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Cardiovascular System
Lecture 13
Supplies the raw materials for metabolism and establishes
the environment of the extracellular fluid
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CARDIOVASCULAR SYSTEM
Blood serves as medium of transport
Blood Vessels tubes that carry blood
Pulmonary Circulation
Systemic Circulation
Heart two side-by-side pumps that
move blood through the vessels
Right pump powers the pulmonary circulation
Left pump powers the systemic circulation
RightLung
LeftLung
Pulmonary Circulatory SystemRight Heartpumpsdeoxygenatedblood to thelungs
Blood becomesoxygenated andunloads CO
2Oxygenatedblood is returnedto the Left Heart
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Systemic CirculatorySystem
Oxygenated blood is
pumped from the Left Heart
Oxygenated blood is
circulated to the tissues
O2 is unloaded and CO2 is
picked up
Blood is returned to the
Right Heart
Anterior View of the Heart
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SuperiorVena Cava
InferiorVena Cava
RightAtrium
Right Ventricle
PulmonaryArtery
RightAtrioventricularValve
PulmonarySemilunarValve
Right Pump
To Left LungTo Right Lung
PulmonaryVeins (4)
Left Atrium
Left AtrioventricularValve (mitral)
Left Ventricle
Aortic SemilunarValve
Aorta Left Pump
Why is the wall of the left ventricle so muchthicker than the right?
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Cardiac Cycle
The heart beats in a rhythmic pattern at arate of about 70 beats per minute
Resting 100 bpm = tachycardia
Each cycle consists of two stages:
The filling stage of the cardiac cycle is called
diastole The contraction (emptying) stage of the
cardiac cycle is called systole
Cardiac Cycle
The cycle is regulated by the operation ofan internal electrical conduction system
Heart rate can be increased or decreasedby the action of the:
Autonomic Nervous System (ANS) Parasympathetic branch SLOWS heart rate
Sympathetic branch INCREASES heart rate
Hormones
Adrenalin (epinephrine)speeds the heart rate
Thyroid hormones (T3 and T4)speeds the heartrate
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Cardiac Cycle animation
Electrical Conduction SystemOrganizes the Cardiac Cycle
Sinoatrial (SA)node is thepacemaker
AV node
AV Bundle
PurkinjeFibers
PurkinjeFibers
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Electrocardiogram (ECG)
Recording of electrical changes during a cardiac cycle
P wave = SA node
triggers impulse, atria
are stimulated
QRS wave = ventricles
are stimulated
T wave = heart relaxes
Abnormalities: Ventricularfibrillation = uncoordinated
contraction of ventricles
Need to be defibrillated
Blood Vessels
Arteries and arterioles
Carry blood away from the heart
Capillaries
Tiniest vessels; thin, allows diffusion
Exchange of materials between blood & body cells
Venules and veins Return blood to the heart
Valves prevent backflow of blood
Stitched end-to-end, the blood vessels would be
60,000 miles long
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Arterial Circulation
The hollow interior of all blood vessels iscalled the lumen
Arteries
Thick-walled, muscular vessels
Carry blood away from the heart
Elasticexpand and contract with heart
beat
We feel expansion as a pulse
Pulse Points
Pulse pointsfeel pulsing ofblood inarteries close
to skin Used to
determineheart rate
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Arterial Circulation
Arterioles
smallest arterial vessels
prime controllers of blood pressure
In certain organs, arterioles control bloodflow by using precapillary sphincters
Vasocontrictionclose sphincters
Vasodilationopen sphincters Organs include skin, GI tract, muscles)
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Capillary Perfusion
Venous Circulation
Veins are thin walled vessels that serve tocarry blood back to the heart
They also function as a reservoir for bloodvolume
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To deal with
increased demands
for blood:
The heart rate
increases
Some capillary beds
dilate to increase
blood flow
Some capillary beds
constrict to reduce
blood flow
Measuring Blood Pressure
Systolic Pressure =
Pressure in the large
arteries while the
ventricles are contracting
Diastolic Pressure =pressure in the large
arteries while the
ventricles are filling
Measured in mm Hg
110-130
60-80
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Hypotension
Can be OK in athletes May indicate serous problems in others
Systolic pressure < 90 mm Hg
Diastolic pressure < 60 mm Hg
Causes Heart disease
Medication
Infection
Dehydration Severe blood loss
Severe allergic reaction (anaphylactic shock)
Hypotension
Symptomsrelated to low oxygen in brain Dizziness or lightheadedness
Fainting (syncope)
Lack of concentration
Blurred vision
Nausea
Cold, clammy, pale skin--vasoconstriction
May lead to SHOCKlife threatening,may cause organ failure
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Hypertension
Systolic 140 and/or diastolic 90
Affects ~20% of Americans
Forces heart to work harder, can lead to
major health problems
Causes: genetic predisposition, obesity,
arteriosclerosis, smoking, stress Treatment: lifestyle changes and medication
High blood pressure
Silent killer because seldom causes warning symptoms
Arteriosclerosis
Known as hardening of the arteries
Lining of the walls accumulates fatty tissue
called plaquerestricts blood flow
Risk factors include:
High LDL cholesterol in blood
Hypertension
Diabetes
Obesity
Inactivity
Genetics/family history
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http://www.youtube.com/watch?v=fLonh7ZesKs&feature=related
Aneurysm
Vessel may rupture with
massive bleeding, can be fatal;
can compress nearby nerves
Causes: congenital,
hypertension, atherosclerosis
Treatments: reduce risk factors,
surgical excision (excellent
prognosis), replace with plastic
tube
Abnormal widening or ballooning of blood vessels
http://www.youtube.com/watch?v=fLonh7ZesKs&feature=relatedhttp://www.youtube.com/watch?v=fLonh7ZesKs&feature=relatedhttp://www.youtube.com/watch?v=fLonh7ZesKs&feature=relatedhttp://www.youtube.com/watch?v=fLonh7ZesKs&feature=related8/6/2019 Lecture 13 Cardiovascular System
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Stroke
Lack of O2 causes:
Tissue death
Loss of brain function
Paralysis
Death possible
Symptoms include:
Changes in vision, speech, comprehension Weakness
Loss of sensation
Loss of consciousness
Interruption of blood supply to the brain
Causes of Stroke Hemorrhagic stroke (20%) bleeding,
trauma, ruptured aneurysm
Ischemic stroke (80%)stoppage of blood
flow to brain region
Thrombotic strokeblood clot forms in brain
(thrombus) and blocks flow of blood
Embolic strokeblood clot travels to the brain
(embolus) and blocks flow of blood
TIA (transient ischemic attack)temporary
loss of blood flow to the brain, reversible
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Embolic Stroke
The heart muscle
(myocardium) is nourished
by coronary circulation
Coronary arteries are the
first to emerge from the aorta
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Heart Disease
Coronary artery disease
Cardiac muscle suffers
ischemiareduced
blood flow
Blockage causes pain
angina
If completely blocked,
may result in heart
attack (myocardialinfarction)
If large vessel, heart
may stop beating
Angioplasty and stentingvideo
http://www.youtube.com/watch?v=gvRtP3wl_AY&NR=1
http://www.youtube.com/watch?v=gvRtP3wl_AY&NR=1http://www.youtube.com/watch?v=gvRtP3wl_AY&NR=1http://www.youtube.com/watch?v=gvRtP3wl_AY&NR=1http://www.youtube.com/watch?v=gvRtP3wl_AY&NR=18/6/2019 Lecture 13 Cardiovascular System
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Coronary Bypass
Surgeon grafts segments ofanother blood vessel to
bypass an obstructed
coronary artery
blocked vessels
Graftedveins carryarterial blood
New approaches:
tissue engineeringusestem cells to grow new heart
muscle
Heart Transplants
Congestive heart failure = heart no longer able to
pump blood adequately
If irreparable require heart transplant
>2000 transplants performed yearly in US; ~70%
survival rate
Problems: lack of donor organs, host rejection of
foreign organ
Alternatives: artificial hearts (temporary),
xenotransplants (organs from other species)
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Preventing Cardiovascular Disease
Avoid:
Smoking nicotine increases blood pressure,
heart has to pump harder
Drug abuse stimulants can cause heart attacks,
excessive alcohol can destroy heart
Obesity more strain on heart, hypertension
Do:
Eat healthy diet low in saturated fats andcholesterol, get antioxidants, fruits & vegetables
Exercise keeps weight under control, minimizes
stress, reduces hypertension
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