Trabajo de campo

Blood is an important component of the circulatory system.

Anatomically and functionally, blood is a connective tissue.

Plasma, which makes up 50 – 65% of the total volume of blood, is a

straw-colored liquid containing water (90%) and solids (10%). The solids in plasma include

inorganic salts and organic

substances such as antibodies, hormones, vitamins, enzymes,

The non-plasma, or cellular, portion of blood is composed of red blood

cells, white blood cells, and platelets.

Photo from U. S. Federal Government courtesy of Wikipedia.

From left to right:

Red blood cell

(erythrocyte);

Platelet

(thrombocyte);

White blood cell

Red blood cells, called erythrocytes, are responsible for carrying oxygen

from the lungs to various body tissues.

Red blood cells contain hemoglobin, which gives them their characteristic red color and helps them carry the oxygen.

Red blood cells are biconcave discs, a shape that provides a large area for oxygen exchange.

Red blood cells are produced in the red marrow of bones.

Anemia is a condition caused by low levels of red blood cells and

hemoglobin.

Anemia can be caused by the following: • Loss of blood due to injury,

• Infestations of blood-sucking parasites, or

• Low levels of red cell production due to poor nutrition.

Hemoconcentration is a

condition in which there is an above normal level of red blood cells.

Hemoconcentration is normally

caused by dehydration (loss of body fluid), which can be the result of

vomiting, diarrhea, or any chronic disease characterized by high body temperatures.

Blood platelets, or thrombocytes, are oval-shaped discs that are

formed in the bone marrow.

Blood platelets help prevent blood loss from injuries to blood vessels

Platelets may secrete a substance that causes the clot to contract

and solidify.

Platelets may also secrete a

substance that causes an injured vessel to constrict at the injury.

White blood cells, or leukocytes, are divided into two general categories:

• Granulocytes, and • Agranulocytes.

Granulocytes are the category of leukocytes that contain granules

within the cytoplasm. Granulocytes include:

• Neutrophils,

• Eosinophils, and • Basophils.

Neutrophils – produced by bone

marrow, neutrophils fight disease by migrating to the point of infection,

absorbing bacteria, and destroying them.

Neutrophils dissolve

dead tissue resulting in a semi-liquid

material called pus.

Abscess – a concentrated area of pus.

Neutrophil (purple) migrating through tissue to engulf bacteria through phagocytosis.

Eosinophils - a type of granulocyte that plays a role in combating

infection by parasites, as well as, impacting allergies and asthma.

They contain most

of the histamine

protein in the blood,

which is an

indication of allergic reaction when elevated.

Basophils – rare granulocytes that are responsible for the symptoms

of allergies, including inflammation.

Basophils

Agranulocytes are the category of leukocytes that contain very

little, if any, granules.

Agranulocytes are produced by

the lymph nodes, spleen, thymus, and other lymphoid tissue.

• Lymphocytes, and • Monocytes.

Lymphocytes – agranulocytes that produce and release antibodies at

site of infections to fight disease.

Lymphocytes also

produce antibodies

that allow an animal

to build up immunities to a particular disease.Image from U. S. Federal Government courtesy of Wikipedia.

Monocytes are agranulocytes that absorb disease-producing materials, such as bacteria that cause

tuberculosis, through phagocytosis. Unlike neutrophils,

monocytes do not produce pus.

Monocytes join body tissue to form larger, disease-absorbing masses called macrophages.

When bacterial infections occur, the number of white blood cells normally increases.

When viral infections occur, the number of white blood cells

normally decreases.

Therefore, the concentration of white blood cells can help

Blood clotting is called

coagulation and is important in reducing blood loss caused by

Fibrin is a thread-like mass

produced by fibrinogen (fibrous protein in blood) and thrombin. Fibrin holds the red blood cells, white blood cells, and platelets together to form a blood clot.

Blood types are classified based on certain antigens and antibodies found on surface of red blood cells.

For example, in humans there are a

total of 29 blood group systems based on antigens on the surface of the red blood cells, but the ABO and Rhesus factor (positive or negative) are the commonly used groups to determine blood type.

Human ABO Blood Types

Young animals can receive certain antibodies from their mothers.

These antibodies must be passed on to the young animal through the colostrum milk because the placental membrane is fairly

When two different blood types, an antigen and its antibody, combine as a result of mating, the reaction would cause agglutination or the clumping together of red blood cells.

This may cause some deaths during the early embryonic

Many blood types and groups have been identified in domestic animals.

• Cattle have 9 recognized blood groups;

• Horses have 8 recognized blood groups; and

• Canine have 13 described groups, but only 8 recognized groups.