2. A blood cell, fall into three general categories:
• Red blood cells — Erythrocytes
• White blood cells — Leukocytes
• Platelets — Thrombocytes.
Together, these three kinds of blood cells add up to a
total 45% of the blood tissue by volume, with the
remaining 55% of the volume composed of plasma, the
liquid component of blood. This volume percentage (e.g.,
45%) of cells to total volume is called hematocrit,
determined by centrifuge or flow cytometry. Hemoglobin
(the main component of red blood cells) is an iron-
containing protein that facilitates transportation
of oxygen and other respiratory gases to tissues.

3. The blood vessels are the part of the circulatory
system that transports blood throughout
the body. There are three major types of blood
vessels: the arteries, which carry the blood away
from the heart; the capillaries,
which enable the actual
exchange of water and
chemicals between the blood
and the tissues; and the veins,
which carry blood from the
capillaries back toward the heart.

4. The most common type of grouping is the ABO grouping. The
varieties of protein coating on red blood cells divides blood into four
groups:
• A (A oligosaccharide is present)
• B (B oligosaccharide is present)
• AB (A and B oligosaccharides are present)
• O (neither A nor B oligosaccharides are present)
Apart from this there is a protein which plays an important part in the
grouping of blood. This is called the Rh factor. If this is present, the
particular blood type is called positive. If it is absent, it is called
negative. Thus we have the following broad categories:
• A Negative (A -ve) and A Positive (A +ve)
• AB Negative (AB -ve) and AB Positive (AB +ve)
• B Negative (B -ve) and B Positive (B +ve)
• O Negative (O -ve) and O Positive (O +ve)

5. • Blood pressure (BP), sometimes referred to
as arterial blood pressure, is the pressure
exerted by circulating blood upon the walls
of blood vessels, and is one of the principal vital
signs. When used without further specification,
"blood pressure" usually refers to the
arterial pressure of the systemic circulation.
During each heartbeat, blood pressure varies
between a maximum (systolic) and a minimum
(diastolic) pressure.

6. • The heart is a muscular organ found in all animals with
a circulatory system , which pumps blood throughout
the blood vessels by repeated, rhythmic contractions.
The term cardiac means "related to the heart“.
• The vertebrate heart is principally composed of cardiac
muscle and connective tissue. Cardiac muscle is an
involuntary striated muscle tissue found only in this
organ and responsible for the ability of the heart to pump
blood. The average human heart, beating at 72 beats
per minute, will beat approximately 2.5 billion times
during an average 66 year lifespan. It weighs
approximately 250 to 300 grams (9 to 11 oz) in females
and 300 to 350 grams (11 to 12 oz) in males.

8. • It is enclosed in a double-walled protective sac called
the pericardium. The double membrane of pericardium
consist of the pericardial fluid which nourishes the heart
and prevents from shocks.
• The human heart has four chambers, two superior atria
and two inferior ventricles. The atria are the receiving
chambers and the ventricles are the discharging
chambers.
• The pathways of blood through the human heart is part
of the pulmonary and systemic circuits. These pathways
include the tricuspid valve, the mitral valve, the aortic
valve, and the pulmonary valve.
• The interatrioventricular septum separates the left atrium
and ventricle from the right atrium and ventricle, dividing
the heart into two functionally separate and anatomically
distinct units.