Cardiovascular System:
Heart and Blood Vessels
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Overview of CV:
Heart and Blood Vessels (BV)
Overview of cardiovascular (CV) system
Structure and function of blood vessels
Anatomy of heart and path of blood flow
Cardiac cycle
Control of heart beat and the ECG
Pulses and blood pressures
Pulmonary and systemic circuit
Disorders of cardiovascular system
Lymphatic system
Components
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The heart pumps blood
The blood vessels are conduits
through which blood flows
Overall functions
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Transportation of blood which
contains gases, nutrients,
wastes…
Defend against disease
Helps control body temperature,
fluid, and pH balance
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Main Path of Blood
in the Body
Anatomy of Blood Vessels
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Capillaries
Arteries
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Carry blood away from the heart
Walls have 3 layers (tunica)
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Simple squamous epithelium - endothelium
Thick smooth muscle layer
Outer connective tissue
Smallest blood vessels
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Aorta is the largest artery
Arterioles are small arteries that regulate blood pressure and blood
flow to capillaries
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One cell thick with a basement
membrane
Connect arterioles to venules
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Microscopic
Endothelium
Arteriole end—exit of O2, water, and
nutrients
Venus end—entrance of CO2,
water, and wastes
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Exchange at the Capillary
Beds…
…is primarily a result of diffusion, osmosis, and blood pressure
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Nutrient Exchange Animation
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Venules and Veins
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Venules receive blood from the capillaries
Veins carry blood toward the heart
Veins that carry blood against gravity have valves to
keep blood flowing toward the heart
Veins act as a blood volume reservoir
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Walls have three layers:
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~2/3 of all blood in the body
Simple squamous epithelium - endothelium
Smooth muscle and CT layers are thinner than arteries but
lumen is larger
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Allow veins to hold a large volume of blood
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External View of the
Heart and its Vessels
Heart is a Muscular Pump
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Two Circulatory
Pathways
Internal View of the Heart
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The right side of the heart
pumps blood through the
pulmonary circuit, which
carries blood to and from
the lungs
The left side of the heart
pumps blood through the
systemic circuit, which
conducts blood to and from
the body tissues
Heart Function Animation
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Passage of Blood
Through the Heart
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Superior and Inferior vena cava
(O2-poor) Æ Right Atrium
Right Atrium Æ Tricuspid Valve
Æ Right Ventricle
Right Ventricle Æ Pulmonary
Semilunar valve Æ Pulmonary
Arteries Æ Lungs
4 Pulmonary veins (O2-rich) Æ
Left Atrium
Left Atrium Æ Atrialventricular
valve Æ Left Ventricle
Left Ventricle Æ Aortic
Semilunar valve Æ Aorta Æ
ALL body tissues
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Valves of the Heart
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Coronary Circulation
Cardiac Cycle…
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…is the sequence of heart muscle contraction and relaxation
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Heart contracts ~70 bpm and lasts 0.85 secs
Normal adults rate 60-80 bpm
Heartbeat and heart sounds
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Systole—when ventricles contract and pump blood out of the heart
Diastole—when ventricles relax and receive blood from atria
Lub = AV valves closing Dup = louder semilunar valves closing
Heart murmur—swishing sound from blood flow back into atria due
to ineffective valves
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Can usually be corrected surgically
Heart requires 1/20 of body’s total blood flow at rest
Cardiac Cycle Animation
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Specialized Cardiac Muscle Cells
and the Heart’s Conduction System
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Sinoatrial (SA) node serves
as the pacemaker that
determines HR
Electrical signal from the SA
node spreads through atrial
walls causing them to
contract - every 0.85 sec
Signals stimulate the AV
node which in turn sends
signals to AV bundle and
finally to Purkinje fibers in
walls of ventricles causing
them to contract
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Conduction System
of the Heart
Slight delay at AV node
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Control of the Heartbeat
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Internal control
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External control
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Cardiac Conduction System Animation
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The SA node (pacemaker) initiates the heartbeat and causes the
atria to contract
This impulse reaches the AV node, also in the right atrium, to
send a signal down the AV bundle and finally the Purkinje fibers
that cause ventricular contraction
These impulses travel between gap junctions at intercalated disks
Autonomic nervous system (cardiovascular center) and hormones
can modify the rate of the heartbeat
Other factors are age, gender, fitness level
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Baroreceptors Maintain
Arterial Blood Pressure (BP)
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Electrocardiogram (ECG)
Located in aorta and carotid arteries and detect
changes in BP
When BP rises, arterial BVs are stretched
Stretch of baroreceptors causes them to send nerve
signals to cardiovascular (CV) center in medulla
oblongata
CV center responds by sending nerve signals to
heart and BV
Reduces cardiac output, vasodilates arterioles
Net effect is return of BP to normal
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A record of the electrical changes
in cardiac muscle
The atria produce an electrical
current when stimulated by the SA
node called the P wave
The contraction of the ventricles is
the QRS complex
The recovery of the ventricles is
called the T wave
Used to detect abnormalities
Opposite sequence of events occurs if baroreceptors
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detect drop in BP
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Blood Pressure
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Pressure that blood exerts
against the walls of blood
vessels
The highest pressure is during
blood ejection from the heart
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Systolic pressure
The lowest pressure is when
the ventricles relax
Diastolic pressure
Highest in aorta and lowest in
venae cavae
Average blood pressure is
recorded at about 120/80
mmHg (systolic/diastolic)
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Blood Pressure Values in Adults
Blood pressure varies with age, weight, race, mood, etc…
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Pulse
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Blood Flow
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Blood flow is under the
highest pressure in the
arteries
Blood flow is slower in
the capillaries
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Alternating expansion and
recoil of an arterial wall
Pulse rate = heart rate
because the arterial walls
pulse whenever the left
ventricle contracts
Some other vital signs
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Allows time for exchange
between cells
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Blood pressure is minimal
in the veins and venules
yet blood flow increases
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Respiratory rate, body
temperature
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More on Blood Flow and
Pressures
Hepatic Portal System
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Venus return depends on
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A system that brings blood from the digestive
tract to the liver
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Skeletal muscle
contraction
One-way valves
Pressures associated with
breathing
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Gets first claim to the nutrients in the blood
Also removes any bacteria or toxins before they can
move on in the body
The blood will return to the heart via the inferior
vena cava
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Cardiovascular Disorders are Leading
Cause of Death in Western Countries
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Disorders of the Blood Vessels
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Hypertension
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Hypertension
Atherosclerosis
Stroke
Heart attack
Aneurysm
AKA high blood pressure
Results when blood moves through vessels at a rate
higher than normal
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A silent killer because there are few symptoms
Can lead to a heart attack, stroke or kidney failure
Prevention
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Often due to arterial plaque or atherosclerosis
140/90 mmHg or greater
Lower salt intake, control weight, exercise, don’t smoke, limit
alcohol intake, don’t abuse drugs such as cocaine and
amphetamines, sleep, limit stress
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Atherosclerosis
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A build up of plaque in blood vessels that reduces
blood flow and results in progressive occlusion
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Result of accumulation of fatty materials beneath inner
linings of the arteries and inflammatory response
Plaque that is stationary is called a thrombus and an
embolus if it detaches and can move to distant sites
Associated with stroke, heart attack, and aneurysm
Begins in early adulthood and develops progressively
during middle age
Prevention
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Atherosclerosis Animation
Diet low in saturated fat and cholesterol and rich in omega37
3-polyunsaturated fats; exercise
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“Good” vs “Bad” Cholesterol
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Most cholesterol in blood is found bound to carrier
proteins- lipoprotein
“Good” = High Density Lipoprotein (HDL)
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“Bad” = Low Density Lipoprotein (LDL)
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Targets cholesterol for removal in the liver
60 mg/dl and above considered protective against heart
disease
Carries cholesterol to all body cells and makes it available
to them
Less than 100 mg/dl is optimal
Total cholesterol
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Less than 200 mg/dl is desirable; 200-239 mg/dl borderline
Stroke
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AKA cerebrovascular accident (CVA)
Usually occurs when a cranial artery is blocked or
bursts
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Myocardial Infarction (MI)
Part of the brain dies dues to lack of oxygen
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AKA heart attack
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Part of the heart dies due to lack of oxygen
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Symptoms may occur including numbness of
hands or face, difficulty speaking, and inability to
see in one eye
Blockage of a coronary artery or arteries
Most common cause is coronary thrombosis
Scar tissue replaces dead cardiac muscle
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Results in diminished pumping ability
Can begin with angina pectoris
Pain that radiates down the left arm due to partial blockage
of a coronary artery
Nitroglycerin or nitric oxide dilate BV and helps relieve pain
Coronary angiography
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Procedure to determine if and where there are blockages42
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Aneurysm
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A ballooning of a blood vessel
Atherosclerosis and hypertension can
weaken a vessel and cause ballooning
Occurs most commonly in abdominal artery
or the arteries leading to the brain
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Dilated and Inflamed Veins
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Varicose veins
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Develop when the valves of the veins become weak
and ineffective
Abnormal and irregular dilations apparent
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Congestive Heart Failure
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Superficial veins of leg
When occur in the rectum—hemorrhoids
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Symptoms include shortness of breath, fatigue,
weakness, and fluid retention
Treatment can include
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Inflammation of a vein
Blood clots may form
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Condition in which the heart is no longer an efficient
pump
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Phlebitis
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Heart attack damage, faulty valves, lung disease…
Medications to strengthen heart contractions, diuretics,
vasodilators
If clot blocks a pulmonary vessel, it can kill
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Medical Treatments
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Dissolving blood clots
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Gene therapy
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Vascular endothelial growth factor (VEGF)
Injected into area of heart that needs improved blood flow forming
collateral BV
60% patients show signs of vessel growth 2-4wks
Coronary bypass surgery
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Tissue plasminogen activator (t-PA)
Vein taken and is stitched with one end to aorta and other to end to a
coronary artery past the blockage
Angioplasty and coated stent
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Plastic tube with balloon that is inflated and forces vessel open
Stent with small metal mess cylinder inserted and is coated with drug
that discourage cells growth
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Recipients need anti-clotting measures due to possibility of clotting
Coronary Artery Bypass Graft
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Tips for Prevention of
Cardiovascular Disease
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Do not smoke
Do not abuse drugs
Keep your weight down to decrease chances of
hypertension and Type II diabetes
Eat a healthy diet
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Benefits of Exercise to the
Cardiovascular System
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Know your blood cholesterol
Exercise
Avoid chronic stress and get adequate sleep
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Lymphatic System
Increases amount of hemoglobin, numbers of
RBCs, and blood volume
Lowers blood pressure
Shifts balance of lipids in blood to “good” form
(HDLs)
Need to elevate HR to target zone for at least 20
minutes, 3 times/week
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Low in saturated and trans fats
Low in cholesterol
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Consists of lymph, lymphatic
vessels, and lymphoid organs
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Functions
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222 minus age = maximum attainable HR
Target zone = 70 to 85% of maximum attainable HR
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No more than 2 days between sessions
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Lymph vessels also have valves
Return the interstitial fluid to the
blood stream
Transport products of fat
digestion
Helps defend the body against
disease-causing organisms and
abnormal cells
CV system + lymphatic system =
circulatory system
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