The Urinary System
LT: I can identify the different parts of the urinary
system and explain their function.
General Functions
• Filtration
• Storage and excretion of waste (urea, uric acid)
• Production of hormones (blood pressure, volume)
• Homeostasis
• Na+, K+
• pH (H+, bicarbonate ions)
• Blood pressure
Structures and Function
• Kidney
• Location- posterior wall
of abdominal cavity
• Filtration
• Production of urine
• Right Kidney lower to
accommodate the liver
Structures and Function
• Ureter
• Structure- narrow long
tubes with expanded
upper end
• Function- drain urine
from renal pelvis to
urinary bladder
Structures and Function
• Urinary Bladder
• Structure
• Elastic muscular organ
• Lining arranged in rugae
• Function- stores urine
before voiding
Structures and Function
• Urethra
• Structure
• Narrow short tube
• Lined with mucous
membrane
• Urinary meatus
• Function- passageway
for urine to leave
bladder
A
D
B
E
C
Kidney Structures and Function
• Renal Cortex
• Superficial layer of
kidney
• Renal Medulla
• Inner layer of the
kidney
Kidney Structures and Function
• Minor Calyx
• Structure
• Cup shaped cavity
• Base of renal papillae
• Function- drains urine
from the renal papillae
into major calyx
Kidney Structures and function
• Renal Pelvis
• Structure
• Funnel shaped cavity
• Formed by convergence
of calyces
• Function- collect urine
from major calyces and
joins ureter
Kidney Structures and Function
• Renal Pyramid
• Structure
• Darker conical region
• Renal medulla
• Function- house tubules
of nephrons
Kidney Structures and Function
• Renal Vein
• Carries unoxygenated
and filtered blood from
the kidney to the
inferior vena cava
Kidney Structures and Function
• Major Calyx
• Structure
• Cavity formed by
convergence of minor
calyces
• Function- drain urine
from minor calyces into
renal pelvis
Kidney Structures and Function
• Renal Capsule
• Connective tissue
covering the external
surface of the kidney
1.
8.
2.
3.
4.
9.
5.
6.
10.
7.
Lab Reflection
• What was the purpose of the dialysis lab?
• What is dialysate?
• What in the lab represented dialysate?
• In the lab, list which each of the following
represented:
• Red Beads
• Water with yellow food coloring
• Salt
• If proteins, glucose, and salt are present, describe
what will happen to each indicator strip (color
change).
Structure and Function of
Nephron
• Functional units of the
kidney
• 1 million
• Filtration and
absorption
Nephron Structure
• Efferent arteriole
• Carries blood away from
glomerulus
• Helps maintain filtration
rate
Nephron Structure
• Glomerulus
• Cluster of capillaries
• Site of filtration
• Filtering unit
Nephron Structure
• Afferent Arteriole
• Brings blood to the
glomerulus from renal
artery
Nephron Structure
• Proximal convoluted
tubule
• Bowman’s Capsule –
Loop of Henle
• Reabsorption of:
• Sugar
• Na+
• Water
Nephron Structure
• Peritubular capillary
• Surrounds nephrons
tubular portion
• Fills with blood from
efferent arteriole
Nephron Structure
• Distal convoluted tube
• Continues from
proximal tubule
• Reabsorption of:
• Na+
• Water
Nephron Structure
• Collecting Duct
• Collects urine from
nephron and sends it to
the ureter
Nephron Structure
• Loop of Henle
• Long loop located in the
medulla of the kidney
• Reabsorption of
• Water
• Salts
Nephron Structure
• Bowman’s Capsule
• Saclike structure
• Surrounds glomerulus
• Collects filtrate from glomerulus
Nephron Structure
• Vasa Recta
• Carries blood at rate
• Maintains
countercurrent
mechanism
• Helps to maintain NaCl
concentration gradient
Urine Formation
• Occurs in three stages
• Glomerular Filtration
• Tubular Reabsorption
• Tubular Secretion
Urine Formation
• Glomerular Filtration
• Water, other small dissolved molecules, and ions are
filtered out of glomerular capillaries
• Glomerular filtrate
• Composition of filtrate
• Water
• Same solutes as in blood plasma (except larger protein
particles)
• Average adult filtration rate
• 45 gallons in 24 hours
Urine Formation
• Filtration rate is affected by:
• Sympathetic Nervous System
• Responds to changes in blood pressure (ex. Bp drops)
• Antidiuretic Hormone
• Released in response to increased osmotic pressure
• Vasodilation and Vasoconstriction
Urine Formation
• Tubular Reabsorption
• Process that transports
substances out of
tubular fluid and into
peritubular capillary
• Prevents needed
materials from going in
urine
Urine Formation
• Tubular Reabsorption
• Nutrients that can be used by the body are reabsorbed
• Water, glucose, sodium, etc.
• Occurs through osmosis, diffusion, and active transport
Urine Formation
• Secretion
• Substances move into urine in the distal and collecting
tubules from blood
• Substances secreted
•
•
•
•
Hydrogen ions
Potassium ions
Ammonia
Certain drugs
Urine
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Emptying Reflex
• Initiated by stretch
reflex in bladder wall
• Bladder wall contracts
• Internal sphincter
relaxes
• External sphincter
relaxes and urination
occurs
Urine Flow
Urine Flow
• Bowman’s Capsule – Proximal Convoluted Tubule –
Descending Limb – Loop of Henle - Ascending Limb
– Distal Convoluted tubule – Collecting Duct Papillary Duct – Minor Calyx – Major Calyx – Renal
Pelvis – Ureter – Urinary Bladder – Urethra
Bellwork
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
Nephron
A.
Glomerulus
B.
Filtrate
C.
Secretion
D.
Urinalysis
Aldosterone
E.
Proximal convoluted tubule
F.
Filtration
G.
Bladder
ADH
H.
Cortex
I.
J.
K.
Performs filtration
The opposite of reabsorption
The basic structural and functional unit of
the kidney
Under the control of the hypothalamus, this
hormone increases the permeability of water
A fluid consisting of water, glucose, amino
acids, some salts, and urea
An examination of urine
Store urine until about 500cc has
accumulated
The first step in urine formation
Adrenal hormone that controls urinary
secretion
Contains the nephron
Where 80% of the water filtered out of the
blood by the glomerulus is reabsorbed
Label the Diagram Below
10
1
6
11
7
12
5
8
2
9
3
4
13