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HOMEOSTASIS Homeostasis (aka Homoeostasis): the tendency of a system to STAY THE SAME Our body is an example of a system
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DIFFUSION / OSMOSIS
•What does the prefix ‘homo’ mean?
•Same
HOMEOSTASIS•Homeostasis (aka Homoeostasis): the
tendency of a system to STAY THE SAME
•Our body is an example of a system
• There are two ways that homeostasis can be maintained:– Diffusion– Osmosis
OSMOSIS
• Osmosis is the movement of WATER from high to low concentration.
• Membranes (barriers) can be permeable Permeable (def.): allowing things (such as liquid or solids) to pass through
• What does the word ‘selective’ mean?
*Think of charter schools that are described as selectively enrolled students
So what does selective permeability mean?
SELECTIVE PERMEABILITY
•Selective Permeability: a PARTIALLY selective membrane that allows only CERTAIN things to go through
DIFFUSION • Diffusion is movement of solid, gases, and
other substances molecules (solutes) from high to low concentration.
PRACTICE/PREDICTION
3 TYPES OF CONCENTRATION • Hypertonic
• Hypotonic
• Isotonic
• Hyper = More
• Hypo = Less
• Iso = Same
concentration of solute outside of
the cell is EQUAL to the
concentration of solute inside the
cell.
H2O
H2O
Water MoleculeDissolved Molecule
ISOTONIC SOLUTION
HYPOTONIC SOLUTIONConcentration of solute is LOWER
(higher water concentration)
outside of the cell than the
concentration of solute inside the cell.
H2O
H2O
Water MoleculeDissolved Molecule
• In a HYPOtonic solution - The cell swells because more water goes in the cell. Less solutes outside of the cell, high concentration of solutes in the cell, so water moves in.
HYPERTONIC SOLUTION
Concentration of solute is HIGHER
(water concentration is lower) outside of
the cell than theConcentration of solute inside of the
cell
H2O
H2O
Water moleculeDissolved molecule
• In a HYPERtonic solution - The cell shrinks because water leaves the cell. High concentration of solids on the outside of the cell, so the cell loses water and shrinks.
What type of solution is this Hypo-, Hyper- or Iso- tonic?
Which way will the water move?
Hypotonic
Water moves INTO the cell
What type of solution is this Hypo-, Hyper- or Iso- tonic?
Which way will the water move?
Isotonic
Water moves at an EQUAL rate into and out ofthe cell
What type of solution is this Hypo-, Hyper- or Iso- tonic?
Which way will the water move?
Hypertonic
Water moves OUT of the cell
water
water
waterwater
Cell SWELLS
Cell stays the SAME
Cell Shrinks
ANIMAL CELL
PLANT CELL
Isotonic Hypotonic Hypertonic
Isotonic Hypotonic Hypertonic