A, B, AB, O and K +ve and-ve.
Blood is considered a connective tissue for two basic reasons: (1) embryologically, it has the same origin (mesodermal) as do the other connective tissue types and (2) blood connects the body systems together bringing the needed oxygen, nutrients, hormones and other signaling molecules, and removing the wastes.  They are classified by the unmutated version of blood (type O) and by the two two different mutations (Type-A, and Type-B). There are 2 different alleles for the Rh factor known as Rh+ and Rh-. Type A-first mutation recognized B-second AB-caused geneticly from a Type A parent & Type B parent O-unmutated. Blood is a highly specialized, fluid tissue. Blood is traditionally classified as a specialized form of connective tissue. To appreciate the basic unity of blood and other varieties of connective tissue, consider the following. 1  All of the several blood cell types originate in the connective tissue of bone marrow. Certain white blood cells, notably lymphocytes and monocytes, move freely back and forth between blood and other connective tissues. The ABO system consists of A, B, AB, and O blood types. People with type A have antibodies in the blood against type B. People with type B have antibodies in the blood against type A. People with AB have no anti-A or anti-B antibodies. People with type O have both anti-A and anti-B antibodies. People with type AB blood are called universal recipients, because they can receive any of the ABO types. People with type O blood are called universal donors, because their blood can be given to people with any of the ABO types. Rh system. The Rh system classifies blood as Rh-positive 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 Rh-positive blood. People with type O have both anti-A and anti-B antibodies. People with type AB blood are called universal recipients, because they can receive any of the ABO types. People with type O blood are called universal donors, because their blood can be given to people with Answer   Answer: Those who were not classified as Jews but who had some Jewish blood were categorized as Mischlinge (hybrids)and were divided into two groups:   … Mischlinge of the first degree--those with two Jewish grandparents; Mischlinge of the second degree--those with one Jewish grandparent. There are 2 different alleles for the Rh factor known as Rh+ and Rh-. Type A-first mutation recognized B-second AB-caused geneticly from a Type A parent & Type B parent O-unmutated. Hypertension is classified as either primary (essential) hypertension or secondary hypertension. About 90–95% of cases are categorized as primary hypertension, defined as high blood pressure with no obvious underlying cause. Hypertension (HTN or HT), also known as high blood pressure or arterial hypertension, is a chronic medical condition in which the blood pressure in the arteries is persistently elevated.
http://lifesci.dls.rutgers.edu/~babiarz/Bloodtx.htm http://www.answers.com/Q/How_is_blood_classified http://www.siumed.edu/~dking2/intro/blood.htm http://www.webmd.com/a-to-z-guides/blood-transfusion-blood-types http://www.webmd.com/a-to-z-guides/blood-transfusion-blood-types http://www.answers.com/Q/How_is_blood_classified https://en.wikipedia.org/wiki/Hypertension
blood is classified as