Textbook notes for lecture 8 & 9

34 views1 pages
user avatar
Published on 13 May 2011
School
UTSC
Department
Biological Sciences
Course
BIOA02H3
Lecture 8 & 9 Salt & H2O Balance & N. Excretion
(Chapter 49)
Key Points:
What Roles Do Excretory Organs Play in Maintaining Homeostasis?
How Do Animals Excrete Toxic Wastes from Nitrogen Metabolism?
How Do Invertebrate Excretory Systems Work?
How Do Vertebrates Maintain Salt and Water Balance?
How Does the Mammalian Kidney Produce Concentrated Urine?
What Mechanisms Regulate Kidney Function?
Overview: A Balancing Act
Life evolved in the oceans (= salt water)
Physiological systems of animals operate in fluid environment
Relative concentrations of water and solutes in internal environment must be maintained within
fairly narrow limits
Simplest marine animals (e.g. protists) still live in seawater
- Directly exposed to external environment
- Easier to maintain water and ionic balance across small cellular distances
More complex animals have cells isolated from external environment bathed in tissue
fluids. PROBLEM: relative concentrations of water and solutes in internal fluid environment
must be maintained within narrow limits to avoid cell damage
Water Balance Crucial for Animal Cells
Animal cells - lack cells walls
- Must remain in osmotic balance with external environment to prevent destructive loss or gain of
water by cells = isotonic or iso-osmotic
www.notesolution.com
Unlock document

This preview shows half of the first page of the document.
Unlock all 1 pages and 3 million more documents.

Already have an account? Log in

Document Summary

Lecture 8 & 9 salt & h 2o balance & n. excretion (chapter 49) Life evolved in the oceans (= salt water: physiological systems of animals operate in fluid environment, relative concentrations of water and solutes in internal environment must be maintained within fairly narrow limits. Simplest marine animals (e. g. protists) still live in seawater. Easier to maintain water and ionic balance across small cellular distances: more complex animals have cells isolated from external environment bathed in tissue fluids. Problem: relative concentrations of water and solutes in internal fluid environment must be maintained within narrow limits to avoid cell damage.