Electrical properties of cell tissues
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Electrical Properties of Cell & Tissues. Lecture Objectives . Cell physiology Electrical zones of the cell Effect of changing the electrical environment of the nerve Identify methods of ion transfer across cell membrane Identify differences between electric & biological circuit

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Electrical Properties of Cell & Tissues

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Electrical properties of cell tissues

Electrical Properties of Cell & Tissues

Lecture objectives

Lecture Objectives

  • Cell physiology

  • Electrical zones of the cell

  • Effect of changing the electrical environment of the nerve

  • Identify methods of ion transfer across cell membrane

  • Identify differences between electric & biological circuit

  • Explain causes & importance of current of injury

  • Discuss causes & importance of strain potential

  • Discuss the uses of bioelectricity

Cell physiology

Cell physiology

  • The cell is the functional unit in organisms, it is the building block of the body

  • The cell is very very small

  • Cell membrane is composed of a a bilayer of phospholipids

  • Cell membrane is almost 5 – 5.7 nm

Cell physiology1

Cell physiology

  • Inside the cell there are electrical charges, these electrical charges move inside and outside of the cell

  • Some of the electrical charges are bound to be inside

  • Cells usually are bind together by junctions, forming tissues

Types of tissue

Types of Tissue

  • Excitable tissue, like muscle & nerves

  • Non-excitable tissues, they have charges but the can not be stimulated like excitable tissues, e.g. skin, bone, adipose tissue, connective tissue & epithelial tissue

Electric charges

Electric Charges

  • Electric charges can be found either single or compound (multiple)

  • They can be found inside the cell or outside the cell

  • Because some ions are able to move from the inside to the outside or from the outside to the inside, they are creating what we call a the convection current.

Zones of the cell

Zones of The Cell

  • Each excitable cell has 4 electrical zones:

  • The innermost zone (central zone ) which is negative because it has proteins & amino acids

  • The inner zone, it is positive, it has cations such as potassium

  • The outer zone, it is positive, it has ions such as sodium, calcium and potassium

  • The outermost zone which is negative, it has glycolipids

Zones of the cell1

Zones of The Cell

  • the most two important layers are the two negative layers

  • These two layer are responsible for the electrical charges of the cell, the are the ones which change the cell properties

Charges across the cell membrane

Charges Across The Cell Membrane

  • Intracellular  high potassium (K+), low sodium (Na+)

  • Extracellular  low potasiom ,high sodium, hi calcium

Why electricity of the cell is important

Why Electricity of The Cell Is Important ?

  • It is one way in which the cells communicate with each other

  • Signals come to the cell in a form of electric charges

  • Failure in this communication will result in disease or malfunction

  • In order to correct that disease we give external electricity

  • When we treat patient with electric modalities we are trying to correct that electrical charges within the cell

Why electricity of the cell is important1

Why Electricity of The Cell Is Important ?

  • Normally, the signals come to the cell thought what we call a first messenger (hormone or neurotransmitter)

  • When these signals reaches the cell it activates the second messenger (enzymes or calcium)

  • This will result in a change in cell function

Why electricity of the cell is important2

Why Electricity of The Cell Is Important ?

  • In case of a disease the problem lies in the first messenger

  • We apply electricity to work as first messenger

  • So, electricity will activate the second messenger & will change cell function & will correct the disease

Resting membrane potential

Resting Membrane Potential

  • The difference in potential across the cell membrane is what causes the resting membrane potential

  • Inside is more negative than the outside

  • Resting membrane potential for skeletal muscle is -80

  • Resting membrane potential for nerve & smooth muscle is -70

Action potential

Action Potential

  • First there is a stimulus (hormone, neurotransmitter, mechanical stimulus)

  • Then we have Depolarization, channels are open , ion are rushed in inside the cell

  • It reaches a peak then goes down (Repolarization)

  • Then we have a refractory period, in which the cell can not be stimulated again

  • Then back to the resting membrane potential

Action potential1

Action Potential

Action potential2

Action Potential

  • Action potential results from a chemical, electrical stimulus

  • To have an action potential the difference shouldn't be less than 15 from the original value of resting membrane potential (e.g. reversal of membrane potential from -90 to +30)

  • All or none (either there is an action potential or there isn’t

Nerve impulse

Nerve Impulse

  • Information come to the nerve through dendrites  nucleus of the cell  axon  dendrites of the other cell

  • Saltatory transmission happens in mylenated axons, the myelin sheath form nodes of Ranvair

  • Impulses within the nerve move in one direction orthodromic

  • If we stimulate a nerve artificially the signal will move in 2 directions, either orthodromic or antidromic

Nerve impulse1

Nerve Impulse

  • The characteristics of the nerve determines the nature of the nature & the speed of the impulse

  • If we have large diameter nerve conduction will be faster

  • If we have a mylenated axon conduction will be faster

Movement of ions across the cell membrane

Movement of Ions Across The Cell Membrane

  • There are 4 methods in which ions could move across the cell membrane:

  • Diffusion

  • Facilitated diffusion

  • Active transport

  • Pinocytosis



  • It is a passive process, usually small ions use this method to move across the cell, it moves from high concentration to low concentration

  • The rate of concentration is governed by factors such as:

  • Ion concentration,

  • Temperature (temperature diffusion)

  • Electrical charges (repulsion & attraction between charges)

Facilitated diffusion

Facilitated Diffusion

  • A passive process

  • Molecules attached to protein carriers to pass through the membrane

  • Large molecules such as glucose & amino acid use this methods for transfer

Active transport

Active Transport

  • An active process, energy is needed, it comes from ATP

  • Ions and molecules are moving against their concentration and electrical charges

  • We have pumps that will help them move across the membrane (e.g., Na+ pumps, K+ pumps)

  • Sodium, potassium, calcium, hydrogen & chloride, use this method of transport



  • It is used by large molecules

  • Part of the cell membrane surround the molecule, then detaches itself in a vesicle into the cell

Differences between electric biological circuit

Biological circuit:

Electric charge in wet environment

Atoms & ions

Components of circuit are always changing

There is a continuous leakage

There need to be areas charge differences

Short pathway

Energy is needed all the time

Slower, the response rate is in millisecond

Electric circuit:

Electric charge in dry environment

Uses electrons

Need occasional replacement of components

Move electric charges without leakage (or there will be a shock)

Long pathway

Energy is needed only when the circuit is working

Faster, the response rate is in nanosecond

Differences Between Electric & Biological Circuit

Current of injury

Current of Injury

  • It occurs when there is a wound in the skin, always found in & around the traumatized & healing area

  • The skin has charges, the positive charges in the skin move to the site where there is a cut or a wound

  • It happens a distance of 3mm from the open wound the wound

  • This movement is associated with closure in the wound

Current of injury1

Current of Injury

  • If there is large amount of current in the wound the closure will be faster

  • If there is a minimal current the closure will take longer

  • one of the factors that helps in closing the wound faster is moist

  • If the wound is most  current will be higher  closure will be faster

Strain potential

Strain Potential

  • Strain potential can be found when there is mechanical deformation, either compression or distraction

  • When there is compression there will be negative charge

  • When there is distraction there will be positive charge

  • Strain potential increase bone growth

Strain potential1

Strain Potential

  • If we have a broken bone & they placed electrodes on either side of this bone, there will be a current

  • When we put pressure on the bone, the area where the bone is convex (distracted) the charge will be positive

  • The are where the bone in concave (compresses) the charge will be negative

Strain potential2

Strain Potential

  • Strain potential may increase bone growth

  • Signals instruct cells to either increase or decrease formation

  • The current also forms in the connective tissue  remodeling of connective tissue alignment

Strain potential3

Strain Potential

  • Scientist observed that the skin has a negative current compared to lower layers (dermis, epidermis)

  • Normally in bones, the midpoint is positive, and the periphery is negative

  • Scientist observed that there are positive charged areas around the brain, brachial & lumber plexuses, while the peripheries have negative charges

Strain potential4

Strain Potential

  • Scientist observed that the circuit within the bone is affected by the metabolism of the body

  • Scientist observed that when they applied electricity on small animals, they can control where the head & tail grow

Strain potential5

Strain Potential

  • The scientist put electrodes on the salamander’s tail to study it, normally there was a very low current, but once they cut it there will be charges & the current will increase & the tail will start to grow

  • The scientist put electrodes on the frog’s tail to study it, normally there was a minimal current, and once they cut it there wasn’t a change & the tail didn’t grow

How can we use bioelectricity

How Can We Use Bioelectricity

  • We can use it in two ways:

  • Evaluation

  • Treatment



  • Electroencephalogram (EEG):

  • Used to record electrical activity of the brain

  • Electromyogram (EMG)

  • Used to observe the muscle function

  • Electrocardiogram (ECG)

  • Record the activity of the heart



  • In some disease the second messenger may not be working because it is not getting impulses from the first messenger

  • We give electricity to act as a first messenger to initiate or change cell function

  • Frequency window: some cells are sensitive to certain frequencies of electromagnetic field



  • In some disease their could be a first messenger but the signals the cell receiving are weak

  • The applied energy may strengthen the weak current to result in strong signals that could modify cell function

Other therapeutic uses

Other Therapeutic Uses

  • To educate a nerve or a muscle

  • To relief pain & other symptoms (spasm, swelling edema)

  • Improve neural growth (inflammation around the nerve)

  • Heating tissues

  • When giving some drugs (iontopherisis)

Study hard good luck

 Study Hard & Good Luck 

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