Clinical Methods and Communication
Examination of the Cardiovascular System – 10 hours
Unit Outline
1) Review of anatomy and physiology - 2 hours
2) History taking - 1 hour
3) Introduction and general examination - 2 hours
4) Inspection and Palpation - 2 hours
5) Percussion and Auscultation - 2 hours
6) Investigations and therapeutic procedures - 1 hour
Topic 1: Review of Anatomy and Physiology
Objectives
At the end of the lesson the learner will be able to: -
1) Describe the structure of the organs of the cardiovascular system
2) Describe the functions of the cardiovascular system
3) Explained the functional organization of the cardiovascular system
1.0 Introduction
The Circulatory system is a continuous circuit comprising of the cardiovascular system (heart and blood
vessels) and lymphatic system (lymph vessels, lymph nodes and lymphoid-organs -spleen, thymus and
tonsils). Blood serves numerous functions including the transport of respiratory gases, nutritive molecules,
metabolic wastes and hormones. Blood is transported through the body in a system of vessels leading from
and returning to the heart.
Figure 1.1: The Cardiovascular system
subdavian vein \'rt-subclav,ao artery
�e-----pulmonary vein
left a1rium
right vootride
A�i--f--t>epaUc artery
gastric vein ,tf----------aorta
veoa cava ---------+ gastnc artery
h-�c PQ1'1
al -n --f-f-1--:::
&mal lnteau,..
,..,al vein reoal artery
�iac vein 11,ac artery
Page 1
,2.0 Functions of the Circulatory System
1) Transportation
Respiratory - red blood cells (erythrocytes) transport oxygen to tissue cells and carbon dioxide is
transported by blood to the lungs foe elimination
Nutritive - blood carries absorbed products of digestion through the liver to body cells
Excretory - metabolic wastes, excessive water and ions are filtered through the capillaries of the
kidney and excreted in urine
2) Regulation
Blood carries hormones and other regulatory molecules from the site of origin to target tissues
3) Protection
Protects against injury and foreign microbes or toxins
Clotting mechanism prevents blood loss when vessels are damaged
Leucocytes (white blood cells) provide immunity
THE CARDIOVASCULAR SYSTEM
Is made up of the heart and blood vessels
The Heart
The heart is a four chambered; double pump that keeps blood flowing through the circulation and a normal
heart weighs 250 – 350 g in an adult. Its pumping action creates the pressure needed to push blood in the
vessels to the lungs and body cells. The function of the heart is to pump sufficient oxygenated blood
containing nutrients, metabolites and hormones to meet the moment to moment metabolic needs and
preserve a constant milieu. The flow of blood through the circulatory system is made possible by the
pumping action of the ventricles and atria
Figure 2: The Heart
Pulmonary Mary
Left Atrium
M1tral valve
Left Venlride
lntenor
Vena Cava
Right Ventricle Papillary Muldes
Page 2
,The Heart Pump
The heart has 2 main pumps that operate as connected in series i.e. the left pump (for the peripheral
organs) and the right pump (for the lungs). The right and left pumps are separated by a muscular wall
(septum) which prevents mixing of blood from the two sides of the heart. Each pump has 2 chambers (the
ventricle and the atria). In detail the heart has 4 pumps of which 2 are primer pumps (the atria) and 2
power pumps (the ventricles). The atria receive blood from the venous system then pump it into the
ventricles which pump blood into the arterial system.
The Heart Valves
Normal functioning of the heart depends on the mechanical efficiency of the 4 valves namely aortic valve,
mitral valve, tricuspid valve and pulmonary valve. The atrioventricular valves (mitral and tricuspid
valves) consist of 4 kinds of structures namely an annulus ring, cusps, papillary muscles and chordae
tendinae. Normal functioning depends on the mechanical efficiency of the cusps, chordae tendinae,
papillary muscles, pliability and size of the fibrous ring or annulus and adequacy of left ventricular
contraction. The semi-lunar valves (aortic and pulmonary valves) each consist of 2 kinds of structures
namely an annulus and semi-lunar cusps
The Conducting System
The contraction and relaxation of the heart‟s musculature is highly coordinated during the cardiac cycle.
The coordination is controlled by a system of highly specialized myocardial cells (the conducting system).
The conducting system provide a nodular cluster of cells which initiate the conduction signal and supplies
cellular tracts to propagate this signal through the atria and ventricular musculature. The 3 parts of the
conducting system found in the walls of the right atrium are: - sino-atrial node (SAN), the internodal tracts
and atrio-ventricular node (AVN). The atrioventricular (AV) bundle (bundle of his) is a tract of cells
originating from the AV node and passing through an opening in the fibrous annulus of tricuspid valve
extending through the membranous part of the inter-ventricular septum. At the boarder between
membranous and muscular parts of the inter-ventricular septum it divides into 2 major branches (left and
right bundle branches). Purkinje fibres are the terminal cells of the conducting system in both ventricles.
They are very large diameter cells whose terminal process ends in the sub-endocardial myocardium.
Transmit the contraction signal directly to the sub-endocardial myocardium of the ventricular walls
Functioning of the Heart
It has 2 essential characteristics of contractility and rhythmicity
Is a pumping organ whose physiological function is maintained by healthy muscles, efficient Heart
valves, efficient conducting system and coordination of the chambers and normal peripheral resistance
Has 3 major types of cardiac muscle - atrial, ventricular and specialized excitatory and conductive
muscles
The Atrial and ventricular muscle types contract as skeletal muscles but the duration of contraction is
much longer
The specialized excitatory and conductive fibres contract feebly but have rhythmical properties and
rapid conduction
The cardiac muscles as a syncytium
o Comprises of many cells connected in series with intercalated discs(contain specialized structures)
separating the cells
o The special structures are: -
Page 3
, Facia adherens that give the mechanical links
Mucula adherens(desmosome) the site for cytoplasmic filaments and is the lattice structure for
the cell
Gap junction which makes adjacent cells close and allows low permeability of ions through the
membrane prolonging the electrical signal
The heart is composed of 2 separate syncytium namely the atrial and ventricular which are separated
by fibrous tissue
Energy for contraction
The coronary blood flow is 0.8ml/min/g
Arterial oxygen content is 180ml/L
Coronary sinus oxygen content is 68ml/L(oxygen saturation of 37% and PCO2 = 25mmHg)
The heart weighs 300mg therefore oxygen consumption is 27ml/min for the whole heart or 0.09/ml/g
68 x 37 = 27.16(27ml/min) = 27/300 = 0.09/ml/g/min
100
The oxygen utilized in the mitochondria to generate ATP which is transported across the mitochondria
membrane
Calcium
When sufficient ATP is present, contraction of the cardiac muscle is brought about by changes in
concentration of calcium within the cell
All or Nothing Principle
Due to syncytial and interconnecting, stimulation of any single atrial muscle fibre causes the action
potential to travel over the entire muscle mass. The same holds for the ventricles
If the A-V bundle is intact the action potential spreads from the atria to the ventricles (All Or Nothing
Principle)
Action Potentials in Cardiac muscle
The resting membrane potential of normal cardiac muscle is -85 t0 –95mV and for the specialized
areas is –90 to –100mV
Action potential of ventricular mass of +105mV indicates a rise from the normal very negative( -85mV
to –95Mv) value to slight positive value of +20mV( -85Mv + 105Mv = +20mV).This change of potential
from –ve to +ve , the positive portion is called overshoot potential
After the initial spike, the membranes remain depolarized (0.2 sec for the atria and 3.0sec for
ventricles) exhibiting a plateau
The plateau in the action potential causes contraction to last 20 to 50 times longer than the skeletal
muscles
The action potential for cardiac muscle is long and has a plateau because:
1. Skeletal muscles action potential is caused by sudden opening of sodium channels which remain
open for a short time whereas in the cardiac muscle the action potential is caused by 2 types of
channels
Fast sodium channels
Page 4
Examination of the Cardiovascular System – 10 hours
Unit Outline
1) Review of anatomy and physiology - 2 hours
2) History taking - 1 hour
3) Introduction and general examination - 2 hours
4) Inspection and Palpation - 2 hours
5) Percussion and Auscultation - 2 hours
6) Investigations and therapeutic procedures - 1 hour
Topic 1: Review of Anatomy and Physiology
Objectives
At the end of the lesson the learner will be able to: -
1) Describe the structure of the organs of the cardiovascular system
2) Describe the functions of the cardiovascular system
3) Explained the functional organization of the cardiovascular system
1.0 Introduction
The Circulatory system is a continuous circuit comprising of the cardiovascular system (heart and blood
vessels) and lymphatic system (lymph vessels, lymph nodes and lymphoid-organs -spleen, thymus and
tonsils). Blood serves numerous functions including the transport of respiratory gases, nutritive molecules,
metabolic wastes and hormones. Blood is transported through the body in a system of vessels leading from
and returning to the heart.
Figure 1.1: The Cardiovascular system
subdavian vein \'rt-subclav,ao artery
�e-----pulmonary vein
left a1rium
right vootride
A�i--f--t>epaUc artery
gastric vein ,tf----------aorta
veoa cava ---------+ gastnc artery
h-�c PQ1'1
al -n --f-f-1--:::
&mal lnteau,..
,..,al vein reoal artery
�iac vein 11,ac artery
Page 1
,2.0 Functions of the Circulatory System
1) Transportation
Respiratory - red blood cells (erythrocytes) transport oxygen to tissue cells and carbon dioxide is
transported by blood to the lungs foe elimination
Nutritive - blood carries absorbed products of digestion through the liver to body cells
Excretory - metabolic wastes, excessive water and ions are filtered through the capillaries of the
kidney and excreted in urine
2) Regulation
Blood carries hormones and other regulatory molecules from the site of origin to target tissues
3) Protection
Protects against injury and foreign microbes or toxins
Clotting mechanism prevents blood loss when vessels are damaged
Leucocytes (white blood cells) provide immunity
THE CARDIOVASCULAR SYSTEM
Is made up of the heart and blood vessels
The Heart
The heart is a four chambered; double pump that keeps blood flowing through the circulation and a normal
heart weighs 250 – 350 g in an adult. Its pumping action creates the pressure needed to push blood in the
vessels to the lungs and body cells. The function of the heart is to pump sufficient oxygenated blood
containing nutrients, metabolites and hormones to meet the moment to moment metabolic needs and
preserve a constant milieu. The flow of blood through the circulatory system is made possible by the
pumping action of the ventricles and atria
Figure 2: The Heart
Pulmonary Mary
Left Atrium
M1tral valve
Left Venlride
lntenor
Vena Cava
Right Ventricle Papillary Muldes
Page 2
,The Heart Pump
The heart has 2 main pumps that operate as connected in series i.e. the left pump (for the peripheral
organs) and the right pump (for the lungs). The right and left pumps are separated by a muscular wall
(septum) which prevents mixing of blood from the two sides of the heart. Each pump has 2 chambers (the
ventricle and the atria). In detail the heart has 4 pumps of which 2 are primer pumps (the atria) and 2
power pumps (the ventricles). The atria receive blood from the venous system then pump it into the
ventricles which pump blood into the arterial system.
The Heart Valves
Normal functioning of the heart depends on the mechanical efficiency of the 4 valves namely aortic valve,
mitral valve, tricuspid valve and pulmonary valve. The atrioventricular valves (mitral and tricuspid
valves) consist of 4 kinds of structures namely an annulus ring, cusps, papillary muscles and chordae
tendinae. Normal functioning depends on the mechanical efficiency of the cusps, chordae tendinae,
papillary muscles, pliability and size of the fibrous ring or annulus and adequacy of left ventricular
contraction. The semi-lunar valves (aortic and pulmonary valves) each consist of 2 kinds of structures
namely an annulus and semi-lunar cusps
The Conducting System
The contraction and relaxation of the heart‟s musculature is highly coordinated during the cardiac cycle.
The coordination is controlled by a system of highly specialized myocardial cells (the conducting system).
The conducting system provide a nodular cluster of cells which initiate the conduction signal and supplies
cellular tracts to propagate this signal through the atria and ventricular musculature. The 3 parts of the
conducting system found in the walls of the right atrium are: - sino-atrial node (SAN), the internodal tracts
and atrio-ventricular node (AVN). The atrioventricular (AV) bundle (bundle of his) is a tract of cells
originating from the AV node and passing through an opening in the fibrous annulus of tricuspid valve
extending through the membranous part of the inter-ventricular septum. At the boarder between
membranous and muscular parts of the inter-ventricular septum it divides into 2 major branches (left and
right bundle branches). Purkinje fibres are the terminal cells of the conducting system in both ventricles.
They are very large diameter cells whose terminal process ends in the sub-endocardial myocardium.
Transmit the contraction signal directly to the sub-endocardial myocardium of the ventricular walls
Functioning of the Heart
It has 2 essential characteristics of contractility and rhythmicity
Is a pumping organ whose physiological function is maintained by healthy muscles, efficient Heart
valves, efficient conducting system and coordination of the chambers and normal peripheral resistance
Has 3 major types of cardiac muscle - atrial, ventricular and specialized excitatory and conductive
muscles
The Atrial and ventricular muscle types contract as skeletal muscles but the duration of contraction is
much longer
The specialized excitatory and conductive fibres contract feebly but have rhythmical properties and
rapid conduction
The cardiac muscles as a syncytium
o Comprises of many cells connected in series with intercalated discs(contain specialized structures)
separating the cells
o The special structures are: -
Page 3
, Facia adherens that give the mechanical links
Mucula adherens(desmosome) the site for cytoplasmic filaments and is the lattice structure for
the cell
Gap junction which makes adjacent cells close and allows low permeability of ions through the
membrane prolonging the electrical signal
The heart is composed of 2 separate syncytium namely the atrial and ventricular which are separated
by fibrous tissue
Energy for contraction
The coronary blood flow is 0.8ml/min/g
Arterial oxygen content is 180ml/L
Coronary sinus oxygen content is 68ml/L(oxygen saturation of 37% and PCO2 = 25mmHg)
The heart weighs 300mg therefore oxygen consumption is 27ml/min for the whole heart or 0.09/ml/g
68 x 37 = 27.16(27ml/min) = 27/300 = 0.09/ml/g/min
100
The oxygen utilized in the mitochondria to generate ATP which is transported across the mitochondria
membrane
Calcium
When sufficient ATP is present, contraction of the cardiac muscle is brought about by changes in
concentration of calcium within the cell
All or Nothing Principle
Due to syncytial and interconnecting, stimulation of any single atrial muscle fibre causes the action
potential to travel over the entire muscle mass. The same holds for the ventricles
If the A-V bundle is intact the action potential spreads from the atria to the ventricles (All Or Nothing
Principle)
Action Potentials in Cardiac muscle
The resting membrane potential of normal cardiac muscle is -85 t0 –95mV and for the specialized
areas is –90 to –100mV
Action potential of ventricular mass of +105mV indicates a rise from the normal very negative( -85mV
to –95Mv) value to slight positive value of +20mV( -85Mv + 105Mv = +20mV).This change of potential
from –ve to +ve , the positive portion is called overshoot potential
After the initial spike, the membranes remain depolarized (0.2 sec for the atria and 3.0sec for
ventricles) exhibiting a plateau
The plateau in the action potential causes contraction to last 20 to 50 times longer than the skeletal
muscles
The action potential for cardiac muscle is long and has a plateau because:
1. Skeletal muscles action potential is caused by sudden opening of sodium channels which remain
open for a short time whereas in the cardiac muscle the action potential is caused by 2 types of
channels
Fast sodium channels
Page 4
