Blood and stuff
Blood makes up about 7% of your body's weight
An average adult has about 14 to 18 pints of Blood
A smear of human blood under a microscope
What is in blood? Let's look at several types of blood cells and the watery part of your blood.
Each has an important job to do.
Platelets
White blood cells
Red blood cells
Plasma
Photo credit: NANOWORLD
Photo credit: NANOWORLD
Photo credit: NANOWORLD
More information...
Part
Red Blood Cells
also called erythrocytes
White Blood Cells
also called leukocyte
Job and other facts
% of blood
Live for:
carry oxygen to cells
carry carbon dioxide to the
lungs
make blood red,
concave shape, about
5,000,000 in a speck of
blood
45% of your
blood
100-120
days
fight infections,
break down dead cells
colorless, irregular shape,
can change shape,
larger than red blood cells,
about 10,000 in a speck of
blood
less than 1%
of your blood
most up to 3
days
7-10 days
Platelets
also called thrombocytes
disk shape,
help blood to clot, or thicken smaller than red blood cells,
(Photo)
about 250,000 in a speck of
blood
about 5% of
your blood
Plasma
watery part
mostly water,
carries red blood cells, white
but also sugars, salts,
blood cells, platelets, and
nutrients, proteins, minerals,
other necessary things for
wastes vitamins, hormones,
your body
and fats.
more than
50% of your
blood
White Blood cells have a rather short life cycle, living from a few days to a few weeks
One drop of Blood can contain from 7,000 to 25,000 white Blood cells. If an invading infection
fights back and persists, that number will significantly increase.
Red Blood Cells (RBCs) make up approximately 40% of Blood volume
There are five types of White Blood Cells (WBCs):
basophil - acts on smooth muscle and Blood cell walls;
eosiniphil - acts against infestations of parasitic larvae;
lymphocyte - recognizes surface markers on cells and targets them
for destruction if foreign to the body;
monocyte - formed bone marrow, monocytes migrate into
connective tissue and become macrophages; and,
neutrophil - the first line of defense, 100 billion mature neutrophils
are released into the body everyday
Red Blood cells live about 120 days in our bodies
Plasma, the fourth major component of Blood, is a sticky, pale yellow fluid mixture of water, protein
and salts. It is 95% water. The other 5% is made up of nutrients, proteins and hormones
Red blood cells are most common in blood



Women average about 4.8 million of these cells per cubic millimeter (mm3)
of blood.
Men average about 5.4 million per mm3
These values can vary over quite a range depending on such factors as
health and altitude. (Peruvians living at 18,000 feet may have as many as
8.3 million per mm3)
Functions of the blood
Blood performs two major functions:


transport through the body of
o oxygen and carbon dioxide
o food molecules (glucose, lipids, amino acids)
o ions (e.g., Na+, Ca2+, HCO3−)
o wastes (e.g., urea)
o hormones
o heat
defense of the body against infections and other foreign materials. All the WBCs participate in
these defenses.
Where are blood cells made?
Blood cells are made in the bone marrow. The bone marrow is the soft, spongy
material in the center of the bones that produces about 95 percent of the body's blood
cells.
There are other organs and systems in our bodies that help regulate blood cells. The
lymph nodes, spleen, and liver help regulate the production, destruction, and
differentiation (developing a specific function) of cells. The production and
development of new cells is a process called hematopoiesis.
Blood cells formed in the bone marrow start out as a stem cell. A "stem cell" is the
initial phase of all blood cells. As the stem cell matures, several distinct cells evolve
such as the red blood cells, white blood cells, and platelets. Immature blood cells are
also called blasts. Some blasts stay in the marrow to mature and others travel to other
parts of the body to develop into mature, functioning blood