Urinary System
Published on 21st May 2018
FUNCTION
- Control composition and volume of blood by regulating
- water and solute levels
- Remove waste products
2 KIDNEYS (10-12cms)
- Consists of 3 parts
- The Cortex – outer
- The Medulla – inner contains pyramids
- The Pelvis – opens into the ureters
- Cortex and Medulla contain Nephrons - the functional units of the kidneys
NEPHRONS
- Filter from blood:
- Protein, Chloride, Sodium, Bicarbonate, Glucose, Urea, Potassium, Uric acid, Water
- Water, Glucose and Proteins are re-absorbed into the capillaries
- 1.5 litres leaves body as urine
- Process occurs in nephrons
COMPONENTS OF THE URINARY SYSTEM
2 URETERS
Urine passes from kidney to bladder through ureters by peristalsis (wave like muscular contraction)
BLADDER
- Hollow, muscular organ – reservoir for urine
- Capacity 700-800ml of urine
- When 200-400ml of urine is in bladder, stretch receptors send
- messages via spinal cord to the brain, causing urge to urinate
- 2 sphincters at the base of the bladder – internal (involuntary) and external (voluntary) control emptying of the bladder
URETHRA
- 95% water plus
- Urea – waste product of protein metabolism
- Uric acid – waste product of nucleic acid metabolism derived from food
- Sodium Chloride
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