respiration is the process of
oxidizing food molecules, like
glucose, to carbon dioxide and water.
The energy release is trapped in the
form of ATP for use by all the
energy-consuming activities of the
The study of cells (cytology) dates back to
1665. But not until 1840, with
improved microtechniques, was much
understood about the fluid content of cells
- the true substance of life. It was
then that scientists first concluded that
all plants and animals are composed of
principles about cells:
1. Cells are units that make up all living matter.
2. Cells are units that carry on the function of all
3. Cells come from pre-existing cells.
Three basic principles about cells have
not changed with time.
The health of individual cells is
determined by the ability of the cells to
carry out their full range of functions.
job: To perform the many jobs necessary
to stay alive, such as moving oxygen around
your body, taking care of the fuel supply,
communications, and waste removal:
The enzymatic breakdown and absorption
of substances to provide more than 40
known nutrients for the building, repair
and maintenance of tissue and for energy
Synthesis, or putting together of
organic compounds from smaller units
obtained from digestion and absorption
or some other synthesis reaction in the
cell. This results in the functions of
cell growth, secretion and replacement
of worn-out cellular parts.
Cell respiration which results in the
release of energy from the final stage
of the digestion of food.
Cell movement and the movement of
substances inside the cell which
determine its efficiency in functioning.
Excretion of waste producst (toxins
and the "clinkers" of
metabolism) from cells. Some waste
materials to be removed are soluble,
others are nonsoluble and nondigestible.
To maintain a steady state within a
cell (called homeostasis) which permits
its existence and formation of new
There are 26 billion cells in a newborn baby and 50 trillion cells in
A typical cell has two major parts:
1. Nucleus (Referred to as the cells command
center. It has the coded information
for the manufacture of protein within the
2. Cytoplasm (all the material inside the cell except
for the nucleus).
Cells contain highly
organized structures called organelles
essential to their functioning. One of
these organelles, mitochondria, is
responsible for 95% of the cell's energy
Cells of a similar
type that are grouped together are called
tissues. Tissues of one kind depend
upon other kinds of tissues to supply some
of their needs to carry out their specific
functions. Muscles need oxygen
supplied by the blood tissue, food from the
digestive track and regulation of movement
by the tissues of the nervous
Organs are groups of
tissues joined together to perform specific
tasks. The stomach has a tissue lining which
is different from the stomach muscles that
cause the food to be mixed. The gastric
glands that secrete digestive juices are
another kind of tissue and are different
from the nerve tissues that signal the
emptying of the stomach.
Several organs can work together in a system.
The organs of a system may be close
together, or spread across the body. Some
examples are the digestive, reproductive,
respiratory, excretory, and nervous systems.
Some kinds of tissue may be found in more
than one system. Muscle tissue, for example,
is part of the muscular, respiratory, and
circulatory systems. Some organs, like the
pancreas (which is part of the digestive and
endocrine systems) pull double duty.
The body gives us
many illustrations of the interdependence of
cells and tissues.
Some Different Cells:
The egg is
the largest human cell. Once it is
fertilized, all other cells begin
help build your skeleton by secreting
the fibers and minerals from which bone
store fat. They can shrink or grow. Once
you have them you can't get rid of them.
are organized into muscles, which move
pass nerve messages around your body.
cells carry oxygen around your body.
cells fight disease
Your cells need to breakdown, assimilate
and utilize specific substances to perform
their designated functions. We'll be
covering that in Cell
Dr. Mary Ruth Swope, Green Leaves of
Barley. Dr. Swope is a nutrition
educator with more than 50 years experience
in foods and nutrition.
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Last update: 02/16/2012
put upon this earth every ingredient
needed to promote and sustain cell
life...He also put on this earth the
stems, roots, leaves, and bark
containing every ingredient necessary
to change a sick cell to a healthy
Dr. Mary Ruth Swope Green Leaves of Barley