5D: The Excretory System Flashcards
Which organs are used in the urinary system?
Kidneys, bladder, urethra, and ureters
What is the function of the excretory system?
Removes waste substances and regulates water + ion concentrations
How is urea formed?
- Amino acids converted to ammonia
- Ammonia broken down into less toxic urea (safely transported in bloodstream)
What is urine made up of?
Water, urea, and solutes (extra salts)
What are the functions of a kidney?
- Filters blood
- Reabsorbs useful substances
What are the parts of a nephron?
Glomerulus, Bowman’s capsule, proximal convoluted tubule, loop of Henle, distal convoluted tubule, and collecting duct
What is the function of the Bowman’s capsule?
The high blood pressure in the glomerulus forces fluid into the Bowman’s capsule (primary filtrate). Small molecules and water can pass, but large proteins and blood cells stay in the glomerular capillaries.
What is not included in the primary filtrate?
Large proteins + blood cells
How does water leave the nephron?
It is reabsorbed at the descending arm of the loop of Henle (aquaporins), and the collecting duct (osmosis).
How do ions leave the nephron?
At the ascending arm of the loop of the Henle (because of the ion concentration outside)
What are some examples of other excretory organs?
Lungs -> removes CO2 from cellular respiration
Liver -> detoxifies blood + breaks down toxins, converts ammonia into urea
Skin and sweat glands -> removes excess water and salt
Why does so much blood pass through the kidneys?
- High blood pressure allows the forcing of fluid to pass through the capillary walls
