Biofísica Mecânica e Eléctricadei-s1.dei.uminho.pt/pessoas/pmendes/biofisica/downloads/...Biofísica mecânica e eléctrica–2. 2 • Biofísica eléctrica do nervo e do músculo

Biofísica mecânica e eléctrica – 2. 1

Aula 2

Licenciatura em Engenharia Biomédica

- RAMO II: Electrónica Médica-

Paulo Mateus Mendes

http://dei-s1.dei.uminho.pt/pessoas/pmendes

Outubro de 2005

Biofísica Mecânica e Eléctrica


• Biofísica eléctrica do nervo e do músculo.• Condução eléctrica num tecido excitável.• Modelo quantitativo do nervo e músculo incluindo

as equações de Hodgkin-Huxley.• Mapeamento biopotencial. • Electrofisiologia cardíaca.• Estimulação funcional eléctrica.

1. Jaakko Malmivuo & Robert Plonsey: Bioelectromagnetism - Principles and Applications of Bioelectric and Biomagnetic Fields, Oxford University Press, New York, 1995.

2. D Jennings A Flint BCH Turton LDM Nokes, Introductionto Medical Electronics Applications, Edward Arnold A Member of the Hodder Headline Group London Boston Sydney Auckland


Introdução


•BEN = bioengineering,

• BPH = biophysics,

• BEM = bioelectromagnetism,

• MPH = medical physics,

• MEN = medical engineering,

• MEL = medical electronics.

Biophysics: Solução dos sistemas biológicos utilizando conceitos físicos.

Bioengineering: Utilização da engenharia para dispositivos de cuidados de saúde, análise de sistemas biológicos.

Biotechnology: Estudo dos processos microbiológicos. Agricultura, alimentação e medicamentos. Medical electronics: Dispositivos e métodos electrónicos para a medicina. Medical physics: Ciência que se baseia nos problemas físicos da medicina clinica. Biomedical engineering: Aplicação dos métodos e técnicas da engenharia à biologia e medicina.



Table 1.1 I ) Measurements of fields

(A) Bioelectricity (B) Bioelectromagnetism(Biomagnetism)

(C) Biomagnetism

Neural cells

electroencephalography (EEG) magnetoencephalography (MEG)

electroneurography (ENG) magnetoneurography (MNG)

electroretinography (ERG) magnetoretinography (MRG)

Muscle cells

electrocardiography (ECG) magnetocardiography (MCG)

electromyography (EMG) magnetomyography (MMG)

Other tissue

electro-oculography (EOG) magneto-oculography (MOG)

electronystagmography (ENG) magnetonystagmography (MNG)

magnetopneumogram

magnetohepatogram


Table 1.2 II ) Stimulation and magnetization


(C)Biomagnetism

Stimulationpatch clamp, voltage clamp

electric stimulation of the central nervous systemor of motor nerve/muscle

magnetic stimulation of the central nervous system or of motor nerve/muscle

electric cardiac pacing magnetic cardiac pacingelectric cardiac defibrillation magnetic cardiac defibrillation

Therapeutic applicationselectrotherapy electromagnetotherapy magnetotherapy

electrosurgery (surgical diathermy)

Magnetization magnetization offerromagnetic

material


Table 1.3 III ) Measurement of intrinsic properties


(C) Biomagnetism

electric measurement ofelectric impedance

magnetic measurement ofelectric impedance

measurement of magneticsusceptibility

impedance cardiography magnetic susceptibilityplethysmography

impedance pneumography magnetic remanence measurement

impedance tomography impedance tomography magnetic resonance imaging (MRI)

electrodermal response (EDR)


a) Neurofisiológico

b) Cardíaco

c) Outros orgão e tecidos


Sistema Nervoso Central

•Cérebro


Sistema Nervoso Central

•Espinal medula


Sistema Nervoso Periférico

• Células nervosas e fibras que emergem do cérebro e da espinal medula e comunicam com o resto do corpo

• 2 tipos

• Sensitivas – recebem informação - visão

• Motoras – enviam informação - músculos


Nervo Periférico Humano


Reflexo


Lesões da Espinal Medula


Neurónios e Nervos

Anatomia do neurónio


Células Nervosas - Neurónios

1um - m


Células Nervosas - Neurónios


Membrana da célula


Membrana da célula


Sinapse


Estrutura do músculo esquelético


Célula muscular


Estrutura Muscular


Cooperação entre músculos e esqueleto


Célula muscular

- Smooth muscles are involuntary (i.e., they cannot be controlled voluntarily). Their cells have a variable length butare in the order of 0.1 mm. Smooth muscles exist, for example, in the digestive tract, in the wall of the trachea, uterus, and bladder. The contraction of smooth muscle is controlled from the brain through the autonomic nervous system.


Célula muscular

Striated muscles, are also called skeletal muscles because of their anatomical location, are formed from a large number of muscle fibers, that range in length from 1 to 40 mm and in diameter from 0.01 to 0.1 mm. Each fiber forms a (muscle) cell and is distinguished by the presence of alternating darkand light bands. This is the origin of the description "striated," as an alternate terminology of skeletal muscle


Célula muscular

Cardiac muscle is also striated, but differs in other ways from skeletal muscle: Not only is it involuntary, but also when excited, it generates a much longer electric impulse than does skeletal muscle, lasting about 300 ms. Correspondingly, the mechanical contraction also lasts longer. Furthermore, cardiac muscle has a special property: The electric activity of one muscle cell spreads to all other surrounding muscle cells, owing to an elaborate system of intercellular junctions



Potencial de repouso


Funcionamento Bioeléctrico da Célula

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Biofísica Mecânica e Eléctricadei-s1.dei.uminho.pt/pessoas/pmendes/biofisica/downloads/...Biofísica mecânica e eléctrica–2. 2 • Biofísica eléctrica do nervo e do músculo