Transcript 1. Diffusion

th
8
Grade Science
Unit 4:
Interdependence Among the
Systems of the human Body
Lesson 2:
Feedback Mechanisms
Vocabulary of instruction
1. Diffusion
• A process where a
substance
redistributes from an
area of relatively
high concentration
to an area of
relatively low
concentration due
to random thermal
motion.
2. Equilibrium
• Balance, stable,
state in which all
forces act in
perfect
opposition and
cancel the
effects of one
another.
3. External stimulus
• Is an external action
or something from the
external environment
that causes a
reaction in an
organism.
4. Feedback mechanisms
• A process or a way that
interconnects one
aspect of a system to
another as to maintain
internal equilibrium or
homeostasis.
Positive Feedback
Negative Feedback
5. Homeostasis
• Is a process by which
the body’s internal
environment is in
kept in equilibrium in
spite of changes in
the external
environment the selfregulation of the
internal environment
of organisms or cells.
6. Internal stimulus
•
Is an internal
action or
something from
within your body
that gets you to
do react or do
something. (If you
hungry, you need
to get something
to eat.
7. Metabolism
• The process by which
plants and animals
release energy from
food and get rid of
waste products.
• The chemical
changes in living cells,
by which the energy is
provided for the vital
processes and
activities, and new
material is assimilated
to repair the waste.
8. Turgor pressure
• Is the pressure of
the cell contents
against the cell
wall, in plant
cells, determined
by the water
content of
the vacuole,
resulting
from osmotic
pressure.