BLOOD
What is it?
Blood is the red fluid that circulates in our blood
vessels, i.e. veins and arteries. The main function
of blood is to act as the body’s transport system,
but it also has a major role in the body’s defense
against infection.
Blood is a constantly circulating fluid providing
the body with nutrition, oxygen, and waste
removal. Blood is mostly liquid, with numerous
cells and proteins suspended in it, making blood
"thicker" than pure water. The average person
has about 5 liters (more than a gallon) of blood.
Blood has many different functions, including:
1. transporting oxygen and nutrients to the lungs
and tissues
2. forming blood clots to prevent excess blood
loss
3. carrying cells and antibodies that fight infection
4. bringing waste products to the kidneys and
liver, which filter and clean the blood
5. regulating body temperature
White Cell
Red cell
Platelet
Components?
It has four main components:
1.
2.
3.
4.
plasma,
red blood cells,
white blood cells, and
platelets.
Blood cells are produced
in bone marrow (μυελόσ/
μεδοφλι)
Plasma
•
Plasma
The liquid component of blood is called
plasma, a mixture of water, sugar, fat,
protein, and salts.
The main job of the plasma is to
transport blood cells throughout your
body along with nutrients, waste
products, antibodies, clotting proteins,
chemical messengers such as hormones,
and proteins that help maintain the
body's fluid balance.
Plasma
carries blood cells.
Red Blood Cells (RBCs)
(also called erythrocytes)
Known for their bright red color, red cells are
the most abundant (άφκονοσ) cell in the
blood, accounting for about 40-45 percent of
its volume. The shape of a red blood cell
looks like a donut.
Red blood cells start in the bone marrow and
after approximately seven days of maturation
are released into the bloodstream.
Red blood cells have no nucleus and can
easily change shape, helping them fit through
the various blood vessels in your body.
However, while the lack of a nucleus makes a
red blood cell more flexible, it also limits the
life of the cell as it travels through the
smallest blood vessels, damaging the cell's
membranes.
The red blood cell survives on average
Red cells carry oxygen
only 120 days.
White Blood Cells (leukocytes)
White Blood Cells (also called leukocytes)
White blood cells protect the body from
infection. They are much fewer in number
than red blood cells.
They make antibodies, which are proteins
that specifically target bacteria, viruses,
and other foreign materials.
Platelets (αιμοπετάλια)
Platelets (also called thrombocytes)
Platelets are not actually cells but rather small
colorless cell fragments in the blood whose
main function is to interact with clotting
proteins to stop or prevent bleeding.
• A higher than normal number of platelets
(thrombocytosis -θρομβοκυττάρωση) can
cause unnecessary clotting, which can lead
to strokes and heart attacks;
• lower than normal number of platelets
(thrombocytopenia -θρομβοπενία)
can lead to extensive bleeding.
Blood clots (θρόμβοι)
Blood must flow continuously and
smoothly throughout your body for an
entire lifetime, but quickly shut off
(αποςυνδζω, διακόπτω παροχι) to
prevent spills when you get a cut or
injury.
Blood clots are healthy and lifesaving
when they stop bleeding. But when they
aren't needed they cause a heart attack,
stroke, or other serious medical
problems.
What Causes Blood Clots?
The process begins whenever flowing blood comes into contact with specific substances
in your skin or in blood vessel walls. When they touch, it usually means the skin or blood
vessel wall is broken.
Cholesterol plaques that form in arteries have these things inside, too. If the plaque
breaks open, they'll start the clotting process. Most heart attacks and strokes happen
when a plaque in your heart or brain suddenly bursts.
Blood clots can also form when your blood doesn't flow properly. If it pools in your blood
vessels or heart, the platelets are more likely to stick together. Slowly moving blood can
cause clotting problems.
Blood type (Blood groups)
A classification of blood based on the
presence or absence of inherited
antigenic substances on the surface of
red blood cells. These antigens may be
proteins, carbohydrates, glycoproteins,
or glycolipids, depending on the blood
group system.
The Rhesus (Rh) system
•
Rh system (ςφςτθμα ταξινόμθςθσ
αίματοσ) Ρζηουσ
The Rh system classifies blood as Rhpositive or Rh-negative, based on the
presence or absence of Rh antibodies in
the blood. People with Rh-positive blood
can receive Rh-negative blood, but
people with Rh-negative blood will have a
transfusion reaction if they receive Rhpositive blood. Transfusion reactions
caused by mismatched Rh blood types
can be serious.
Blood types/ Donors recipients
•
Our blood is typed, or classified, according to
the presence or absence of certain markers
(antigens-αντιγόνα) found on red blood cells
and in the plasma that allow your body to
recognize blood as its own. If another blood
type is introduced, your immune system
recognizes it as foreign and attacks it, resulting
in a transfusion reaction. i.e. People with type A
have antibodies in the blood against type B.
O = It is the universal donor
Blood
cells
Blood types/ Donors
recipients
plasma
Whole
Blood
(red cells,
white cells,
and platelets
suspended in
plasma)
Bibliography
http://www.redcrossblood.org
http://kidshealth.org
http://www.americasblood.org
https://my.blood.co.uk/
http://www.webmd.com
http://study.com/academy
https://en.wikipedia.org