Excretory System
Urinary system
Structures of the Urinary System
2 kidneys – produce urine, filter blood 180 L of blood per 24
hours filtered 2 ureters – tube that
leads to the bladder Bladder – stores urine Urethra – tube for
eliminating urine
Kidney Function
A. filter blood that has collected wastes from cells. B. Excrete waste – urea, uric acid, creatine,
ammonium C. Maintain blood volume – regulating water
excretion D. Monitor electrolytes in blood E. Monitor blood pH F. Secrete Renin – enzyme to help maintain blood
pressure G. Stimulates red blood cell production
Structure of Kidney
Renal cortex – outer layer, filtration
Renal medulla – middle layer, filtration, absorption
Renal pelvis – urine collection and transport
Renal artery - Renal vein -
Urine Analysis Lab: Crystals
Lab: RBC’s in urine
Will look red under microscope
WBC’s in urine
Blue pigment
Production of Urine –
Nephron – filtering unit (about 1 million) p. 408.
Rate of filtration: 125 ml/min or 45 gallons each day.
Blood in your whole body gets filtered 20 – 25x per day.
1. Filtration – filters blood
Caused by pressure difference between glomerulus and bowman’s capsule.
Glomerular filtrate – 180L/day, water, sodium, potassium, chloride, sugar, uric acid, creatine.
No red blood cells or large proteins found
Passive transport
Tubular Reabsorbtion
- Valuable molecules reabsorb in blood
178.5 L reabsorbed (glomerular filtrate back into blood)
active and passive transport o glucose, water (passive),
sodium (active) o hormones help
reabsorbtion – ADH and aldosterone
o diuretics affect this process
Tubular Reabsorbtion (continued)
Loop of Henle Counter- current
exchange Used to create a
concentration gradient to absorb water
Active transport of Na+ and facilitated diffusion of C-
Tubular Secretion
Small amount of substances (uric acid, ammonium, H ions) move from blood back to nephron
(tubular secretion)Hormonal Control Antidiuretic Hormone – (ADH)1. Produced by hypothalamus2. Stimulates reabsorbtion of water3. Hydrated – decrease in production of ADH; increase in
urine.4. Dehydrated – increase ADH production5. Diurectics – inhibit the absorption of water i.e.
caffeine, alcohol
(secretion)Aldosterone
A. adrenal hormone, maintains sodium and potassium balance. Increase blood volume
Diabetes mellitus (endocrine)
Chronic disease of insulin deficiency or resistance
Insulin – allows sugar to be used as fuel Type 1 – pancreatic cells destroyed
(autoimmune) Type 2 – resistance to insulin
Kidney Stones
Renin-Angiotensin System
Regulates the body’s sodium and water levels for blood pressure.
Steps of System: Glomerular cells secrete renin into blood 2. Angiotensinogen (inactive in blood plasma), 3. In the liver coverts Angiotensinogen to hormone
Angiotensin II 4. Constricts blood vessels 5. Also, causes Aldosterone to be secreated to help retain
water and decrease renin production.
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