Download The Urinary System

The Urinary System
Function
1. Remove nitrogenous wastes
2. Maintain electrolyte, acid-base,
and fluid balance of blood
3. Homeostatic organ
4. Acts as blood filter
5. Release hormones: calcitriol &
erythropoietin
Kidneys as Filters
• Diuretic- loose water; coffee, alcohol
• Antidiuretic- retain water; ADH
• Aldosterone- sodium & water reabsorption,
and K+ excretion
• GFR= 180 liters (50 gal) of blood/day
• 178-179 liters are reabsorbed back into
blood
• Excrete a protein free filtrate
Maintaining
Chemical
Homeostasis
The
Urinary
System
The Urinary System
blood
filtration
General
Functioning
of the Kidney
tubular
reabsorption
and secretion
urine “refreshed” blood
Nitrogenous
Wastes
urea
uric acid
ammonia
kidneys
Organs
of the
Urinary
System
ureters
urinary
bladder
urethra
Kidney
Anatomy
renal
pelvis
ureter
renal
pyramids
renal
cortex
renal
capsule
renal
medulla
nephron
renal artery
renal vein
Kidney
Anatomy
blood
Nephron
Functioning
filtration
tubular
reabsorption
and secretion
urine “refreshed” blood
efferent
arteriole
afferent
arteriole
glomerulus
artery
peritubular
capillaries
loop of
Henle
vein
Bowman’s
capsule
proximal
convoluted
tubule
distal
convoluted
tubule
collecting
duct
Each kidney contains over 1 million nephrons and thousands
of collecting ducts
Glomerulus
DCT
renal
cortex
PCT
renal
medulla
Collecting duct
Loop of Henle
efferent
arteriole
afferent
arteriole
Glomerular
Filtration
Bowman’s
capsule
Filters blood; proteins can’t pass through
glomerulus
Composition of
Glomerular Filtrate
• Water
• Small Soluble Organic
Molecules
• Mineral Ions
Proximal Convoluted
Tubule
Reabsorbs: water, glucose,
amino acids, and sodium.
•
•
•
•
65% of Na+ is reabsorbed
65% of H2O is reabsorbed
90% of filtered bicarbonate (HCO3-)
50% of Cl- and K+
Loop of Henle
Creates a gradient of increasing
sodium ion concentration towards
the end of the loop within the
interstitial fluid of the renal pyramid.
• 25% Na+ is reabsorbed in the loop
• 15% water is reabsorbed in the loop
• 40% K is reabsorbed in the loop
Distal Convoluted
Tubule
Under the influence of the hormone
aldosterone, reabsorbs sodium and
secretes potassium. Also regulates
pH by secreting hydrogen ion when
pH of the plasma is low.
• only 10% of the filtered NaCl and 20% of water
remains
Collecting Duct
Allows for the osmotic
reabsorption of water.
ADH (antidiuretic hormone)- makes
collecting ducts more permeable to
water-- produce concentrated urine
Urine
Water- 95%
Nitrogenous waste:
• urea
• uric acid
• creatinine
Ions:
• sodium
• potassium
• sulfate
• phosphate
From the original 1800 g NaCl, only 10 g appears in
the urine
Hormonal
Control of
Kidney
Function
Hormonal Control
of Kidney Function
high plasma
solute
concentration
low blood volume
heart receptors
hypothalamus
Hormonal Control
of Kidney Function
hypothalamus
posterior pituitary
antidiuretic hormone
collecting ducts
Hormonal
Control of
Kidney
Function
INQUIRY
1.
2.
3.
4.
5.
List several functions of the kidneys.
What does the glomerulus do?
What are several constitutes you should not find in urine?
What is specific gravity?
What two hormones effect fluid volume and sodium
concentration in the urine?
6. Where are the pyramids located in the kidney?
7. What vessel directs blood into the glomerulus?
8. Where does most selective reabsorption occur in the
nephron?