The Urinary System Ch. 22 HBHD

The Urinary System
Ch. 22 HBHD

Urinary System =
Excretory System
We are focusing on the urinary system,
but the following systems work
interdependently to maintain homeostasis
Urinary System: System:
excretes water, salts, &
waste products = urine
Digestive System: System:
excretes water, some
salts, bile, & residue of digestion = feces
Respiratory System: System:
excretes CO2 & water
(vapor)
Integumentary System: System:
water, salts &
nitrogenous wastes = perspiration

Structures of the Urinary
2 Kidneys
System
Extract waste from blood,
balance body fluids, form
urine
2 Ureters
Transports urine from
kidneys to bladder
Urinary Bladder
Receives & stores urine
Urethra
Urethra
Urine elimination

Lie against the
The Kidneys
muscles of the back
in the upper
abdomen. They are
protected by the lower
ribs & costal
cartilages
Located in the
retroperitoneal space

Structure:
The Kidneys
“Bean Bean” shaped
Measurements:
Measurements:
Length: 4” 4
Width: 2” 2
Thickness: 1”
1

External:
Capsule
Kidney Structure
Capsule: : covers &
protects the kidney; also
has a protective fatty
layer called an adipose
capsule
Hilus: : notch where the
renal artery, renal vein,
and ureters connect with
the kidney
Hilus

Internal
Kidney Structure
Internal
Cortex: Cortex:
outer portion of the
kidney
Medulla: Medulla:
interior portion;
contains tubes that collect urine
(urine formed here)
Renal Pyramids: Pyramids:
cone-shaped
cone shaped
structures – point toward the
renal pelvis
Renal Pelvis: Pelvis:
“funnel funnel-shaped shaped”
forms the upper end of the
ureter
Calyces (calyx): (calyx) : cuplike
extensions that collect urine

Kidney Blood Supply
Renal Artery: supplies
the kidney with blood
Branch of the abdominal
aorta
Branching of vessels to
supply entire kidney
Eventually reaches
nephrons
Nephron: functional unit
of the kidneys
Renal Vein: blood
leaves the kidneys
Carries blood to inferior
vena cava

The Microscopic Kidney
Nephron:
Structure
The basic unit of the
kidney
Most of the work done
here
Important Facts:
There are approx. 1 million
nephrons in each kidney
If all uncoiled and placed
end-to end to-end end ≈ 75 miles

Structures of a nephron
Bowman’s s capsule:
Bowman
A bulb at the end of the coiled tube of the nephron
Surrounds a cluster a capillaries called the
glomerulus
Glomerulus:
Glomerulus:
A cluster of capillaries inside the Bowman’s Bowman s
capsule
Where water and impurities leave the blood
Afferent arteriole = carries blood TO the glomerulus
Efferent arteriole = carries blood AWAY FROM the
glomerulus

Structures of a nephron
Proximal convoluted tubule:
The coiled portion leading from Bowman
The coiled portion leading from Bowman’s s capsule
Loop of Henle:
The bottom portion of the nephron between the Proximal & Distal
Convoluted Tubules
Distal Convoluted Tubule:
The coiled portion farthest from Bowman
The coiled portion farthest from Bowman’s s capsule
Excess water is reabsorbed & urine is concentrated
Amount of water reabsorbed is controlled by ADH (antidiuretic
hormone –produced produced by pituitary)
Empties into a collecting duct, which then continues through the
medulla toward the renal pelvis
Juxtaglomerular apparatus:
“near near the glomerulus”
glomerulus
Helps regulate kidney functions by releasing hormones

Kidney Functions
Excretion of unwanted substances
excess salts, toxins, & waste products
from cells
Maintain water balance
pH balance (acids vs. bases)
Production of Hormones
Renin – helps regulate BP
Erthropoietin – stimulates red bone
marrow to produce RBCs in an effort to
prevent anemia

Urine Formation
Glomerular filtration allows all
diffusible material to pass from
the blood to the nephron.
Tubular reabsorption moves
useful materials back to the blood
Tubular secretion moves
additional substances from the
blood to the nephron
Countercurrent mechanism
concentrates the urine and
reduces the volume excreted.
Hormone involved is ADH
(antidiuretic hormone)

The Ureters
Long, Slender muscular tubes
that extend from the kidneys to
the bladder
Length is dependent on individual
structure, but it ranges from 10- 10
13” 13
~1” ~1 of the lower ureter enters the
bladder by passing obliquely
through the bladder wall.
Causes a full bladder to compress the
ureters and prevent backflow of urine
Urine is moved from the kidney to
the bladder by gravity &
peristalsis

The Bladder
Temporary storage pouch for urine
Moderately full bladder holds about 1 pint
Contains rugae which allow the bladder
to stretch
Empty bladder is firm due to thick
muscular wall
As the bladder fills the muscle wall
becomes thinner and the organ may
increase in size
increase in size
Can stretch 2-5” 2
Has an internal sphincter (which
contracts to prevent urine from escaping
from the bladder involuntarily
Voluntary Control – extrenal sphincter
around the urethra, located below
internal sphincter
Urination: Urination:
(micturition) – the
process of expelling urine from the
bladder

The Urethra
The tube that extends from the bladder to the
outside of the body
Means by which the bladder is emptied
Male & Female differ
Male: part of both urinary & reproductive systems
Much longer than females
~8 inches : passes through the prostate
Female: ~ 1.5 inches long
Separate from reproductive system
Opens in front of the vagina

Disorders
Can be acute or chronic
Acute: : typically result from infection.
Imflammation of nephrons. Run course in a
few weeks and heel completely
Acute
Chronic: : arise slowly and can result in
eventual loss of kidney function
Chronic

Kidney Disorders
Acute Acute glomerulonephritis:
glomerulonephritis
Most common disease of the kidneys.
Usually occurs in children about 1-4 1 4 weeks after a strep
infection
Antibodies injure the glomeruli so that blood and protein
filter into urine
Usually treatable, but can be chronic
Pylonephritis:
Pylonephritis:
Inflammation of renal pelvis and kidney tissue
May be acute or chronic
Cause: passed on by a urinary tract infection
Treatment: antibiotics, fever control, rest, and adequate fluids

Kidney Disorders
Hydronephrosis:
Distention of the renal pelvis and calyces with
accumulated fluid caused by obstruction of urine
flow.
Pregnant women, enlarged prostate, kidney
stones, tumor
Treatment: prompt removal of the obstruction
Polycystic Kidney:
Many fluid-containing fluid containing sacs develop in the active
tissue and gradually destroy functioning parts
Runs in the family
Treatment: transplant or dialysis

Tumors:
Tumors:
Kidney Disorders
Typically slow growing
Signs:
Signs:
Blood in urine
Dull pain in kidney region
Treatment:
Treatment:
Surgical removal of the kidney
Chemo and radiation are not effective

Renal Failure
Acute renal failure:
Sudden, serious decrease in kidney function – may be
fatal
Occurs as a complication of other serious illnesses
Chronic renal failure:
Due to gradual loss of nephrons resulting in loss of
normal kidney function
Signs & Symptoms: Dehydration, edema, electrolyte
imbalance, hypertension, anemia, uremia
Causes: uremia: accumulation of nitrogenous waste
in blood or renal insufficiency

Kidney Disorders
Kidney Stones:
Kidney Disorders
Calculi: Made of Calcium salts
or uric acid. Precipitate out of the
urine instead of staying in
solution
Calculi:
Formation site: renal pelvis or
bladder
Causes: dehydration, stagnation of
urine, urinary tract infection
Size: variable
Many are impassable so surgery is
required.
Lithotriptor: “stone stone-cracker cracker”

Finish reading pages 408-411, 408 411, beginning with
treatment of kidney failure
Classwork pg 450-451 450 451 # 16-23 16 23