Download The Cardiovascular System

The Cardiovascular System
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Objectives:
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Describe the functions of the cardiovascular system
List and describe the structure of the types of blood vessels
Compare and contrast pulmonary and systemic circulation
Identify the external and internal structures of the heart and
their functions
Describe how the heart beat is generated
Describe the events of a cardiac cycle
Describe blood pressure and how it is measured
Describe the composition of whole blood
Describe the composition of plasma
Describe the various formed elements and their functions
Describe the process of hemostasis
Identify and describe various disorders of the cardiovascular
system
Identify risk factors associated with coronary disease
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Functions:
• A closed system of the heart and blood
vessels
– The heart pumps blood
– Blood vessels allow blood to circulate to
all parts of the body
• to deliver oxygen and nutrients to and
remove carbon dioxide and other waste
products from the bodies tissues
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Blood Vessels: Types
• Taking blood to the tissues and back
– Arteries - large, thickest walled, carry blood away
from heart, blood is moved by the pumping of the
heart
– Arterioles - smaller, thinner walled, carry blood
away from heart, blood is moved by pumping of
the heart
– Capillaries - smallest, thinnest vessels, one cell
layer thick, site of exchange of materials between
the blood and body tissues
– Venules - thinner walled vessels, carry blood back
towards heart
– Veins - thin walled vessels, large lumen, have
valves present which keep blood moving in one
direction, blood is moved by “milking” action due
to the contraction of skeletal muscles
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Structure of Vessels
• Three layers (tunics)
– Tunic interna
• Endothelium
• Lines interior of vessels
• Decreases friction from blood flow
– Tunic media
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Smooth muscle
Middle layer
Changes diameter of vessels
Controlled by sympathetic nervous system
– Tunic externa
• Mostly fibrous connective tissue
• External layer
• Supports and protects vessels
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Structure of Vessels
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Blood Movement Through Veins
• Blood is squeezed
forward through vein
when skeletal
muscles contract
• A valve opens
allowing blood to fill
chambers
• Valves close when
backflow of blood
occurs, preventing
blood from going
backwards
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Capillaries
• Only one cell layer thick, just tunica interna
• Due to thinness exchanges can be made
across the membrane between the blood
and tissues
• Microcirculation – blood flow moves from
arteries into capillaries where materials
are exchanged, then into veins
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Capillary Transport Mechanisms
• 4 routes for materials to cross the capillary
walls
– Diffusion across the plasma membrane
– Endocytosis/Exocytosis
– Intercellular clefts – gaps in plasma
membrane
– Fenestrated capillaries – mainly areas of
filtration and absorption (like intestines or
kidneys)
• Intercellular clefts and fenestrated
capillaries depend on osmotic pressure in
interstitial fluid surrounding capillaries
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External Coverings of the Heart
• Pericardium – a double serous
membrane
– Visceral pericardium
• Next to heart
– Parietal pericardium
• Outside layer
• Serous fluid fills the space between the
layers of pericardium
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External Coverings of the Heart
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Muscular Tissue
• Cardiac muscle: branched at the end with
striations present, usually only one nucleus is
present per cell
• branches of each fiber come into contact at
specialized junctions called intercalated discs
• involuntarily controlled
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External Structure of the Heart
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Great Vessels of Heart
• Aorta (largest blood vessel in the body)
– Leaves left ventricle, carries oxygenated blood to all parts of
the body
• Pulmonary arteries
– Leave right ventricle, carries deoxygenated blood to the
lungs
• Vena cava (Superior and Inferior)
– Enters right atrium
– superior vena cava brings deoxygenated blood from the
upper part of the body
– inferior vena cava brings deoxygenated blood from the
lower part of the body
• Pulmonary veins (four)
– Enter left atrium, brings oxygenated blood from the lungs
• Ligamentum Arteriosum
– ligament between aorta and pulmonary trunk that holds the
vessels in place
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External Anatomy of the Heart
• Heart is divided into four chambers
– Atria
• Receiving chambers
– Right atrium
– Left atrium
– Ventricles
• Discharging chambers
– Right ventricle
– Left ventricle
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Blood Circulation
• Pulmonary circulation – process of blood flow from right
side of heart  lungs  back to left side of heart
– Pulmonary trunk – heart pumps oxygen poor blood out of heart
to lungs to get oxygen and release carbon dioxide; breaks into
the pulmonary arteries
• Systemic circulation – process of blood flow from the left
side of heart  pump to body tissues  back to right
side of heart
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Blood Circulation:
Pulmonary and
Systemic Pathways
CO2 is given off by
the blood into the lungs
and O2 is picked up
by the blood from the
lungs.
O2 is given off by
the blood and
and CO2 is picked up
by the blood from the
body’s tissue.
Animation video
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Coronary Blood Supply
• Blood in the heart chambers does not
nourish the myocardium
• The heart has its own nourishing
circulatory system
– Coronary arteries
– Cardiac veins
– Blood empties into the right atrium via the
coronary sinus
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Internal Structures of the Heart:
Heart Wall
• Three layers
– Epicardium
• Outside layer
• This layer is the parietal pericardium
• Connective tissue layer
– Myocardium
• Middle layer
• Mostly cardiac muscle
– Endocardium
• Inner layer
• Endothelium
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Internal Structures of Heart
• Right and left side act as separate pumps
• Four chambers
– Atria
• Receiving chambers
– Right atrium
– Left atrium
– Ventricles
• Discharging chambers
– Right ventricle
– Left ventricle
• The valves allow blood to flow in only one direction
• Four valves
– Atrioventricular valves – between atria and ventricles
• Bicuspid valve (left)
• Tricuspid valve (right)
– Semilunar valves between ventricle and artery
• Pulmonary semilunar valve
• Aortic semilunar valve
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Internal Structures of the Heart
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The Heart’s Pace Maker:
Regulation of Heartbeat
Special tissue sets the
pace
• Sinoatrial node
– Pacemaker
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Atrioventricular node
Atrioventricular bundle
Bundle branches
Purkinje fibers
• Contraction is initiated
by the sinoatrial node
• Sequential stimulation
occurs at other
autorhythmic cells
Fibrillation results when SA node
is not working properly.
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ECG: Electrocardiagram
• This graph shows the electrical changes which occur when the
muscles of the heart wall depolarize and repolarize.
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ECG: Electrocardiogram
• The first little upward notch of the ECG tracing is
called the "P wave." The P wave indicates that the
atria (the two upper chambers of the heart) are
contracting to pump out blood.
• The next part of the tracing is a short downward
section connected to a tall upward section. This next
part is called the "QRS complex." This part indicates
that the ventricles (the two lower chambers of the
heart) are contracting to pump out blood to the body.
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ECG: Electrocardiogram
• The next short upward segment is called the "ST
segment." The ST segment indicates the amount of
time from the end of the contraction of the ventricles
to the beginning of the rest period before the
ventricles begin to contract for the next beat.
• The next upward curve is called the "T wave." The T
wave indicates the resting period of the ventricles. 27
Cardiac Cycle
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Atria contract simultaneously
Atria relax, then ventricles contract
Systole = contraction
Diastole = relaxation
Cardiac cycle – events of one complete heart
beat
– Mid-to-late diastole – blood flows into ventricles
– Ventricular systole – blood pressure builds before
ventricle contracts, pushing out blood
– Early diastole – atria finish re-filling, ventricular
pressure is low
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Cardiac Cycle
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Cardiac Cycle: Valves
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The Heart’s Pace Maker:
Regulation of Heartbeat
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Cardiac Output
• The amount of blood pumped out by each
side of the heart in 1 minute.
• Stroke volume – the volume of blood
pumped out by a ventricle with each
heartbeat.
• Heart rate – the number of heart beats per
minute
• CO = HR x SV
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Cardiac Output
• Example:
– Resting values
• HR = 75 beats/min
• SV = 70 ml/min
–CO = HR (75 beats/min) x SV (70
ml/beat)
–CO = 5250 ml/min
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Pulse
 Pulse –
pressure wave
of blood as it
passes
through an
artery
 Monitored at
“pressure
points” where
pulse is easily
palpated
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Blood Pressure
• Measurements by health professionals are
made on the pressure in large arteries
– Systolic – pressure at the peak of ventricular
contraction
– Diastolic – pressure when ventricles relax
• Pressure in blood vessels decreases as the
distance away from the heart increases
• Human normal range is variable
– Normal
• 140–110 mm Hg systolic
• 80–75 mm Hg diastolic
– Hypotension
• Low systolic (below 110 mm HG)
• Often associated with illness
– Hypertension
• High systolic (above 140 mm HG)
• Can be dangerous if it is chronic
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Blood Pressure
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Diseases and Disorders of the
Cardiovascular System
Myocardial infarction: heart attack
• blockage of coronary artery which
supplies the myocardium
• cardiac muscle dies causing the
heart not to function properly
• can be due to formation of deposits
of cholesterol and lipids called
plaques, blood clots called
thrombus, or an embolism which is a
blood clot that forms somewhere
else in the body, breaks free and
lodges in a coronary artery stopping
the flow of blood
Angina pectoralis: sharp pain radiating
into the left arm and /or neck
accompanied by a feeling of
pressure within the chest - a classic
symptom of problems with blood
flow to the heart muscle itself
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Diseases and Disorders of the
Cardiovascular System
• Congestive Heart Failure: Cardiac decompensation
causes blood circulation to become inadequate 
tissues don’t get the support needed to supply oxygen
and carry out wastes
• Ectopic Focus – the sinoatrial node doesn’t work
properly causing abnormal pacing
• Fibrillation – condition in which the heart becomes
uncoordinated and can no longer function as a pump
• Heart Block – the atrioventricular nodes are damaged
• Incompetent valve – one or more valves in the heart
become damaged causing blood to leak back through
(no longer one way flow)
• Pulmonary congestion – initial condition when the left
side of the heart fails (blood still pumping through right
side, but gets backed up when left side stops pumping.)38
Diseases and Disorders of the
Cardiovascular System
• Atherosclerosis:
commonly called
“hardening of the
arteries”
• arteries began to loose
elasticity due to aging
and formation of
plaques in their walls
• They narrow and
reduce blood supply to
regions of the body
particularly the brain
and heart
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Diseases and Disorders of the
Cardiovascular System
• Aneurysm: a weakened
area within the wall of
an artery or arteriole
• Because of the high
pressure, the vessel
wall balloons out and
can rupture when the
wall becomes stretched
too thin  leads to a
serious internal
hemorrhage (internal
bleeding)
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Diseases and Disorders of the
Cardiovascular System
• Arrhythmia: due to the
irregular beat of the
heart
• may be due to damage
to the SA or AV node, or
the myocardium
• commonly treated with
medications or by the
implantation of an
artificial pace-maker
Bradycardia: the heart
is beating too slow
• Tachycardia: the heart
is beating too fast
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Blood
• The only fluid tissue in the human body
• Classified as a connective tissue
– Living cells = formed elements
– Non-living matrix = plasma
• Color range
– Oxygen-rich blood is scarlet red
– Oxygen-poor blood is dull red
• pH must remain between 7.35–7.45
• Blood temperature is slightly higher than
body temperature
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Blood: Plasma
• Composed of approximately 90 percent water
• Includes many dissolved substances
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Nutrients
Salts (metal ions)
Respiratory gases
Hormones
Proteins : Albumin – regulates osmotic pressure,
Clotting proteins – help to stem blood loss when a
blood vessel is injured, Antibodies (globulins) –
help protect the body from antigens
– Waste products
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Blood: Formed Elements
• Erythrocytes = red blood cells
• Leukocytes = white blood cells
• Thrombocytes or Platelets = cell
fragments
• Formed in red bone marrow
(hematopoiesis)
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Whole Blood Composition
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Blood: Formed Elements p. 313
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Blood: Formed Elements
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Red Blood Cells
• Anucleate – no nucleus (unable to grow and
divide)
• Live about 100-120 days – remains eliminated
by spleen and liver
• Developing RBCs divide many times and begin
hemoglobin synthesis
– After enough hemoglobin produced, the cell ejects the
nucleus and organelles causing the cell to collapes
inward (concave shape) (takes 3-5 days)
• RBC production controlled by hormone
erythropoietin
– Production not based on number of RBCs, based on
amount of oxygen in blood
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Blood: Formed elements
Red Blood Cells
Basophil
Monocyte
Platelets
Lymphocyte
Eosinophil
Neutrophil
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Blood Mini-Lab
• Obtain prepared slide of blood
• Identify and sketch at least 5 different
formed elements (use color pencils)
– You’ll sketch 1 picture – please see me to get
approval for your drawing BEFORE you draw!
• Analysis:
– Explain the differences between the various
white blood cells you saw in your slide.
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Hematopoiesis
• Blood cell formation
• Occurs in red bone marrow
– Skull, pelvis, ribs, sternum, humerus and
femur
• All formed elements from hemocytoblast
(stem cell)
– Lymphoid stem cell: produces lymphocytes
– Myeloid stem cell: produces all other formed
elements
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Blood: Formed Elements
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Hemostasis
• Stoppage of blood flow
• Result of a break in a blood vessel
• Hemostasis involves three phases
– Platelet plug formation
– Vascular spasms
– Coagulation
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Hemostasis: Platelet Plug
Formation
• Collagen fibers are exposed by a break
in a blood vessel
• Platelets become “sticky” and cling to
fibers
• Anchored platelets release chemicals
to attract more platelets
• Platelets pile up to form a platelet plug
• Positive Feed-back Mechanism
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Hemostasis: Vascular Spasms
• Anchored platelets release serotonin
• Serotonin causes blood vessel muscles
to spasm
• Spasms narrow the blood vessel,
decreasing blood loss
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Hemostasis: Coagulation
• Injured tissues release thromboplastin
• PF3 (a phospholipid) interacts with
thromboplastin, blood protein clotting
factors, and calcium ions to trigger a clotting
cascade
• Prothrombin activator converts prothrombin
to thrombin (an enzyme)
• Thrombin joins fibrinogen proteins (water
soluble) into hair-like fibrin (insoluble in
water)
• Fibrin forms a meshwork
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(the basis for a clot)
Forming Blood Clot
fibrin
erythrocytes
thrombocytes
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Blood Groups
• What happens if blood loss occurs?
– 15-30% = weakness
– >30% = shock & possible death
• Classifications:
– Based on proteins (antigens) of plasma
membrane
– Antibodies act to agglutinate (clump) and lyse
foreign RBCs because of the antigens
– 2 groups: ABO types & Rh types
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Blood Groups
• Transfusions of wrong blood type can
cause death. If wrong blood type is given:
– Antibodies recognize foreign antigens causing
clumping
– Clogs small vessels throughout body
– A few hours later, RBCs are lysed and
hemoglobin is released into blood (hemolysis)
– Released hemoglobin blocks kidneys causing
kidney failure
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Diseases and Disorders of the
Blood
• Hemophilia: a genetic
disorder due to the fact
that there is a clotting
factor missing
necessary for clot
formation to stop
bleeding.
• can bleed to death from
simple injuries or
bruising of the body
• more common in males
than females (sexlinked)
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Diseases and Disorders of the
Blood
• Leukemia: cancer of
the bone marrow which
produces blood cells
• many different forms of
this disease depending
upon which type of
blood stem cells are
involved
• the cells typically do
not mature and inhibit
the production of other
types of blood cells
necessary for survival
Noamal Bone Marrow
AML Bone Marrow
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Diseases and Disorders of the
Blood
• Anemia: due to the
lack of Erythrocytes or
low levels of
hemoglobin in
erythrocytes, or
abnormal erythrocytes
(sickle cell)
• inhibits the proper
transport of oxygen in
the body
• several forms of anemia
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