Blood – Medical Terminology

Blood contains cells, a liquid ground substance (called plasma), and “dissolved” protein fibers, nutrients, gases, ions…

Components of Blood
Erythrocytes red blood cells
44% of a blood

leukocytes (or white blood cells) and platelets (thrombocytes)
less than 1% of a blood sample

Plasma
about 55% of blood

Blood
Formed elements
Erythrocytes (RBC)
99% of cells
Carry oxygen
Leukocytes (WBC)
Protect against infection and cancer
Platelets (cell fragments)
Blood clotting

Erythrocyte
~7.5 µm diameter fresh;  7.2 – 7.4 in stained smears; 0,8 – 2,6 µm thick
Macrocytes > 9 µm,
Microcytes < 6 µm
Anisocytosis = variation in size
Poikilocytosis = variation in shape
Biconcave disc shape which provides a 20-30% greater surface area than a sphere
no nucleus
Surface area is adapted for gas exchange
Flexible; squeeze through capillaries
Rouleaux formation

Erythrocyte
Cell membrane:
Interior – 33% hemoglobin, and other enzymes
Hemoglobin
Every erythrocyte is filled with approximately 280 million molecules of a red-pigmented protein called hemoglobin.

Transports oxygen (& very little carbon dioxide), and is responsible for the characteristic bright red color of blood.

Hemoglobin in Erythrocytes
Oxygen binds iron ions (Fe2+) for transport in the blood.

Each hemoglobin molecule has four iron ions and is capable of binding four molecules of oxygen.

Oxygen binds to the hemoglobin when the erythrocytes pass through the capillaries of the lungs.

Oxygen leaves the hemoglobin when the erythrocytes pass through the capillaries of body tissues.

Erythrocyte
Survive 120 days in circulation

Old RBC removed by macrophages in spleen

Reticulocytes about 1% of total RBC

Leukocytes
on the basis of presence or absence of  SPECIFIC granules leucocytes are divided into 2 major group:

granular leucocytes (or granulocytes) have specific granules

nongranular leucocytes (or agranulocytes)  do not have specific granules
Leukocytes
6-10,000 per µL
Granulocytes (polymorphonuclear leukocytes)
neutrophils 60-70%
eosinophils 2-4%
basophils 0.5-1%

Agranulocytes
lymphocytes 20-30%
monocytes 3-8%
Neutrophils
12-15 µm diameter

are spherical in shape

multi-lobed nucleus

lifespan 1-4 days in tissue

Neutrophils
Diapedesis = cells crossing over the vascular endothelium/wall
play a central role in inflammatory processes
Form H2O2, (powerful cytotoxic substance)
Lysozyme (breaks down bacterial cell wall)
Lactoferrin binds Fe (needed by some bacteria) – (bactericidal action)
Diapedesis
Eosinophils
12-15 µm diameter,

bi-lobed nucleus

are spherical in shape

Circulate in the blood for about 8-12 hrs

Eosinophils
Are associated with allergic reactions

Also Antiparasitic

Phagocytose Ag-Ab complexes formed in allergy

Implicated in chronic inflammation

Basophils
Less than 0.5% of total leukocytes,
12-15 µm diameter,
Lobed nucleus,

Lymphocytes
The most common agranulocytes
6-8 µm diameter
Round, dark, large nucleus
Thin layer of basophilic, non-granular cytoplasm
B, T and NK types

Monocytes
12-20 µm diameter

differentiate into tissue macrophages

oval or kidney shaped nucleus

Are major phagocytes

Platelets
2-5 µm diameter
Round or oval
Non-nucleated
Life span 10 days in blood

Platelets Function
1)They form plugs to occlude sites of vascular damage by adhering to the collagenous tissue at the margin of the wound
Later the platelet plug is reinforced by fibrin
2)They promote clot formation by providing a surface for the assembly of coagulation protein complex
3)Secrete factors that modulate coagulation and vascular repair

Blood
Considered Can be broken down into its liquid and cellular components by a machine called a centrifuge.
blood is withdrawn from a vein and collected in a centrifuge tube
tube is placed into the centrifuge, which then spins it in a circular motion for several minutes
rotational movement separates the blood into liquid and cellular components 

Components of Blood
Erythrocytes and the components of the buffy coat are called the formed elements.

Formed elements and the liquid plasma compose whole blood.
plasma
Blood plasma is the yellow liquid component of blood,
about 55% of the total blood volume.
It is the intravascular fluid part of extracellular fluid.

water (90% by volume) and contains
dissolved proteins,
glucose,
clotting factors,
mineral ions,
hormones and
carbon dioxide (plasma being the main medium for excretory product transportation).