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Key Points From Last Lecture
Homeostasis is made possible by physiological negative feedback loops
Osmoregulation: Evolutionary trend towards greater control of osmoregulation, waste secretion
Outline/Key Points:
Kidneys filter blood, regulate osmolarity (two functions)
- Human kidneys
- Concentration gradient/kidney function
Water/salt needs of different animals are different
- Too much water/too little salt
- Too little water/too much salt
The Kidney Filters Wastes from Blood, and is the Effecter of Osmoregulation
Fig 32_13
The Kidney performs two functions - osmoregulation and recovery of valuable materials
Low salt concentration - No water crosses tubule
High salt concentration - allows passive diffusion of water out of waste - birds and mammals
Active recovery of valuable materials
The Kidney is an Effecter in a Negative Feedback Loop Allowing Osmoregulation
Pg 626
Organisms Face Different Challenges to Osmoregulation Based on their Environment
Fig 32_10
Either too little or too much water/salt
Marine environments are analogous to deserts
In freshwater environments salts and minerals are limited
Three Types of Nitrogenous Waste
Fig 32_14
Type of waste and the amount of dilutions follows phylogeny
Too Much Water/Too Little Salt
Bodies are saltier than environment = water moves in salt moves out
Fig 32_8
Too Little Water/Too Much Salt
Environment is saltier than body = water moves out salt moves in
Fig 32_8
Additional Physiological Adaptations Involved in Osmoregulation
Fig 32_9
Fig 32_12
Urea is deteoxified, used to raise osmolarity of blood which prevents water loss
Salt in diet, specialized organ to eliminate salt
Elasmobranch (marine) Marine bird