Download Osmosis

How do your cells get the Nutrients
they need from the food you eat?
EAT
FAT
CHEW
SUGAR
PROTEIN
DIGEST
Nutrients Move Through Blood
Vessels
FAT
BLOOD VESSEL
CELL
SUGAR
PROTEIN
SMALL
INTESTINE
Homeostasis

Your body is constantly trying to maintain a
balance of all of its systems and processes.

Homeostasis: steady state of the internal
operations of a living organism regardless of
external changes.

For your body to maintain homeostasis the
internal environment of a cell needs to have the
appropriate amount of everything that it needs.
Energy

Your body maintains homeostasis by moving the
materials required by cells throughout the body.

Kinetic Energy: energy of movement. The
molecules in air, liquid, and solids have constant
motion and bounce off of each other
RANDOMLY.
Diffusion

Diffusion: The random movement of solute (a
substance dissolved in a solution) from an area of HIGH
concentration TO an area of LOW concentration until
they reach DYNAMIC EQUILIBRIUM.

This is a form of PASSIVE TRANSPORT which requires
NO ENERGY!

Dynamic Equilibrium: when the number of particles
entering and leaving a region are equal. The movement
continues but there is no net change.
Diffusion Cont…
 When
there is a higher concentration of
solute outside the cell, then the net
movement of solute is to the inside of the
cell until equilibrium is achieved.
= solute
Diffusion Cont…
 When
there is a higher concentration of
solute inside the cell, then the net
movement of solute is to the outside of the
cell until equilibrium is achieved.
Cell Membrane
 Nutrients,
water, and waste diffuse in and
out of a cell through the cell membrane.
 Cell




membrane:
Is the outer boundary of the cell which
encloses the cell’s contents.
Serves to maintain homeostasis.
Is made up of lipids and proteins.
Is selectively-permeable (only allows certain
substances to pass through).
Cell Membrane Cont…
 Folded
cellular membranes increase the
efficiency of the cell by increasing the
surface area.

Increased surface area = increased space for
molecules (nutrients and wastes) to pass in
and out of the cells.
Cell Membrane Anatomy
•
Cell Membrane Cont…

Some things move freely across and some
don’t.
 Water always diffuses freely.
 Many larger molecules can’t diffuse without
help from:

Transport Proteins: proteins in the cell membrane
that help bigger molecules move across the
membrane.
Facilitated Diffusion

Facilitated Diffusion:
Uses transport proteins to
help the passage of larger
molecules, like glucose, in
and out of the cell across
the cell membrane.
 A type of PASSIVE
TRANSPORT which
requires NO ENERGY!
Osmosis
(no, you can’t watch “Osmosis Jones”)

Osmosis: The diffusion of WATER. This is a type
of PASSIVE TRANSPORT which requires NO
ENERGY!.

Water diffuses based on the concentration of
water compared to other dissolved particles, like
salts or sugars.
= Water
= Solute

Osmosis Cont…
Hypotonic Solutions: Solutions in which more
solute is present in the cell than outside of the
cell.
More water outside
the cell then inside
the cell, therefore,
the net movement
of water will be into
the cell where more
solute is present.
Osmosis Cont…

Hypertonic Solution: A solution where there is
more solute present outside of the cell than
inside the cell.
More water was
located inside the cell
then outside of the
cell, therefore the net
movement of water
will be out of the cell
to where there was
more solute.
Osmosis Cont…

Isotonic Solution: A solution where there is
equal concentration of water inside and outside
of the cell, therefore the net movement of water
is equal in and out of the cell.
Turgidity/Plasmolysis
 Turgor
pressure: When a plant is fully
watered and the cell vacuoles are full.
 Plasmolysis: The shrinking or wilting of a
cell due to water leaving the cell.
Cytolysis
 Cytolysis:
The intake by a cell of so
much water that it bursts.
Osmosis Cont…

Plasmolysis and cytolysis in plant and animal cells
Active Transport

Active Transport: An ENERGY REQUIRING
process in which particles are moved from an
area of LOW concentration to an area of HIGH
concentration.
Endocytosis
 Endocytosis:
the process by which a cell
engulfs substances that are too large to
pass through the membrane. ENERGY
REQUIRING process.
Exocytosis

Exocytosis: The
passage of large
molecules such
as manufactured
proteins out of the
cell. ENERGY
REQUIRING
process.
Review
 Go
to the Web.