Transcript Blood - Dr. RICK MOLESKI

Blood
Chapter 11
Pgs 343-359
Overview
• Functions of Blood
• Composition of Blood
• Plasma
– Plasma proteins
• Formed Elements
– Production of formed elements
– Red blood cells
– White blood cells
– Platelets
Functions of Blood
• Transportation of dissolved gases,
nutrients, hormones, and metabolic
wastes
• Regulation of pH and electrolyte
composition of ISF
• Restriction of fluid loss through damaged
vessels and other injury sites
• Defense against toxins and pathogens
• Stabilization of body temperature
Composition of Blood
• Plasma
• Formed elements
– Red blood cells (RBC) or Erythrocytes
– White blood cells (WBC) or Leukocytes
– Platelets
• Both constitute whole blood
– 5-6 L in men
– 4-5 L in women
Plasma
• Electrolyte concentration similar to ISF
• Plasma proteins
– Lg so cannot diffuse
– 3 primary classes
• Albumins
• Globulins
• Fibrinogen
• Serum
Formed Elements: The Production
• Hemopoiesis
– Embryonic blood cells
– Stem cells
• Hemocytoblasts
Hemocytoblasts
Myeloid stem cells
Lymphoid stem cells
Red Blood Cells (Erythrocytes)
• Accounts for 99.9% of formed elements
• RBC count (#RBCs per microliter)
– Adult male: 5.4million/μl
• Hematocrit: % of whole blood occupied by
cellular elements
– Determined by centrifuge
– Adult male: avgs 46%
– Closely approx vol of erythrocytes
• Hematocrit values often reported as:
– Volume of packed red cells (VPRC)
– Packed cell volume (PCV)
Structure of RBCs
• Specialized to transport
oxygen and carbon
dioxide
• Shape has 2 important
effects on function:
– Lg SA:vol
• Increases rate of diffusion
between cytoplasm and
plasma
– Enables bending and
flexing to fit through narrow
capillaries
• Contains hemoglobin
(Hb)
RBC Formation (Erythropoiesis)
• Occurs in red bone
marrow (myeloid tissue)
• Erythroblasts
Hemocytoblasts
– Very immature RBCs
• Actively synthesizing Hb
• After 4 days differentiates
into:
• Reticulocyte
– Enter circulation after 2
days in bone marrow
– After 24 hrs in circ,
complete maturation and
become:
Myeloid stem cells
Lymphoid stem cells
Proerythroblast
Erythroblast
Reticulocyte
• Erythrocyte!
Erythrocyte
RBCs and Blood Types
• Blood type classification determined by
presence or absence of specific surface
antigens in RBC membrane
– Surface antigens of RBC called agglutinogens
– Genetically determined
• 3 important antigens:
–A
–B
– Rh
RBCs and Blood Typing
•
•
•
•
•
Type A: antigen A only (40% US pop)
Type B: antigen B only (10%)
Type AB: both A and B (4%)
Type O: neither A nor B (46%)
Rh factor: present in some, absent in
others
White Blood Cells (Leukocytes)
• Divided into 2 groups:
– Granulocytes
• Neutrophils
• Eosinophils
• Basophils
– Agranulocytes
• Monocytes
• Lymphocytes
• Microliter typically
contains 6,000-9,000
WBCs
• Most located in
connective tissue
proper or in organs of
lymphatic system
WBC Circulation and Movement
• Do not circulate for extended periods of
time
• 4 characteristics of circulating WBCs:
– Amoeboid movement
– Diapedesis
– Positive chemotaxis
– Phagocytosis
WBCs: General Functions
• Nonspecific defense
– Neutrophils
– Eosinophils
– Basophils
– Monocytes
• Specific defense
– Lymphocytes
Neutrophils
• 50-70% circulating
WBCs
• Dense, twisted
nucleus
• 1st to arrive to injury
scene
• Active phagocytes
– Specialize in attacking
and digesting bacteria
Eosinophils
• 2-4% circulating
WBCs
• Similar in size to
neutrophils
• Contain granules and
2-lobed nucleus
• Attracted to foreign
compounds that have
reacted with
circulating antibodies
Basophils
• Less than 1%
circulating WBCs
• Numerous granules
• Migrate to injury site,
cross cap wall, and
accum w/in damaged
tissue
– Discharge granules
into ISF
• Contain heparin and
histamine
Monocytes
• 2-8% circulating
WBCs
• Lg, oval (kidney)
shaped nucleus
• Remain in circ only 24
hrs before entering
tissue
– Become a free
macrophage
• Very aggressive
Lymphocytes
• 20-30% circulating WBCs
• Lg nucleus w/ thin halo of
cytoplasm
• Continuously migrating
from bloodstream
tissues  blood stream
• Protect but do not rely on
phagocytosis
• Attack foreign and
abnormal cells
Differential Count and Changes in
WBC Profiles
• Differential count
– Number of circulating WBCs obtained in a blood
sample
– Values reported indicate the # of each type of cell
encountered in a sample of 100 WBCs
• Leukopenia
– Too few WBCs
• Leukocytosis
– Too many WBCs
• Leukemia
– Extreme form of leukocytosis (WBC counts of
100,000/μl
White Blood Cell Formation
• Stem cells originate in red bone marrow
• All from myeloid stem cells except for
lymphocytes
• Neutrophils, eosinophils, basophils
complete dev in marrow
• Monocytes begin in marrow, enter circ,
complete development when free
macrophages
WBC Formation: Lymphocytes
• Lymphoid stem cells migrate from bone
marrow to lymphoid tissues
• Process called lymphopoiesis
• Hormones involved in regulation of WBC
populations
– Colony-stimulating factors (CSFs) regulate
WBCs other than lymphocytes
– Thymosins promote differentiation of T-cells
from lymphocytes
Platelets
• Components of formed elements
– Cell fragments; not individual cells
• Derived from megakaryocytes
– Shed packets of cytoplasm
• Platelets!
• Initiate clotting process and help close injured
blood vessels
• Continuously replaced
• Thrombocytopenia: abnormally low count
• Thrombocytosis: abnormally high count
Hemocytoblasts
Myeloid Stem Cells
Erythrocytes
Platelets
Basophils
Lymphoid Stem Cells
Eosinophils
Neutrophils
Monocytes
Lymphocytes
B cells
T cells
NK cells