BIO 111 Lecture Notes - Lecture 3: Water Balance, Nephron, Osmoregulation
Water balance and excretion
Body fluid homeostasis: Nitrogenous Waste
- Inside the digestive tract, enzymes break down proteins into amino acids
- Cells absorb amino acids
- Curing cellular metabolism, amino groups are stripped from amino acids, forming ammonia
- Ammonia enters the blood stream
- Once it gets to the liver it is converted to a waste molecule called urea that is excreted in urine
- Ammonia is very toxic so we convert it
- NH3 (ammonia, very toxic) → Urea (less toxic)
Osmoregulation in fish:
- Salt water fish
o Get a lot of their fresh water from what they consume
o Avoid sending water out
o Send very concentrated urine out
o Get salt water in, excrete a lot of ions out to keep a low concentration
- Fresh water fish
o Very few ions in water
o High concentration of ions in fish
o Consume lots of water
Water budgets
Water gain:
- Rat
o Gets water from mostly metabolism and some food
- Human
o Gets water from mostly liquid and some food and little metabolism
Water loss:
- Rat
o Loses water mostly from evaporation and some urine and feces
- Human
o Loses water mostly from urine and some evaporation and feces
Water balance and excretion continued
Kidney Anatomy:
- Each one contains blood vessels and millions of nephrons
- Nephrons
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Document Summary
Inside the digestive tract, enzymes break down proteins into amino acids. Curing cellular metabolism, amino groups are stripped from amino acids, forming ammonia. Once it gets to the liver it is converted to a waste molecule called urea that is excreted in urine. Ammonia is very toxic so we convert it. Nh3 (ammonia, very toxic) urea (less toxic) Salt water fish: get a lot of their fresh water from what they consume, avoid sending water out, send very concentrated urine out, get salt water in, excrete a lot of ions out to keep a low concentration. Fresh water fish: very few ions in water, high concentration of ions in fish, consume lots of water. Rat: gets water from mostly metabolism and some food. Human: gets water from mostly liquid and some food and little metabolism. Rat: loses water mostly from evaporation and some urine and feces. Human: loses water mostly from urine and some evaporation and feces.
