The Cardiovascular System
Structure of the heart
• Pericardium – encloses heart.
• Visceral pericardium – inner layer;
parietal – outer layer.
• Wall of heart – 3 layers:
• 1Epicardium – protects heart
(reduces friction) – visceral
pericardium.
http://www.texasheartinstitute.org/HIC/Topics/images/myocard.jpg
• 2Myocardium – cardiac muscle; thick
middle layer.
• 3Endocardium – contains blood
vessels – inner lining of blood
vessels.
http://sprojects.mmi.mcgill.ca/embryology/cvs/graphics/tube_trans.gif
• Heart divided into 4 chambers.
• 2 atria – upper chambers, thinwalled; receive blood returning to
heart.
• 2 ventricles – lower chambers,
thicker walled; pump blood into
arteries.
http://web.buddyproject.org/web019/web019/images/Heart2.jpg
• Septum divides atrium and ventricle
on right from left side.
• R atrium receives blood from body
from inferior vena cava and
superior vena cava.
• R atrium separated from R
ventricle by tricuspid valve.
http://www.integrativebiology.ac.uk/images/heart.jpg
• Developing fetus - hole between L
and R atria.
• After birth - hole supposed to
close.
• If hole does not close - hole in
heart (atrial septal defect)
• Blood enters lungs - breathing
problems.
http://texasheart.org/HIC/Topics/images/asd.jpg
• Chordae tendineae – attach cusps
of tricuspid valve.
• Originate from papillary muscles on
walls of ventricles.
• R ventricle pumps blood through
pulmonary artery to lungs.
• Pulmonary valve leads into artery.
http://www.delftoutlook.tudelft.nl/info/images/100703033722010.jpg
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• L atrium receives blood from lungs
through pulmonary vein.
• L atrium and L ventricle separated
by bicuspid (mitral) valve.
• L ventricle pumps through aorta to
entire body.
• Aortic valve leads into aorta.
http://www.lifeisnow.com/Images/Sections/MyHeart/03_ViewOfTheHeartValves.jpg
http://www.med.yale.edu/intmed/cardio/echo_atlas/entities/graphics/bicuspid_aortic_valve.gif
• Mitral valve prolapse – one or both
cusps stretch and bulge into L
atrium during contraction.
• Results in blood going back into L
atrium.
Blood flow
• Blood low in O2, high in CO2 enters
R atrium.
• R atrium passes blood into R
Ventricle.
• R ventricle contracts, blood flows
into pulmonary artery (to lungs)
• Pulmonary vein brings blood high in
O2 back to L atrium.
http://www.shoppingtrolley.net/images/anatomy/heart.gif
• Blood passes to L ventricle.
• Pumped through aorta to body.
• 1st 2 branches of aorta – R,L
coronary arteries – supply blood to
heart tissue.
• Cardiac veins – drain blood, join
together to form coronary sinus –
dump into R atrium.
http://www.nlm.nih.gov/medlineplus/ency/imagepages/18128.htm
Cardiac cycle
• Heart sounds made from opening
and closing of valves.
• 1st sound made from recoil of blood
against closed AV valves (“lub”)
• 2nd sound made from recoil of blood
against semilunar valves. (“dup”)
• Heart murmurs result of incomplete
valve closure resulting in swishing
noise.
http://www.nlm.nih.gov/medlineplus/ency/imagepages/19613.htm
• Sinoatrial node (SA node) –
generates action potentials on its
own (pacemaker).
• Impulse passes along fibers to mass
of specialized tissue
(atrioventricular node)
http://dtc.pima.edu/~biology/202alpha/lesson2/conductionsystem.jpg
• From AV node, moves through
bundle of His (AV bundle)
• Divide into L and R branches
underneath endocardium.
• Give rise to Purkinje fibers.
• Causes ventricular walls to
contract.
http://www.nlm.nih.gov/medlineplus/ency/imagepages/18052.htm
ECG
• Electrocardiogram – recording of
electrical changes in heart muscle.
• QRS complex – depolarization of
ventricular fibers (ventricles
contract)
• T wave – ventricular fibers
repolarize.
http://www.nlm.nih.gov/medlineplus/ency/imagepages/1135.htm
• Heart rate – duration of cardiac
cycle.
• Stroke volume – volume of blood
ejected from ventricles during
contraction.
• Cardiac output = heart rate X
stroke volume.
http://www.pathguy.com/pathphys/pathphy4.gif
• More cells stretched by incoming
blood, more strongly heart walls
contract to eject blood – Starling’s
law of the heart.
• Cardiac output increases with
increasing exercise and blood flow.
http://www.besthealth.com/besthealth/bodyguide/reftext/images/100085.jpg
• Heart rate monitored in medulla
oblongata of brain.
• Increase in blood pressure –
stretch sensors send message to
brain to slow heart rate down.
http://www.gnosticteachings.org/images/stories/energies/medulla_oblongata.jpg
Blood vessels
• Arteries – carry oxygenated blood
away from heart.
• Branch into arterioles, then
capillaries.
• Artery – 3-layered wall surrounding
interior (lumen).
http://www.web-books.com/eLibrary/Medicine/Cardiovascular/Images/Athero.gif
• 1Tunica intima – innermost layer.
• 2Tunica media – thick smooth
muscle layer (middle)
• 3Tunica adventitia – outer layer;
anchors artery to neighboring
structures.
http://www.nlm.nih.gov/medlineplus/ency/imagepages/19194.htm
• Vasoconstriction – vessel decreases
in diameter.
• Vasodilation – vessel increases in
diameter.
• Pulmonary artery – carries
deoxygenated blood away from
heart (toward lungs)
http://www.nlm.nih.gov/medlineplus/ency/imagepages/8983.htm
• Capillaries – smallest vessels.
• Permit exchange of nutrients,
removal of wastes at tissue level.
• Thin, permeable walls to allow
diffusion to occur.
http://www-rocq.inria.fr/who/Marc.Thiriet/Glosr/Bio/AppCircul/ImagCircul/MicroCirc.gif
• Veins – carry deoxygenated blood
back to heart.
• Capillaries join venules, join to form
veins.
• Same 3 layers; tunica media not
very thick.
http://www.merck.com/media/mmhe2/figures/fg036_3.gif
• Blood pressure in veins not high, so
veins need valves to prevent
backflow.
• Blood must flow against gravity
back to heart.
http://www.vascularweb.org/graphics/northpoint_graphics_jpg/Varicose_02_Base_300.jpg
Blood Pressure
• Blood pressure – force exerted by
blood against walls of vessels.
• Systolic pressure – stretch of
arteries to allow for blood flow
pumped from heart.
• Diastolic pressure – relaxation.
http://www.ghi.com/WebMD/topics/bloodpressure.jpg
• Pulse – expanding, recoiling of
arterial walls.
• Represents # of heartbeats per
minute.
http://www.nlm.nih.gov/medlineplus/ency/imagepages/9801.htm
Factors affecting blood pressure
• 1Cardiac output – increase in
cardiac output increases blood
pressure.
• 2Peripheral resistance – friction +
drag in vessels; increases blood
pressure. Vasoconstriction
increases b.p.
http://www-rohan.sdsu.edu/course/ens304/public_html/section1/Image34.gif
• 3Blood volume – decrease causes
drop in b.p.
• Sympathetic nervous system –
causes rise in b.p, heart rate.
• Parasympathetic – decrease.
http://www.biocomtech.com/upload/images/hrs_ce_002pic03.jpg
• Hormones regulate b.p.
• Epinephrine, norephinephrine – rise,
fall of b.p.
• Antidiuretic hormone – rise in b.p.
• Kidneys aid in regulation – drop in
b.p. releases renin; renin causes
formation of angiotensin.
• Angiotensin – vasoconstriction.
• Stimulates release of aldosterone –
increases b.p.
http://www.colorado.edu/kines/Class/IPHY3430-200/image/angiotensin.jpg
Circulatory Pathways
• 1Pulmonary circulation – pulmonary
trunk carries blood from R
ventricle.
• Divides into R and L pulmonary
artery, into capillaries.
• O2 picked up in lungs, brought back
to heart via pulmonary veins.
http://webschoolsolutions.com/patts/systems/pul-circ.gif
Arteries
• 2Systemic – blood leaves L ventricle
into ascending aorta.
• Branches into R, L coronary
arteries (supply heart wall).
• Aorta curves to back (aortic arch)
• 3 branches – brachiocephalic, L
common carotid, L subclavian.
http://butler.cc.tut.fi/~malmivuo/bem/bembook/06/fi/0602.gif
• Aorta turns downward (descending
aorta).
• Section above diaphragm – thoracic
aorta; branch into intercostal
arteries (supply thoracic wall).
• Below diaphragm – abdominal aorta.
http://healthlink.uhseast.com/library/healthguide/en-us/images/media/medical/hw/nr551517.jpg
• Branches into celiac artery (liver,
spleen, stomach, pancreas), superior
mesenteric artery (small intestine),
suprarenal arteries (adrenal glands),
renal arteries (kidneys), inferior
mesenteric artery (large intestine).
• Divides into R, L iliac (to lower legs)
http://www.merck.com/media/mmhe2/figures/fg034_1.gif
• Pelvis, lower limbs – common iliac
divides into internal, external iliac.
• External iliac – becomes femoral.
• Forms deep femoral artery (flexor
muscles of thigh), popliteal artery
(knee), anterior, posterior tibial
arteries.
• Head, neck – from common carotid,
subclavian.
• R common carotid arises from
brachiocephalic.
• R, L common carotid branch into
external, internal carotid.
http://www.nlm.nih.gov/medlineplus/ency/imagepages/9552.htm
• Shoulder, upper limbs – from
subclavian.
• Axillary artery – near armpit.
• Continues down arm as brachial
artery; divides into ulnar, radial
arteries.
http://www.eorthopod.com/images/ContentImages/elbow/elbow_anatomy/elbow_anatomy09a.jpg
Veins
• Head, face veins – blood drained
into R, L external jugular.
• Merge with subclavian veins 
internal jugular  brachiocephalic
vein  superior vena cava.
http://www.anaesthesiauk.com/images/frca_img_ijv.gif
• Upper limbs – ulnar, radial vein 
brachial vein  axillary vein.
• Major superficial arm veins – basilic
(forearm to middle of upper arm),
cephalic (wrist to shoulder), median
cubital vein (where blood is drawn).
http://www.dartmouth.edu/~anatomy/assets/self-tests/elbow/surface/surf-ant-elbow-st.jpg
• Inferior vena cava – longest vein in
body – great saphenous vein, joins
with femoral vein.
• Abdomen – hepatic portal system –
blood from capillaries of digestive
tract to liver only.
• Dumps blood into superior, inferior
mesenteric veins.
http://www.nlm.nih.gov/medlineplus/ency/imagepages/8733.htm
Diseases
• 1Congestive heart failure – can’t
pump blood to body.
• Bad circulation to body  increased
pressure, fluid leaking in lungs.
• Caused by damage to cardiac
muscle.
• Symptoms – shortness of breath,
swelling in lower legs.
http://www.valley-homecare.com/resource/images/chf_hearts.gif
• 2Hypertension – increase in blood
pressure.
• Due to narrowing of blood vessels
(atherosclerosis) or hardening of
vessels (arteriosclerosis)
http://www.nlm.nih.gov/medlineplus/ency/imagepages/18077.htm
• 3Endocarditis – infection of lining
of heart due to bacterial infection.
• Can cause embolus (blood clot)
• 4Aneurysm – sac formation in vessel
or heart chamber; can produce tear
in vessel (hemorrhage)
http://www.nlm.nih.gov/medlineplus/ency/imagepages/17031.htm