CARDIOVASCULAR CARDIOVASCULAR SYSTEM PART 1

DANIL HAMMOUDI.MD

Links and referencesLinks and references

Please refer to the vocabulary and links on the Please refer to the vocabulary and links on the webside

CARDIOVASCULAR EMBRYOLOGYCARDIOVASCULAR EMBRYOLOGY

Cardiovascular Development3rd gestational week … heart formed8th gestational week… heart functional

Heart AnatomyHeart AnatomyApproximately the size of your fistpp y yLocation

Superior surface of diaphragmp p gLeft of the midlineAnterior to the vertebral column, posterior to the sternum

The heart is positioned obliquely between thelungs in the mediastinumlungs in the mediastinum

Orientation of the Heart

The heart and roots of the great vessels within the pericardial sac are related anteriorly•to the sternum,

t l til•costal cartilages, •and the medial ends of the 33rdrd and 5th ribs on the left sideand 5th ribs on the left side.

The heart and pericardial sac are situated obliquely, about two thirds to the left and one third to the p q y,right of the median plane.

The heart is shaped like a tippedover, three-sided pyramid with an apex, base, and four surfaces.

The apex of the heart The base of the heart

Is the heart's posterior aspect.

Is formed mainly by the left atrium, with a lesser Is formed mainly by the left atrium, with a lesser contribution by the right atrium.contribution by the right atrium.

Is directed anteriorly and to the left and is formed by the inferolateral part of the left ventricle.� Is located posterior to the left 5th

Faces posteriorly toward the bodies of vertebrae T6/T9, and is separated from them by

the pericardium,

bli i di l i � Is located posterior to the left 5th intercostal space in adults, usually 9 cm from the median plane.� Is where the sounds of mitral valve mitral valve closure are maximal (apex beatclosure are maximal (apex beat); the

oblique pericardial sinus,

esophagus, and aorta.

Extends superiorly to the bifurcation of the pulmonary trunk and inferiorly to the coronary groove.closure are maximal (apex beatclosure are maximal (apex beat); the

apex underlies the site where the Receives the pulmonary veins on the right and left sides of its left atrial portion and the superior and inferior venaecavae at the superior and inferior ends of its right atrialportionportion.

Heart AnatomyHeart Anatomy

Figure 18.1

•Anterior (sternocostal) surface, formed mainly by the right ventricle.

•Diaphragmatic (inferior) surface, formed mainly by the left ventricle and partly by the right ventricle; it isrelated to the central tendon of the diaphragmrelated to the central tendon of the diaphragm.

•Left pulmonary surface, formed mainly by the left ventricle; it forms the cardiac impression of the left lung.

•Right pulmonary surface formed mainly by the right atriumRight pulmonary surface, formed mainly by the right atrium.

The heart appears trapezoidal in both anterior and posterior views.The heart appears trapezoidal in both anterior and posterior views.

The four borders of the heart are the The four borders of the heart are the

•Right border (slightly convex), formed by the right atrium and extending between the SVC and the IVC.Right border (slightly convex), formed by the right atrium and extending between the SVC and the IVC.•Inferior border (nearly horizontal), formed mainly by the right ventricle and only slightly by the left ventricle.•Left border (oblique), formed mainly by the left ventricle and slightly by the left auricle.•Superior border, formed by the right and left atria and auricles in an anterior view; the ascending aorta andpulmonary trunk emerge from the superior border, and the SVC enters its right side. Posterior to the aorta andpulmonary trunk emerge from the superior border, and the SVC enters its right side. Posterior to the aorta andpulmonary trunk and anterior to the SVC, the superior border forms the inferior boundary of the transverse•pericardial sinus.

Coverings of the Heart: AnatomyCoverings of the Heart: Anatomy

P i di d bl ll d Pericardium – a double-walled sac around the heart composed of:

A superficial fibrous pericardiumA superficial fibrous pericardiumA deep two-layer serous pericardium

The parietal layer parietal layer lines the internal surface of the fibrous pericardiumthe fibrous pericardiumThe visceral visceral layer or epicardium lines the surface of the heartTh d b h fl id fill d They are separated by the fluid-filled pericardial cavity

FibrousFibrous Pericardium• Collagenous sac enclosing the• Collagenous sac enclosing theheart.• Stabilizes heart’s position andprevents over distentionprevents over distention.

Serous PericardiumSerous Pericardium• Deep to the fibrous pericardium.

• 2 layered structure.• Relationship with the heart is similar to that of

f h b lla fist punching a balloon.

EpicardiumCorresponds to the visceral pericardium. Corresponds to the visceral pericardium. Functions as an outer protective layer. Serous membrane that consists of connective tissue covered by epithelium. Includes blood capillaries, lymph capillaries, and nerve fibersIncludes blood capillaries, lymph capillaries, and nerve fibers. p , y p p ,p , y p p ,

MyocardiumRelatively thick. Consists largely of cardiac muscle tissue responsible for forcing blood out of the heart responsible for forcing blood out of the heart chambers. chambers. Muscle fibers are arranged in planes, separated by connective tissues that are richly supplied with blood capillaries, and nerve fibers.

EndocardiumConsists of epithelial and connective tissue that contains many elastic and collagenous fibers. Connective tissue also contains blood vessels and some specialized cardiacmuscle fibers called Purkinje fibers. Lines all of the heart chambers and covers heart valves. Is continuous with the inner lining of blood vessels--endothelium.

Pericardium

Coverings of the Heart: PhysiologyCoverings of the Heart: Physiology

The The pericardium function :pericardium function :The The pericardium function :pericardium function :Protects and anchors the heartProtects and anchors the heartPrevents overfilling of the heart with bloodPrevents overfilling of the heart with bloodPrevents overfilling of the heart with bloodPrevents overfilling of the heart with bloodAllows for the heart to work in a relatively frictionAllows for the heart to work in a relatively friction--free free

i ti tenvironmentenvironment

Pericardial Layers of the HeartPericardial Layers of the Heart

Figure 18.2

Microscopic Anatomy of Heart MuscleMicroscopic Anatomy of Heart Muscle

Cardiac muscle is striated, short, fat, branched, and interconnectedThe connective tissue endomysium acts as both tendon and insertionIntercalated discs anchor cardiac cells together and allow free passage of ionsp gHeart muscle behaves as a functional syncytium

Mi i Microscopic Anatomy of yCardiac M lMuscle

Figure 18.11

Heart WallHeart WallEpicardiumEpicardium – visceral layer of the serous pericardiumEpicardiumEpicardium visceral layer of the serous pericardiumMyocardiumMyocardium – cardiac muscle layer forming the bulk of the heartthe heartFibrous skeleton of the heart – crisscrossing, interlacing layer of connective tissuelayer of connective tissueEndocardiumEndocardium – endothelial layer of the inner

di l fmyocardial surface

Cardiac Muscle Cardiac Muscle Bundles

Figure 18.3

HistologyStriated muscle but fibres divide and recombine.Though each cell is dictinct withits own nucleus, the cells are joined end to end by specialised cell junctions called g , j y p jintercalated disks. These junctions offer a veru weak resistance to electrical flow and thus the heart muscle acts as a syncetium.In contrast with skeletal muscle, the heart muscle tissue can contract without a nervous stimulation.

Other differences between cardiac and skeletal muscle tissue•Sarcoplasmic Reticulum is less extensive in cardiac muscle.•Calcium sensitivity of intact cardiac muscle is greater than skeletal muscle. Because of this increased sensitivity, cardiac y g y,muscle contraction is longer than skeletal muscle.•Cardiac muscle cannot undergo tetanisation. This occurs as the absolute refractory period in the cardiac muscle cell is longer than for skeletal muscle. In fact absolute refractory period is almost as long as the contraction period - 200 msecs.•Cardiac muscle resists wear and tear better than skeletal muscle. This is important as cardiac muscle contracts somp100,000 times/day (in 70 years this totals to 2.5 billion times).•Cardiac muscle is very susceptible to oxygen lack - can withstand not more than 30secs without oxygen before they stop working.•The cardiac muscle as a whole, and not only the single muscle fibre, obeys the all or none rule i.e. if one muscle cell in , y g , ythe syncetium contracts, the rest contract at the same time.

External Heart: Major Vessels of the Heart (Anterior View)Heart (Anterior View)Vessels returning blood Vessels returning blood to the heart i l dinclude:

Superior and inferior Superior and inferior venaevenae cavaecavaeRight and left pulmonary veinsRight and left pulmonary veinsg p yg p y

Vessels conveying blood away from Vessels conveying blood away from the heartthe heart:

Pulmonary trunk which splits into Pulmonary trunk which splits into Pulmonary trunk, which splits into Pulmonary trunk, which splits into right and left pulmonary arteriesright and left pulmonary arteriesAscending aorta (three branches) Ascending aorta (three branches) ––b hi h lib hi h li l ft tid l ft tid brachiocephalicbrachiocephalic, left common carotid, , left common carotid, and and subclaviansubclavian arteriesarteries

External Heart: Vessels that Supply/Drain the Heart (Anterior View)Supply/Drain the Heart (Anterior View)

Arteries right and left Arteries – right and left coronary (in atrioventriculargroove), marginal, circumflex, and anterior interventricularand anterior interventriculararteriesVeins – small cardiac, anterior cardiac and great anterior cardiac, and great cardiac veins

BrachiocephalictrunkSuperiorvena cava

Left common carotid artery

Left subclavian arterySuperiorvena cava

Rightpulmonary artery

Ascending Ascending aortaaorta

Aortic archLigamentum arteriosum

Left pulmonary artery

Pulmonary trunkRightpulmonary veins

p y y

Left atriumAuricle

Left pulmonary veins

pulmonary veinsRight atriumRight coronaryartery (in coronarysulcus)

Circumflex arteryLeft coronaryartery(in coronary sulcus)

Anterior cardiac veinRight ventricleMarginal arterySmall cardiac vein Anterior interventricular artery

(in anterior interventricular

Great cardiac veinLeft ventricle

Figure 18.4b(b)

Inferiorvena cava

(in anterior interventricularsulcus)Apex

External Heart: Major Vessels of the Heart (Posterior View)Heart (Posterior View)

Vessels returning blood to the heart include:Vessels returning blood to the heart include:Vessels returning blood to the heart include:Vessels returning blood to the heart include:Right and left pulmonary veinsSuperior and inferior venae cavaeSuperior and inferior venae cavae

Vessels conveying blood away from the heart Vessels conveying blood away from the heart include:include:include:include:

AortaRight and left pulmonary arteriesRight and left pulmonary arteries

External Heart: Vessels that Supply/Drain the Heart (Posterior View)Supply/Drain the Heart (Posterior View)

Arteries – right coronary artery (in atrioventriculargroove) and the posterior interventricular artery (in interventricular groove)Veins – great cardiac vein, posterior vein to left g , pventricle, coronary sinus, and middle cardiac vein

SuperiorAorta Superiorvena cavaRightpulmonary arteryRight

Left pulmonary arteryLeft Right

pulmonary veinsRight atrium

Left atrium

Auricleof left atrium

Great cardiac vein

pulmonary veins

Inferior

Right coronaryartery (in coronarysulcus)Coronary sinus

Posterior veinof left ventricle

Great cardiac vein vena cava

su cus)Coronary sinus

Left ventriclePosterior interventricular artery(in posterior interventricular sulcus)

Figure 18.4d

(d) Right ventricleMiddle cardiac veinApex

Superior vena cavaAorta

Superior vena cavaRightpulmonary arteryPulmonary trunkRight atrium

Leftpulmonary arteryLeft atriumLeft

l iRight atriumRightpulmonary veinsFossaovalisPectinate

pulmonary veins

Aorticvalve

Mitral (bicuspid) valve

PectinatemusclesTricuspidvalveRight ventricle

Pulmonaryvalvevalve

Left ventriclePapillaryRight ventricle

ChordaetendineaeTrabeculaecarneae

muscleInterventricularseptumMyocardiumVisceral

Figure 18.4e(e)

carneaeInferiorvena cava

VisceralpericardiumEndocardium

Atria of the HeartAtria of the Heart

Atria are the receiving chambers of the heartAtria are the receiving chambers of the heartEach atrium has a protruding auriclePectinate muscles mark atrial wallsBlood enters right atria from superior and inferior venae cavae and coronary sinusBlood enters left atria from pulmonary veinsBlood enters left atria from pulmonary veins

Ventricles of the HeartVentricles of the HeartVentricles are the discharging chambers of the g gheartPapillary muscles and trabeculae carneae muscles Papillary muscles and trabeculae carneae muscles mark ventricular wallsRight ventricle pumps blood into the pulmonary Right ventricle pumps blood into the pulmonary trunkLeft ventricle pumps blood into the aortaLeft ventricle pumps blood into the aorta

Right and Left VentriclesRight and Left Ventricles

Figure 18.6

Pathway of Blood Through the Heart and LungsLungs

Right atrium tricuspid valve right ventricleg p gRight ventricle pulmonary semilunar valve pulmonary arteries lungspulmonary arteries lungsLungs pulmonary veins left atriumLeft atrium bicuspid valve left ventricleLeft atrium bicuspid valve left ventricleLeft ventricle aortic semilunar valve aortaAorta systemic circulation

Figure 18.5

Fetal CirculationFetal Circulation

placenta(blood is rich

in oxygen andnutrients)

umbilical vein

(liver isb d)bypassed)

posterior

Via venous duct

posteriorvena cava

right atria

(Since blood is already rich in oxygen and nutrients, it isshunted directly from the right atria to the left atria through the ovalopening bypassing the lungs )

left atriaopening, bypassing the lungs.)

left ventricle

right atria aortaBlood is shunted via thearterial duct directly from thei h i h i right atria to the aorta, again

bypassing the lungs.

umbilical artery placentablood low in oxygenumbilical artery pand nutrients movesfrom fetus back to mother

Coronary CirculationCoronary Circulation

Coronary circulation is the functional blood supply Coronary circulation is the functional blood supply to the heart muscle itselfCollateral routes ensure blood delivery to heart Collateral routes ensure blood delivery to heart even if major vessels are occluded

Coronary Circulation: Arterial SupplyCoronary Circulation: Arterial Supply

Figure 18.7a

COO

RONN

ARYY SINN

US

Coronary Circulation: Venous SupplyCoronary Circulation: Venous Supply

Figure 18.7b

Heart ValvesHeart ValvesHeart ValvesHeart ValvesHeart valves ensure unidirectional blood flow through the heartAtrioventricular (AV) valves lie between the atria and th t i lthe ventriclesAV valves prevent backflow into the atria when ventricles contractventricles contractChordae tendineae anchor AV valves to papillary muscles

Valves

AV atrioventricular valvesTricuspidMitral or bicuspidMitral or bicuspid

Semilunar valvesAorticAorticPulmonic

PAMT

Myocardial Segment AnatomyMyocardial Segment Anatomy

Heart ValvesHeart Valves

Aortic semilunar valve lies between the left ventricle d th t and the aorta

Pulmonary semilunar valve lies between the right ventricle and pulmonary trunkSemilunar valves prevent backflow of blood into the pventricles

Heart ValvesHeart Valves

Figure 18.8a, b

Heart ValvesHeart Valves

Figure 18.8c, d

Atrioventricular Valve FunctionAtrioventricular Valve Function

Figure 18.9

Semilunar Valve FunctionSemilunar Valve Function

Figure 18.10