollow, muscular sac in pelvic cavity
• Located between pubic symphysis
and rectum in men AND pubic
symphysis and uterus and vagina in
women
• Serves as a temporary reservoir
• Resembles inverted pyramid when
empty
Structures of the Urinary System

11. • The innermost lining of the
urinary bladder is a mucous
membrane layer,
• The second layer is called the
submucosa. It contains elastic
connective tissue fibers.
• The third layer is the muscularis:
this collection of smooth muscle
is known as the detrusor muscle.
• Contraction of this muscle
expels urine from the bladder.
• The outermost layer is dense
connective tissue.

12. Urethra
Thin walled tube – conveys urine from bladder to external environment.
Similar structure to ureter
Sphincters: internal urethral [involuntary] & external urethral [ voluntary]
Male Urethra
• 20 cm long [7-8 in]
• Transports both urine & semen
Eternal urethral orifice opens
at tip of penis
Female Urethra
• 3-4 cm long [1.5 in]
• External urethral orifice opens
just anterior to the vaginal
opening

13. 13
• Nephron-Structural and functional unit
of kidney
• Kidneys: Components of Nephron
– Glomerulus
• Ball-shaped collection of very
tiny, coiled, and intertwined
capillaries
– Bowman’s capsule (renal capsule)
• Double-walled cup surrounding
the glomerulus
– Renal tubule
• Proximal convoluted tubule
• Loop of Henle
• Distal convoluted tubule,CT
– Peritubular capillaries
Structures of the Urinary System

14. A Typical Nephron

16. ,
• Proximal Convoluted Tubule [PCT] – H2O, Na+
, Cl-
, glucose, amino acids,
Ca+
, Mg+
, K+
, micronutrients [ zn,cu,fe]
• Descending Loop – H2O, Cl-
, Na+
• Ascending Loop – Cl-
, Na+
[ not permeable to H2O]
• Distal Convoluted Tubule [DCT] – H20, Na+
, Cl-
, HCO3
-
• JUXTAGLOMERULAR APPARATUS
• Monitors blood pressure and secretes renin, is formed from modified
cells in the afferent arteriole and the ascending loop of the nephron
• The cells of the arteriole are called juxtaglomerular cells and the cells
of the loop are called macula densa.

17. Blood Supply of the
Kidney
Renal artery branches inside the kidney
• Supplies the pyramids and the
cortex
• Renl artery divided into anterior
and poterior division
↓
• Passes across the pyramids and
forms interlobular arteries
↓
Enters into glomerulus as afferent
artery
↓
The vessel coming out from glomerulus
as efferent artery
↓
Divided as peritubular network
↓
Finally opens into renal vein.

18. Renin-Angiotensin-Aldosterone
• Renin: secreted by juxtaglomerular cells if blood pressure in afferent
arteriole is low, or [Na+
] of urine decreases as it passes the macula densa cells.
• Renin: enters the gen’l circulation via peritubular capillaries and activates
angiotensinogen to angiotensin I. Angiotensin I  angiotensin II via a
converting enzyme found in the plasma.
• Angiotensin II is a vasoconstrictor, acts on the hypothalamus causing the
sensation of thirst, salt appetite and ADH secretion. It also causes the
secretion of aldosterone from the adrenal cortex.
• Aldosterone [ a steroid hormone] acts on the cells of the nephron [ esp. those
of the ascending loop and DCT] to reabsorb more Na+
.

19. 19
Formation of Urine
Process begins as blood enters kidneys
via left and right renal arteries
1.Glomerular Filtration
• Blood in afferent arteriole is under
high pressure
• Glomerulus acts as a filter
• Filtrate = the substance that is
filtered from the blood into the
renal tubule
• Blood leaves the glomerulus
through the efferent arteriole
• Normal GFR: 125ml/mt
Blood is actually “filtered” in
glomerulus
Blood pressure is used to push
plasma into the Bowman’s capsule.

20. 2.Tubular Reabsorption
– As glomerular filtrate passes
through renal tubules, water,
sugar, and salts are returned
to bloodstream through
network of capillaries that
surround them
• Filtrate contains useful
substances which are
returned to the blood
• Most occurs in the
proximal convoluted
tubules
Nutrients (salts, vitamins, etc.)
are moved out of the tubule
through active transport.
Water follows the nutrients by
osmosis.

21. Loop of Henle
• Tissue around the Loop of
Henle is salty, from active
transport and diffusion of
sodium chloride.
• The salty conditions allow
water to diffuse out of the
loop.

22. • Tubular Secretion
– Materials are selectively transferred
from blood into the filtrate to be
excreted in the urine
• Glomerular Filtrate = water, sugar,
salts, and nitrogenous waste
products such as urea, creatinine,
and uric acid that filter out of the
blood through the thin walls of the
glomeruli
• Substances move from blood
(capillaries) into the filtrate
• Important in controlling pH of blood
Active transport is used to move
more nutrients out of the
concentrated urine.
Some ions, drugs, and toxins are
actively pumped into the tubule.

23. Colllecting Duct
More water leaves the tube by
osmosis, since the tube is
surrounded by salty tissue.
Some urea leaves by diffusion, and
may be cycled through the system.

24. Nephron

25. Control of Blood Composition by Kidneys
Excretion of nitrogen-containing compounds
• Urea
• Uric acid
– Water and electrolyte balance
• Regulated by hormones
– ADH – increases water reabsorption
– Aldosterone – increases sodium reabsorption
» Second effect of aldosterone – increase water
reabsorption.
– Acid-base balance of blood
» Blood pH must be 7.35 – 7.45 (very narrow range)
» Urine pH = 4.5 – 8.0

26. 26
Characteristics of Normal Urine
Urine
– Urine consists of water and other materials that were filtered or
secreted into the tubules but not reabsorbed
• Normally 1% of glomerular filtrate is excreted as urine
• Color
– Varies from pale yellow to a deep golden color
– Darker the urine, the greater the concentration
• Odor
– Normal urine is aromatic
– Has a strong but agreeable odor
• Specific Gravity
– Normal urine has specific gravity of 1.003 – 1.030
• pH
– Normal urine is slightly acid, pH of 6.0
• pH range is 4.5 – 8.0
• Protein
– Normal urine may have small amounts of protein present
– Only in insignificant amounts, too small to be detected by reagent strip
Glucose
– Normal urine does not contain glucose AND ketone bodies result from the
breakdown of fats

27. Factors that affect kidney function
• Antidiuretic hormone (ADH) – prevents excess water loss
from kidneys
• Alcohol – inhibits secretion of ADH = more urine volume
• Aldosterone – prevents excess loss of sodium and water
from kidneys
• Caffeine – increases rate of salt and water loss from
kidneys
• Increased blood pressure – increase rate of water loss
from kidneys.

28. 28
Abnormalities
• Albuminuria
– Presence in urine of abnormally large quantities of protein, usually albumin.
– Also known as proteinuria
• Anuria
– Cessation (stopping) of urine production, or a urinary output of less than 100 ml
per day
• Polyuria
– Excretion of abnormally large amounts of urine
• Dysuria
– Painful urination
• Enuresis
– Condition of urinary incontinence, especially at night in bed = bedwetting
• Glycosuria
– Abnormal presence of sugar, especially glucose, in the urine
• Hematuria
– Abnormal presence of blood in the urine
• Ketonuria
– Presence of excessive amounts of ketone bodies in the urine
• Oliguria
– Secretion of a diminished amount of urine in relation to the fluid intake
• Pyuria
– Presence of pus in the urine, usually a sign of an infection of the urinary tract

29. 29
PATHOLOGICAL CONDITIONS
Cystitis
– Inflammation of the urinary bladder
• Characterized by urgency and frequency of urination, and by hematuria
Glomerulonephritis
An inflammation of the glomerulus of the kidneys
• Condition characterized by proteinuria, hematuria, and decreased urine
production
Nephrotic Syndrome
– Group of clinical symptoms occurring when damage to the glomerulus of the
kidney is present and large quantities of protein are lost through the
glomerular membrane into the urine
• Results in severe proteinuria . . Also called nephrosis
Pyelonephritis
– Bacterial infection of the renal pelvis of the kidney
• Infection begins in the bladder and travels up the ureters to the renal
pelvis
Renal Calculi
Stone formations in the kidney
Wilm’s Tumor
– A malignant tumor of the kidney occurring predominately in childhood
• Most frequent finding is palpable mass in the abdomen

30. Kidney Stones
• Kidney stones are solid masses of mineral salt deposits
that are normally filtered through the kidney and
voided in urine.
• Urine naturally contains substances that dissolve the
waste materials that form these solids or calculi.
However, when the amounts of these salts are
excessive, the urine may be unable to dissolve them all,
leaving crystals that accumulate in the kidney and
gradually increase in size.
• Most renal calculi are so small they are passed through
the urinary tract without any symptoms. Larger calculi
can obstruct the renal ducts, or become lodged in the
ureters.
• These larger obstructions cause sharp, severe pain in
the sides and back as they move through the urinary
tract. In medical parlance, this condition is called renal
colic.
• The stones can be as small as a grain of sand or as
large as a golf ball. The size, shape, and location of the
stone can cause many different symptoms.

31. 31
Renal Failure
– Progressively slow development of kidney
failure occurring over a period of years
• Late stages are known as end-stage
renal disease (ESRD)
Treatment of Renal Failure
• Peritoneal Dialysis
– Mechanical filtering process used to
cleanse the blood of waste products, draw
off excess fluids, and regulate body
chemistry when kidneys fail to function
properly
• Peritoneal membrane is used as the
filter
• Continuous Ambulatory Peritoneal Dialysis
(CAPD)
– Dialysate solution remains in abdomen for
approximately 4 hours after exchange
• Process is repeated 3 – 5 times daily
– Advantage: No machine, convenient for
travel
CAPD

32. 32
• Continuous Cycling Peritoneal
Dialysis (CCPD)
– Uses a machine that warms
the solution and cycles it in
and out of the peritoneal
cavity at evenly spaced
intervals at night while the
patient sleeps
• Process takes 8 – 10
hours
• Last exchange remains
in abdomen during the
day for approximately
12 – 15 hours

33. 33
• Hemodialysis
– Process of removing excess
fluids and toxins from the
blood by continually shunting
the patient’s blood from the
body into a dialysis machine
for filtering, and then
returning the clean blood to
the patient’s bloodstream
• Usually 3 treatments a
week, 3 – 4 hours at a time
• May be performed at
dialysis center or at home

34. 34
• Kidney Transplantation
– The surgical implantation of a healthy, human donor kidney into
the body of a patient with irreversible renal failure
• Kidney function is restored with a successful transplant and
the patient is no longer dependent on dialysis
• Donor kidney may come from living donor (usually blood
relatives) or cadaver donors (nonliving matches)
• Kidney Transplantation (continued)
– Donor kidney surgically placed in iliac fossa
– Donor renal artery connected to recipient’s iliac artery
– Donor renal vein connected to recipient’s iliac vein
– Donor ureter connected to recipient’s bladder
• Donor kidney usually functions once it is in place