Lecture 13 Cardiovascular System

8/6/2019 Lecture 13 Cardiovascular System

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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=related


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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=1


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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

Lecture 13 Cardiovascular System

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