The document summarizes key aspects of nerve physiology:
- The nervous system is divided into the central nervous system (brain and spinal cord) and peripheral nervous system. The peripheral nervous system is further divided into the somatic and autonomic nervous systems.
- A neuron consists of a cell body, dendrites, and an axon. Neurons transmit electrical signals called action potentials via their axons.
- An action potential occurs when a neuron is stimulated - sodium ions rush into the neuron, depolarizing the membrane. Then potassium ions exit, repolarizing the membrane back to its resting potential. This allows signals to propagate along axons.
these slides contain a brief introduction of neurons and its classification as well as details of generation of action potential, resting potential and eletrotonic potential.
it is very useful content for the basic knowledge of motor units .
Dedicated to my father shri satyaveer singh , my mother bateri devi and the entire lnipe family .
Degeneration & regeneration of nerve fiber.ppt by Dr. PANDIAN M.Pandian M
INTRODUCTION
CLASSIFICATION OF NERVE INJURIES
INJURY OF THE NERVE CELL BODY
INJURY OF THE NERVE CELL PROCESS
CHANGES IN THE DISTAL SEGMENT OF THE AXON
CHANGES IN THE PROXIMAL SEGMENT OF THE AXON
CHANGES IN THE NERVE CELL BODY
RECOVERY OF THE NEURONS FOLLOWING INJURY
REGENERATION OF AXONS IN THE PERIPHERAL NERVES
REGENERATION OF AXONS IN THE CNS
these slides contain a brief introduction of neurons and its classification as well as details of generation of action potential, resting potential and eletrotonic potential.
it is very useful content for the basic knowledge of motor units .
Dedicated to my father shri satyaveer singh , my mother bateri devi and the entire lnipe family .
Degeneration & regeneration of nerve fiber.ppt by Dr. PANDIAN M.Pandian M
INTRODUCTION
CLASSIFICATION OF NERVE INJURIES
INJURY OF THE NERVE CELL BODY
INJURY OF THE NERVE CELL PROCESS
CHANGES IN THE DISTAL SEGMENT OF THE AXON
CHANGES IN THE PROXIMAL SEGMENT OF THE AXON
CHANGES IN THE NERVE CELL BODY
RECOVERY OF THE NEURONS FOLLOWING INJURY
REGENERATION OF AXONS IN THE PERIPHERAL NERVES
REGENERATION OF AXONS IN THE CNS
Muscle spindles are proprioceptors that consist of intrafusal muscle fibers enclosed in a sheath (spindle). They run parallel to the extrafusal muscle fibers and act as receptors that provide information on muscle length and the rate of change in muscle length. The spindles are stretched when the muscle lengthens. This stretch causes the sensory neuron in the spindle to transmit an impulse to the spinal cord, where it synapses with alpha motor neurons. This causes activation of motor neurons that innervate the muscle. The muscle spindles determine the amount of contraction necessary to overcome a given resistance. When the resistance increases, the muscle is stretched further, and this causes spindle fibers to activate a greater muscle contraction.
https://nabeelbeeran.blogspot.com/
https://youtu.be/ur3LZGVuLI0
CLASSIFICATION & PROPERTIES OF NERVE FIBERS-
CLASSIFICATION OF NERVE FIBERS
PROPERTIES OF NERVE FIBERS :
1. EXCITABILITY
2. CONDUCTIVITY
3. ALL OR NONE LAW
4. REFRACTORY PERIOD
Stimulus – A change in environment which brings about a change in potential across a membrane in an excitable tissue
Electrical Chemical Thermal Mechanical 14
STRENGTH-DURATION CURVE TIME
UTILISATION TIME
STRENGTH RHEOBASE 2 X RHEOBASE
CHRONAXIE
Receptor by Pandian M, Tutor, Dept of Physiology, DYPMCKOP, MH. This PPT for ...Pandian M
Introduction
SENSORY RECEPTORS
Structurally 3 types of receptors
Transducers
CLASSIFICATION OF RECEPTORS
A. Depending on the source of stimulus(Sherrington’s classification)
B. Depending upon type of stimulus
C. Clinical or anatomical classification of receptors
Production of receptor potential
Properties of receptors
Properties of receptor potential
COORDINATION 1
Coordination is a linking together of the functions of different organs so that they work at a fine time and rate required by the body.
Coordination is achieved through a nervous and endocrine or hormonal system.
DIFFERENCE BETWEEN NERVOUS AND ENDOCRINE
Muscle spindles are proprioceptors that consist of intrafusal muscle fibers enclosed in a sheath (spindle). They run parallel to the extrafusal muscle fibers and act as receptors that provide information on muscle length and the rate of change in muscle length. The spindles are stretched when the muscle lengthens. This stretch causes the sensory neuron in the spindle to transmit an impulse to the spinal cord, where it synapses with alpha motor neurons. This causes activation of motor neurons that innervate the muscle. The muscle spindles determine the amount of contraction necessary to overcome a given resistance. When the resistance increases, the muscle is stretched further, and this causes spindle fibers to activate a greater muscle contraction.
https://nabeelbeeran.blogspot.com/
https://youtu.be/ur3LZGVuLI0
CLASSIFICATION & PROPERTIES OF NERVE FIBERS-
CLASSIFICATION OF NERVE FIBERS
PROPERTIES OF NERVE FIBERS :
1. EXCITABILITY
2. CONDUCTIVITY
3. ALL OR NONE LAW
4. REFRACTORY PERIOD
Stimulus – A change in environment which brings about a change in potential across a membrane in an excitable tissue
Electrical Chemical Thermal Mechanical 14
STRENGTH-DURATION CURVE TIME
UTILISATION TIME
STRENGTH RHEOBASE 2 X RHEOBASE
CHRONAXIE
Receptor by Pandian M, Tutor, Dept of Physiology, DYPMCKOP, MH. This PPT for ...Pandian M
Introduction
SENSORY RECEPTORS
Structurally 3 types of receptors
Transducers
CLASSIFICATION OF RECEPTORS
A. Depending on the source of stimulus(Sherrington’s classification)
B. Depending upon type of stimulus
C. Clinical or anatomical classification of receptors
Production of receptor potential
Properties of receptors
Properties of receptor potential
COORDINATION 1
Coordination is a linking together of the functions of different organs so that they work at a fine time and rate required by the body.
Coordination is achieved through a nervous and endocrine or hormonal system.
DIFFERENCE BETWEEN NERVOUS AND ENDOCRINE
These slides contain the basic information and principle of nervous transduction, It also includes the information about the type of the neurons, structure of the neuron, resting and active membrane potential, synapes and events occurring in it, and introduction to the neurotransmitters.
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basic nervous system-CNS-PNS -cell bodie- axon-dendron-grye matter- white mat...shailesh sangle
The nervous system is a complex network of cells, tissues, and organs that coordinates and regulates the body's responses to internal and external stimuli. It is responsible for the control and coordination of all the body's functions, including movement, sensation, thought, and behavior.
The nervous system can be divided into two main parts: the central nervous system (CNS) and the peripheral nervous system (PNS). The CNS consists of the brain and spinal cord, while the PNS consists of all the nerves that extend from the CNS to the rest of the body.
The nervous system is made up of different types of cells, including neurons and glial cells. Neurons are specialized cells that transmit signals through the body in the form of electrical impulses. Glial cells, on the other hand, support and protect the neurons and help maintain the proper functioning of the nervous system.
The nervous system is responsible for many vital functions, including:
Sensory processing: The nervous system receives sensory information from the environment and the body's internal organs, and processes and interprets this information to generate appropriate responses.
Motor control: The nervous system controls the muscles and other organs of the body to produce movement and other responses.
Cognitive functions: The nervous system is responsible for the processes of learning, memory, language, and other complex mental activities.
Autonomic functions: The nervous system regulates the body's automatic functions, such as breathing, heart rate, digestion, and other bodily processes that are not under conscious control.
Overall, the nervous system is a complex and intricate system that plays a critical role in maintaining the body's homeostasis and overall well-being.
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Nerve Impulse is defined as a wave of electrical chemical changes across the neuron that helps in the generation of the action potential in response to the stimulus. This transmission of a nerve impulse across the neuron membrane as a result of a change in membrane potential is known as Nerve impulse conduction.
Mechanism of Nerve Impulse Conduction
Nerve impulse conduction is a major process occurring in the body responsible for organized functions of the body. So, for conduction of nerve impulse there are two mechanisms:
Continuous conduction
Saltatory conduction
The following power point presentation talks about neural control and coordination in humans. In this, we study about neurons, the conduction of nerve impulse, about Central Nervous System and also about sense organs
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Title: Sense of Taste
Presenter: Dr. Faiza, Assistant Professor of Physiology
Qualifications:
MBBS (Best Graduate, AIMC Lahore)
FCPS Physiology
ICMT, CHPE, DHPE (STMU)
MPH (GC University, Faisalabad)
MBA (Virtual University of Pakistan)
Learning Objectives:
Describe the structure and function of taste buds.
Describe the relationship between the taste threshold and taste index of common substances.
Explain the chemical basis and signal transduction of taste perception for each type of primary taste sensation.
Recognize different abnormalities of taste perception and their causes.
Key Topics:
Significance of Taste Sensation:
Differentiation between pleasant and harmful food
Influence on behavior
Selection of food based on metabolic needs
Receptors of Taste:
Taste buds on the tongue
Influence of sense of smell, texture of food, and pain stimulation (e.g., by pepper)
Primary and Secondary Taste Sensations:
Primary taste sensations: Sweet, Sour, Salty, Bitter, Umami
Chemical basis and signal transduction mechanisms for each taste
Taste Threshold and Index:
Taste threshold values for Sweet (sucrose), Salty (NaCl), Sour (HCl), and Bitter (Quinine)
Taste index relationship: Inversely proportional to taste threshold
Taste Blindness:
Inability to taste certain substances, particularly thiourea compounds
Example: Phenylthiocarbamide
Structure and Function of Taste Buds:
Composition: Epithelial cells, Sustentacular/Supporting cells, Taste cells, Basal cells
Features: Taste pores, Taste hairs/microvilli, and Taste nerve fibers
Location of Taste Buds:
Found in papillae of the tongue (Fungiform, Circumvallate, Foliate)
Also present on the palate, tonsillar pillars, epiglottis, and proximal esophagus
Mechanism of Taste Stimulation:
Interaction of taste substances with receptors on microvilli
Signal transduction pathways for Umami, Sweet, Bitter, Sour, and Salty tastes
Taste Sensitivity and Adaptation:
Decrease in sensitivity with age
Rapid adaptation of taste sensation
Role of Saliva in Taste:
Dissolution of tastants to reach receptors
Washing away the stimulus
Taste Preferences and Aversions:
Mechanisms behind taste preference and aversion
Influence of receptors and neural pathways
Impact of Sensory Nerve Damage:
Degeneration of taste buds if the sensory nerve fiber is cut
Abnormalities of Taste Detection:
Conditions: Ageusia, Hypogeusia, Dysgeusia (parageusia)
Causes: Nerve damage, neurological disorders, infections, poor oral hygiene, adverse drug effects, deficiencies, aging, tobacco use, altered neurotransmitter levels
Neurotransmitters and Taste Threshold:
Effects of serotonin (5-HT) and norepinephrine (NE) on taste sensitivity
Supertasters:
25% of the population with heightened sensitivity to taste, especially bitterness
Increased number of fungiform papillae
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These simplified slides by Dr. Sidra Arshad present an overview of the non-respiratory functions of the respiratory tract.
Learning objectives:
1. Enlist the non-respiratory functions of the respiratory tract
2. Briefly explain how these functions are carried out
3. Discuss the significance of dead space
4. Differentiate between minute ventilation and alveolar ventilation
5. Describe the cough and sneeze reflexes
Study Resources:
1. Chapter 39, Guyton and Hall Textbook of Medical Physiology, 14th edition
2. Chapter 34, Ganong’s Review of Medical Physiology, 26th edition
3. Chapter 17, Human Physiology by Lauralee Sherwood, 9th edition
4. Non-respiratory functions of the lungs https://academic.oup.com/bjaed/article/13/3/98/278874
Tom Selleck Health: A Comprehensive Look at the Iconic Actor’s Wellness Journeygreendigital
Tom Selleck, an enduring figure in Hollywood. has captivated audiences for decades with his rugged charm, iconic moustache. and memorable roles in television and film. From his breakout role as Thomas Magnum in Magnum P.I. to his current portrayal of Frank Reagan in Blue Bloods. Selleck's career has spanned over 50 years. But beyond his professional achievements. fans have often been curious about Tom Selleck Health. especially as he has aged in the public eye.
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Introduction
Many have been interested in Tom Selleck health. not only because of his enduring presence on screen but also because of the challenges. and lifestyle choices he has faced and made over the years. This article delves into the various aspects of Tom Selleck health. exploring his fitness regimen, diet, mental health. and the challenges he has encountered as he ages. We'll look at how he maintains his well-being. the health issues he has faced, and his approach to ageing .
Early Life and Career
Childhood and Athletic Beginnings
Tom Selleck was born on January 29, 1945, in Detroit, Michigan, and grew up in Sherman Oaks, California. From an early age, he was involved in sports, particularly basketball. which played a significant role in his physical development. His athletic pursuits continued into college. where he attended the University of Southern California (USC) on a basketball scholarship. This early involvement in sports laid a strong foundation for his physical health and disciplined lifestyle.
Transition to Acting
Selleck's transition from an athlete to an actor came with its physical demands. His first significant role in "Magnum P.I." required him to perform various stunts and maintain a fit appearance. This role, which he played from 1980 to 1988. necessitated a rigorous fitness routine to meet the show's demands. setting the stage for his long-term commitment to health and wellness.
Fitness Regimen
Workout Routine
Tom Selleck health and fitness regimen has evolved. adapting to his changing roles and age. During his "Magnum, P.I." days. Selleck's workouts were intense and focused on building and maintaining muscle mass. His routine included weightlifting, cardiovascular exercises. and specific training for the stunts he performed on the show.
Selleck adjusted his fitness routine as he aged to suit his body's needs. Today, his workouts focus on maintaining flexibility, strength, and cardiovascular health. He incorporates low-impact exercises such as swimming, walking, and light weightlifting. This balanced approach helps him stay fit without putting undue strain on his joints and muscles.
Importance of Flexibility and Mobility
In recent years, Selleck has emphasized the importance of flexibility and mobility in his fitness regimen. Understanding the natural decline in muscle mass and joint flexibility with age. he includes stretching and yoga in his routine. These practices help prevent injuries, improve posture, and maintain mobilit
ARTIFICIAL INTELLIGENCE IN HEALTHCARE.pdfAnujkumaranit
Artificial intelligence (AI) refers to the simulation of human intelligence processes by machines, especially computer systems. It encompasses tasks such as learning, reasoning, problem-solving, perception, and language understanding. AI technologies are revolutionizing various fields, from healthcare to finance, by enabling machines to perform tasks that typically require human intelligence.
Lung Cancer: Artificial Intelligence, Synergetics, Complex System Analysis, S...Oleg Kshivets
RESULTS: Overall life span (LS) was 2252.1±1742.5 days and cumulative 5-year survival (5YS) reached 73.2%, 10 years – 64.8%, 20 years – 42.5%. 513 LCP lived more than 5 years (LS=3124.6±1525.6 days), 148 LCP – more than 10 years (LS=5054.4±1504.1 days).199 LCP died because of LC (LS=562.7±374.5 days). 5YS of LCP after bi/lobectomies was significantly superior in comparison with LCP after pneumonectomies (78.1% vs.63.7%, P=0.00001 by log-rank test). AT significantly improved 5YS (66.3% vs. 34.8%) (P=0.00000 by log-rank test) only for LCP with N1-2. Cox modeling displayed that 5YS of LCP significantly depended on: phase transition (PT) early-invasive LC in terms of synergetics, PT N0—N12, cell ratio factors (ratio between cancer cells- CC and blood cells subpopulations), G1-3, histology, glucose, AT, blood cell circuit, prothrombin index, heparin tolerance, recalcification time (P=0.000-0.038). Neural networks, genetic algorithm selection and bootstrap simulation revealed relationships between 5YS and PT early-invasive LC (rank=1), PT N0—N12 (rank=2), thrombocytes/CC (3), erythrocytes/CC (4), eosinophils/CC (5), healthy cells/CC (6), lymphocytes/CC (7), segmented neutrophils/CC (8), stick neutrophils/CC (9), monocytes/CC (10); leucocytes/CC (11). Correct prediction of 5YS was 100% by neural networks computing (area under ROC curve=1.0; error=0.0).
CONCLUSIONS: 5YS of LCP after radical procedures significantly depended on: 1) PT early-invasive cancer; 2) PT N0--N12; 3) cell ratio factors; 4) blood cell circuit; 5) biochemical factors; 6) hemostasis system; 7) AT; 8) LC characteristics; 9) LC cell dynamics; 10) surgery type: lobectomy/pneumonectomy; 11) anthropometric data. Optimal diagnosis and treatment strategies for LC are: 1) screening and early detection of LC; 2) availability of experienced thoracic surgeons because of complexity of radical procedures; 3) aggressive en block surgery and adequate lymph node dissection for completeness; 4) precise prediction; 5) adjuvant chemoimmunoradiotherapy for LCP with unfavorable prognosis.
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June 20, 2024, Prix Galien International and Jerusalem Ethics Forum in ROME. Detailed agenda including panels:
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- Prix Galien International Awards Ceremony
2. Nervous system controls all the activities of the body.
Primarily, nervous system is divided into two parts:
1. Central nervous system
2. Peripheral nervous system.
Central nervous system (CNS) includes brain and spinal cord.
• It is formed by neurons and supporting cells called neuroglia.
• Structures of brain and spinal cord are arranged in two layers, gray matter and
white matter.
• Gray matter is formed by nerve cell bodies and the proximal parts of nerve
fibers, arising from nerve cell body. White matter is formed by remaining parts
of nerve fibers.
3. Peripheral nervous system (PNS) is formed by neurons and their processes present
in all regions of the body.
• It consists of cranial nerves, arising from brain and spinal nerves, arising from
the spinal cord.
It is again divided into two subdivisions:
a) Somatic nervous system
Somatic nervous system is concerned with somatic functions. It includes the nerves
supplying the skeletal muscles. Somatic nervous system is responsible for muscular
activities and movements of the body
b) Autonomic nervous system.
Autonomic nervous system is concerned with regulation of visceral or vegetative
functions. Also called as involuntary nervous system.
Autonomic nervous system consists of two divisions, sympathetic division and
parasympathetic division.
4. Neuron
Neuron or nerve cell is defined as the structural and functional unit of nervous system.
STRUCTURE OF NEURON
Neuron is made up of three parts:
1. Nerve cell body
2. Dendrite
3. Axon.
Dendrite and axon form the processes of neuron. Dendrites are short processes and the
axons are long processes. Dendrites and axons are usually called nerve fibers.
CLASSIFICATION OF NEURON
❖ Depending upon the number of poles neurons are divided into three types:
1. Unipolar neurons
2. Bipolar neurons
3. Multipolar neurons.
5. ❖ Depending upon the function nerve cells are classified into two types:
1. Motor or efferent neurons
2. Sensory or afferent neurons.
❖ Depending upon the length of axon, neurons are divided into two types:
1. Golgi type I neurons
2. Golgi type II neurons
The properties of the nerve
a. Excitability
b. Conductivity
c. Refractory period
d. Summation
e. Adaptation
f. Infatigability
g. All or none law.
6. Excitability
Excitability is defined as the physiochemical change that occurs in a tissue when
stimulus is applied
Excitability in the nerve gets manifested in the form of electrical change. The
electrical change leads to generation of an action potential (impulse) from the
resting state(resting membrane potential) of the nerve.
Rheobase—is the minimum strength of stimulus required to stimulate (excite) a
tissue without considering the time duration for which the stimulus has to be
applied.
Chronaxie—is the minimum time required to excite a tissue with double the
rheobasic current.
7. Response Due to Stimulation of Nerve Fiber:
When a nerve fiber is stimulated, based on the strength of stimulus, two types of
response develop:
1. Action potential or nerve impulse
Action potential develops in a nerve fiber when it is stimulated by a stimulus with
adequate strength. Adequate strength of stimulus, necessary for producing the
action potential in a nerve fiber is known as threshold or minimal stimulus.
2. Electrotonic potential or local potential
When the stimulus with subliminal strength is applied, only electrotonic potential
develops and the action potential does not develop. Electrotonic potential is non-
propagated.
8. Conductivity
Conductivity is the ability of nerve fibers to transmit the impulse from the area of
stimulation to the other areas.
Action potential is transmitted through the nerve fiber as nerve impulse.
The important factors which affect the velocity of impulse conduction in nerve
fibers is whether the nerve fiber is myelinated.
In a myelinated nerve fiber the impulse jumps from one node of Ranvier to the
next node. This type of conduction is called as saltatory or leaping conduction
9. Myelin sheath is not permeable to ions. So, the entry of sodium from extracellular fluid
into nerve fiber occurs only in the node of Ranvier, where the myelin sheath is absent.
It causes depolarization in the node and not in the internode. Thus, depolarization
occurs at successive nodes. So, the action potential jumps from one node to another.
Hence, it is called saltatory conduction (saltare = jumping).
In an unmyelinated nerve the impulse conducted by, the Depolarization occurs first at
the site of stimulation in the nerve fiber. It causes depolarization of the neighboring
depolarization travels throughout the nerve fiber. Depolarization is followed by
repolarization.
10. Refractory period
Refractory period is the period at which the nerve does not give any response to
a stimulus.
Refractory period is of two types:
1. Absolute Refractory Period
Absolute refractory period is the period during which the nerve does not
show any response at all, whatever may be the strength of stimulus.
2. Relative Refractory Period
It is the period, during which the nerve fiber shows response, if the strength
of stimulus is increased to maximum.
11. Summation
When one subliminal stimulus is applied, it does not produce any response in the
nerve fiber because, the subliminal stimulus is very weak. However, if two or
more subliminal stimuli are applied within a short interval of about 0.5
millisecond, the response is produced. It is because the subliminal stimuli are
summed up together to become strong enough to produce the response. This
phenomenon is known as summation
Adaptation
While stimulating a nerve fiber continuously, the excitability of the nerve fiber is
greater in the beginning. Later the response decreases slowly and finally the nerve
fiber does not show any response at all. This phenomenon is known as
adaptation or accommodation.
12. Infatigability
Nerve fiber cannot be fatigued, even if it is stimulated continuously for a long
time. The reason is that nerve fiber can conduct only one action potential at a
time.
All-or-none law
All-or-none law states that when a nerve is stimulated by a stimulus it gives
maximum response or does not give response at all.
13. Resting membrane potential (RMP)
Resting membrane potential (RMP) is the potential difference that exists between
the extracellular fluid (ECF) and intracellular fluid regions (ICF) (that is across the
cell membrane)
For a cell’s membrane potential, the reference point is
the outside of the cell. In most resting neurons,
neurons have a resting membrane potential of about -
30mV to -90 mV
Because there is a potential difference across the cell
membrane, the membrane is said to be polarized.
14. If the membrane potential becomes more positive than it is at the resting potential,
the membrane is said to be depolarized.
If the membrane potential becomes more negative than it is at the resting
potential, the membrane is said to be hyperpolarized.
15. when the tissue is at rest, Normally when compared to extracellular fluid, the intra-
cellular fluid part is negative. Hence the resting membrane potential value is always
is prefixed with a -ve symbol. In a nerve fiber it is mostly around -79mV.
Resting membrane potential is always due to the
unequal distribution of the charged Substances
in extracellular and intracellular fluid regions.
Types of ions found in neurons In neurons
are:
Positively charged (cations): Sodium Na+
and potassium k+
Negatively charged (anions): Chloride Cl-
and organic anions
16. Sodium tries to move (diffuse) into intra-cellular fluid along the electrochemical
gradient, potassium tries to move out into extracellular fluid along concentration
gradient and chloride tries to move in along concentration gradient alone.
The cell membrane is more permeable for potassium ion diffusion than sodium.
Unlike for the inorganic ions, the cell membrane is impermeable for the organic
anions. Hence the retention of the organic anions inside the cell is responsible for
the negative membrane potential at rest.
Even at rest there will be some amount of diffusion of the inorganic ions along
either the concentration or electrical gradient or both.
But the restoration of the ions at respective regions is brought about by the activity
of the pump, Na+ - K+ ATPase pump which removes sodium from intra cellular to
extra cellular fluid and vice versa for potassium.
17. Action potential
An action potential is a rapid rise and fall in voltage or membrane potential across a
cellular membrane.
An action potential occurs when a neuron sends information down an axon, away
from the cell body.
• During the action potential development the membrane of the tissue becomes
permeable for sodium.
• So the sodium ions move from the extracellular fluid into the intracellular fluid
region. Because of the influx of the sodium ions, the interior becomes positive as
against the negative state observed during the resting condition.
• The reversal of polarity due to sudden influx of sodium ions is responsible for the
process of depolarization.
• The sodium ion influx is so much that the membrane potential exceeds the zero
potential and over shoots. The potential reaches as much as + 35 mV.
18. • During the later part of depolarization the sodium channels begin to close and
potassium channels start opening up.
• Because Of this there will be efflux of potassium ions. The outward movement
of potassium ions will bring about the re-establishment of Polarized state
(repolarisation) of the membrane.