Biomedical Instrumentation

CHAPTER 1 FUNDAMENTALS OF MEDICAL INSTRUMENTATION PHYSIOLOGICAL SYSTEM OF THE BODY:The physiology of human system of the body and source of biomedical system are shown in fig. Inside the human body one can find electrical, mechanical, thermal, hydraulic, pneumatic, chemical & various other types of system, each of which communicates with an external environment & internally with the other system of the body. The integrated operation of all these system & their various sub systems help to sustain life learn to perform useful task. The functional system of the body are the nervous system the cardiovascular system & pulmonary system. The major system communicates with each other as well as external environment. The major physiological system of the body are given below. 1. Cardiovascular system 2. Respiratory system 3. Nervous system 1. CARDIOVASCULAR SYSTEM:- The cardiovascular system helps in blood circulation

from heart to body parts & vice versa there heart plays an important role it acts as hydraulic h ydraulic pump & circulate the blood through a complex network of blood vessel. This is subdivided into two parts. (a.) Heart & (b.) Circulatory system (a.) HEART:- It has four walls. i.e. TRICUSPID VALVE, PULMONARY VALVE, BISCUSPID VALVE, AORTIC VALVE. WORKING OF HEART:- The deoxygenated blood i.e. blood with CO2 & waste transported to right atrium through vena cava. Similar with the oxygen reach blood from lungs transported to the left atrium. Due to this pressure develop d evelop in right and left atrium which opens tricuspid valve of right heart & bicuspid valve of left side. At this situation S.A. S .A. NODE generate an electrical signal which is propagated through muscles of atrium. Due to excitation of atrium muscles both the atrium contracted & thus CO2 blood reached into right ventricle & O 2 reached blood into left ventricle. This is the first phase of blood circulation known as diastole process because of A.B. NODE the electrical signal delays for .12 sec. to

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ensure that the muscles of atrium contracted successfully after delay signal propagated through ventricular muscles rapidly through bundle of hiss & perking n/w. Due to this muscles of ventricle are excided at contracted. Thus deoxygenated blood from right ventricle transported to lungs to pulmonary pulmonar y artery to valve. Similarly the O2 reach blood from left ventricle transported to body tissue & cells through aortic valve, aorta, arteries, capillaries.







(b.) CIRCULATORY SYSTEM:- It is of two types (i.) PULMONARY CIRCULATION:- Deoxygenated blood circulated from body tissue to heart in this case the capillaries collect CO2 & waste from body tissue & transport tra nsport towards heart. The deoxygenated blood enter into right atrium through superior and inferior vena-cava. After diastole & systole process deoxygenated de oxygenated blood transported from right atrium to right ventricle to lungs through pulmonary arteries. (ii.) SYSTEMATIC CIRCULATION:- This is the circulation of O 2 reach blood from heart to body tissue. In this case the oxygen reach blood transported to body parts from left atrium to left ventricle, left ventricle to aorta, aorta to arteries & provide oxygen and nourishment to body tissue & cells through capillaries. (2.) RESPIRATORY SYSTEM:- This is pneumatic system in which air pump diaphragm alternatively create positive and negative pressure in a related chamber known as thoracic cavity air to force out and suck into pair of elastic bags known as lungs. The respiration is nothing but acquiring O2 from environment & eliminating CO2 from body. Respiration is the entire process of inhaling O2 from the environment & transporting O 2 to the cell removing CO 2 from cells & exhausting this waste product into the atmosphere. (a.) INTERNAL RESPIRATION:- It is exchange of gases between blood stream (capillaries) through out the body except lungs. (b.) EXTERNAL RESPIRATION:- It is exchange of gases between blood stream, lungs environment.







SEQUENCE OF EXTERNAL RESPIRATION:INSPIRATION

EXPIRATION

O2+CO2+N

CAPILLARIES

ENVIRONMENT

ALVEOLI

NASALOPENINA

BRANCHIOLES

PHARYNX

BRONCHI

LARYNX

TRACHEA

TRACHEA

LARYNX

BRONCHI

PHARYNX

BRANCHIOLES

NASALOPENINA

ALVEOLI

ENVIRONMENT

CAPILLARIES

CO2+O2+N

The lungs are connected to external environment through alveoli, bronchioles, bronchi, trachea, larynx, pharynx, nasalopenina. The wind pipe that is trachea is divided into two parts called as bronchi, bronchi is connected to right & left lungs. Bronchi are again divided into no. of bronchioles to circulate air inside the lungs. All the bronchioles & into tiny air spaces known as alveolies. Alveolies are used to trap the air & allow exchange of O2 & CO2. Total respiratory system is controlled by brain or nervous system. (3) NERVOUS SYSTEM:- The nervous system is the control & communication N/W of human body it control all the activities of organs of human body and keep coordination between various system of body. The centre of this control system & communication N/W is brain so the brain is called as central processing unit of human body & the brain with memory, decision making capability & computational power is known as physiological microcomputer system. Nervous







(1) CENTRAL NERVOUS SYSTEM:(i) BRAIN:- An large collection of cell bodies & fibres inside the skull is known as brain. It is protected from shock, light, chemical or temperature. The lower set of the brain is connected

with the spinal cord. Brain is divided into 3 parts. (a.) CEREBRUM:- This part of brain helps for decision making, hearing intelligence. (b.) CEREBELLUM:- It is the physiological microcomputer system of the body. It enables a person to make the body balance. (c.) BRAIN STEM:- It connect to spinal cord to mid brain. SPINAL CORD:- It is the continuous of medulla from brain to first lumber. It consist of cylinder of nervous of thickness 1 cm. It consist of white metal on the surface and grey metal inside. Show white metal maintain link between brain and rest of the body. The grey metal are neurons which control reflex action. This reflex action is due to stemullus applied to tissue. NEURON:- Neuron is basic unit of the nervous system neuron is also known as soma. A neuron is a single cell which cell body having one or more dendrites i/p fiber & the axon than this along transmitting fiber.







Cell body

axon im ulse dendrite









CHAPTER 2 BIOMEDICAL ELECTRODES In human body there are various types of cells, some special cells are used for generating ionic potential, it is also called bioelectric potential. The sources of bioelectric potential are brain b rain activity, heartbeat, muscles activity & nerve condition. Special type of cell such as nerve & muscle cells of human body are encased in a semipermeable membrane. This semipermeable membrane permits some substance to pass through while other are not permitted. +

+

-

The primary ions are responsible to produce ionic potential are Na , K , Cl . The semipermeable membrane has a characteristics which allow K+ & Cl- ions to move inside where as Na+ are restricted. +

(1) RESTING POTENTIAL:- The concentration of Na ions inside the cell become much + lower then in the inter cellular fluid outside. outs ide. The Na ions are +ve, therefore this makes outside the cell more +ve then the inside. In attempt to balance the electric charge the additional K+ ions which are +ve, enter the same is shown in fig







Hence equilibrium is achieved with a potential difference across the membrane. The inside of the cellk is negative & outside is positive. This membrane potential called the resting potential. The resting potential ranges from -60 mv to -100 mv. The second fig. b. illustrates the resting potential, a cellk in the resting state is said to be polarized.

fig. b. A polarized with the resting potential. (2.) ACTION POTENTIAL:- When ionic current is applied to the cell at resting condition. It is excited and semipermeable membrane changes its property that is it allow Na+ ions to move inside. +

Due to this all Na ions rush inside the membrane. This ionic imbalance to is formed inside the







Fig. c. Depolarization of cell.







fig. e. A depolarized cell showing an action potential.

BIOELECTRODES :- Electrodes which are used to measure biological parameter or bioelectric event from a living system are known as bio electrodes. In biomedical most of electrodes are surface electrodes. Hence to reduce movement (artifacts) and to have sufficient contact a layer of conducting jelly known as electrolyte electrode and body surface. Thus we have a dual interface







































Biomedical Instrumentation

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