The heart and circulation

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The heart and circulation Transportation- oxygen
and carbon dioxide red blood cells Regulation-ho
rmones, temperature Protection- against blood
loss (clotting) infection (immune system)
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Components of the circulatory system Cardiovascul
ar system- heart and blood vessels Lymphatic
system- lymph nodes, lymphatic vessels
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Plasma- water, ions, proteins Plasma
proteins albumin- provides osmotic
pressure globulins- alpha and beta-
transport gamma- antibodies (produced
by lymphocytes other proteins by
liver) fibrinogen- clotting Plasma volume
regulated by hormones like ADH
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Formed elements (cells) Erythrocytes- (red
blood cells) no nuclei or mitochondria circulate
for about 120 days 280 million hemoglobin
molecules per cell Leukocytes (white blood
cells) granular and agranular granular
neutrophils, eosinophils, basophils agranular
lymphocytes, monocytes capable of amoeboid
movement Platelets- involved in clotting
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Hematopoiesis- blood cell formation Erythropoiesi
s- red blood cell formation Leukopoiesis-
leukocyte formation Controlled by cytokines that
regulate cell growth and formation Growth
factors Colony-stimulating factors Erythropoietin
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Red blood cell antigens and blood
typing Antigen a molecule that is recognized as
foreign by the immune system Lots of these
several different types of antigens found on red
blood cells (RBCs) ABO system especially
important Four blood types A, B, AB, O A and B
are dominant, O is recessive
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People with type A blood can tolerate type
A blood from other individuals But type A
people make antibodies to type B antigens People
with type AB can tolerate all blood
types universal recipient (of CELLS) People
with type O blood can donate to all but have
antibodies to both A and B antigens universal
donor (of CELLS)
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Rh antigen is another important blood
group antigen- people are either Rh-positive or
Rh-negative Significance when Rh-negative woman
is pregnant with Rh-positive baby Mother might
produce antibodies to Rh antigen on fetus blood
cells?erythroblastosis fetalis, or hemolytic
disease of the newborn Prevention Rhogam
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Blood clotting- hemostasis Vasoconstriction Form
ation of platelet plug platelets stick to
collagen proteins coated by von Willebrand
factor (secreted by damaged endothelium) platele
ts stick together and secrete factors that
promote vasoconstriction- cascade Formation of
fibrin web that surrounds plug intrinsic
pathway- spontaneous extrinsic- initiated by
factors from damaged tissue
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Clot dissolution Factor XII?kallikrein?plasminoge
n?plasmin Anticoagulants calcium
chelators heparin- inactivates
thrombin coumarin- inhibits vitamin K
activation aspirin- inhibits prostaglandin
production, affects platelet release reaction
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Acid-base balance of blood Blood plasma pH
ranges between 7.35 and 7.45 CO2
H2O?H2CO3?HHCO3- Carbon dioxide transported
through blood concentration controlled by
breathing Kidneys release excess H and
reabsorb bicarbonate pH too low- acidosis pH
too high- alkalosis metabolic ore respiratory
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Acidosis respiratory- hypoventilation metabolic
- excess production of ketone bodies, fatty
acids, lactic acid diabetes- fat
metabolism diarrhea- loss of bicarbonate
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Alkalosis respiratory- hyperventilation metabol
ic- too much bicarbonate excess vomiting loss
of fatty acids, ketone bodies, etc. loss of
acids in gastric juice So critical blood
chemicals are carbon dioxide and bicarbonate
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Structure of the heart Two atria, two
ventricles Atria receive blood from venous
system Ventricles pump blood into arterial
system Septum separates right from left side
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Valves embedded in fibrous skeleton AV valve
between right atrium and ventricle- tricuspid
valve AV valve between left atrium and
ventricle bicuspid (mitral) valve Semilunar
valves at base of pulmonary artery and aorta
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Cardiac cycle and heart sounds Contraction-
systole Relaxation- diastole Atria contract
simultaneously Then ventricles contract (while
atria are relaxed) Stroke volume- amount of
blood ejected from ventricles during
systole end-systolic volume- whats left
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Electrical activity of the heart Myocardial
cells beat automatically Action potential is
usually originated in sinoatrial
node Spontaneous depolarization (pacemaker
potential) diffusion of calcium through slow
channels threshold- fast calcium channels open,
voltage regulated sodium channels
open repolarization produced through diffusion
of potassium
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Other parts of the heart can produce
pacemaker potentials Depolarize more slowly
than SA node usually stimulated by action
potentials from SA node before they could start
their own pacemaker potentials ectopic
pacemakers can set a rhythm if SA node
conduction is blocked pace will be slower
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Heart muscle cannot sustain contraction Long
refractory periods- heart cannot be stimulated
until it has relaxed from previous
contraction Arrhythmias- something affects the
cardiac cycle treatment depends on what it
is Fast Na channel blockers Slow Ca channel
blockers ?-adrenergic receptor blockers
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Electrocardiogram Conduction of electrical
potentials through heart P wave- atrial
depolarization QRS- ventricular
depolarization beginning of systole T wave-
repolarization of the ventricles beginning of
diastole
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Blood vessels- arteries and veins Arteries,
arterioles, capillaries Veins and
venules Arteries are more muscular Veins have
valves
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Capillaries deliver blood to cells Specialized
types of capillaries in different organs Fenestr
ated- kidneys, endocrine glands,
intestines Discontinuous- bone marrow, liver and
spleen Continuous- everywhere else
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Veins Veins can expand to accommodate
increasing amounts of blood arteries
cant Venous pressure is low compared to
arterial pressure Blood flow through veins is
facilitated by contraction of skeletal
muscles valves that prevent backflow
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Atherosclerosis Damage to endothelium Fatty
streaks (macrophages and lymphocytes) Fibrous
plaques High blood cholesterol, LDL contribute
to atherosclerosis HDL also help transport
cholesterol, but do not contribute to
atherosclerosis
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Arrhythmias Bradycardia- slow rate (less than 60
bpm) Tachycardia- fast rate (more than 100
bpm) Can occur normally is abnormal if
rate increases during rest (ectopic
pacemakers) Flutters- extremely rapid
contractions Fibrillation- different groups of
fibers are activated so coordinated pumping of
chambers is not possible
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Lymphatic system Fluid transport from
tissues Fat transport from intestines Immune
response
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