Physical Characteristics and Volume

Physical Characteristics and Volume

• Color ranges from scarlet to dull red.

• It is slightly alkaline between 7.35 abd 7.45

• Temperature is slightly higher than body

temperature.

• It accounts for 8% of our body weight.

• In a healthy male its

volume is 5 to 6 liters.

Plasma

• Plasma, liquid component, is 90% water.

• Over 100 different

substances are dissolved in it.

• Plasma proteins produced in the liver are the most abundant solutes, e.g.

albumin controls osmotic pressure

• Homeostasis of blood is strictly controlled.

• Plasma helps distribute heat

throughout the body.

Formed Elements

• Erythrocytes or red blood

cells (RBC) function primarily to carry oxygen.

• RBCs lack a nucleus

• The iron-containing protein of RBC, hemoglobin, transports the bulk of oxygen in blood.

• Their flattened and

depressed center increase its surface area for gas

exchange.

• 5 million RBCs can be found in a tiny drop of blood.

• As RBC/mm ³ increases blood viscosity increases.

• Each RBC can carry up to 1

billion molecules of oxygen.

• Leukocytes or white blood cells are crucial to body defense.

• WBCs make up less than 1% of total blood volume.

• WBCs unlike RBCs contain nuclei.

Formed Elements

Formed Elements

• WBCs that contain granules include:

1) Neutrophils are phagocytes

2) Eosinophils kill parasitic worms and respond to allergens.

3) Basophils contain histamine that makes blood vessels attract other WBCs at

inflammation sites.

• WBCs that do not contain granules include:

1) Lymphocytes play an important role in the immune response

2) Monocytes change into macrophages as they migrate into tissues.

• Platelets are fragments of ruptured multinucleate cells called

megakaryocytes.

• Platelets are needed for the blood

clotting process.

Homeostatic Imbalance of Formed Elements

• Anemia is a reduced oxygen

carrying capacity of the blood caused by a decreased number of RBCs or decreased % of hemoglobin in the blood.

• Sickle cell anemia causes

deformities of RBCs under stress

that cause rupturing and consequent pain.

• Polycythemia is a condition of an abnormally large number of RBCs that causes an increase of blood viscosity.

• Leukemia is the result of bone marrow cancer that causes the release of huge numbers of

immature WBCs that leave the body susceptible to pathogens.

Leukemia

Hematopoesis

• Hematopoiesis occurs in red bone marrow.

• A hemocytoblast is a stem cell in red blood marrow that gives rise to all formed elements.

• They produce either lymphoid stem cells or myeloid stem cells.

• RBCs live for 100 to 120 days and are eliminated by phagocytes.

• Development of mature RBCs from hemocytoblasts takes 3 to 5 days.

• Erythropoietin is a hormone produced primarily from the kidneys that targets red bone marrow to produce RBCs when blood oxygen levels decrease.

• Colony stimulating factors or interleukins are hormones that help regulate the production of WBCs.

• thrombopoietin is a hormone that regulates

platelet formation.

Chapter 10 Blood

Be Able To

•Describe the blood-clotting process.

•Explain factors that inhibit blood clotting.

•Describe ABO and Rh blood groups.

•Explain the basis for blood transfusions.

•Describe blood disorders in elderly.

Hemostasis

• Hemostasis is a fast and localized stoppage of blood flow in response to the

breakage of blood vessel walls.

• Hemostasis involves 3 phases:

1) Vascular spasm

2) Platelet plug formation 3) Blood clot formation

• Blood clots normally form between 3 and 6 minutes.

• Why apply pressure with

sterile gauze to a cut then?

Disorders of Hemostasis

• A thrombus is a clot that develops and persists in an unbroken blood vessel.

• An embolus is freely moving clot in the bloodstream.

• Undesirable clotting is caused by anything that makes the

endothelium sticky to platelets.

• Thrombocytopenia is a condition resulting from an

insufficient number of circulating platelets.

• Hemophilia is a hereditary bleeding disorder that results from a lack of any factors

needed for clotting.

Blood Groups and Transfusion

• Blood stored in a blood bank is mixed with an anticoagulant and can be stored at 4 ⁰ C for 35 days.

• The plasma membranes of all body cells (including RBCs) bear protein markers.

• An antigen is a substance that the immune system recognizes as foreign.

• Antibodies recognize non-self antigens on RBCs from a donors blood.

• Agglutination is clumping of

foreign cells by antibody-antigen binding.

• There are over 30 common RBC

antigens in humans.

• The ABO blood groups are based on which of two antigens (A or B) a

person inherits.

• Absence of each results in blood type O and presence of both results in

blood type AB.

• Antibodies are formed during infancy against ABO antigens not present in the body.

• 8 antigens make up the Rh blood group, of which the D antigen is the most common in humans.

• Most Americans are Rh+

• Rh- individuals will produce anti-Rh+

antibodies if given a transfusion of Rh+ blood.

Blood Groups and Transfusion

• What happens during pregnancy when a Rh- mother is carrying a Rh+ baby?

• She will produce anti-Rh+ on

succeeding pregnancies unless treated with an immune serum called

RHoGAM.

• If the mother is not treated with

RhoGAM her anti-Rh+ antibodies will attack RBCs of her Rh+ baby during her next pregnancy which leads to

hemolytic disease of the newborn.

• Blood typing involves mixing immune serum with blood samples to determine if agglutination occurs.

Blood Groups and Transfusion

• Blood cells begin to circulate through blood vessels by the 28 ^th day of development of the embryo.

• Fetal RBC have a slightly different form of hemoglobin.

• Jaundice results from a rapid rate of fetal RBCs destruction that cannot be rid from the body fast enough.

• With increasing age, chronic

types of leukemia, anemias, and diseases related to clot

formation become more common.

Developmental Aspects of Blood