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
Action potential By Dr. Mrs. Padmaja R Desai Physiology Dept
To study the Concept of Action Potential and describe the stages of action potential.
Ionic basis of Action Potential & its Propogation.
Properties of Action Potential.
Types action Potential
It is over 60 years since Hodgkin and
Huxley1 made the first direct recording of
the electrical changes across the neuronal
membrane that mediate the action
potential. Using an electrode placed inside a
squid giant axon they were able to measure a
transmembrane potential of around 260 mV
inside relative to outside, under resting
conditions (this is called the resting membrane
potential). The action potential is a
transient (,1 millisecond) reversal in the
polarity of this transmembrane potential
which then moves from its point of initiation,
down the axon, to the axon terminals. In a
subsequent series of elegant experiments
Hodgkin and Huxley, along with Bernard
Katz, discovered that the action potential
results from transient changes in the permeability
of the axon membrane to sodium (Na+)
and potassium (K+) ions. Importantly, Na+ and
K+ cross the membrane through independent
pathways that open in response to a change
in membrane potential.
As testimony to their pioneering work, the
fundamental mechanisms described by
Hodgkin, Huxley and Katz remain applicable
to all excitable cells today. Indeed, the
predictions they made about the molecular
mechanisms that might underlie the changes
in membrane permeability showed remarkable
foresight. The molecular basis of the action
potential lies in the presence of proteins
called ion channels that form the permeation
pathways across the neuronal membrane.
Although the first electrophysiological
recordings from individual ion channels were
not made until the mid 1970s,2 Hodgkin and
Huxley predicted many of the properties now
known to be key components of their
function: ion selectivity, the electrical basis
of voltage-sensitivity and, importantly, a
mechanism for quickly closing down the
permeability pathways to ensure that the
action potential only moves along the axon in
one direction.
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.
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.
They are produced when high-velocity electrons collide with the metal plates, thereby giving the energy as the X-Rays and themselves absorbed by the metal plate.
The X-Ray beam travels through the air and comes in contact with the body tissues, and produces an image on a metal film.
Soft tissue like organs and skin, cannot absorb the high-energy rays, and the beam passes through them.
Dense materials inside our bodies, like bones, absorb the radiation.he X-Rays properties are given below:
They have a shorter wavelength of the electromagnetic spectrum.
Requires high voltage to produce X-Rays.
They are used to capture the human skeleton defects.
They travel in a straight line and do not carry an electric charge with them.
They are capable of travelling in a vacuum.Medical science recognizes different types of X-Rays. A few important types of X-Rays are given in the points below.
Standard Computed Tomography
Kidney, Ureter, and Bladder X-ray
Teeth and bones X-rays
Chest X-rays
Lungs X-rays
Abdomen X-rays
Action potential By Dr. Mrs. Padmaja R Desai Physiology Dept
To study the Concept of Action Potential and describe the stages of action potential.
Ionic basis of Action Potential & its Propogation.
Properties of Action Potential.
Types action Potential
It is over 60 years since Hodgkin and
Huxley1 made the first direct recording of
the electrical changes across the neuronal
membrane that mediate the action
potential. Using an electrode placed inside a
squid giant axon they were able to measure a
transmembrane potential of around 260 mV
inside relative to outside, under resting
conditions (this is called the resting membrane
potential). The action potential is a
transient (,1 millisecond) reversal in the
polarity of this transmembrane potential
which then moves from its point of initiation,
down the axon, to the axon terminals. In a
subsequent series of elegant experiments
Hodgkin and Huxley, along with Bernard
Katz, discovered that the action potential
results from transient changes in the permeability
of the axon membrane to sodium (Na+)
and potassium (K+) ions. Importantly, Na+ and
K+ cross the membrane through independent
pathways that open in response to a change
in membrane potential.
As testimony to their pioneering work, the
fundamental mechanisms described by
Hodgkin, Huxley and Katz remain applicable
to all excitable cells today. Indeed, the
predictions they made about the molecular
mechanisms that might underlie the changes
in membrane permeability showed remarkable
foresight. The molecular basis of the action
potential lies in the presence of proteins
called ion channels that form the permeation
pathways across the neuronal membrane.
Although the first electrophysiological
recordings from individual ion channels were
not made until the mid 1970s,2 Hodgkin and
Huxley predicted many of the properties now
known to be key components of their
function: ion selectivity, the electrical basis
of voltage-sensitivity and, importantly, a
mechanism for quickly closing down the
permeability pathways to ensure that the
action potential only moves along the axon in
one direction.
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.
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.
They are produced when high-velocity electrons collide with the metal plates, thereby giving the energy as the X-Rays and themselves absorbed by the metal plate.
The X-Ray beam travels through the air and comes in contact with the body tissues, and produces an image on a metal film.
Soft tissue like organs and skin, cannot absorb the high-energy rays, and the beam passes through them.
Dense materials inside our bodies, like bones, absorb the radiation.he X-Rays properties are given below:
They have a shorter wavelength of the electromagnetic spectrum.
Requires high voltage to produce X-Rays.
They are used to capture the human skeleton defects.
They travel in a straight line and do not carry an electric charge with them.
They are capable of travelling in a vacuum.Medical science recognizes different types of X-Rays. A few important types of X-Rays are given in the points below.
Standard Computed Tomography
Kidney, Ureter, and Bladder X-ray
Teeth and bones X-rays
Chest X-rays
Lungs X-rays
Abdomen X-rays
Olfaction, or the sense of smell, is an ancient sensory system that together with taste enables an organism to detect chemicals in the external environment. Olfaction is one of the five major human senses (vision, hearing, olfaction, taste, and touch) that occurs when odorants bind to specific sites in olfactory receptors.Olfaction is present in most species such as insects, worms, fish, amphibians, birds, and mammals. It is essential for survival by permitting the location of food, mates, and predators, although in humans, olfaction is often viewed as an esthetic sense capable of triggering emotion and memory.
Tannins are a class of astringent, polyphenolic biomolecules that bind to and precipitate proteins and various other organic compounds including amino acids and alkaloids. The term tannin refers to the use of oak and other bark in tanning animal hides into leather.
Hearing, or auditory perception, is the ability to perceive sounds by detecting vibrations, changes in the pressure of the surrounding medium through time, through an organ such as the ear. The academic field concerned with hearing is auditory science. Sound may be heard through solid, liquid, or gaseous matter.
Learning and memory functions are crucial in the interaction of an individual with the environment and involve the interplay of large, distributed brain networks. Recent advances in technologies to explore neurobiological correlates of neuropsychological paradigms have increased our knowledge about human learning and memory. In this chapter we first review and define memory and learning processes from a neuropsychological perspective. Then we provide some illustrations of how noninvasive brain stimulation can play a major role in the investigation of memory functions, as it can be used to identify cause–effect relationships and chronometric properties of neural processes underlying cognitive steps.
Memory refers to the processes that are used to acquire, store, retain, and later retrieve information. There are three major processes involved in memory: encoding, storage, and retrieval. Human memory involves the ability to both preserve and recover information we have learned or experienced.
The three main forms of memory storage are sensory memory, short-term memory, and long-term memory.
Neurotransmitters are chemical messengers that transmit a signal from a neuron across the synapse to a target cell, which can be a different neuron, muscle cell, or gland cell. Neurotransmitters are chemical substances made by the neuron specifically to transmit a message.
In order for neurons to send messages throughout the body, they need to be able to communicate with one another to transmit signals. However, neurons are not simply connected to one another. At the end of each neuron is a tiny gap called a synapse and in order to communicate with the next cell, the signal needs to be able to cross this small space. This occurs through a process known as neurotransmission.
There are a number of different ways to classify and categorize neurotransmitters. In some instances, they are simply divided into monoamines, amino acids, and peptides
Photoperiodism is the phenomenon of physiological changes that occur in plants in
response to relative length of day and night (i.e. photoperiod). The response of the plants to
the photoperiod, expressed in the form of flowering is also called as photoperiodism. The
phenomenon of photoperiodism was first discovered by Garner and Allard (1920).Depending
upon the duration of photoperiod, the plants are classified into three categories.
1. Short day plants (SDP)
2. Long day plants (LDP)
3. Day neutral plants (DNP)
Vernalization is the induction of a plant's flowering process by exposure to the prolonged cold of winter, or by an artificial equivalent. After vernalization, plants have acquired the ability to flower, but they may require additional seasonal cues or weeks of growth before they will actually flower.The vernalization requirement ensures that plants do not flower in the fall when the environmental conditions are unfavorable for reproduction. The strength of the vernalization requirement can vary within plant species.
The nervous system is the part of an animal's body that coordinates its behavior and transmits signals between different body areas. In vertebrates it consists of two main parts, called the central nervous system (CNS) and the peripheral nervous system (PNS). The CNS contains the brain and spinal cord
Striated muscle contracts to move limbs and maintain posture. The contraction of skeletal muscles is an energy-requiring process. In order to perform the mechanical work of contraction, actin and myosin utilize the chemical energy of the molecule adenosine triphosphate (ATP).Muscle contraction results from a chain of events that begins with a nerve impulse traveling in the upper motor neuron from the cerebral cortex in the brain to the spinal cord.When the signal to contract is sent along a nerve to the muscle, the actin and myosin are activated. Myosin works as a motor, hydrolyzing adenosine triphosphate (ATP) to release energy in such a way that a myosin filament moves along an actin…
Excitation–Contraction Coupling
Excitation–contraction coupling is the link (transduction) between the action potential generated in the sarcolemma and the start of a muscle contraction.
Sliding Filament Model of Contraction
For a muscle cell to contract, the sarcomere must shorten. However, thick and thin filaments—the components of sarcomeres—do not shorten. Instead, they slide by one another, causing the sarcomere to shorten while the filaments remain the same length. The sliding filament theory of muscle contraction was developed to fit the differences observed in the named bands on the sarcomere at different degrees of muscle contraction and relaxation. The mechanism of contraction is the binding of myosin to actin, forming cross-bridges that generate filament movement
In the muscular system, muscle tissue is categorized into three distinct types: skeletal, cardiac, and smooth. Each type of muscle tissue in the human body has a unique structure and a specific role.
Once the oxygen diffuses across the alveoli, it enters the bloodstream and is transported to the tissues where it is unloaded, and carbon dioxide diffuses out of the blood and into the alveoli to be expelled from the body. Although gas exchange is a continuous process, the oxygen and carbon dioxide are transported by different mechanisms.
What You’ll Learn to Do
Describe how oxygen is bound to hemoglobin and transported to body tissues
Explain how carbon dioxide is transported from body tissues to the lungs
Although the pH of blood ranges from 7.35-7.45, the pH of other body fluids is different. pH indicates the level of H+ ions, where low pH indicates too many H+ ions and high pH indicates too many OH- ions. Different organs function at their optimal level of pH. For example, the enzyme pepsin requires low pH to act and break down food, while the enzymes in intestine require high pH or alkaline environment to function. Similarly, any increase or decrease in the blood pH can lead to several disorders. pH is maintained in the body using primarily three mechanisms: buffer systems, respiratory control, and renal control.The abnormalities in acid-base balance are of two types: acidosis and alkalosis. In acidosis, the blood pH is low or there is too much acid in the blood, while in alkalosis, the blood pH is high or there is too much base in the blood. Acidosis and alkalosis may be caused either due to imbalance of acid-base secretion by the kidneys or altered levels of CO2 in the blood due to breathing disorders.
A wonderful biological technique to create Test tube babies.
In vitro fertilization (IVF) is the joining of a woman's egg and a man's sperm in a laboratory dish to help couple overcome Infertility and become parents
Operation “Blue Star” is the only event in the history of Independent India where the state went into war with its own people. Even after about 40 years it is not clear if it was culmination of states anger over people of the region, a political game of power or start of dictatorial chapter in the democratic setup.
The people of Punjab felt alienated from main stream due to denial of their just demands during a long democratic struggle since independence. As it happen all over the word, it led to militant struggle with great loss of lives of military, police and civilian personnel. Killing of Indira Gandhi and massacre of innocent Sikhs in Delhi and other India cities was also associated with this movement.
Palestine last event orientationfvgnh .pptxRaedMohamed3
An EFL lesson about the current events in Palestine. It is intended to be for intermediate students who wish to increase their listening skills through a short lesson in power point.
How to Make a Field invisible in Odoo 17Celine George
It is possible to hide or invisible some fields in odoo. Commonly using “invisible” attribute in the field definition to invisible the fields. This slide will show how to make a field invisible in odoo 17.
The Roman Empire A Historical Colossus.pdfkaushalkr1407
The Roman Empire, a vast and enduring power, stands as one of history's most remarkable civilizations, leaving an indelible imprint on the world. It emerged from the Roman Republic, transitioning into an imperial powerhouse under the leadership of Augustus Caesar in 27 BCE. This transformation marked the beginning of an era defined by unprecedented territorial expansion, architectural marvels, and profound cultural influence.
The empire's roots lie in the city of Rome, founded, according to legend, by Romulus in 753 BCE. Over centuries, Rome evolved from a small settlement to a formidable republic, characterized by a complex political system with elected officials and checks on power. However, internal strife, class conflicts, and military ambitions paved the way for the end of the Republic. Julius Caesar’s dictatorship and subsequent assassination in 44 BCE created a power vacuum, leading to a civil war. Octavian, later Augustus, emerged victorious, heralding the Roman Empire’s birth.
Under Augustus, the empire experienced the Pax Romana, a 200-year period of relative peace and stability. Augustus reformed the military, established efficient administrative systems, and initiated grand construction projects. The empire's borders expanded, encompassing territories from Britain to Egypt and from Spain to the Euphrates. Roman legions, renowned for their discipline and engineering prowess, secured and maintained these vast territories, building roads, fortifications, and cities that facilitated control and integration.
The Roman Empire’s society was hierarchical, with a rigid class system. At the top were the patricians, wealthy elites who held significant political power. Below them were the plebeians, free citizens with limited political influence, and the vast numbers of slaves who formed the backbone of the economy. The family unit was central, governed by the paterfamilias, the male head who held absolute authority.
Culturally, the Romans were eclectic, absorbing and adapting elements from the civilizations they encountered, particularly the Greeks. Roman art, literature, and philosophy reflected this synthesis, creating a rich cultural tapestry. Latin, the Roman language, became the lingua franca of the Western world, influencing numerous modern languages.
Roman architecture and engineering achievements were monumental. They perfected the arch, vault, and dome, constructing enduring structures like the Colosseum, Pantheon, and aqueducts. These engineering marvels not only showcased Roman ingenuity but also served practical purposes, from public entertainment to water supply.
Read| The latest issue of The Challenger is here! We are thrilled to announce that our school paper has qualified for the NATIONAL SCHOOLS PRESS CONFERENCE (NSPC) 2024. Thank you for your unwavering support and trust. Dive into the stories that made us stand out!
This is a presentation by Dada Robert in a Your Skill Boost masterclass organised by the Excellence Foundation for South Sudan (EFSS) on Saturday, the 25th and Sunday, the 26th of May 2024.
He discussed the concept of quality improvement, emphasizing its applicability to various aspects of life, including personal, project, and program improvements. He defined quality as doing the right thing at the right time in the right way to achieve the best possible results and discussed the concept of the "gap" between what we know and what we do, and how this gap represents the areas we need to improve. He explained the scientific approach to quality improvement, which involves systematic performance analysis, testing and learning, and implementing change ideas. He also highlighted the importance of client focus and a team approach to quality improvement.
How to Split Bills in the Odoo 17 POS ModuleCeline George
Bills have a main role in point of sale procedure. It will help to track sales, handling payments and giving receipts to customers. Bill splitting also has an important role in POS. For example, If some friends come together for dinner and if they want to divide the bill then it is possible by POS bill splitting. This slide will show how to split bills in odoo 17 POS.
The Indian economy is classified into different sectors to simplify the analysis and understanding of economic activities. For Class 10, it's essential to grasp the sectors of the Indian economy, understand their characteristics, and recognize their importance. This guide will provide detailed notes on the Sectors of the Indian Economy Class 10, using specific long-tail keywords to enhance comprehension.
For more information, visit-www.vavaclasses.com
Students, digital devices and success - Andreas Schleicher - 27 May 2024..pptxEduSkills OECD
Andreas Schleicher presents at the OECD webinar ‘Digital devices in schools: detrimental distraction or secret to success?’ on 27 May 2024. The presentation was based on findings from PISA 2022 results and the webinar helped launch the PISA in Focus ‘Managing screen time: How to protect and equip students against distraction’ https://www.oecd-ilibrary.org/education/managing-screen-time_7c225af4-en and the OECD Education Policy Perspective ‘Students, digital devices and success’ can be found here - https://oe.cd/il/5yV
2. CONTENTS
1. Structure of a nerve cell
2. Resting Potential
3. Action Potential
• Formation of an action potential
4. Propagation of Action Potentials as an Impulse
• Saltatory conduction
5. Neurotransmission: Jumping the Synaptic Cleft
3. TYPICAL NEURON
Neurons in the mammalian central nervous system come in many different
shapes and sizes. Most of them have the same parts as a typical spinal motor
neuron
4. Direction of impulse
The cell body (soma) contains the nucleus and is the metabolic center of the neuron.
Neurons have processes known as dendrites which extend outward from the cell body and
arborize extensively. Particularly in the cerebral and cerebellar cortex, the small knobby
projections over dendrites are called dendritic spines. The dendrites are the receptive part
of the neuron. A typical neuron has long fibrous axon that originates from thickened area of
the cell body, the axon of hillock. The first portion of the axon is called the initial segment.
The axon divides into presynaptic terminals, each ending in a number of synaptic knobs
which are also called terminal buttons or boutons. They contain granules or vesicles in
which the synaptic transmitters secreted by the nerves are stored. The axonal process is
responsible for transmission of propagated impulses to the nerve endings.
5.
6. RESTING POTENTIAL
Resting potential may be defined as
the difference in voltage between
the inside and outside of the cell as
measured across the cell
membrane.
• When a neuron is not being
stimulated, it maintains a resting
potential
Ranges from –40 to –90
millivolts (mV) Average about
–70 mV
7.
8.
9. RESTING POTENTIAL
• Two major forces act on ions in establishing the
resting membrane potential
1. Electrical potential produced by unequal
distribution of charges
2. Concentration gradient produced by
unequal concentrations of molecules from
one side of the membrane to the other
10. • During this process,
potassium floods out
of the neuron cell.
• Depolarization results
because inward
diffusion of sodium is
much greater than a
outward diffusion of
potassium
DE
DEP
POLARIZAT
OL
DEPOLARIZATION
10
11.
12. ACTION POTENTIAL
Action potential may be defined as the entire series of
changes which contribute towards the changes in membrane
potential.
13. ACTION POTENTIAL
• Voltage-gated Na+ channels
– Activation gate and inactivation gate
– At rest, activation gate closed, inactivation gate open
– Transient influx of Na+causes the membrane to
depolarize
• Voltage-gated K+channels
– Single activation gate that is closed in the resting state
– K+channel opens slowly
– Efflux of K+repolarizes the membrane
14. ACTION POTENTIAL
• The action potential has three phases
– Rising, falling, and undershoot
• Action potentials are always separate, all-or-
none events with the same amplitude
• Do not add up or interfere with each other
• Intensity of a stimulus is coded by the
frequency, not amplitude, of action potentials
11
18. PROPAGATION OF ACTION
POTENTIAL
• Propagation of action potentials
– Each action potential, in its rising phase,
reflects a reversal in membrane polarity
– Positive charges due to influx of Na+can
depolarize the adjacent region to threshold
– And so the next region produces its own
action potential
– Meanwhile, the previous region repolarizes back
to the resting membrane potential
• Signal does not go back toward cell
body
20. PROPAGATION OF ACTION
POTENTIAL
• Two ways to increase velocity of conduction
–Axon has a large diameter
• Less resistance to current flow
• Found primarily in invertebrates
–Axon is myelinated
• Action potential is only produced at the
nodes of Ranvier
• Impulse jumps from node to node
• Saltatory conduction
16
26. Overview of Transmission of Nerve Impulse
• Action potential
synaptic knob
opening of Ca+channels
neurotransmitter vesicles fuse with membrane
release of neurotransmitter into synaptic cleft
binding of neurotransmitter to protein receptor molecules on
receiving neuron membrane
opening of ion channels
triggering of new action potential.
28. Defination:
Synapse is the junction between two neurons. It is not
an anatomical continuation. But, it is only a
physiological continuity between two nerve cells.
CLASSIFICATION OF SYNAPSE
Synapse is classified by two methods:
A. Anatomical classification
B. Functional classification.
29. ANATOMICAL CLASSIFICATION
Usually synapse is formed by axon of one neuron
ending on the cell body, dendrite or axon of the next
neuron. Depending upon ending of axon, synapse is
classified into three types:
1. Axoaxonic synapse in which axon of one neuron
terminates on axon of another neuron
2. Axodendritic synapse in which the axon of one
neuron terminates on dendrite of another neuron
3. Axosomatic synapse in which axon of one neuron
ends on soma (cell body) of another neuron
30.
31. „FUNCTIONAL CLASSIFICATION
Functional classification of synapse is on the basis of
mode of impulse transmission
1. Electrical Synapse
Electrical synapse is the synapse in which the
physiological continuity between the presynaptic and
the postsynaptic neurons is provided by gap junction
between the two neurons.
2. Chemical synapse
Is the junction between a nerve fiber and a muscle
fiber or between two nerve fibers, through which the
signals are transmitted by the release of chemical
transmitter
32.
33. On the basis of functions, synapses are divided into two types:
1. Excitatory synapses, which transmit the impulses (excitatory
function)
Excitatory Postsynaptic Potential
Excitatory postsynaptic potential (EPSP) is the non propagated
electrical potential that develops during the process of synaptic
transmission
2. Inhibitory synapses, which inhibit the transmission of
impulses (inhibitory function
Postsynaptic or Direct Inhibition
Postsynaptic inhibition (IPSP) is the type of synaptic
inhibition that occurs due to the release of an inhibitory
neurotransmitter from presynaptic terminal instead of an
excitatory neurotransmitter substance. It is also called direct
inhibition. Inhibitory neurotransmitters are
gammaaminobutyric acid (GABA), dopamine and glycine
34. PROPERTIES OF SYNAPSE
1. ONE WAY CONDUCTION – BELL-
MAGENDIE LAW
According to BellMagendie law, the
impulses are transmitted only in one
direction in synapse, i.e. from
presynaptic neuron to postsynaptic
neuron
35. 2. SYNAPTIC DELAY
Synaptic delay is a short delay that occurs during the
transmission of impulses through the synapse. It is due to
the time taken for:
i. Release of neurotransmitter
ii. Passage of neurotransmitter from axon terminal to
postsynaptic membrane
iii. Action of the neurotransmitter to open the ionic channels in
postsynaptic membrane.
• Normal duration = is 0.3 to 0.5 millisecond.
36. 3. Fatigue
Fatigue at synapse is due to the depletion of neurotransmitter
substance, acetylcholine.
Depletion of acetylcholine occurs because of two
factors:
Soon after the action, acetylcholine is destroyed by
acetylcholinesterase.
Due to continuous action, new acetylcholine is not
synthesized.
37. 4. SUMMATION
Summation is the fusion of effects or progressive
increase in the excitatory postsynaptic potential in
post synaptic neuron when many presynaptic
excitatory terminals are stimulated simultaneously or
when single presynaptic terminal is stimulated
repeatedly.
i. Spatial Summation
Spatial summation occurs when many presynaptic
terminals are stimulated simultaneously
ii. Temporal Summation
Temporal summation occurs when one presynaptic
terminal is stimulated repeatedly.