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CARDIOVASCULAR SYSTEM(Anatomy & Physiology)

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S.S.MOORTHY SEMENCHALAM

M.Sc. Comm Health (Occ Health) UKM

B.HSc. Nursing (Aust)

Dip Med Sc. (Moh)

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Learning Objectives: At the end of the session, students will be

able to:1. Label the structure of the heart2. List the 3 layers of heart wall3. List all the chambers and valves of the heart4.State the function of the chambers and valves5. Define the physiology of the heart6.List 3 stages in cardiac cycle7. Understand how the heart sound is produced8.Define cardiac output

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Cardiovascular system: Components

1) HeartPumps blood into blood vesselsLocated in the mediastinum (within the

pericardial cavity between the two lungs).

2) Blood VesselsCarry blood throughout the bodyArteries, arterioles, capillaries, venules & veins

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An Overview of the Cardiovascular System

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Anatomy of heart

• Lies in thoracic cavity, 2/3 is to the left of midline (mediastinum)

• Size: about a size of closed fist

• Cone-shaped with apex & base

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Apex

most inferior part of the heart,directed anteriorly and to the left

situated at the level of 5th intercostal space, 9cm to the left of the midline

Basedeep into sternum and extends to the 2nd

intercostal space

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Base

Apex

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ANATOMY OF THE HEARTPERICARDIUMDouble layered closed sac that surrounds the heart and

anchors it within the mediastinumConsists of:

fibrous pericardium: - enclosing the heart & vessels

serous pericardium- allow heart to move freely- parietal layer & visceral layer- between the 2 layers = pericardial cavity

(filled with pericardial fluid to reduce friction)

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Membranes around heart

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The Superficial Anatomy of the HeartThe heart consists of four chambers

Two atria and two ventricles separated by septum

Major blood vessels of the heart include Inferior vena cavaSuperior vena cavaAorta Pulmonary trunkBlood vessels

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The Superficial Anatomy of the Heart

Figure 20.3a•3/26/2009 •11

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The Superficial Anatomy of the Heart

Figure 20.3b, c•3/26/2009 •12

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The Heart WallComposed of 3 layers

Epicardium: Outermost, serous membrane forming the smooth outer surface consists of blood vessels that nourish the heart wall.

Myocardium: Middle, muscular layer,responsible for the ability of the heart to contract (cardiac muscle tissue)

Endocardium: Innermost, endothelium(simple squamous epithelium overlying connective tissue.Also forms the valves of the heart.

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Connective Tissues

Connective tissue fibers of the heartProvide physical supportDistribute the force of

contractionPrevent overexpansion

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Heart wall

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Heart Chambers &Internal Anatomy4 Chambers :2 Atria and 2 ventriclesRt & Lt atria receive blood from veins and act

as resevoirs before it enters into the ventriclesRt & Lt ventricles are the major pumping

system that forces blood into the arteries and flow through the circulatory system

Septum : wall that divides the heart to the Lt & Rt side

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Con`tThe wall of the left

ventricle is thicker than the right ventricle because it generates a greater pressure as it pumps blood to the tissues of the whole body. Whereas right ventricle pumps blood to the lungs.

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The Sectional Anatomy of the Heart

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Heart chambers and valvesHEART VALVESAtrioventriculars valves (AV) – located between the Rt

atrium and Rt ventricle and Lt atrium and Lt ventriclesThe AV between Rt atrium and Rt ventricle – TRICUSPID

VALVEThe AV between Lt atrium and Lt ventricles – BICUSPID or

MITRAL VALVEThe AV valves are connected to the heart wall by thin ,strong

connective tissue – CHORDAE TENDINAEThe aorta and pulmonary trunks has – SEMILUNAR

VALVES (aortic semilunar valve and pulmonary semilunar valve)

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Functions of valves•AV (atrio-ventricular) valves prevent backflow of blood from the ventricles to the atria•Semilunar (SL) valves prevent backflow into the ventricles from the pulmonary trunk and aorta

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Valves of the Heart

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Structures leading to & from heart:Superior & inferior vena cava – carry blood from the

body to the Rt atriumPulmonary artery- arises from the Rt ventricle,spilt

into the Rt and Lt pulmonary arteries,carry blood to the lungs ( pulmonary circulation)

Pulmonary vein –carries blood from the lung to the Lt atrium

Aorta- carries blood from the Lt ventricle to the body (systemic circulation)

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Pathway of blood through the Heart

2 Coronary arteries supply blood to the heart- Lt and Rt coronary arteries

Cardiac veins drain blood from the heart & send it to the body.

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Coronary Circulation

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Physiology of the heart:

Superior & Inferior Vena Cavae

Right Atria

Right Ventricle

Pulmonary ArteryLUNG

BODY

Pulmonary Vein

Left Atria

Left Ventricle

AORTA

Tricuspid valve

Pulmonary valve

Aortic valve

Bicuspid valve

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1

2

3

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Left atriumRight atrium

Left ventricleRight ventricle

LUNG

BODY

1 2

3

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Blood flow through Heart

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Cardiac muscle cell typesAutorhythmic cells: Specialized muscle cells-Self depolarizing-Form the conduction system and carry impulse

Contractile cells: - Cells that contract in response to impulse - Branched fibers - Connected to one another by gap junctions.

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Cardiac Muscle Cells

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Conduction System of the Heart

Contraction of the atria and ventricles is coordinated by specialized cardiac muscle in the wall of heart that forms the conduction system of the heart

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The Conduction SystemThe conduction system includes:

Sinoatrial (SA) node (pace maker of the heart)Inter nodal pathwayAtrioventricular (AV) nodeAV Bundle (Left and right branches)Purkinje fibers☺Conduction system sets sinus rhythm

(Responsible for heart beat)

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Impulse Conduction through the heart

SA node (pacemaker)

Travels through atria by inter-nodal pathway

Spreads to AV node

Travels through AV bundle (Bundle of His)

Distributed throughout ventricles by Purkinje fibers

impulse

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The cardiac cycleThe event takes place within a single beatBegins with the onset of cardiac muscle

contraction and ends with the beginning of the next contraction

During a cardiac cycleEach heart chamber goes through systole

and diastoleLasts for 0.8 sec (75beats/min)

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Stages of Cardiac cycle

Atrial systoleVentricular systoleVentricular diastole

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Heart soundsAuscultation – listening to heart sound via stethoscopeTwo main heart sounds

S1 – “lubb” caused by the closing of the AV valves

S2 – “dupp” caused by the closing of the SL valves (shorter & higher pitched)

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Cardiac OutputCardiac output – the amount of blood pumped by

each ventricle/minuteStroke volume - the volume of blood pumped per

ventricles

COCardiac output

(ml/min)

= HRHeart rate

(beats/min)X

SVStroke volume

(ml/beat)

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Cardiac output

CO = HR X SV = 75 X 70 ml/min = 5250 ml/min = 5.25 L/min

All factors that control HR and SV will influence CO

Example…

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Factors Affecting Cardiac Output

Figure 20.20•3/26/2009 •40

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Thank you

Questions please….

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