Transcript Cardiovascular System: The Blood

Cardiovascular System: The Blood
Dr. Michael P. Gillespie
Constituents Of Blood
 Blood is a connective tissue composed of a liquid matrix
called plasma that dissolves and suspends various cells and
fragments.
 Interstitial fluid is the fluid that bathes body cells.
Functions of Blood
 Transportation – oxygen, carbon dioxide, nutrients,
hormones, heat, & waste products.
 Regulation – maintains homeostasis (ph, heat, osmotic
pressure).
 Protection – clotting, WBCs, & antibodies.
Physical Characteristics Of Blood
 Blood is denser and more viscous than water.
 The temperature is 38 degrees C (100.4 degrees F).
 Slightly alkaline ph ranging from 7.35 to 7.45.
 20% of the extracellular fluid (about 8% of total body
mass).
 The blood volume is 5 to 6 liters (1.5 gal) in an average
adult male and 4 to 5 liters (1.2 gal) in an average adult
female.
Withdrawing Blood
 Blood samples for laboratory testing are obtained in
various ways.
 Venipuncture (the most common method).
 A finger or heel stick is utilized for children and people
who must monitor their blood daily (I.E. Diabetics).
 An arterial stick is utilized when the level of O2 must be
determined.
Components Of Blood
 Whole blood has two components:
 Blood plasma, a watery liquid matrix that contains dissolved
substances.
 Formed elements (cells and cell fragments).
 45% formed elements and 55% plasma.
Blood Plasma
 A straw-colored liquid which is about 91.5% water and
8.5% solutes.
 Plasma proteins – maintain osmotic pressure.
 Albumins, globulins, and fibrinogen (synthesized by
hepatocytes).
 Gamma globulins (antibodies 0r immunoglobulins).
 Electrolytes, nutrients, regulatory substances (i.E.
Enzymes and hormones), gases, & waste products (urea,
uric acid, creatinine, ammonia, and bilirubin).
Formed Elements
 RBCs.
 WBCs – perform many functions.
Formed Elements
 Platelets – cell fragments.
Formed Elements
 Hematocrit – the percentage of total blood occupied by
RBCs.
 Males have a higher hematocrit than females because
testosterone stimulates the production of erythropoeitin
(EPO).
 Menstruation leads to lower values for females during their
reproductive years.
 Anemia is a significant drop in the hematocrit.
 Polycythemia is an.
 Abnormally high percentage of RBCs.
Causes of Polycythemia
 Abnormal increase in RBC production.
 Tissue hypoxia.
 Dehydration.
 Blood doping or use of Epoetin alfa (Procrit or Epogen)
by athletes.
 This increases the work load of the heart.
 The increased #s of RBCs raise the viscosity of the blood,
which increases the resistance to blood flow. This can cause high
blood pressure and stroke.
Formation of Blood Cells
 Hemopoiesis (hematopoiesis) – the process by which the
formed elements of blood develop.
 Blood cells, macrophages, reticular cells, mast cells, and
adipocytes arise from the red bone marrow.
 Pluripotent stem cells in the bone marrow reproduce
themselves, proliferate and differentiate into mature
blood cells.
Two Types of Pluripotent Stem Cells
 Myeloid stem cells.
 Give rise to red blood cells, platelets, monocytes, neutrophils,
eosinophils, and basophils.
 Lymphoid stem cells.
 Give rise to lymphocytes.
Generations Of Cell Lines In The
Development Of Blood Cells
 Pluripotent stem cells – mesenchymal cells which have the
capacity to develop into many different types of cells. They
can reproduce themselves.
 Progenitor cells – cannot reproduce themselves.
 Precursor cells (blasts) – they develop into the actual formed
elements of the blood.
Hormones That Regulate Blood Cell
Development
 Hemopoietic growth factors – regulates differentiation
and growth of progenitor cells.
 Erythropoietin (EPO) from the kidneys – increases the
# of RBC precursors.
 Thrombopoietin (TPO) from the liver – stimulates the
formation of platelets.
 Colony-stimulating factors (CSFs) or interleukins
stimulate WBC formation.
Medical Uses of Hemopoietic Growth
Factors
 EPO is utilized in end stage kidney disease to increase RBC
formation.
 CSFs are utilized to stimulate WBC formation in cancer
patients undergoing chemotherapy.
 Thrombopoietin helps induce platelet formation in
chemotherapy patients.
Red Blood Cells
 Red blood cells (RBCs) or erythrocytes:
 Contain hemoglobin – oxygen-carrying protein which gives the
cell its color.
 Approximately 5 million RBCs are present per microliter of
blood.
 Approximately 2 million RBCs are created and destroyed per
second.
RBC Anatomy
 Biconcave discs with a diameter of 7-8 micrometers.
 The plasma membrane is flexible, which allows them to
deform without rupturing as they squeeze through
capillaries.
 RBCs lack a nucleus and other organelles.
 RBCs cannot reproduce or carry on extensive metabolic
activities.
RBC Physiology
 With no nucleus, RBCs have more space available for oxygen
transport.
 RBCs lack mitochondria and generate ATP anaerobically;
Consequently, they do not use up the oxygen they are
transporting.
RBC Physiology
 The biconcave disc has a greater surface area allowing greater
diffusion of gas molecules.
 Hemoglobin binds to oxygen, carbon dioxide, and nitric
oxide (NO).
 NO causes vasodilation which enhances oxygen delivery to
cells.
RBC Life Cycle
 Red blood cells live only about 120 days.
 Macrophages in the spleen and liver remove dead RBCs
through phagocytosis.
 Hemoglobin is broken down into its globin and heme
portions.
 Globin is broken down into amino acids, which are reused for
proteins.
 Heme is converted into the yellow-orange pigment bilirubin.
Reticulocyte Count
 The rate of eryhtropoiesis is measured by a reticulocyte
count.
 Low “retic” count – could indicate a shortage of
erythropoietin due to a nutritional deficiency or leukemia.
 High “retic” count – could indicate a good response to
previous blood loss, iron therapy, or illegal use of Epoetin by
an athlete.
White Blood Cells
 White blood cells (WBCs) or leukocytes have a nucleus and
do not contain hemoglobin.
 Classified as either granular or agranular.
Types Of White Blood Cells
 Eosinophil
 Basophil
 Neutrophil
 Small lymphocyte
 Monocyte
Numbers Of WBCs
 RBCs outnumber WBCs by about 700:1.
 There are approximately 5000 – 10,000 cells per
microliter of blood.
 Leukocytosis – an increase in the number of WBCs due
to stresses such as microbes, strenuous exercise,
anesthesia, or surgery.
 Leukopenia – a decrease in the number of WBCs due to
radiation, shock, or chemotherapy.
Functions Of WBCs
 The WBCs combat pathogens by phagocytosis and other
immune responses.
 WBCs leave the bloodstream by emigration.
Functions Of WBCs
 Neutrophils and macrophages are active in phagocytosis.
 Phagocytes are attracted to inflamed tissues through a
process called chemotaxis.
 Phagocytes release the enzyme lysozyme, which destroys
certain bacteria.
Functions Of WBCs
 Eosinophil – release histamines. Respond to allergic
responses and parasitic infection.
 Basophil – liberate heparin, histamine, and serotonin. They
intensify the inflammatory reaction and are involved in
hypersensitivity (allergic) reactions.
Functions Of WBCs
 Neutrophil – active in phagocytosis and ingest bacteria and
dead matter. They respond to bacteria and fungi.
 Lymphocyte – “soldiers” of the immune system.
 Monocyte – turn into macrophages and clean up cellular
debris after an infection.
Differential WBC Count
 Utilized to detect infection, inflammation, poisoning, blood
disorders, effects of chemotherapy, allergic reactions, and
parasitic infections.
Significance Of High & Low WBC
Counts
WBC Type
High Count
Low Count
Neutrophils
Bacterial
infection, burns,
stress,
inflammation
Viral infection,
leukemia
Radiation, drug
toxicity, B12
deficiency, SLE
Lymphocytes
Prolonged
illness,
immunosuppress
ion, cortisol tx.
Significance Of High & Low WBC
Counts
Monocytes
Eosinophils
Basophils
Viral or fungal
infection,
chronic diseases
Allergic rx.,
parasites,
autoimmune dis.
Allergic rx.,
cancers,
hypothyroidism
Bone marrow
suppression,
cortisol tx.
Drug toxicity,
stress
Pregnancy,
ovulation, stress,
hyperthyroidism
Platelets
 The hormone thrombopoietin influences the production of
platelets (thrombocytes).
 Platelets help stop blood loss by forming a platelet plug.
Complete Blood Count (CBC)
 A test that screens for anemia and various infections.
 Counts of RBCs, WBCs, platelets, hematocrit, and a
differential white blood cell count are included.
Blood Clotting
 Serum is a straw colored liquid and the gel is called a clot.
 The process of gel formation is called clotting or
coagulation.
 Clotting factors are involved in the coagulation cascade.
Blood Clotting
 Normal clotting requires vitamin K, which is produced by
bacteria in the intestines.
 Dissolution of a clot is called fibrinolysis.
 Anticoagulants (heparin & Warfaring a.K.A. Coumadin) are
utilized for patients at risk of forming a blood clot.
Intravascular Clotting
 Thrombosis – clotting in an unbroken blood vessel.
 Thrombus – the clot itself.
 Embolus – a blood clot, bubble of air, fat from broken
bones, or a piece of debris transported by the
bloodstream.
 Pulmonary embolism – when an embolus lodges in the
lungs.
ABO Blood Group
 Type A blood - RBCs display only antigen A.
 Type B blood – RBCs display only antigen B.
 Type AB blood – RBCs display both antigens A & B.
 Type O blood – RBCs display neither antigen A or B.
ABO Blood Group
 The blood plasma contains isoantibodies or agglutinins that
react with A or B antigens if mixed.
 You do not have the antibodies that react with the antigens of
your own RBC type, but you most likely have the antibodies
for antigens your own blood lacks.
Rh Blood Group
 People with Rh antigens in their blood are Rh positive and
people without the Rh antigen are Rh negative.
 Normally, plasma does not contain anti-Rh antibodies.
Rh Blood Group
 If an Rh- person receives Rh+ blood transfusion, he or she
will start to make antibodies that will remain in the blood.
 The next time he or she receives Rh+ blood, the antibodies
will cause hemolysis of the donated blood.
Hemolytic Disease Of The Newborn
ABO Blood Group Interactions
Characteristics
A
B
AB
O
Antibody Anti-B
in plasma
Antigen on A
RBCs
Anti-A
Neither
Both
B
A&B
Neither
Donors
B, O
A, B,
AB, O
None
O
A, O
Hemolysis B, AB
A, AB
A, B, AB