Blood

What is Blood? Blood is a circulating liquid tissue The human body contains 5 to 6 L of blood 8% of body weight

3 Functions of Blood Transportation Transport oxygen and nutrients to the body cells Carry waste products away from the body cells Distributes hormones from the endocrine glands

3 Functions of Blood Regulation Maintains constant body temperature Maintains constant pH and water balance

3 Functions of Blood Protection Distribute antibodies and cells that help the body to defend against infection and disease Provides substances that form blood clots in damaged blood vessels to protect the body against blood loss

Blood Components Blood is made up of two major components: A solid portion: Red Blood Cells, White Blood Cells, Platelets Fluid portion: Plasma

Plasma Liquid portion of the blood that holds the solid portion 55% of total blood amount It is a transparent, yellowish fluid

Plasma Composition 90% water 10% dissolved components hormones, nutrients (glucose, amino acids, fatty acids), vitamins, minerals, cellular wastes, dissolved salts 3 major blood proteins: Albumin = maintains water levels in blood Fibrinogen = involved in blood clotting Globulin = involved in body’s defense against disease (antibodies)

Red Blood Cells (Erythrocytes) 45% of total blood, 99% of all blood cells (30 trillion RBCs circulate in the blood) (5-6 million RBCs/mL (mm3) Produced with the red bone marrow of long bones (ribs, sternum, vertebrae) Purpose is transport: oxygen from the lungs to all of the cells carbon dioxide from the cells to the lungs

Red Blood Cells (Erythrocytes) Contain hemoglobin, an iron containing respiratory pigment (protein) Hemoglobin contains iron and binds with oxygen allowing RBC to carry oxygen Since hemoglobin is red, it gives red blood cells their color (diet deficient in iron can cause anemia)

Anemia Condition where a person has a deficiency of hemoglobin or too few red blood cells Causes blood to not transport enough oxygen to the cells in the body Can be dietary (not enough iron intake) or hereditary (sickle cell anemia) Causes you to feel tired and weak

RBC Structure RBCs are biconcave disks with no nuclei More surface area for more gas exchange (oxygen & carbon dioxide) More flexible for moving through small spaces Short-lived (lifespan of about 100-120 days) Move through the liver and spleen and are broken down. Iron is returned to the bone marrow and recycled into new hemoglobin. Every second, more than 2 million RBCs die and are replaced by new ones!

White Blood Cells (Leukocytes) Less than 1% of all blood cells Many different types Specialized to defend the body against infections, harmful bacteria, viruses and other microorganisms. May engulf a foreign substance May produce antibodies that stop foreign substances May eject chemicals that kill bacteria and viruses Body is able to increase the number of WBC present during infection

White Blood Cells Colorless Change shape Larger than RBCs Contain a nuclei Pus is composed of WBC that have died after attacking bacteria. Short lifespan when fighting (1 to 4 hours), months to years when not fighting

Types of WBCs Neutrophils: Kill bacteria by phagocytosis. Eosinophils: Kill parasitic worms; inactivate allergic reactions. Basophils: Release histamines that cause inflammation; release anticoagulants which prevent blood clots and allergies. Lymphocytes: Produce antibodies to fight disease. Monocytes (macrophages): Destroy bacteria, infected cells, and old RBC’s by phagocytosis.

Cancerous White Blood Cells Normal White Blood Cells Leukemia Marked by abnormally high numbers of WBC’s Become poor infection fighters if such a quantity is produced Decrease in amount of platelets and RBC’s produced due to overcrowding Cancerous White Blood Cells Normal White Blood Cells

Platelets (Thrombocytes) Not whole cells; rather they are cell fragments with no nuclei Formed in the red bone marrow by pinching off of cytoplasm of large cells Live an average of ~10 days Play an important role in preventing the loss of blood by beginning a chain of reactions that result in blood clotting Easily caught on ruptured blood vessels