Top Banner
The Cardiovascular system & Physiology of Heart Presented By: Bhupendra Kumar Integrated M.Tech.
41

the cardiovascular system and Physiology of heart

Nov 18, 2014

Download

Science

bhupendra kumar

 
Welcome message from author
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
Page 1: the cardiovascular system and Physiology of heart

The Cardiovascular system & Physiology of Heart

Presented By:Bhupendra KumarIntegrated M.Tech.

Page 2: the cardiovascular system and Physiology of heart

ContentsComponents of the cardiovascular system

(CVS)The systemic and pulmonary circulationBasic functions of the various parts of the

CVS.General function of the CVS.Physiological anatomy of the heart.Blood vesselsHeart soundsCharacteristics of blood

Page 3: the cardiovascular system and Physiology of heart

Cardiovascular systemIn order to pump blood through the

body, the heart is connect to the vascular system of the body. 

It is the closed system.It is designed to transport oxygen

and nutrients to the cells of the body and remove carbon dioxide and metabolic waste products from the body. 

Page 4: the cardiovascular system and Physiology of heart

Components of CVSHeart: It is a pump composed of 4 chambers (2 atria

& 2 ventricles.The heart provides the driving force for the

cardiovascular system.

Blood Vessels: The blood vessels are systems of tubes

including: Arteries and arterioles which carry the blood

from the heart to all parts of the body. The arteries serve as distribution channels to

the organs.

Page 5: the cardiovascular system and Physiology of heart

Components of CVS Venules and veins which carry the blood

back from the tissues to the heart. The veins serve as blood reservoirs and

collect the blood to return it to the heart.

Blood capillaries which form a network of fine vessels connecting the arterioles with the Venules.

The blood capillaries are the sites of exchange of gases (O2 & CO2), nutrients and waste products between blood and tissues.

Page 6: the cardiovascular system and Physiology of heart

Construction of CVS The cardiovascular system is

actually made up of two major circulatory systems, acting together. 

The right side of the heart pumps blood to the lungs through the pulmonary artery (PA), pulmonary capillaries, and then returns blood to the left atrium through the pulmonary veins (PV). 

The left side of the heart pumps blood to the rest of the body through the aorta, arteries, arterioles, systemic capillaries, and then returns blood to the right atrium through the Venules and great veins

Page 7: the cardiovascular system and Physiology of heart

In the cardiovascular system, blood passes through two circulations in series. One full circulation consists of these two circulations together. Both circulations start and end in the heart. These two circulations are:

 The systemic (or greater or high-pressure)circulation:

It starts in the left ventricle → the aorta → systemic arteries → systemic capillaries → systemic veins → superior and inferior vena cava → ends in the right atrium.

The pulmonary (or lesser or low-pressure) circulation:

It starts in the right ventricle → the pulmonary trunk → pulmonary arteries → pulmonary capillaries → pulmonary veins → ends in the left atrium.

Page 8: the cardiovascular system and Physiology of heart

The two circulations are in series. So, blood finishes one circulation to start the other.

This allows the whole blood volume to carry out its respiratory function more efficiently as blood goes once through the systemic capillaries and once through the pulmonary capillaries.

Thus, both ventricles must pump the same volume of blood during any significant time interval because of the series arrangement of the systemic and pulmonary circulations.

Page 9: the cardiovascular system and Physiology of heart

Systemic and pulmonary circulations

Page 10: the cardiovascular system and Physiology of heart
Page 11: the cardiovascular system and Physiology of heart
Page 12: the cardiovascular system and Physiology of heart

From an Engineering stand point, systemic circulation is a high resistance circuit with a large pressure gradient between the arteries and veins.

Heart is analogous to the pump but the analogy to pump and hydraulic piping system should not be used too discriminately.(Blood is not a pure Newtonian fluid).

Muscle contraction of the left side of heart is larger and stronger than that of right heart because of the greater pressure required for the systemic circulation.

Page 13: the cardiovascular system and Physiology of heart

a)HEART: 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.

b) BLOOD VESSELS:1) The arteries: the aorta and the pulmonary artery are elastic arteries i.e. they have the properties of stretch (=distension or compliance) and recoil.

During ventricular contraction (systole), they distend by the blood ejected into them; and energy is at load in their walls.

Basic Function of the various parts of the CVS

Page 14: the cardiovascular system and Physiology of heart

During ventricular relaxation (diastole), this energy is released causing elastic recoil of their walls, which acts as an additional pump to blood during diastole.

Thus on efficient pressure is maintained during systole and diastole, resulting in a continuous blood flow through the tissues.

2) The arterioles are resistance vessels that act as variable resistors because their diameters continuously undergo changes in order to regulate the amount of blood flow into the capillaries. Therefore, the arterioles are considered the “taps” regulating blood flow to the tissues.

.

Page 15: the cardiovascular system and Physiology of heart

3) The veins act as capacitance vessels (volume reservoir) that hold most of the blood volume.

Veins have a high distending capacity (=high compliance) and they can store or mobilize blood depending upon the underlying condition.

GENERAL FUNCTION OF THE CVS:The normal function of the CVS is to maintain homeostasis (i.e. a constant optimum internal environment). Thus, in spite of continuous metabolic activity of the tissue cells, homeostasis is maintained by continuous adequate blood flow to the tissues.

Page 16: the cardiovascular system and Physiology of heart

VEINS

CAPACITYVESSELS

HEART

80 mmHg 120 mmHg

SYSTOLE

DIASTOLE

ARTERIES (LOW COMPLIANCE)

CAPILLARIES

Page 17: the cardiovascular system and Physiology of heart

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

.

Page 18: the cardiovascular system and Physiology of heart
Page 19: the cardiovascular system and Physiology of heart
Page 20: the cardiovascular system and Physiology of heart

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 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 ventricular myocardium (wall) is much thicker and stronger than the atrial myocardium (wall). The atrial muscle (of both atria) is completely separated from the ventricular muscle (of both ventricles) by a fibrous ring called AV ring (atrioventricular ring).

Page 21: the cardiovascular system and Physiology of heart

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 and about 75% of the blood that ventricles during their diastole pass passively i.e. by its own weight.

The ventricles, on the other hand , 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.

.

Page 22: the cardiovascular system and Physiology of heart

Cardiac Valves and their functions

The human heart contains four valves

Two atrioventricular valves (AV valves) between the atria and the ventricles:- Tricuspid valve between the right atrium and the right ventricle.- Mitral or tricuspid valve between the left atrium and there left ventricle.

Two semi lunar valves:- Aortic valve between the left ventricle and the aorta.- Pulmonary valve between the right ventricle and the pulmonary trunk.

.

Page 23: the cardiovascular system and Physiology of heart

Functions of the cardiac valvesThe cardiac valves allow for the blood to pass only in one direction i.e.- The AV valves allow for the blood to pass from the atria into the ventricles during ventricular diastole. During ventricular systole, the AV valves close to prevent back flow of blood from the ventricles into the atria.- The semi lunar valves allow for the blood to pass from the ventricles into the arteries during ventricular systole. During ventricular diastole, these valves prevent back flow of blood from the arteries into the ventricles (as these valves become closed during ventricular diastole).

Page 24: the cardiovascular system and Physiology of heart

It should be noted that:a) The valves open or close depending upon the

pressure gradient of the blood on both sides of the valves e.g.

The AV valves:- Open when the atrial pressure becomes higher than

the ventricular pressure or- Close when the ventricular pressure becomes higher

that the atrial pressure. The semi lunar valves:

- Open when the ventricular pressure becomes higher than the arterial pressure and

- Close when the arterial pressure becomes higher than the ventricular pressure.

Page 25: the cardiovascular system and Physiology of heart

The right ventricle pumps relatively large volumes of blood at a low pressure through the pulmonary circulation (the right ventricle is essentially flow generator).

The normal cross-section of the right ventricle is crescent-shaped.

If the right ventricle must eject blood against a high pressure for prolonged periods (as seen in certain pulmonary diseases), it assumes a much more cylindrical appearance and there is a thickening of the right ventricular free wall (right ventricular hypertrophy).

The right ventricle

Page 26: the cardiovascular system and Physiology of heart

The left ventricle pumps blood through the systemic circulation.

It is cylindrical in shape and normally has a thicker wall than does the right ventricle.

The left ventricle works much harder than the right ventricle because of the higher pressure in the systemic circulation (the left ventricle is essentially pressure generator).

Consequently, the left ventricle is more commonly affected by disease processes than is the right ventricle.

The left ventricle

Page 27: the cardiovascular system and Physiology of heart

During ventricular systole, blood is pumped into the circulation.

During diastole, the pumping of blood stops and the ventricles get filled with blood.

In this way, the flow of blood from the ventricles into the systemic and pulmonary circulations is an intermittent pulsatile flow.

Blood flow from the heart

Page 28: the cardiovascular system and Physiology of heart

The heart of a normal adult male beats automatically and regularly at a rate of 75 beats/minute during rest. The normal range of heart rate is between 60 – 100.

The heart rate is under neural control. Cardiac sympathetic efferent activity increases the heart rate, whereas parasympathetic (vagal) efferent impulses decreases heart rate.

The stroke volume for each ventricle averages 70 ml of blood, and a normal heart rate is approximately 70-75 beats/minute; therefore, the cardiac output at rest is approximately 5 L/min.

Page 29: the cardiovascular system and Physiology of heart

Blood flow from the heart

Page 30: the cardiovascular system and Physiology of heart

Blood vessels

Page 31: the cardiovascular system and Physiology of heart

1. Elastic vessels.2. Low-resistance vessels.3. High-resistance vessels.4. Exchange vessels.5. Capacitance vessels.

Blood vessels

Page 32: the cardiovascular system and Physiology of heart
Page 33: the cardiovascular system and Physiology of heart
Page 34: the cardiovascular system and Physiology of heart

As the blood flows from the arterial to the venous side of the circulation, it meets resistance because of the smaller caliber of the vessels and the viscous nature of the blood. This is called the peripheral resistance.

It is an important factor in generating and maintaining the arterial blood pressure. Vasoconstriction of the small vessels increases the peripheral resistance, which in turn elevates the arterial blood pressure. Whilst vasodilatation decreases the resistance and lowers the pressure.

The peripheral resistance

Page 35: the cardiovascular system and Physiology of heart

Pressure Drop in the Vascular System

LARGE ARTERIES

SMALL ARTERIES

ARTERIOLES

CAPILLARIESVENULES &VEINS

MEA

N P

RESS

UR

E

INSIDE DIAMETERSMALL LARGELARGE

ELASTIC TISSUE

MUSCLE

INSIDE DIAMETER

Page 36: the cardiovascular system and Physiology of heart

Pressure Drop in the Vascular System

Page 37: the cardiovascular system and Physiology of heart

* The wall of the left ventricle is much thicker (15 mm) than the wall of the right ventricle (5 mm), yet the capacities and outputs of both ventricles are equal.

* The thickness of the ventricular wall reflects the pressure load on the ventricle. The pressure load on the left ventricle (the aortic pressure) is much higher than the pressure load on the right ventricle (the pulmonary arterial pressure).

Page 38: the cardiovascular system and Physiology of heart

Heart SoundsHeart sounds are the noises generated by the

beating heart and the resultant flow of blood through it.

Specifically, the sounds reflect the turbulence created when the heart valves snap shut.

In cardiac auscultation, an examiner may use a stethoscope to listen for these unique and distinct sounds that provide important auditory data regarding the condition of the heart.

In healthy adults, there are two normal heart sounds often described as a lub and a dub (or dup), that occur in sequence with each heartbeat.

These are the first heart sound (S1) and second heart sound (S2), produced by the closing of the AV valves and semilunar valves, respectively.

Page 39: the cardiovascular system and Physiology of heart

Functions and Characteristics of the Blood

Blood is the only liquid tissue in the body. It is a connective tissue.

Consists of formed elements (cells and cell fragments) in a liquid intercellular matrix (plasma)

Average adult blood volume is around 5 liters (8% of body weight)

Page 40: the cardiovascular system and Physiology of heart

Blood Functions

Transportation: Blood transports oxygen and nutrients to cells, CO2 and waste away from cells, hormones to target tissues

Regulation: Helps maintain stable body temperature, pH, water and electrolyte levels

Protection: Clotting prevents fluid loss, white blood cells protect body against disease

Page 41: the cardiovascular system and Physiology of heart