The urinary system helps remove waste from the body through urine. It includes the kidneys, ureters, urinary bladder, and urethra. The kidneys filter waste from the blood to form urine, which travels through the ureters to the bladder. In the bladder, urine is stored until emptying through the urethra. The kidneys contain nephrons, which filter blood and reabsorb useful components back into blood while secreting waste to form urine.

1. HUMAN ANATOMY AND PHYSIOLOGY NOTES
RAMDAS BHAT
KARAVALI COLLEGE OF PHARMACY 1
CHAPTER NO:13
URINARY SYSTEM
Prepared by,
RAMDAS BHAT
Associate Professor
Karavali college of Pharmacy
Mangalore
7795772463
Ramdas21@gmail.com

2. HUMAN ANATOMY AND PHYSIOLOGY NOTES
RAMDAS BHAT
KARAVALI COLLEGE OF PHARMACY 2
• As result of the cellular metabolism many metabolic wastes accumulate in the body that
must be removed from the body in order to prevent the toxicity in the body
• Excretion is a process by which the metabolic wastes are removed from the body and
osmotic balance is maintained
• Urinary system is a type of the excretory system that helps in the removal of the wastes
from the body in the form of urine.
• URINARY SYSTEM includes Kidneys (2), Ureters (2), Urinary bladder (1), Urethra (1).
KIDNEYS:
• Bean shaped structure
• 150gm of weight
• 2 in number present in abdominal cavity on either side of vertebral column
• 10cm long, 5cm wide, 2.5cm thick
• Right kidney is lower to the left as the space is occupied by liver
• has 3 layers externally
• Renal facia: made of the dense irregular connective tissue
• Adipose tissue capsule: contains the adipocytes
• Renal capsule: 3rd layer of dense connective tissue that protects kidney

3. HUMAN ANATOMY AND PHYSIOLOGY NOTES
RAMDAS BHAT
KARAVALI COLLEGE OF PHARMACY 3
• On the medial surface kidneys contains HILUM THROUGH WHICH THE BLOOD VESSELS,
URETER enters and leaves the kidney
• Hilum then enters into kidney to form a cavity called renal sinus
• Kidney has 2 surfaces
• Cortex is reddish in colour
• Medulla is pale in colour contains renal pyramids (10-15) that terminate medially to form
renal papillae
• The renal papillaes will form the calyces i.e., major and minor
• 10-15 minor calyces togetherly form the major calyces
• The major calyces then come out of the kidney through the pelvis region and form uterus
• The uterus exits from the hilum and then pass on to the urinary bladder

4. HUMAN ANATOMY AND PHYSIOLOGY NOTES
RAMDAS BHAT
KARAVALI COLLEGE OF PHARMACY 4
Microscopy:
• Microscopy shows nephrons
• Nephrons forms the structural and functional unit
of the kidney
• They are 1-1.3 million nephrons
• The nephrons drain into the pelvis
• Length of nephrons is 45-65nm
• It has various regions
• Bowman's capsule
• Glomerulus
• Proximal convoluted tubule
• Loop of Henle
• Vasa recta
• Distal convoluted tubule
• Collecting duct
BOWMAN'S CAPSULE:
• It is initial dilated part of the nephron
GLOMERULUS:
• Formed by group of capillaries highly coiled in the
glomerulus
• In the glomerulus the blood vessels enter i.e.,
afferent and leaves the glomerulus i.e., efferent
arterioles
• Glomerulus along with the bowman's capsule are
called as the MALPHIGIAN CORPUSCLE
• BOWMANS CAPSULE HAS 2 LAYERS
• PARIETAL and VISCERAL layers.

5. HUMAN ANATOMY AND PHYSIOLOGY NOTES
RAMDAS BHAT
KARAVALI COLLEGE OF PHARMACY 5
• Parietal layer is made of the squamous epithelium which is covering Bowman’s capsule
externally and is continuous till the PCT
• Visceral layer is closely associated with the Glomerular Capillary on all sides more
abundant in the entrance of the afferent and the efferent arterioles.
• Space between the Parietal and the visceral layer is called as the Bowman's space
• There is a membrane that help in the exchange of the salts or the filtration of the blood
takes place that membrane is called as the Glomerular capillary membrane or the
Glomerular membrane.
• Each glomerulus has 5-6 loops of the capillary and this capillary maintains the high
pressure of 55mm hg and that of other capillaries is 25.
• The ultrafiltrate or glomerular filtrate is formed by the Capillary membrane and the
filtrate is called as the glomerular filtrate and the rate at which it is produced / min is
called as the glomerular filtration rate.
PROXIMAL CONVOLUTED TUBULE:
• Single layer of cells with the curved and brushed bordered epithelium
• The brushes are called as the microvilli that increases the surface area.
LOOP OF HENLE:
• Starts with the descending loop of the Henle and then that forms the thin-walled tubule
and then arises the ascending limb of the Henle having the cuboidal epithelium.
• The vasa recta move parallel to the loops and tubules that helps in the exchange of the
substances with the tubule and the blood in capillary (VASA RECTA)
DISTAL CONVOLUTED TUBULE:
• Ascending loop is continuous to the DCT and the DCT is in the close proximity with the
Afferent and efferent arterioles
COLLECTING DUCT:
• Continous from the DCT to form collecting duct
• They pass from renal cortex into renal medulla finally into renal pelvis where the urine is
emptied.
JUXTA GLOMERULAR APPARTUS:
• At a point where the DCT meet with the afferent and efferent arterioles there are closely
packed cells called MACULA DENSA
• They come in contact with the specialised cells over the afferent and the efferent
arterioles called as the juxtaglomerular cells
• Macula densa along with the juxta glomerular cells are called as the juxtaglomerular
apparatus

6. HUMAN ANATOMY AND PHYSIOLOGY NOTES
RAMDAS BHAT
KARAVALI COLLEGE OF PHARMACY 6
• These helps in the release of the hormone called renin that regulates BP and maintaining
GFR.
Physiology of URINE formation:
PHYSIOLOGY OF THE Urine formation involves the 3 steps
1. Glomerular filtration
2. Selective tubular reabsorption
3. Renal tubular secretion
The process involves how the Glomerular filtrate is formed and how the electrolytes and essential
components are reabsorbed and how the toxic or unwanted substances are secreted from blood
into urine.

7. HUMAN ANATOMY AND PHYSIOLOGY NOTES
RAMDAS BHAT
KARAVALI COLLEGE OF PHARMACY 7
GLOMERULAR FILTRATION:
• Happens in the semipermeable membrane of the glomerular capillary and the bowman's
capsule
• The useful with the harmful substance will move into the glomerulus through the afferent
arterioles and the filtered blood will move onto to the efferent arterioles
• The diameter of afferent is more than the efferent as a result a pressure called hydrostatic
pressure is exerted into the efferent arterioles by the blood
• The hydrostatic pressure forces the blood to leave the glomerulus with high pressure and
thus resulting in the filtration of blood.
• Hydrostatic pressure is 55 mm hg is exerted in the glomerular capillary which is opposed by
the osmotic pressure of blood having plasma protein ie 30mm hg
• The filtrate formed exerts a pressure of 15mm hg
• Thus, net filtration pressure is 55-30-15=10mm hg that leads to filtration
SELECTIVE TUBULAR REABSORPTION:
• As the filtrate moves on to the other parts of the nephron the essential components are
reabsorbed where the non-essential components remain in the filtrate
• PCT reabsorbs amino acids, water (some amount), Na, Cl, vitamins, hormones, HCO3-
• Some are passively absorbed some are by passive process and reabsorption of water happens
by Osmosis
• Only 60-70% of total filtrate moves into the Henle loop, most of water, Na and Cl will be
reabsorbed and the only 15-20% of filtrate will move onto DCT where more amount of Na is
now reabsorbed and also HCO3- and the fluid will be somewhat dilute when it enters
collecting duct
• Collecting ducts helps in reabsorption most of water by osmosis.
TUBULAR SECRETION:
• Secretion of the nonessential components happens from the blood in vasa recta (peritubular
capillaries) into the filtrate the Renal tubules
• The waste such as H+, urea, uric acid, K+, creatinine gets actively secreted into the tubules
• H+ is removed from the blood to maintain the optimum pH of the blood and K+ is removed
in order to prevent the condition called as hyperkalaemia
• The drugs like Aspirin, Penicillin are not filtered completely but they remain in the glomerular
capillary which then move on to the Vasa recta where they get secreted into the tubules
The tubular filtrate once the reabsorption of the water in collecting duct happens will be
hypertonic and this concentrated fluid is called as the URINE.

8. HUMAN ANATOMY AND PHYSIOLOGY NOTES
RAMDAS BHAT
KARAVALI COLLEGE OF PHARMACY 8
URETER:
• 2 in number
• Help in the transport of the urine from the kidney to the urinary bladder
• 25-30cm in length, 3-4cm diameter
• Start from level of 2nd lumbar vertebrae
• Then travel behind peritoneum and empty into the urinary bladder containing trigone
• Has outer fibrous layer(adventia) that protects the urethra as a insulator
• Middle layer is muscularis layer having smooth muscle provided with autonomic nervous
system that can undergo peristalsis and propels the urine smoothly into the bladder
• The inner layer is the mucosal layer that secretes the mucous made of the transitional
epithelium
URINARY BLADDER:
• Hollow distensible organ that is present in
the pelvic cavity
• Suspended in a position with the
peritoneum
• Pear shaped
• 700-800ml capacity in males and 600ml in
females
• Has the 3 layers
• Adventia with a fibrous coat protects the
bladder along the adventia it has a serosa
coat
• Muscular coat: made of the smooth
muscle called as the detrusor muscle has
both longitudinal and the circular muscles.
• Detrusor muscle forms the band of the smooth
muscle around the opening of the urethra
called as the internal urethral sphincter.
• Mucosal layer is made of the transitional
epithelium.
• This layer protects the bladder from the urine
pH
• Surface is highly folded due to presence of the
rugae

9. HUMAN ANATOMY AND PHYSIOLOGY NOTES
RAMDAS BHAT
KARAVALI COLLEGE OF PHARMACY 9
• Ureter enters into the posterolateral surface into the urinary bladder obliquely.
• This type of the arrangement is needed in order to prevent the backflow of the urine when
the bladder is full.
TRIGONE:
• Small triangular region found in the
bladder
• It lies near to the internal urethral
sphincter
• They have 2 urethral orifices
• This area is very sensitive to the stretch
reflexes and sends the impulses to the
brain for emptying the bladder
URETHRA:
• Terminal part of the urinary tract
• Drains the urine out of the urinary bladder to outside the body
• It also has adventia, muscular and the
mucosal layer
• Starts from the internal urethral sphincter
• Has another sphincter called as the external
urethral sphincter formed by the levator ani
muscle that are skeletal muscle with the
somatic nervous system supplied that shows
the voluntary function
• Urethra of male and female is different
• The length of the urethra in male and female
is different.
• The various regions are present in the
urethra
• Prostatic urethra that passes through the
prostate gland
• Membranous urethra passing through the external urethral sphincter
• Spongy urethra that passes through the later part of the penis

10. HUMAN ANATOMY AND PHYSIOLOGY NOTES
RAMDAS BHAT
KARAVALI COLLEGE OF PHARMACY 10
• In the female there is a separate urethral orifice for the exit of urine and vulva that form
orifice of vagina
• In male the penis will act for the dual purpose of the exit of the urine and Semen
Composition of urine:
• Water 96%
• Urea 2%
• Uric acid, creatinine, pigments(urobilinogen) 0.3%
• Inorganic salts 2%
• Bad smell is due to Urinoid
• Pale yellow colour is due to the pigment urochrome or urobilinogen end product of the
Haemoglobin.
PHYSIOLOGY OF MICTURATION
• Carried out the central, autonomic and somatic nervous system
• Brain has a centre called as the pontine centre that controls the micturition and the centre is
called a Pontine Micturition centre
• Another centre are the periaqueductal centre and the cerebral cortex
• All these centres will help in the voluntary and the involuntary control of micturition
• Process of the micturition occurs by the 2 phases
• Storage phase and voiding phase
• Storage phase includes filling of the bladder by the urine by the distension of the bladder and
closure of the internal sphincter and voiding phase includes the opening of the internal
urethral sphincter with the opening of the external urethral sphincter leading to the
micturition
• Sympathetic nerves: preganglionic nerve fibres arise from the lumbar segment of the spinal
cord and end up at the ganglion and postganglionic nerve fibres innervate into the muscles
and the blood vessels
• Para sympathetic nerve fibres: arise from the sacral segment of the spinal cord. They
innervate into the muscles of bladder and the Internal sphincter
• Somatic nerves: arise from the sacral segment of the spinal cord in form of the pedundal
nerve that innervate into the External sphincter
• In storage phase the detrusor muscle relaxes by the stretch reflex caused by the sym. and
parasym. nervous system and increasing the tension of the internal sphincter leading to its
closure

11. HUMAN ANATOMY AND PHYSIOLOGY NOTES
RAMDAS BHAT
KARAVALI COLLEGE OF PHARMACY 11
• Voiding phase involves the relaxation of the Internal sphincter by the parasym. nerves and
causes the opening of the external sphincter by the somatic nerves leading to the propelling
of the urine from the bladder when person feels to urinate.
Physiological role of kidney in acid base balance:
• The kidney plays important role in the reabsorption of the HCO3- into the blood and the
excretion of the H+ into the urine.
• Within the body the body fluids must be maintained at a ph of 7.35-7.45 for the homeostasis
• If the ph fall or it is above the range it can cause protein denaturation, enzymes inactivation,
loss of the body function.
• There are various system that helps in maintaining the ph of the blood in the body they are
• BUFFER SYSTEM, RESPIRATORY SYSTEM, KIDNEY EXCRETION
BUFFER SYSTEM:
• The various buffers systems are present in the body that are helpful in the regulation of the
ph in body
• Most of the buffers in the body are the weak acids or weak bases
• Buffers system in the body are
a) Carbonic acid-bicarbonate system
b) Phosphate system
c) Haemoglobin-Oxyhaemoglobin system
d) Protein system

12. HUMAN ANATOMY AND PHYSIOLOGY NOTES
RAMDAS BHAT
KARAVALI COLLEGE OF PHARMACY 12
Carbonic acid-Bicarbonate system:
Hcl + NaHCO3 H2CO3 + NaCl
NaOH + H2CO3 NaHCO3 + H2O
• This process of body tends to make the blood slight acidic by formation of carbonic acid
• Thus, the more amount of carbonic acid makes the blood slight alkaline by combining with
the sod. Hydroxide forming Sod. Bicarbonate that is a weak base
• But the more amount of the Bicarbonate in blood causes the reaction with the hydrochloric
acid to form the weak acid carbonic acid.
Phosphate buffer system:
NaOH + NaH2PO4 H2O + Na2HPO4
Hcl + Na2HPO4 NaH2PO4 + NaCl
• Here Sodium hydrogen phosphate acts as a weak acid and the sodium monohydrogen
phosphate acts as a weak base
• This buffer system is helpful in maintaining ph
• Sod. Hydrogen phosphate are formed when excess of the excess of the H+ in the filtrate reacts
with the sodium monohydrogen phosphate
• Na+ formed by this process then reacts with the HCO3
• The H+ formed here will now move on to the urine where NaHCO3 will be re absorbed back
into blood making the blood alkaline and decreases the Acidity.
Haemoglobin- Oxyhaemoglobin system:
• This method happens by the chloride shift mechanism
Protein system:(amphoteric):
• Here the Amino group of the amino acid acts as a weak base and the carboxyl group will acts
as a acid
RESPIRATION:
• Respiration plays important role in the maintaining acid base balance
• As the conc. of carbon dioxide increases in the blood the pH will decrease.
• The reaction between the water and carbon dioxide yields the Carbonic acid which later
dissociates to form the bicarbonate and hydrogen ion

13. HUMAN ANATOMY AND PHYSIOLOGY NOTES
RAMDAS BHAT
KARAVALI COLLEGE OF PHARMACY 13
• The formed hydrogen ion that decreases the ph of the blood
• The decrease in the ph can be brought to normal by maintain the normal breathing rate
• Inspiration causes the increase in oxygen inside the blood whereas the expiration causes the
expulsion of the carbon dioxide
• The respiration is controlled by the Respiratory centres in the Medulla.
KIDNEY:
• Kidney helps in the excretion of the H+ and reabsorption of HCO3
• The tubules of the kidney secrete ammonia that later combines with the H+ to form
ammonium ion NH4+
• The ammonium ion then combines with the Chloride ion in the urine to form ammonium
chloride
This process causes the increase in the HCO3 in the ECF.
RENAL FUNCTION TEST/ RENAL CLEARANCE TEST:
• These are the group of the test performed to assess the normal functionality of the kidney
• The test includes
A. Analysis of the urine
B. Analysis of the blood
C. Assessing the concentration and the dilution power of the kidney
D. Plasma clearance test
E. Radiological examination
ANALYSIS OF THE URINE:
• Volume of the urine: to detect polyuria, oliguria, anuria
• Colour: red colour(haematuria), Yellow colour (Jaundice)
• Ph: lesser ph is called acidosis
• Microscopy: presence of the microorganism, puss in urine
• Chemical analysis: presence of the glucose(glucosuria), ketone bodies(ketonuria) in urine
• SG: determines the conc. / dilution power of kidney
ANALYSIS OF THE BLOOD:
• Wastes product like urea, uric acid and creatinine will be present in the blood During the GF
they get filtered into the filtrate
• The conc. of the wastes in the blood will be normal if the kidney works properly
• The urea concentration in the blood is 15-40mg/100ml which is normal

14. HUMAN ANATOMY AND PHYSIOLOGY NOTES
RAMDAS BHAT
KARAVALI COLLEGE OF PHARMACY 14
ASSESSMENT OF THE CONCENTRATION/ DILUTION POWER OF THE KIDNEY:
TO ASSESS THE DIUTION POWER OF KIDNEY:
• Person is given 2Lt of the water and urine is collected
• The urine gets excreted
• After 5 hours the 70% of the fluid is lost in the urine
• Then the SG of the urine is estimated
• If the SG is less than 1.011 the kidney shows the dilution power
• If the SG is more than 1.011 the kidneys show less dilution power.
TO ASSESS THE CONCENTRATION POWER OF KIDNEY:
• The water of the subject is held for 2hrs then the SG is noted
• If the SG is more 1.022 kidney has the ability of concentration
PLASMA CLEARANCE TECHNIQUE:
• Ability of the plasma to clear the certain substance/ min
• They are various types
1. Inulin clearance
2. PAHA clearance
3. Creatinine clearance
4. Urea clearance
INULIN CLEARANCE:
• Inulin is polysaccharide of fructose
• It has MW of 5000
• They get filtrated in the GF but not reabsorbed or secreted by the tubules
• 5ml of the inulin is taken IV
• The sample of the urine is now collected by cannula or by the catheter
• Now the plasma conc. of the inulin and that in the urine is determined
• Normal inulin clearance is 125ml/min
• Used to determine the GFR of kidney
PAHA CLEARANCE:
• PAHA are filtered by kidney but are not reabsorbed but secreted more
• Normal PAHA clearance is 585ml/min
• Used to determine renal blood flow

15. HUMAN ANATOMY AND PHYSIOLOGY NOTES
RAMDAS BHAT
KARAVALI COLLEGE OF PHARMACY 15
RADIOLOGICAL EXAMINATION:
• X-ray or the ultrasonic examination of the kidney are done here
• It is done to determine the CALCULI in the kidney or tumour growth in the kidney.