Transcript Unit 4 Lesson ppt1(1)(1)

CELLS AND THEIR
ENVIRONMENT:
Homeostasis and Diffusion
HOMEOSTASIS
and
diffusion
LIFE’S BALANCING ACT
When we are too
cold we shiver, it
warms us up.
When we are too
hot we sweat, it
cools us down.
Your body is made up of
cells. And, just like your
body, cells must stay
balanced too. They
must have just the right
amount of materials to
maintain the proper
environment for your
body.
HOMEOSTASIS
The balance that all living
things have to maintain is
called HOMEOSTASIS.
Everything we eat and drink is made
of small particles called molecules.
These particles are always moving
around and bumping into each other.
They will move from areas that are
crowded to areas that are less
crowded until they spread out evenly.
The movement of particles in our cells from areas
that are more crowded to areas that are less
crowded is called DIFFUSION.
mmore crowded
less crowded
Diffusion happens in cells.
nucleus
????
mitochondria
????
cytoplasm
????
Cell
membrane
????
Remember the cell? How many of these parts do
you remember?
This is a cell membrane. Can you find the
parts where particles might go in and out of
the cell? Click to check your answer.
This is one of
five channels in
the diagram
that moves
particles in and
out of the cell.
The cell membrane is like the doors of a school. It
has special entryways that allow particles to move
into and out of the cell. Like in the cell membrane,
students only go into and out of school through the
doors.
Students are like the
particles in cellular
diffusion. They move
from the crowded
buses into the school
through the doors.
Once inside, they
spread out relatively
evenly into their
classrooms.