Transcript L6-circulation

Circulation: The Cardiovascular
and Lymphatic Systems
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Cardiovascular System
 Cardiovascular system
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Consists of heart and blood vessels
Encompasses blood circulation
Delivers oxygen and nutrients to cells
Carries away waste products
 Lymphatic system
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Drains fluid and proteins from tissues, returns
them to bloodstream
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Cardiovascular
System
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The Heart
 Located between
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lungs
Myocardium = thick
muscle layer
Endocardium =
inside lining
Epicardium =
Outside lining
Pericardium =
surrounding fibrous
sac
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Location of Heart
 The heart is encased in and separated from the walls
of the pericardial cavity by three linings: the
epicardium, which forms the outer part of the heart;
the pericardial sac and the pericardium
 The heart fits tightly inside the pericardial cavity, a
subcavity of the thoracic cavityu. The pericardial
cavity is lined with a serous ( thin) membrane called
the pericardium, and the heart is within yet a second
lining called the pericardial sac. This sac contains
about half an ounce of fluid, which lies between it
and the heart’s outer lining
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The structure of the heart
 The membrane forming the outer lining of the heart
is called the epicardium
 Immediately beneath the epicardium is the
myocardium, comprising the muscles, blood vessels
and nerve tissue that make up the bulk of the heart
 The heart’s inner surface is called the endocardium
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Heart (cont’d)
 Atrium
Upper receiving chambers
 Atria are separated by interatrial septum (plural
septa)
 Ventricle
 Lower pumping chambers
 Pulmonary circuit (right side to lungs)
 Systemic circuit (left side to rest of body)
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Ventricles are separated by interventricular septum
 Also, each atrium is divided from each ventricle by
an atrioventricular septum, which contains various
valves
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Illustrated
Heart
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Heart valves
 The right atrioventricular valve, also sometimes
called the tricuspid valve, leads from the right atrium
into the right ventricle
 The pulmonary semilunar valve connects the right
ventricle to the lungs, which also connect to the left
ventricle through the left atrium by way of the left
atrioventricular valve, also sometimes called the
bicuspid ot mitral valve
 The aortic semilunar valve leads out of the left
ventricle
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Blood Flow Through the Heart
 When blood comes back to the heart after having
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delivered oxygen and other nutrients to the body’s cells, it
needs to be replenished before going out again. It re-enters
the heart at the atrium
Right atrium receives blood from body
Enters right ventricle and is pumped to lungs
Oxygenated blood returns to left atrium
Enters left ventricle and is pumped to rest of body
One-way valves force blood flow forward
Heart sounds produced when valves close
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The Heartbeat
 Systole = contraction (emptying the heart)
 Diastole = relaxation ( refilling chambers)
 Heart beats start with both atria contracting
 Immediately thereafter both Ventricles contract
 Wave of increased pressure in the vessels following
ventricular contraction is pulse
 Contractions are stimulated by electrical impulse
Blood Pressure
 Force of blood exerted against wall of blood vessel
 Measured by sphygmomanometer
 Measured as both systolic and diastolic, such as 120/80
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Pacemaker and conduction system of
the heart
 Contractions are stimulated by a built-in system that
regularly transmits electrical impulses through the
heart
 They include the sinoatrial (SA) node, called the
pacemaker because it sets the rate of the heart beat
 The atriopventricular (AV) node, the AV bundle
(bundle of His) the left and right bundle branches
and Purkinje fibers
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Conduction System of the Heart
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Clinical Aspects of the
Circulatory System
 Atherosclerosis
Accumulation of fatty deposits within artery
 Risk factors:
 High levels of lipoproteins (especially LDL’s)
 Smoking
 High blood pressure
 Poor diet
 Inactivity
 Stress
 Family history
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Thrombosis and Embolism
 Definitions:
Thrombosis = formation of blood clot
 Thrombus = blood clot
 Embolism = blockage of blood vessel
 Embolus = blockage mass
 Blockage is usually blood clot
 Blockage can also be air, fat, bacteria, or other solid
materials
 Stroke = blockage in a cerebral vessel
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Aneurysm
 Weakened arterial wall ballooning out
 Caused by:
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Atherosclerosis
Malformation
Injury
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Heart Diseases
 Coronary artery disease
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Results from atherosclerosis
Early sign is angina pectoris (chest pain)
Diagnosed by:
 ECG
 Stress tests
 Coronary angiography
 Echocardiography
Treatments:
 Control of exercise, administration of nitroglycerin
 Angioplasty (PTCA)
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 Bypass (CABG)
Heart Diseases (con’t)
 Myocardial infarction = heart attack
 Symptoms:
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Epigastric pain
Pain extending to jaw, arms
Pallor (turns pale)
Diaphoresis
Nausea
Dyspnea (difficulty breathing)
May also be burning sensation similar to
heartburn
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Heart Diseases (cont’d)
 Arrhythmia
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Irregularity of heart rhythm
 Bradycardia = slower than average
 Tachycardia = faster than average
 Fibrillation = extremely rapid, ineffective
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Controlled on Long term with pacemaker
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Heart Diseases (cont’d)
 Heart failure
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Heart fails to empty effectively, leading to
edema
 Congenital heart disease
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Birth defects
Most can be corrected surgically
 Rheumatic heart disease
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Streptococcus infection damaging heart valves
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The Vascular System
 Arteries and arterioles
Carry blood away from heart
 Vasoconstriction and vasodilatation
 Become smaller as they go away from the heart?
 Capillaries
 Smallest vessels
 Where exchange between blood and tissues
happens
 Veins and venules
 Carry blood back to heart
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Conducting arteries
 Sometimes called elastic arteries and can have an
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inside diameter as great as an inch
The aorta is an example of a conducting artery
The pulmonary artery and aortic trunk are examples
of conducting arteries which move blood away from
the heart
Three major conducting arteries branch from aortic
arch. They are the brachiocephalic trunk, the left
common carotid artery and the left subclavian artery
Both the right subclavian artery and the right
common carotid artery attach to the brachiocephalic
trunk
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 Medium size arteries, ( also called muscular arteries
because they contain a lot of muscle tissue) typically have
an inside diameter of about a sixth of an inch (eg external
carotid artery)
 Arterioles are the smallest arteries, with an average inside
diameter of 0.0018 of an inch or about 1/100 the size of a
medium size artery
 Arteries and arterioles connect to the capillaries which can
be as tiny as one blood cell ( or about ¼ the size of an
arteriole in diameter)
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Principal
Arteries
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Veins
 Veins carry blood back to the heart. They follow the same path
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as the arteries ( with blood flowing in the reverse direction)
Also, like arteries, they vary in diameter, becoming larger as
they approach the heart because of the increasing volumes of
blood they must carry
The vein counterparts of the conducting arteries are the superior
vena cava and the inferior vena cava. Together they are known as
the venae cavae
Medium veins and venules are the counterparts of the muscular
arteries and arterioles
Superior vena cava drains blood from upper body, including
head neck shoulders and arms
Inferior vena cava receives blood from the lower body, the
dividing line being the diaphragm
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Principal
Veins
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Disorders of the Veins
 Varicose veins
 Breakdown
in valves with chronic dilatation
 Contributing factors:
Heredity
 Obesity
 Prolonged standing
 Pregnancy
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Disorders of the Veins (con’t)
 Phlebitis = inflammation of veins
 Causes:
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Infection
Injury
Poor circulation
Valve damage
 Can result in thrombophlebitis (blood clot)
 Most damaging if occurring deep
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Hypertension
 Commonly known as high blood pressure
 Contributing factor in many conditions
 Defined as systolic > 140, diastolic > 90
 Causes left ventricle to enlarge
 First defense: diet and life habits
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Blood and Immunity
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Blood Plasma
 90% water
 Rest contains:
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Nutrients
Electrolytes (dissolved salts)
Gases
Albumin (protein)
Clotting factors
Antibodies
Wastes
Enzymes
Hormones
 Relative acidity (pH) steady at 7.4
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Blood Cells
 Produced in red bone
marrow
 Three kinds:
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Red =
erythrocytes
White =
leukocytes
Platelets =
thrombocytes
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Erythrocytes
 Main function: carry oxygen to cells
 Most numerous of blood cells
 Short lifespan (120 days) requires constant replacement
 Production regulated by erythropoietin (hormone made in
kidneys)
Leukocytes Protect against foreign substances
 Five different types:
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Neutrophils
Eosinophils
Basophils
Lymphocytes
Monocytes
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Leukocytes
 Phagocytes are often the first immune system cells on the scene
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when injury occurs. They prevent infection by cleaning away
pathogens and debris
Phagocytes are two types: microphages and macrophages
The average human body contains one trillion lymphocytes
which include NK cells, T cells and B cells
T cells make up about 80% of the total number of lymphocytes
T lymphocytes depend on the thymus for their activation
T lymphocytes are prompted by a specific antigen; a substance
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that induces sensitivity
Leukocytes
 Antigens also stimulate the immune system to generate
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antibodies, which can produce immunity from future attacks
by the same type of antigen
Unlike NK cells which roam the body looking for intruders, T
cells attack only when they recognize a specific antigen, and
then only after receiving instructions from special T cells that
distinguish between good and bad antigens
B lymphocytes are derived from bone marrow. Like NK cells,
they roam the body looking for intruders
But unlike NK cells, they stop in lymph tissue to seek out
foreign antigens
However they do not attack until the special T cells instruct
them to do so
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Platelets
 Important for hemostasis
 Most active during coagulation
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Stick together to plug injury site
Interact with clotting factors in plasma to make
wound-sealing clot
Convert fibrinogen to threads of fibrin
Threads of fibrin trap blood cells and plasma to make
clot
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Blood Types
 Determined by genetically inherited proteins
 Most familiar groups are ABO and Rh
 Important to match for blood transfusions
 Compatible types determined by cross-matching
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TEST
ABBREVIATION
DESCRIPTION
Differential count
Diff
Relative % of the different
types of leukocytes
hematocrit
Ht, Hct, crit
Relative % of packed red
cells in a given volume of
blood
Packed cell volume
PCV
hematocrit
Mean corpuscular volume
MCV
Volume of an average red
cell
Mean corpuscular
hemoglobin
MCH
Average weight of
hemoglobin in red cell
Mean corpuscular
hemoglobin concentration
MCHC
Average concentration of
hemoglobin in red cell
Erythrocyte sedimentation
rate
ESR
Rate of setting of
erythrocytes per unit of
time, used to detect
infection or inflammation
complete blood count
CBC
Series of tests including cell
counts, hematocrit,
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volume measurements
The Immune System
 Launches specific attacks on disease organisms
 Involves components of lymphatic system and blood
 Immune system response from T cells or B cells
T cells mature in thymus gland
 B cells mature in lymphoid gland
 Passive immunity: Transfer of antibodies
 Naturally (mother’s milk)
 Artificially (immune serum)
 Active immunity: Individual’s own response to disease
organism
 Natural contact
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 Vaccine
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Clinical Aspects: Blood
 Anemia
Decrease in hemoglobin in blood
 Can result from:
 Too few red blood cells
 Cells are too small
 Too little hemoglobin
Key tests involve blood counts
Symptoms include fatigue, shortness of breath
Aplastic anemia = destruction of bone marrow
Nutritional anemia (includes pernicious anemia) =
deficiency of vitamin B12
Sideroblastic anemia = body doesn’t use iron properly
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Hemorrhagic anemia = results from blood loss
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Types of Anemia (con’t)
 Thalassemia (includes Cooley anemia)
Hereditary disease causing rupture of red cells
 Affects production of hemoglobin
 Sickle cell anemia
 Mutation alters hemoglobin molecule
 Deformed cells block blood vessels and prevent
tissues from receiving oxygen
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Coagulation Disorders
 Thrombocytopenia
Deficiency in number of platelets
 Disseminated intravascular coagulation
 Widespread clotting, obstructing circulation to
tissues
 Hemophilia
 Hereditary deficiency of specific clotting factor
 Sex-linked disease: Passed from mother to son
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Neoplasms
 Leukemia
Rapidly dividing, but incompetent white blood cells
 Causes unknown, but may include radiation,
heredity
 Treatment includes:
 Chemotherapy
 Radiation therapy
 Bone marrow transplantation
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Neoplasms (con’t)
 Hodgkin disease
Disease of lymphatic system that may spread
 Contains Reed-Sternberg cells (giant cells in lymph
nodes)
 Non-hodgkin lymphoma
 Also malignant enlargement of lymph nodes
 More common, deadly than Hodgkin disease
 Multiple myeloma
 Cancer of blood-forming cells in bone marrow
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Clinical Aspects: Immunity
 Hypersensitivity
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Commonly known as allergy
More sensitive to allergens (pollen, dust)
 Anaphylactic reaction
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Severe generalized allergic response
Must be treated with epinephrine (adrenaline)
 Delayed hypersensitivity reaction
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Involves T cells and takes 12 hours for onset
(poison ivy)
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Clinical Aspects: Immunity (con’t)
 Immunodeficiency
Any failure in immune system (AIDS)
 Starts with HIV infection
 Leaves individual susceptible to other infections
 Autoimmune disorder
 Immune response to own tissues
 Cause may be:
 Failure of immune system
 Body cells altered by mutation or disease
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The Lymphatic System
 Role in circulation: return excess fluid and proteins
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from tissues back to bloodstream
Fluid known as lymph
Lower part and upper left side of body drains into
thoracic duct
Upper right side of body drains into right lymphatic
duct
Other roles:
 Absorb digested fats
 Protect body from impurities, microorganisms
 Assist with immunity
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Lymphatic Disorders
 Lymphadenitis = enlargement of lymph nodes
 Lymphedema = tissue swelling
 Lymphoma = neoplastic disease affecting white
blood cells
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Thymus
 Located behind the sternum
 Secretes thymosin, which help T cells develop
Spleen
 It contains phagocytes, removes damaged red blood cells, and
recycles and stores reclaimed iron from others
Tonsils
 Any collection of lymph tissue can be called a tonsil
 include palatine, pharyngeal and lingual tonsils
Lymph nodes
 They are structures of variable size that contain macrophages,
filtering out disease-causing antigens and other debris as the
lymph flows through them. These antigens are exposed to
lymphocytes to start immune response
 Swollen glands reveal the presence of an infection or injury in
the area of swollen gland
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