7th Grade
Unit 5:
The Structure and Function
of Body Systems
Lesson 2:
Nervous, Digestive, and
Excretory Systems
Vocabulary of Instruction:
Absorption
• The uptake of
water or
dissolved
chemicals by a
cell or an
organism (as
tree roots
absorb
dissolved
nutrients from
the soil).
Autonomic Nervous System
• Part of the
nervous
system
which
controls
involuntary
bodily
functions.
Central Nervous System
• Portion of
the nervous
system
which
consists of
the brain
and spinal
cord.
Chemical Digestion
• Involves enzymes that break
down starches, proteins, fats,
etc. in the small intestine.
• Each type of molecule is broken
down into its simplest part
through the use of enzymes.
Excretion
• Is the
process of
eliminating
waste
products of
metabolism
and other
non-useful
materials.
Involuntary Muscles
• Muscles whose activity is not
subject to conscious control.
Kidney
• Are two bean
shaped
organs that
filters wastes
(such as urea)
from the
blood and
excrete them,
along with
water, as urine.
Mechanical Digestion
• Requires the
use of
energy and
the
mechanical
breaking
down of
food via
chewing.
Motor Neurons
• Applies to neurons
located in the
central nervous
system (CNS)
that project their
axons outside the
CNS and directly
or indirectly
control muscles.
Neurons
• Nerve cell, which is the basic functional
unit of the nervous system.
Peripheral Nervous System
• Resides or extends
outside the central
nervous system
(the brain and spinal
cord) to serve the
limbs and organs.
Unlike the central
nervous system,
however, the
Peripheral Nervous
System (PNS), it is
not protected by
bone, leaving it
exposed to toxins
and mechanical
injuries.
Peristalsis
• Involuntary
waves of
muscle
contraction
that keep the
food moving
along in one
direction
through the
digestive
system.
Sensory Neurons
• Are nerve cells within
the nervous
system responsible
for converting
external stimuli from
the organism's
environment into
internal electrical
motor reflex loops
and several forms of
involuntary
behavior, including
pain avoidance.
Somatic Nervous System
• Is part of the peripheral nervous
system associated with
the voluntary control of body movements
through the action of skeletal muscles, and
with reception of external stimuli, which
helps keep the body in touch with its
surroundings.
• Examples:
– Touch
– Hearing
– Sight
Toxins
• Are
poisonous
substances
produced by
living cells of
organisms.
Voluntary Muscles
• Drawn
muscles;
muscles
whose
activities can
be controlled
by the brain
(e.g. skeletal
muscles).