Blood

Blood

Functions• transports vital substances•distributes heat

Blood Cells• form mostly in red bone marrow• red blood cells• white blood cells• platelets (cell fragments)

Blood Volume

• varies with• body size• changes in fluid concentration• changes in electrolyte concentration• amount of adipose tissue

• about 8% of body weight• about 5 liters

Blood Composition

Origin of Blood Cells

Red Blood Cells

• erythrocytes• biconcave• one-third hemoglobin

• oxyhemoglobin•oxygenated

• deoxyhemoglobin•deoxygenated

• can readily squeeze through capillaries• lack nuclei and mitochondria

Red Blood Cell Count

• number of RBCs in a cubic millimeter of blood**Do not memorize these numbers**

• 4,600,000 – 6,200,000 in males

• 4,200,000 – 5,400,000 in adult females

• 4,500,000 – 5,100,000 in children

• reflects blood’s oxygen carrying capacity

Red Blood Cell Production

• low blood oxygen causes kidneys and liver to release erythropoietin which stimulates RBC production

Life Cycle of Red Blood Cell

• circulate for about 120 days

• macrophages in spleen and liver destroy worn out RBCs

• hemoglobin is broken down into heme and globin

• iron returns to red bone marrow to be reused

• eventually biliverdin converted into bilirubin (orangish-yellowish)

• heme breaks down into iron and biliverdin (greenish pigment)

White Blood Cells

• leukocytes• protect against disease

• granulocytes• neutrophils• eosinophils• basophils

• agranulocytes• lymphocytes• monocytes

Neutrophils

•first to arrive at infections• phagocytic• 54% - 62% of leukocyte• elevated in bacterial infections

Eosinophils

•moderate allergic reactions• defend against parasitic worm infestations• 1% - 3% of leukocytes• elevated in worm infestations and allergic reactions

Basophils

•release histamine• release heparin• less than 1% of leukocytes

Monocytes

• largest blood cell•leave bloodstream to become macrophages• 3% - 9% of leukocytes

Lymphocytes

• about the size of RBC•T cells (directly attack)• B cells (make antibodies)• important in immunity• 25% - 33% of leukocytes

Diapadesis

• leukocytes squeeze through capillary walls to enter tissue space outside the blood vessel

Blood Platelets

• thrombocytes• cell fragments of megakaryocytes• 130,000 – 360,000 per cubic millimeter of blood• helps control blood loss from broken vessels; clotters

Blood Plasma

• straw colored• liquid portion of blood• 55% of blood

Plasma Proteins

Albumins• most numerous plasma proteins• originate in liver• help maintain osmotic pressure of blood

Fibrinogen• originate in liver• plays key role in blood coagulation

Alpha and Beta Globulins• originate in liver• transport lipids and fat-soluble vitamins

Gamma Globulins• originate in lymphatic tissues• constitute the antibodies of immunity

Gases and Nutrients

Gases• oxygen• carbon dioxide• nitrogen

Nutrients • amino acids• simple sugars• nucleotides• lipids• lipoproteins

Hemostasis

• stoppage of bleeding

Blood Vessel Spasm• triggered by pain receptors, platelet release, or serotonin• smooth muscle in vessel contracts

Platelet Plug Formation

• triggered by exposure of platelets to collagen• platelets adhere to rough surface to form a plug

Blood Coagulation• triggered by cellular damage and blood contact with foreign surfaces• blood clot forms

Platelet Plug Formation

Blood Clots

• After forming, blood clot retracts and pulls the edges of a broken vessel together

• Platelet-derived growth factor stimulates smooth muscle cells and fibroblasts to repair damaged blood vessels

• Plasmin digests blood clots

• **thrombus – abnormal blood clot• **embolus – blood clot moving through blood

ABO Blood Group

Agglutination

Preferred and Permissible Blood Types for Transfusion

Genotypes of Blood Types

GenotypeBlood Type (Antigen)

Antibody

A AA o

A B

B BB o

B A

A B AB None

o o O A and B

D DD -

Rh+ None

- - Rh- None

How Rare Is Your Blood?

Blood Group and Rh Type

How Many Have It?

Frequency

O Positive One in 3 37.4%

O Negative One in 15 6.6%

A Positive One in 3 35.7%

A Negative One in 16 6.3%

B Positive One in 12 8.5%

B Negative One in 67 1.5%

AB Positive One in 29 3.4%

AB Negative One in 167 0.6%

Rh factor

• Discovered in Rhesus monkeys

• If you have the factor then you are positive

• If you don’t, you are negative

• One is not necessarily better than the other

• However, if a woman is negative it can cause complications with the 2nd pregnancy on (see next slide)

Have no fear: they have developed a shot called Rhogam that they can give to women with negative blood to prevent this from hurting the baby.