CARDIOVASCULAR SYSTEM PHYSIOLOGY AND MANIFISTATIONS PATHOPHYSIOLOGY BMS 243 Lecture 1

References 1.Pathophysiology: Concepts of Altered health states,J.B.Lippincott Company. 2.Pathophysiology: Clinical Concepts of Disease Process.

Components of the cardiovascular system. 123 Mechanism of heart beating. 6 General structure of the heart. 4 Physiological anatomy of the heart. 5 Contents… The systemic and pulmonary circulation. Basic functions of the various parts of the CVS.

Introductio n The cardiovascular system (CVS) consists of the heart and blood vessels.The cardiovascular system (CVS) consists of the heart and blood vessels. It is a closed system in which blood circulates, hence the synonym ‘circulatory system’.It is a closed system in which blood circulates, hence the synonym ‘circulatory system’.

Components of the CVS: 1.Heart: It is a pump composed of 4 chambers (2 atria & 2 ventricles) 2.Blood Vessels: The blood vessels are systems of tube including: a)Arteries and arteriols which carry the blood from the heart to all parts of the body. b) Veins and Venules which carry the blood back from the tissues to the heart. c) Blood capillaries which form a network of fine vessels connecting the arteriols with the venules, and they are the sites of exchange of gases (O2 & CO2).

a)HEART: The left side of the heart (high pressure side) acts a pressure pump that pumps blood into the systemic arteries at a sufficient pressure that drives blood to the tissues. 1) The left side of the heart (high pressure side) acts a pressure pump that pumps blood into the systemic arteries at a sufficient pressure that drives blood to the tissues. 2)The right side of the heart (low pressure side) pumps blood into the pulmonary arteries at a relatively lower pressure that drives blood into the lungs only. Basic Function of the various parts of the CVS

b) BLOOD VESSELS: 1) The arteries: The aorta and the pulmonary artery are elastic arteries i.e. they are the properties of stretch and recoil. The aorta and the pulmonary artery are elastic arteries i.e. they are the properties of stretch and recoil.  During ventricular contraction (systole), they distend by the blood ejected into them; and energy is at load in their walls.  During ventricular relaxation (diastole), this energy is released causing elastic recoil of their walls.

 Thus on efficient pressure is maintained during systole and diastole, resulting in a continuous blood flow through the tissues. 2. The veins: Act as capacitance vessels (volume reservoir) that hold most of the blood volume. Veins have a high distending capacity and they can store or mobilize blood depending upon the underlying condition from the organs to the heart. Act as capacitance vessels (volume reservoir) that hold most of the blood volume. Veins have a high distending capacity and they can store or mobilize blood depending upon the underlying condition from the organs to the heart.

3. The capillaries : Act as exchange vessels between blood and tissues; as through the blood capillaries O2 and nutrients are supplied to the tissues and CO2 as waste products are drained from them. Act as exchange vessels between blood and tissues; as through the blood capillaries O2 and nutrients are supplied to the tissues and CO2 as waste products are drained from them.

Components of CVS 1. The heart provides the driving force for the cardiovascular system. 2. The arteries serve as distribution channels to the organs. 3. The veins serve as blood reservoirs and collect the blood to return it to the heart. 4. The microcirculation, which includes the capillaries, serve as the exchange region.

THE HEART

The heart is the central pump of the CVS that drives blood through the blood vessels. The heart is the central pump of the CVS that drives blood through the blood vessels. It is a muscular structure, which is made up of four chambers. It is a muscular structure, which is made up of four chambers. THE HEART

A heart beat consists of a systole plus a diastole of cardiac chambers. A heart beat consists of a systole plus a diastole of cardiac chambers. The heart of a normal adult male beats automatically and regularly at a rate of The heart of a normal adult male beats automatically and regularly at a rate of 75 beats/minute during rest. 75 beats/minute during rest. The normal range of heart rate is between 60 – 100 beats /minute. The normal range of heart rate is between 60 – 100 beats /minute. Tachycardia Bradycardia Tachycardia Bradycardia

hhjhttnjngh Tachycardia Heart rate that exceeds the normal range. A resting heart rate over 100 beats per minute is generally accepted as tachycardia. Bradycardia Heart rate that is under the normal range. the resting heart rate of under 60 beats per minute is generally accepted as bradycardia.

PHYSIOLOGICAL ANATOMY of the HEART The HEART is the great central pump of the CVS. It lies in the left side of the thoracic cavity partly behind the sternum and between the right and left lungs. It is covered by a fibrous sac called the pericardium.

GENERAL STRUCTURE OF THE HEART The heart is a hollow muscular organ. Its walls are composed of a muscle called the cardiac muscle or the myocardium which is lined by a endothelial layer called the endocardium (in contact with the blood inside the heart cavity) and covered by a thin layer called the epicardium.

CARDIAC CHAMBERS & THEIR FUNCTIONS The human HEART is consist of four chambers: Two atria (right and left) which are separated from each other by the interatrial septum. Two atria (right and left) which are separated from each other by the interatrial septum. Two ventricles (right and left) which are separated from each other by the interventricular septum. The wall of the left ventricle is about 3 times thicker than the wall of the right ventricle. Two ventricles (right and left) which are separated from each other by the interventricular septum. The wall of the left ventricle is about 3 times thicker than the wall of the right ventricle.

The atria have 2 main functions: 1)They act as blood reservoir for the blood returning back to the heart. 2)They act as pumps (primer pumps). Atrial contraction pushes about 25% of the blood filling the ventricles during ventricular diastole.

The function of the ventricles : Are the powerful cardiac pumps filling the arteries with blood. The right ventricle (pulmonary pumps) pushes blood into the pulmonary arteries and the left ventricle (systemic pump) pushes blood into the aorta during ventricular systole.

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