Functions / characteristics of blood Flashcards
describe the functions of blood
Transport, defense against disease, prevents blood loss, redistributes heat , buffers ph
describe the matrix and cellular components of blood:
Connective tissue composed of formed elements suspended in a liquid extracellular matrix called PLASMA.
What are the 3 main categories of blood
Erythrocytes, leukocytes, platelets
on average, blood is what percent of body mass
8%
What is the average blood volume
5 liters
on average, blood is what percent of body mass
8%
what is viscosity
Thickness of a fluid
describe the effect of plasma proteins on viscosity:
Decrease plasma proteins = decrease viscosity
Increase plasma protein = dehydration
define hematocrit
Percent of blood volume that consist of erythrocytes(red blood cells)
what is the average Hct?
45%
What percent of blood volume is plasma
55%
describe how hematocrit is measured
Centrifuge
describe plasma composition
90% or more water; make up about 6-9% of total plasma volume
list the main plasma proteins
Albumin, alpha and beta globulins, gamma globulins, clotting proteins
Function of albumin
Maintains osmotic pressure and makes up 50% of all plasma proteins
Function of alpha and beta globulins
responsible for transporting hydrophobic molecules such as steroids
Functions of gamma globulins
The antibodies involved in immunity
Functions of clotting proteins
Form blood clots during coagulation
define hemopoiesis
Formation of formed elements
Where does hemopoiesis occur
Bone marrow
describe the types of bone marrow
Red bone marrow (active), yellow bone marrow(inactive)
Location of red bone marrow
In spongey bone of axial skeleton, coaxial bone, scapula, proximal edges of humerus and femur
yellow bone marrow
Mostly adipose tissue; if needed can be converted into red bone marrow
describe the histology of bone marrow tissue:
Reticular tissue includes multi potent blood stem cells and immature blood cells in various stages of development
sinusoids run through tissue
what are HSCs
Hematopoietic Stem cells
Where are HSCs found
Red bone marrow
What is the function of HSC
Divides by mitosis
list the main stem cell lineages
Lymphoid and myeloid stem cells
What cells do lymphoid cells produce
Only lymphocytes
What cells do myeloid cells produce
erythrocytes, platelets, neutrophils, eosinophils, basophils, and monocytes
what happens during erythropoiesis
production of erythrocytes; takes 5-7 days; starts with myeloid stem cell and ends with mature erythrocyte
how is erythropoiesis controlled
Low RBC > hypoxia > kidneys secretes EPO> bone marrow ^ rate of mitosis + ^ rate of maturation = ^ RBC formation > ^ blood O2> negative feedback > kidneys secret more EPO
define anemia
Decrease ability of blood to carry oxygen
what general problems cause anemia?
Decreased hemoglobin; decreased hematocrit; abnormal hemoglobin
iron deficiency Anemia
insufficient dietary intake or reduced intestinal absorption
hemorrhagic
Rapid or slow bleeding; caused by slow and chronic blood loss that can occur when there are ulcers in digestive track
pernicious
Inability of the stomach to make intrinsic factor
hemolytic
formation of erythrocytes is normal but they are destroyed sooner than they should be; can be caused by viral and bacterial infections and parasites
aplastic
bone marrow stem cells are destroyed by exposure to radiation, toxic chemicals or chemotherapy drugs
sickle cell
Inherits a defective gene for one of the peptides in hemoglobin; people with sickle cell anemia make HBS
renal
kidneys cannot make enough erythropoietin; caused by trauma, cancer, or kidney disease
define polycythemia
too many erythrocytes
what causes primary polycythemia
Slow growing cancer of the bone marrow; causes over production of erythrocytes
what causes secondary polycythemia
high altitude, having chronic lung disease, hypersecretion of erythropoietin from the kidneys, injections of erythropoietin
physiological effects of polycythemia
high hematocrit; causes increase blood viscosity, increased peripheral resistance, increase mean arterial pressure
what is the general function of leukocytes
Defend the body against pathogens, destroy cancer cells, and remove dead and injured cells
which leukocytes are granulocytes
Neutrophils, eosinophils, basophils
which leukocytes are agranulocytes
Lymphocytes and monocytes
what is the function of platelets?
Involved in hemostasis and tissue repair
what is a platelet’s lifespan and how are old ones removed from blood
10 days; removed from circulation by liver and spleen
describe thrombocytopenia
Thrombocyte count is low and bleeding cannot be stopped as quickly
describe the structure of platelets
Cell fragments consisting of plasma membrane surrounding granules of chemical plus contractile proteins actin and myosin
where are platelets stored
many stored in the spleen and the rest are in the circulating blood
define hemostasis and list the three mechanisms:
-vascular spasm
-platelet aggregation
-coagulation
what is the goal of vascular spasm?
Reduces blood flow therefore reduces blood loss in damaged vessel
what is the function of platelet aggregation
To seal small breaks in blood vessels walls; The platelets form a path that reduces or stops blood loss
what two events initiate platelet aggregation
Vascular disease or trauma