Q.What is the cardiovascular system?The heart is a double pump.

heart arteries arterioles Veins venules capillaries

The cardiovascular system is composed of :1-Heart .

2-Blood vessels.

Three type of blood vessels:

1-Arteries.

2-Veins.

3-Capillaries

Special types of arteries are:

1-End arteries . e.g. Central artery of retina ,central artery of the brain, arteries within the kidney & spleen and coronary arteries of the heart.

2-Tortuous arteries .e.g. Facial artery , Uterine artery, Splenic artery and Lingual artery.

Circulatory system is composed of heart and blood vessels.

Blood vessels is composed of arteries ,veins and capillaries.

1-BLOOD VESSELS:Blood vessels are of three types: arteries, veins, and capillaries.THE ARTERIES: Arteries transport blood from the heart and distribute it to the various tissues of the body by means of their branches . The smallest arteries, <0.1 mm in diameter, are referred to as arterioles. The joining branches of arteries is called an anastomosis. Arteries do not have valves.Anatomic end arteries are vessels whose terminal branches do not anastomose with branches of arteries supplying adjacent areas.Functional end arteries are vessels whose terminal branches do anastomose with those of adjacent arteries, but the caliber of the anastomosis is insufficient to keep the tissue live.Examples for arteries in the body Aorta (ascending, arch, descending) , innominate ,subclavian, carotid, axillary, brachial, common iliac, femoral, popliteal, anterior and posterior tibial arteries.

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Arteries of the body:

THE VEINS:Veins are vessels that transport blood back to the heart; many of them possess valves. The smallest veins are called venules . The smaller veins, or tributaries, unite to form larger veins, which commonly join with one another to form venous plexuses. Medium-size deep arteries are often accompanied by two veins, one on each side, called venae comitantes.Veins leaving the gastrointestinal tract do not go directly to the heart but converge to the portal vein; this vein enters the liver and breaks up again into veins of diminishing size, which ultimately join capillary-like vessels, termed sinusoids, in the liver . A portal system is thus a system of vessels interposed between two capillary beds.Examples for veins in the body: Superior and inferior vena cava ,innominate ,subclavian, internal jugular ,axillary and brachial veins ,common iliac, femoral and popliteal veins.

Veins of the body:

THE CAPILLARIES :They microscopic vessels in the form of a network connecting the arterioles to the venules .The Sinusoids resemble capillaries in that they are thin-walled blood vessels, but they have an irregular cross diameter and are wider than capillaries. They are found in the bone marrow, the spleen, the liver, and some endocrine glands. In some areas of the body, principally the tips of the fingers and toes, direct connections occur between the arteries and veins without the intervention of capillaries. The sites of such connections are referred to as arteriovenous anastomosis.

CAPILLARIES:Microscopic vessels in the form of network connecting the arterioles and the venules.

The heart between two lungs

HeartLung

Lung

Pericardium: It is a fibro serous sac that encloses the heart and roots of the great vessels. Functions: 1. It provides lubricating container in which the heart can contracts easily.2. It restrict excessive movement and over filling of the heart.3. It protects and anchors the heart to the surrounding. Location: It lies within the middle mediastinum, posterior to the body of the sternum. Structure : It has a two layers fibrous and serous. 1-Fibrous pericardium: It is a conical sac, attached firmly below to the central tendon of the diaphragm, and

anteriorly to the sternum by the sternopericardial ligaments, it also fuse with the outer coat of the great blood vessels namely the aorta, pulmonary trunk, superior and inferior vena cava, and the pulmonary veins.

2-Serous pericardium: It is a closed serous sac invaginated by the heart from above and behind. It has two layers, with slit like space in-between ( pericardial cavity) which contains a small

amount of fluid ( pericardial fluid) which acts as lubricants. It consists of two layers:1. Parietal layer:Lines the fibrous pericardium and reflected around the roots of the great vessels to become

continuous with them.2. Visceral layer : (epicardium) closely applied to the heart.

The fibrous pericardium surrounding the heart:

2-THE HEART:It is a hollow muscular organ lies within the pericardium in the middle mediastinum, pyramidal in shape and it is connected at its base to the great blood vessels.Its base is directed upwards and to the right and its apex is directed downwards and to the left.It is about the size of closed fist with an average weight of 300 gm.It is divided into 4 chambers 2 atria and 2 ventricles.Function: It acts as double pump with two functions: 1. The right side receives deoxygenated blood and then pumps it to the lungs. 2. The left side receives the oxygenated blood from the lungs and pumps it to the rest of the body.Position of the heart: The heart lies obliquely in the thorax, with its long axis passing downward and to the left.The right-sided chambers are mainly anterior to the left –sided due to heart rotation during development.

The heart is a hollow muscular organ.It consists of 4 chambers 2 atria and 2 ventricles.1-Right atrium.2-Left atrium.3-Right ventricle.4-Left ventricle.

Functions of the heart:

Summary:

The heart is a double pump, delivering blood to the lungs for oxygenation, and then to the body

Blood leaves the heart through arteries, and returns to the heart through veins.

The heart rate is regulated by a conducting system (the heart beats about 100,000 times per day.

Borders and apex of the heart: It has four borders and apex: Borders:1. Superior border : It formed by the roots of great vessels .2. Right border : It formed by right atrium.3.left border: It formed by left auricle and left ventricle below.4.Inferior border: It formed by right ventricle (2/3) and the apical part of left ventricle

(1/3) . Apex is formed by left ventricle (9cm from midline).. These borders are important when examining the heart radio

graphically.

Upper border of the heart is formed by the root of the great vessels.

Lower border is formed by two ventricles mainly right.

Left border is formed by left auricle and left ventricle.

Right border is formed from right atrium.

Surfaces of the heart: It has four surfaces:1.Sternocostal surface : it is formed mainly by right atrium, right ventricle(2/3), left

ventricle (1/3) which separated from each other by atrioventricular groove and roots of great vessels.

2.Diaphragmatic surface ( inferior) :rested on the central tendon of diaphragm. it is formed mainly by right ventricle (1/3) and left ventricles(2/3) separated by posterior interventricular groove.

3.Right surface: it is formed by right atrium only. it related to right lung and pleura, right phrenic nerve and pericardiaco-phernic artery.

4. left surface: It is formed by left ventricle and left atrium. It related to left lung and pleura, left phrenic nerve and pericardiaco-phernic artery.

The heart has apex and base: The apex of the heart: It is formed by the left ventricle only, it lies at the level of fifth left intercostal

space 9cm from the midline. The base (posterior surface): It consists of two atria mainly left atrium. It lies opposite the middle thoracic

vertebra (5,6,7,8).It separated from the vertebral column by structures in the posterior mediastinum.

NB: The heart does not rest on its base ,it rests on its diaphragmatic surface.

1.Sternocostal surface : it is formed mainly by right atrium, right ventricle(2/3), left ventricle (1/3) which separated from each other by atrioventricular groove and roots of great vessels.

Surfaces of the heart:

2.Diaphragmatic surface ( inferior) :it rested on the central tendon of diaphragm. it is formed mainly by right ventricle (1/3) and left ventricles(2/3) separated by posterior interventricular groove.

3.Right surface: it is formed by right atrium only.4-left surface: It is formed by left ventricle and left atrium.The apex of the heart: It is formed by the left ventricle only.The base (posterior surface):It consists of two atria mainly left atrium.

The heart has sulci on the external surfaces:1-Coronary sulcus (atrio-ventricular): It separated between the 2 atria from the 2 ventricles and lodges the 2 coronary arteries and coronary sinus.2-Anterior and posterior interventricular sulci.It separated the two ventricles anterior and posteriorly and lodges the corresponding interventricular arteries.

Structures of the heart: The heart wall is composed of a thick layer of cardiac muscle, (myocardium), covered externally by(epicardium) visceral layer of serous pericardium and internally by (endocardium).All three layers are richly supplied with blood vessels.It divided into 4 chambers by septum, the atrial portion has thin walls and divided by interatrial septum into right and left atrium.the ventricular portion divided by, interventricular septum .

Chambers of the Heart: The heart is divided by vertical septa into four chambers, the right

atrium which lies in front of left atrium, and right ventricle in front of left ventricle .

The atria of the heart:Functionally, the atria are receiving chambers for blood returning to the heart from the circulation (SVC and IVC).Because they need to contract only minimally to push blood into the ventricles, the atria are relatively small, thin walled chambers.As a rule they contribute little to the propulsive pumping of the heart.

Openings into the RA:1.Superior vena cava : It opens into upper part of RA, it

returns blood from upper half of the body.

2.Inferior vena cava : It opens into lower part of the RA,

it is guarded by a rudimentary non functioning valve, it return blood from lower half of the body.

3.Coronary sinus : It drains most of the blood from

the heart, it opens into RA between the IVC and right atrioventricular opening .It has a valve.

4.The right atrioventricular opening:

it lies anterior to the IVC opening.5. Openings of many other small

veins.

Valves of the heart: Valves control flow of blood from one chamber to another and prevent backflow. The heart has 4 valves.

1-Tricuspid valve:It guards right atrioventricular orifice.it is ovale in shape and admitting the tips of three fingers.It consists of three cusps. Its base are attached to the fibrous ring of the skeleton of the heart.The cusps are : A-Anterior : lies anterior.B-Septal : lies against the Interventricular septum.C-Inferior (posterior) :lies inferior .

2-Pulmonary valve: It guards the pulmonary orifice it is

circular orifice 3cm in diameter. it consists of three semilunar cusps

formed of endocardium and some connective tissue.

The open mouths of the cusps are directed upward and the margin and sides are attached to the arterial wall.

The cusps are one posterior and two anterior, during diastole blood flow back enter the sinuses so the valve cusps fill and come into apposition in the centre of the lumen and close the pulmonary orifice.

3-Mitral valve:It is circular and admitted the tips of two fingers.It is bicuspid (anterior and posterior) the cusps are attached to the margin of the fibrous atrioventricular ring.

4-Aortic valve:It is circular orifice 2.5 cm in diameter.It guard the aortic orifice and is similar in structure to pulmonary valve. It has three cusps one anterior and two posterior (left and right posterior) behind each one is aortic sinus. From the anterior sinus rise the right coronary artery .From the left posterior one rise the left coronary artery.

Interventricular septum:It lies obliquely between the 2 ventricles.It is marked on the surface of the heart by the anterior and posterior interventricular grooves.It separates the Lt. ventricle from Rt. ventricle and lower part of right atrium.It is formed of two parts:1- Muscular part.2- Membranous part .

Nerve supply of the heart: 1-Parasympathetic nerve fibers arise as branches of the Vagus nerve in the neck and thorax. 2-Sympathetic nerves travel to the heart from the cervical and upper thoracic chain ganglia.N.B: All nerves serving the heart pass through the cardiac plexuses on the trachea before entering the heart.

Regulation of the cardiac cycle:Sympathetic and parasympathetic nervous systems.Parasympathetic: from medulla oblongata (vagus nerve).Nerve branches to S-A and A-V nodes, and secretes acetylcholine (slows rate).Parasympathetic activity can increase (slow heart rate) or decrease (increase heart rate).Sympathetic nervous system through celiac plexus to heart secretes norepinephrine increases force of contractions.Cardiac control center in medulla oblongata maintains balance between the two.Normally both sympathetic and parasympathetic function at a steady background level.

Electrocardiogram (ECG) can trace conduction of electrical signals through the heart:

Blood supply of the heart:The arterial supply of the heart is provided by the right and left coronary arteries.They and their branches are distributed over the surfaces of the heart lying within subepicardial connective tissue.1.Right coronary artery: It arises from the anterior ( right) aortic sinus of ascending aorta , runs forward between pulmonary trunk and the right auricle. It descends vertically in the right atrioventricular groove, where it gives branches to right atrium and right ventricle.At the inferior border of the heart it continues posteriorly along the interventricular groove to anastomosis with left coronary artery.

2-The left coronary artery: It usually larger than the right coronary artery.It arises from the left posterior aortic sinus of the ascending aorta and passes forward between the pulmonary trunk and the left auricle.It enters the atrioventricular groove and divided into an anterior interventricular branch and circumflex branch.

Coronary artery disease results when coronary arteries cannot deliver blood adequately.

Usual cause: plaques in arterial walls.

Angina pectoris (pain) when body is not receiving adequate oxygen.

Myocardial infarction (heart attack) when blood supply to heart is completely blocked; muscle dies.

Venous drainage of the Heart:After passing through the myocardium, the venous blood is collected by the cardiac veins.Anterior cardiac veins : a series of small veins which runs transversely to open into the right atrium. Venae cordis minimi :are minutes veins which lies on the muscle wall and drain directly into any chamber of the heart.

Coronary sinus: an enlarged vessel (3 cm in length) which lies in the posterior part of the interventricular groove as a continuation of the great cardiac vein then empties into the right atrium to the left of the IVC opening.

Tributaries of coronary sinus:1)Great cardiac vein: Ascends with the anterior interventricular artery, the curves with the circumflex artery to end in the coronary sinus. 2)Small cardiac vein :Accompany the marginal artery.3) Middle cardiac vein: Accompany the posterior inter-ventricular artery.4) Posterior vein of left ventricle: To the left of middle cardiac vein.5) Oblique vein of left atrium (of Marshal): Descends obliquely on the back of the atrium.

Conduction system of the heart:Heart contracts as a unit.

Atrial and ventricular syncytia help conduct electrical signals through the heart.

Sinoatrial (S-A) node is continuous with atrial syncytium.

S-A node cells can initiate impulses on their own; activity is rhythmic.

Coordination of chambers (contraction and relaxation):

Blood pressure:Blood flow is generally equal to cardiac output.

Blood flow affected by pressure and resistance.

Blood pressure means the force that is exerted by blood against blood

vessel walls.

Resistance depends on size of blood vessel and thickness (viscosity)

of blood.

Baroreceptors detect changes in blood pressure.

Rising pressure stretches receptors vagus nerve

parasympathetic system decrease heart rate decrease blood

pressure.

Increased temperature increases heart rate.

Ions and heart rate:

Excess potassium decreases it .

Excess calcium increases it.

Blood pressure is highest in large arteries and will rise and fall as heart pumps.

highest with ventricular systole and lowest with ventricular diastole.

pulse pressure is the difference between the systole and diastole.

Resistance is highest in capillaries.Control of blood pressure: 1. Regulation of cardiac output.2. Contraction strength.3. Heart rate.4. Venous return.5. Skeletal muscles. 6. Breathing rate.

Causes of increasing blood pressure:

(1) (2) (3)

(4) (5)

Hormonal regulation of blood flow .If blood pressure is too low this leads to:1-ADH (antidiuretic hormone) promotes water retention.2-Angiotensin II- in response to renin signal (renin) produced

by kidney- why? Due to: Drop in blood pressure. Stimulation by sympathetic nervous system. Sodium levels too low.Q:What happens?1. Vasoconstriction (by angiotensin II).2. ADH is secreted.3. Aldosterone is secreted.4. EPO (erythropoietin) secreted by kidneys.If blood pressure is too high this leads to:1- ANP(atrial natriuretic peptide) is secreted.

Q What is hypertension?Is the arterial pressure is too high.Causes:Sometimes cause is unknown, or is secondary to

diseaseVariety of causes/ risk factors are known.Sedentary life style.Smoking.Obesity.Diet (excess sodium; cholesterol; calories in

general).Stress.Arteriosclerosis.Genetic factors.

Treatment of high blood pressure:1.Quit smoking; adjust diet; exercise.2.Drug therapies (strategies differ):A-Reduce heart rateCalcium channel blockers reduce calcium flow into heart muscle and therefore reduce the heart rate and relax smooth muscle lining coronary arteries.Beta blockers (reduce stimulation by sympathetic nervous system).B-Diuretics reduce blood volumeACE inhibitors interfere with renin-angiotensin pathway.C-Vasodilators (such as nitroglycerin) open up blood vessels (reduce resistance).D-If heart is actually failing, digitalis increases efficiency of heat muscle.E-Anti-hypertensive drugs may be taken in combination.

Q Why the exercise is good for the heart?A trained heart is bigger and pumps blood more efficiently (at a lower rate).Stroke volume increases (due to stronger contractions, allowing for lower rate)Other benefits: higher aerobic capacity (contributing to efficiency)

Note that this takes training!

THANKS WITH THE BEST WISHES.

Dr/Morsy Abd Elfattah.