3. Note the concave or “depressed” surface of the erythrocytes. In Red Blood Cells the nucleus is removed to allow for more volume for hemoglobin . This allows for greater 0 2 carrying capacity per cell, but is also why erythrocytes have a limited life span. Erythrocytes
4. Red Blood Cells contain hemoglobin (Hgb), the O 2 carrying protein that also gives blood its distinct color. Hemoglobin is made from a complex protein molecule called “ globin ” combined with an iron (chemical symbol = Fe) containing a pigment called “ heme ”. Iron ( Fe ) Heme Iron ( Fe ) Heme
5.
6. White Blood Cells or Leukocytes WBC : RBC ratio = 1 : 700 – 1000 Main Function = Fight infection There are five different types of leukocytes lymphocyte monocyte eosinophil basophil neutrophil
7. Granulocytes Cytoplasm has a “granular” look Produced in red bone marrow Short-lived ~ 60% Agranulocytes Cytoplasm has a non-granular look Monocytes produced in red bone marrow Lymphocytes produced in lymph tissue monocyte lymphocyte eosinophil basophil neutrophil ~ 2 – 4% ~ 1% ~ 30% ~ 3 – 9% Long-lived (especially lymphocytes) The five are divided into two categories:
8. Platelets or Thrombocytes Actually non-nucleated cellular fragments They function in the process of “ Hemostasis” , which is simply “the stoppage of bleeding,” by the following mechanisms: - Platelet plugs - Vasoconstriction or vessel spasms causing a decrease in vessel diameter, as well as fibrin precipitation are also involved in larger clot formation - Blood clot formation (coagulation) Platelets
9. “ Activated” platelets are “sticky” and cling to damaged tissue and each other at the edge of wounds. For small wounds a platelet plug can prevent further blood loss. Common Hemostasis Mechanisms:
10. Coagulation occurs at the site of larger wounds when fibrinogen precipitates out as fibrin trapping activated platelets and red blood cells in a “web-like” mesh forming a blood clot .
![More on the Formed Elements: Red Blood Cells or Erythrocytes ,[object Object],Shape = “ biconcave ” discs which allows for increased surface area for gas diffusion. 5 million in one mm 3 (about 1/50 th of a drop) 25 trillion total in human body (average) Main Function = carry oxygen (O 2 ) and carbon dioxide (CO 2 )](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)