NOTES-Chapter 42

NOTES-Chapter 42 - Chapter 42: Water and Electrolyte...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
Chapter 42: Water and Electrolyte Balance in Animals The amount of water and electrolytes in animal cells is critical Animals obtain water by o Absorbing it by osmosis o Drinking it o Eating food o As a byproduct of cellular respiration Animals lose water by o Urine o Feces o Sweating o Respiration Animals are continually adjusting the amount of water and electrolytes in their bodies Guiding principles of regulation o Ions move across membranes in a special type of diffusion called dialysis down a concentration gradient. This is passive transport o Ions can be transported across a membrane against a concentration gradient by an ion pump which requires expenditure of ATP energy Water moves across membranes by osmosis from a high water (low solute) to a low water (high solute) concentration. This can involve special proteins called aquaporins or just the regular spaces in the lipid bilayer. This is passive transport. THERE ARE NO PUMPS FOR WATER! Diffusion o Solutes move from areas of higher concentration to areas of lower concentration. o Start with different molecules on different sides of a selectively permeable membrane o Molecules diffuse across the membrane- each along its own concentration gradient o Equilibrium is established. Molecules continue to move back and forth across the membrane but at equal rates Hypetrtonic, hypotonic, isotonic- relative concentrations of specific molecules Hyperosmotic, hypoosmotic, isoosmotic- relative concentrations of all solutes combined Water flows to hypertonic solutions Osmosis o Water moves from areas of higher concentration to areas of lower concentrations o Osmoles=1osmole=amount of osmotic pressure generated by a 1 molar solution of a substance which doesn’t dissociate
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
o Start with more solute on one side of the selectively permeable membrane than the other. In this case, the solutes cannot cross the membrane o Water moves from the region of lower concentration to a higher concentration of solutes. Osmoregulation in Aquatic Environments o Osmoconformers- they conform to the environment in terms of osmolarity. Their bodies are isoosmotic to the environment. They do regulate their electrolytes, the concentration of some electrolytes is different from the environment. Principal examples are marine invertebrates like clams and crabs. The marine environment is very
Background image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 04/07/2011 for the course BIOL 104 taught by Professor Bray-speth during the Fall '11 term at Saint Louis.

Page1 / 5

NOTES-Chapter 42 - Chapter 42: Water and Electrolyte...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online