physiology of the blood
TRANSCRIPT
Physiology of The Blood
Dr. Miada Mahmoud Rady EMS/474 Hematological Emergencies / lecture
1. Learning Objectives By the end of this chapter you should be
able to:
Describe the physiology of blood and its components Discuss the
Pathophysiology and signs and symptoms of specific hematological
disorders. Outline the general assessment and management of
patients with hematological disorders. Introduction The
hematopoietic system consists of organs and tissues involved in the
production of blood components. Hematologic disorder: Any disorder
of the blood , it could be either : Hemolytic disorders : involves
breakdown of red blood cells Hemostatic disorders : Bleeding and
clotting abnormalities. Blood Components Blood and Blood
Components
Blood composed of cell and formed elements surrounded by plasma :
Plasma : Accounts for 55% of total blood volume. 92% water and 6%
to 7% proteins. Formed elements Account for 45% of total blood
volume. 99%of which are RBCs. Function of The Blood Delivery of the
various substances essential for cellular metabolism and function
as oxygen , nutrient and hormones . Removal of carbon dioxide and
waste product resulting from metabolic processes. Defense against
invading microorganisms and injury. Acidbase balance. Blood Forming
Organs Bone marrow :
Blood cells are formed within red bone marrow which is present : At
birth in all bony cavities of the bodies . In adult its primarily
found in membranous bone e.g. Vertebrae, pelvis, sternum, ribs and
head of long bone. Cells producing blood cells are known as
hematopoietic stem cells . Give 6 types of blood cells Lymphoid
stem cell
Stem cells Myeloid stem cell Give 6 types of blood cells RBCS ,
Platelet , and 4 types of WBCS Lymphoid stem cell Remaining 3 types
of WBCS T-lymphocytes B-lymphocytes Natural killer cells Blood
Forming Organs Lymph nodes : Produce lymphocytes and
antibodies.
Spleen Stores large quantities of blood. Produces lymphocytes,
plasma cells, antibodies. Liver Bloodforming organ only during
intrauterine life. Plays important role in coagulation process.
Blood Cells Red blood cells : Bright red in color.
Shape : a biconcave disk with a flattened center. Most abundant
cell accounting for 45% of total volume . Primarily responsible for
tissue oxygenation. Life span of RBCs is about 120 days. Number of
RBCs is about 4.2 to 6.2 million cells/mm2 Normal RBCS Normal and
abnormal RBCS Blood Cells White blood cells :
Primarily responsible for body defense ; Destroy foreign substances
(e.g., bacteria and viruses) and Clear bloodstream of debris.
Normal WBC count is about 5,000 to 11,000 cells/mm2 Leukocyte
production increases in response to infection , inflammation and
stress. Blood Cells Platelets :
Platelets (thrombocytes) are small, sticky cell fragments. Play an
important role in blood clotting and hemostasis . Normal count
150,000 to 450,000 cells/mm2. Average life span: 5 to 11 days.
Blood Groups and Blood Group Testing
System developed to ensure compatibility and prevent medical
problems during blood component transfusion. Two commonly used
system : ABO system : named according to the antigen located on
membrane of the RBCS and include A , B , AB and O. Rh system : also
named according to the antigen located on membrane of the RBCS into
Rh positive and Rh negative. Rh isoimmunization Hemostasis
Hemostasis is the process that allows the body to stop bleeding. It
consists of three steps : Vascular spasm. Platelet plugging.
Coagulation. Hemostasis Vasoconstriction (immediate response)
:
Narrowing of the blood vessel to cut off flow at the affected site.
Platelet plugging: Platelets stick to collagen and become
activated. Activated platelets release chemicals to draw
additionalplatelets to the injury site which causes a plug to form,
helping to stop the bleeding. Coagulation : Involves a dozen
clotting factors that are activated when the body is injured Each
requires the presence and activation of the preceding factor to
work. Summary Home work Give short account on the various component
of the blood and its cells? Enumerate the stages of hemostasis? Any
Question ?