Cardiovascular system:-

The cardiovascular system consists of the heart, blood vessels, and

blood.
• Its primary function is to transport nutrients and oxygen-rich
blood to all parts of the body and to carry deoxygenated blood
back to the lungs.

Components of the cardiovascular system:-

• The cardiovascular system consists of the heart, veins, arteries,
and capillaries.
• The heart: A muscular pump that forces blood around the body.
• A closed system of blood vessels: These vessels include:
o Arteries: Vessels that carry blood away from the heart.
o Veins: Vessels that bring blood back to the heart.
o Capillaries: Tiny vessels that branch off from arteries to
deliver blood to all body tissues.
 • The heart is divided into 4 chambers
They are
1. Right Artium
2. Right Ventricle
3. Left Artium
4. Left Ventrium
• Heart has four valves.
1.Tricuspid valve
2.Mitral Valve
3.Pulmonary valve
4.Aortic Valve

1. Tricuspid valve: It ensures blood flow in one direction from

the right atrium to the right ventricle and prevents backflow.
2. Mitral Valve: Allows blood flow from the left atrium to the
left ventricle
3. Pulmonary valve: It ensures the blood flows in one direction
that is from heart to lungs. RV to pulmonary artery and
prevents backflow.
4. Aortic Valve: Door between the left ventricle and the aorta .It
ensures blood flow in one direction from heart to the rest of
the body.

Common conditions that can affect the cardiovascular system

include coronary artery disease, heart attack, high blood
pressure, and stroke.

The heart works as two pumps; one on the right side and other on the
left side.
Blood flows from right atrium to right ventricle and it is pumped to
the lungs to receive oxygen.
From lungs, the blood flows through the left atrium, then to the left
ventricle and from there it is pumped to the other parts of the body.
 Respiratory System:-
The respiratory system is made up of the organs included in the
exchange of oxygen and carbon dioxide. The respiratory system is
divided into two areas: the upper respiratory tract and the lower
respiratory tract.
The upper respiratory tract is made up of the:
• Nose
• Nasal cavity
• Mouth
• Sinuses
• Throat (pharynx)
• Voice box (Larynx)
• Windpipe (trachea)

The lower respiratory tract is made up of the:

• Lungs
• Large airways (bronchi)
• Small airways (bronchioles)
• Air sacs (alveoli)
 • The respiratory system in the human body acts as pump which
creates positive and negative pressure in the thorax cavity.
• The air is sucked into and forced out of from the lungs.
• The lungs are connected to outside environment through a
passage way consists of nasal opening, Pharynx, Larynx,
Trachea, Bronchi, and Bronchioles.
• Oxygen is taken into blood from the air.
• CO2 is transferred from blood to air.
• The exchange of oxygen and carbon dioxide takes place in
alveoli.

Nervous System:-
The nervous system is a control and communication network for the
body which coordinates the functions of various organs.
Rapid communication between various body parts and contraction of
muscles are controlled by nervous system. That is the nervous system
is the most complex system in the human body.

Central nerve system consists of brain and spiral cord.

The brain consists of 3 parts
1. Cerebrum
2. Cerebellum
3. Brain stem

Cerebrum consists of two hemispheres

The left hemisphere is divided into frontal lobe and temporal lobe.
The right hemisphere is divided into parietal lobe and occipital lobe.
The frontal lobe is essential for intelligence and imagination.
The outer layer of brain is called cerebral cortex.
All sensory inputs from various parts of the body reach the cortex.

Cerebellum
The cerebellum acts as a microcomputer.
It enables a person to maintain his body balance.

Brain Stem:
Brain stem connects spinal cord to the central of the brain. Medulla
Oblangetta is the lowest section of the brain.
Spinal cord:
It consists of a cylinder of nerve tissue about the thickness of our little
finger and has a length of 38-45 cm.
The cord consists of white matter on the surface and grey matter
inside.

Structure of Neuron:-

• The basic functional unit of nervous system is called neuron.

• Neuron consists of a cell body and its branches named as axon
and dendrites.
• The dendrites normally conduct impulses towards the cell and
axons conduct impulses above from the cell.

Sources of bio-electric Potential:-

Bioelectric potentials are voltages produced by electrochemical

activity in cells. Certain excitable cells like nerve and muscle cells
maintain a resting potential across their semi-permeable membranes
due to ion concentration differences.
At rest, the inside of the cell is negatively charged compared to
outside. When a cell is activated, sodium ions rush in, depolarizing
the membrane. The cell then repolarizes as sodium ions are pumped
back out and potassium ions move out.
This action potential can propagate along the cell to transmit
signals. Transducers convert these ionic potentials into electrical
signals that can be measured.

Bioelectric potentials are actually ionic voltages produced as a

result of electro chemical activity of certain cell such as nerve cells
and muscle cells.
Eg:-ECG, EEG, EMG
Transducers are used to convert these ionic potentials into electrical
signals

Resting and Action potentials

Certain types of cells within the body, such as Nerve and muscle
cells are encased in a semi permeable membrane.
This membrane permits some substances to pass through while
others are kept out.
Surrounding the cells of the body are the body fluids
These fluids are conductive solutions containing charged atoms
Known as ions. The principal ions are sodium (Na+), Potassium (k+)
and chloride(Cl-).
Cell membrane allows K+ and chloride Cl- to enter inside but blocks
the Na+
Because of more Na+ outside and k+ and chloride Cl- inside. Due
to less k+, outside cells shows + and inside is -

Resting potentials/Polarization
This resting potential ranging from -60mv to-100 mv.
Cell in the resting state is called polarized cell.

Depolarization of cell
When a cell is exited, the membrane change its characteristic
The sodium ions are rushed in to the cell
At the same time potassium ions try to move from inside
After a equilibrium state is reached, the sodium is moved back to
outside

Action potentials

Repolarization
Cell comes from depolarized state in to polarized state and is
called Repolarization.
Propagation of Action potentials
When a cell is exited and generates an action potential ionic
currents tend to flow.
This process excites neighbouring cell or adjacent area of the same
cell.

Electrodes:-
Electrodes are devices that convert ionic potential into electronic
potential.
Surface electrodes / Limb electrodes
Needle electrodes
Micro electrodes

Electrodes used for ECG measurements:

1. Surface electrodes/Limb electrodes: - These are placed in contact

within the skin in order to obtain bioelectric potentials from the body
surface.
The materials used are germanium silver, Nickel silver and nickel
plated steel.
They are applied to the surface of the body with electrode gell.
The size of limb electrode is usually 3x5 cm
These electrodes are preferable during surgery because patient’s limbs
are immobile during surgery.

2. Floating electrode:
Here the metal electrode does not make direct contact with the skin.
The electrode consists of a metal plate and flat washer which is
connected to the skin.

3. Pregelled Disposable electrode:

The advantages of using disposable electrodes are smaller in size, no
risk of skin infection and less time is required for attaching or
detaching.
4. Suction electrodes.
5. Paste less electrodes.

Electrodes used for EMG measurements:

Needle electrodes are used for the recording of EMG

The material used is stainless steel
Needle electrodes must be sterilised before the usage.
To reduce the interface and noise caused due to electrode movement,
during the measurement of EEG, EMG etc.

One of the main advantages of needle electrode is that they are less
susceptible to movement errors than surface electrodes. Also the
needle electrodes have lower impedance when compared to surface
electrodes as it makes direct contact with the sub-dermal tissues or
intracellular fluid.

Microelectrodes:-

These are used to study the electrical activity of individual cells.

These are small in size with respect to the size of the cells.
These electrodes penetrate into cells and do not damage the cells.
Tip size is ranging from 0.5-5 micro meter. The main functions of
microelectrodes are potential recording and current injection. These
electrodes are having impedances in mega ohm range because of their
smaller size.

Two types of micro electrodes are

1. Metallic electrode
2. Micropipette electrode.
Used to measure the potential within the cell
Instead of metal electrolyte, non- metallic materials is used
Fabricated from glass capillaries.
Biomedical recorders:-
1. ECG (Electrocardiogram)
2. EEG (Electroencephalogram)
3. EMG (Electromyogram)

Electro Cardiogram:-
ECG is an instrument which records the electrical activity of heart.
It provides information about cardiac disorders.
ECG provides a voltage difference of mV range and frequency range
of .05Hz to 150Hz

The potentials picked up by patient electrodes are connected to lead

selector. The output of lead switch is given to preamplifier and finally
given to pen recorder, which moves the pen on to the paper.
Significance of ECG waveform:-
The ECG signal has many features such as P-wave, QRS-complex
wave, T-wave.
The amplitude, shape and relative timing of these features can be used
to diagnose different heart conditions.
ECG Leads:-

Two electrodes placed over different areas of the heart a potential

difference is produced across the electrodes.
For example if an electrode generates a waveform of 1millivolt and
another electrode generates a waveform of 0.2 milli volt then the
result in ECG waveform will have an amplitude of .8milli volt. This
voltage difference is called lead.
There are two types of lead systems.
1. Unipolar: ECG is recorded between a reference electrode and any
other electrode.
2. Bipolar: ECG is recorded by using only 2 electrodes.

EEG:
EEG is an instrument for recording electrical activity of brain. The
electrodes are placed on the scalp. It is used to diagnose many
neurological diseases like tumour, epilepsy etc. EEG electrodes are
smaller than ECG electrodes. The brain waves are picked up and
recorded. Brain waves are the summation of neural depolarization in
the brain due to stimuli from 5 senses as well as from the thought
process on the surface of the brain. Frequency range of EEG is 0.1 Hz
to 100 Hz out of which the diagnostically useful frequency range 0.5
Hz to 70 Hz. Typical signal voltage of EEG is of 50 milli volts.
During recording electrodes are placed around the frontal, parietal,
temporal and occipital lobes.

There are two types of EEG reading.

Bipolar and unipolar.
In bipolar recording voltage difference between two scalps electrodes
are measured.
In unipolar the voltage difference between a reference electrode
(Placed on ear lobe) and a scalp electrode is measured.

EEG electrodes are arranged on the scalp according to a standard

known as 10 to 20 systems that is a total of 21 electrodes are used.
The voltage range of EEG signal is in microvolt.
EEG Recorder Unit:
The block diagram of EEG recorder is shown below. It consists of
four units.

Block diagram of EEG System consists of:

Electrode selector and calibrate unit:

• Montage • Electrode Montage selector • Calibrate
Amplifier unit:
• Filter • Sensitivity
Output Recorder: • Chart drive • Ink – writing oscillograph
Display unit: • Computer • Oscilloscope
Montages: A pattern of electrodes on the head on the channels are connected
together is called Montage. Montage is always symmetrical. EEG electrodes are
arranged on the scalp according to a standard known as 10/20 system adopted
by American EEG society. But these are 21 electrode locations, in 10/20
system.
Electrode Montage selector: EEG signals are transmitted from the electrodes to
the head box and then to the montage selector. Montages are either Bipolar or
Referential. Bipolar montage is made by the subtraction of signals is from the
adjacent electrode pairs. Referential montage is made by subtracting the
potential of a common reference electrode from each electrode on the head.

Preamplifier: The preamplifier must have high gain and low noise
characteristics because the EEG potentials are small in amplitude. The amplifier
must have very high CMMR to minimize stray interference signals from power
lines and other electrical equipment.

Sensitivity Control: The overall sensitivity of an EEG machine is the gain of the
amplifier multiplied by the sensitivity of the writer. The writer sensitivity is
1cm/v, therefore the amplifier must have an overall gain of 20,000 for a 50µv
signal.

EEG machine has two types of gain, one is continuously variable, used to
equalize the sensitivities of all channels. The other control operates in steps, it is
used to increase or reduce sensitivity of a channel by known amount. This
control is usually calibrated in decibels.

Filters: An EEG contains muscle artifacts to contraction of the scalp and neck
muscles which over lie the brain and skull. The upper cut-off frequency can be
controlled by using high frequency filters. Some EEG have a notch filter
sharply turned to 50Hz to eliminate mains frequency interference.

Writer Unit: The writer unit of an EEG is usually of the ink type direct writing
recorder. The best types of pen motors used in EEG have a frequency response
of about 90Hz. For some special applications, the frequency response is about
1000Hz. Modern PC based machine give a printout from a laser printer

Paper drive: In direct writing recorders, the paper drive provided by a

synchronous motor. An accurate and stable paper drive mechanism is necessary
in normal practice, several paper speeds are available for selection. Speeds of
15, 30 and 60mm/s are essential.

Channels: The electrodes are connected to separate amplifiers and writing

system commercial EEG machines have up to 32 channels, although 8 or 16
channels are more common.

Output Unit: Microprocessors are now employed in most of the commercially

available EEG’s permit customer programming montage selection. These
EEG’s also include a video monitor screen to display the selected pattern as
well as position of scalp sites with electrode to skin contact.
Modern EEG’s are mostly PC based with a Pentium processor. The
system can store up to 40 hours of EEG and displayed on 43cm color monitor.
The user interface is through an ASCII keyboard and the output is available in
the hard copy form through laser printers.

EEG Wave Analysis:

EEG wave analysis helps physicians to diagnose the level of consciousness,
sleep disorders, brain tumours, epilepsy and multiple sclerosis. The waves on
the surface of the brain may be as large amplitude as 10mv.
But waves recorded from the scalp have smaller amplitude of approximately
100μv.
The frequencies of brain waves range from 0.5 to 100Hz.
The character of brain wave is highly dependent on the degree of activity of
cerebral cortex.
EMG:-
It is an instrument used for recording the electrical activity of muscles is determined whether the
muscle is contracting or not.
EMG is used for the study of neuron function.
It is usually recorded by using surface electrodes or needle electrodes.
These electrodes pick up the potentials produced by the muscle.
This signal can be amplified and displayed on the screen of an oscilloscope.
It is also applied to a loudspeaker; a trained EMG expert can diagnose various muscular disorders
by listening to the sound.

EMG recording instruments includes audio amplifier and loud speaker to permit
the operator to hear.
• The audio presentation helpful in placement of needle or wire electrodes into a
muscle.
• The oscilloscope displays EMG waveform.
• The tape recorder is used to study of EMG sound waveforms.