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Blood
A.
Formed elements are the
cells and platelets (thrombocytes) and the fluid elements are the plasma and
everything else suspended in it.
B.
Red Blood Cells
(Erythrocytes)
1.
Small, biconcave,
anucleate (no nucleus)
2.
Contain hemoglobin (about
200 million molecules per cell)
a. Four polypeptide chains and four heme groups
b. Heme groups bind oxygen
c. Affinity of hemoglobin for oxygen changes with
conditions – some conditions make it easier for oxygen to come off hemoglobin
and diffuse into tissues
1)
Increased temperature –
working cells raise temp, need more oxygen
2)
Lower pH – working
cells produce lactic acid, need more oxygen to convert lactic acid to Krebs
cycle intermediates
3.
Counts – about 4 – 6 million per cubic
millimeter of blood
4.
Life span is about 120
days
a. Worn out RBCs are recycled in the spleen
b. Heme is broken down to bilirubin, which is converted
to bile pigment in the liver
C.
White Blood Cells
(Leukocytes)
1.
Fight infection, leave
blood and patrol lymph and tissues
2.
Types of White Blood
Cells
a. Granular Leukocytes
1)
Neutrophils
a)
Most abundant
b)
Multilobed nucleus
joined by thin bridges of nucleoplasm – polymorphonuclear (PMNs)
c)
Granules don’t take up
acidic or basic dyes (neutral)
d)
First to respond to
injury
i.
Phagocytize bacteria
and cell debris
ii.
Secrete oxygen free
radicals
iii.
Secrete enzymes
2)
Eosinophils
a)
Bilobed nucleus
b)
Granules take up eosin
(an acidic pink dye)
c)
Control allergic
reactions
d)
Fight parasitic worm
infestations
3)
Basophils
a)
U-shaped or lobed
nucleus
b)
Granules take up basic
dyes (purple)
c)
Release histamine, a
chemical mediator of inflammation and allergic responses
i.
Causes vasodilation,
bronchoconstriction, and secretion
b. Agranular Leukocytes
1)
Monocytes
a)
Spherical or
kidney-shaped nucleus
b)
Leave blood and take up
residence in tissues
c)
Differentiate into
macrophages
d)
Phagocytize bacteria
and cell debris
e)
Secrete enzymes and
oxygen free radicals
f)
Secrete cytokines
g)
Present antigen to
helper T-cells
2)
Lymphocytes
a)
B-cells
i.
Have specific antigen
receptors, only respond to that antigen
ii.
When stimulated
differentiate into memory cells and plasma cells
·
Plasma cells secrete
antibodies
b)
T-cells
i.
Helper (T-4)
·
Secrete interleukins to
stimulate cytotoxic T-cells and B-cells
ii.
Cytotoxic (T-8)
·
Directly attack cells
that have specific antigens recognized by the T-cell receptor
c)
NK cells
i.
Third party cells,
involved in tumor surveillance and anti-viral activity
D.
Platelets
(Thrombocytes)
1.
Fragments of
megakaryocytes
2.
No nuclei
3.
Initiate blood clotting
and plug hole
E.
Hematopoiesis
1.
Formation of blood
cells
2.
Continuous production
in bone marrow of flat bones
3.
Hemocytoblast – stem
cell that gives rise to all blood cells, depending upon stimulus
a. Erythropoietin – produces erythrocytes (RBCs)
b. Colony Stimulating Factors (CSFs) – produce
leukocytes (WBCs)
F.
Plasma
1.
Ninety two percent
water (more or less)
2.
Plasma proteins
a. Gamma globulins
1)
Antibodies
b. Fibrinogen and other clotting factors
1)
Fibrinogen forms basis
for clot when converted to fibrin
c. Complement
1)
Lyse bacteria,
opsonize, stimulate inflammation
d. Transport proteins
e. Albumin
1)
Most common, big
contributor to osmotic pressure in circulatory system
3.
Electrolytes
4.
Nutrients
5.
Wastes
A.
Helps maintain
homeostasis
B.
Regulates body
temperature
C.
Buffers pH
D.
Fluid and electrolyte
balance
E.
Fight infection
F.
Transport
1.
Exchanges between Blood
and Tissue Fluid
a. Oxygen and nutrients
b. Carbon dioxide and wastes
c. Hormones
d. Mechanism
1)
At arterial end of
capillary
a)
Outward forces are
greater than inward forces
b)
Hydrostatic pressure of
blood + osmotic pressure of tissue fluid > hydrostatic pressure of tissue
fluid + osmotic pressure of blood
c)
Fluid and nutrients
move out of circulation
2)
At venous end of
capillary
a)
Inward forces are
greater than outward forces
b)
Osmotic pressure of
blood + hydrostatic pressure of tissue fluid > hydrostatic pressure of blood
+ osmotic pressure of tissue fluid
c)
Fluid and wastes move
back into circulation
3)
More fluid moves out
than back in, excess is taken up by lymphatics
G.
Blood Clotting
1.
The result of a series
of enzymatic reactions (clotting cascade) that ultimately activate prothrombin
to thrombin, the enzyme that converts soluble fibrinogen to fibrin
a. Fibrin forms a mesh that helps trap platelets and
RBCs to form a plug over holes in vessels
b. Platelets stick to underlying connective tissue at
the site of a wound and release chemicals that activate the clotting cascade
c. At least 12 different clotting factors are present in
blood in inactive soluble form
d. Vitamin K is required for formation of good
prothrombin and some other clotting factors
2.
Hemophilia
a. Lack of a clotting factor, leads to prolonged
bleeding times and danger of hemorrhage
b. May be sex linked
3.
Thrombus formation
a. Inappropriate clot formation (inside an unbroken
vessel)
b. Usually due to an imbalance of control mechanisms,
may be due to stasis of blood or increased blood viscosity
4.
Thromboembolism
a. Emboli are floating masses in the blood; if a
thrombus breaks away it is a thromboembolism
b. May occlude vessels in other tissues, shutting off
blood flow and leading to infarction
A.
ABO System
1.
Antigens (proteins
present on the surface of RBCs)
2.
Blood type is
determined by which antigens are present
a. A, B, both (AB), or neither (O)
b. Antibodies (preformed and directed against any ABO
antigen an individual doesn’t have)
1)
Anti-A, attacks any
cell with the A antigen on its surface
2)
Anti-B, attacks any
cell with the B antigen on its surface
3)
Type A people have
anti-B antibodies
4)
Type B people have
anti-A antibodies
5)
Type AB people have no
anti-A or anti-B antibodies
6)
Type O people have both
anti-A and anti-B antibodies
c. Transfusions
1)
If type A people
receive type B blood their anti-B antibodies will lyse the type B RBCs
2)
If type A people
receive type AB blood their anti-B antibodies will lyse the type AB RBCs
3)
If type A people
receive type A or type O blood their anti-B antibodies won’t have anything to
lyse
4)
If type B people receive
type A blood their anti-B antibodies will lyse the type A RBCs
5)
If type B people
receive type A blood their anti-B antibodies will lyse the type A RBCs
6)
If type B people
receive type AB blood their anti-A antibodies will lyse the type AB RBCs
7)
If type B people
receive type B or type O blood their anti-A antibodies won’t have anything to
lyse
8)
Universal donor – type O
9)
Universal recipient –
type AB
B.
Rh System
1.
C, D, and E antigens
most common, D antigen is really the deal
2.
No preformed
antibodies, have to be exposed to the Rh factor to make antibodies against it
3.
Won’t make anti-D
antibodies if Rh+ (your immune system would kill you)
4.
Rh– mother with
Rh+ babies
C.
Blood Typing
1.
Antigens present are
type: A, B, AB, or O; also if Rh is present type is positive, if not type is
negative
A.
Anemias, leukemias,
clotting disorders increase in frequency with age
B.
Atherosclerosis may
contribute to thrombus formation