Potensial Berjenjang (Graded Potential)
Summary
TLDRThe script discusses the concept of graded potentials, which are small deviations from the resting membrane potential in neurons. These potentials can either hyperpolarize or depolarize the membrane, making it more or less negative. Graded potentials occur in response to stimuli, such as the opening of mechanoreceptive or ligand-gated ion channels, leading to the influx of ions like sodium or calcium. The amplitude of these potentials varies with the strength of the stimulus, and they can summate or cancel each other out. They play a crucial role in the generation of action potentials and are named based on their location and the type of stimulus that causes them, such as postsynaptic potentials or receptor potentials.
Takeaways
- 🔬 Grade potentials are small deviations from the resting membrane potential, causing the membrane to become more or less polarized.
- 🌟 Grade potentials can be hyperpolarized (more negative) or depolarized (less negative or more positive) depending on the stimulus.
- 🧠 These potentials occur in the dendrites of sensory neurons and in the cell bodies and dendrites of motor and interneurons.
- 💡 Grade potentials are initiated by the opening of mechanosensitive or ligand-gated ion channels, allowing ions to flow across the membrane.
- 🚪 The opening of these channels is triggered by mechanical stimuli or binding of neurotransmitters like acetylcholine.
- 🔋 The influx of positive ions such as sodium or calcium during depolarizing potentials makes the inside of the cell more positive, leading to membrane depolarization.
- 🔌 Conversely, the influx of negative ions like chloride during hyperpolarizing potentials increases the negative charge inside the cell, making it more hyperpolarized.
- 📊 Grade potentials vary in amplitude, which depends on the strength and duration of the stimulus, as well as the number of open ion channels.
- 🔁 Grade potentials can summate; when multiple depolarizing or hyperpolarizing potentials occur, they can add up to form a larger potential.
- ⚡ Opposing grade potentials can cancel each other out if they are of opposite polarities, potentially neutralizing the membrane potential.
- 🏷 Grade potentials are also known as postsynaptic potentials when they occur in response to neurotransmitter release at the synapse, or as receptor potentials when they occur at sensory receptors.
Q & A
What is the resting membrane potential and its significance?
-The resting membrane potential is the difference in electrical charge across the cell membrane when the cell is at rest. It is significant because it sets the baseline for the cell's ability to generate an action potential in response to stimuli.
What is a graded potential and how does it differ from an action potential?
-A graded potential is a change in the membrane potential that varies in amplitude depending on the strength of the stimulus. It differs from an action potential, which is an all-or-nothing response that reaches a threshold and propagates along the axon.
How do mechanoreceptors and ligand-gated channels contribute to the generation of graded potentials?
-Mechanoreceptors and ligand-gated channels can open in response to mechanical or chemical stimuli, allowing ions such as sodium or calcium to enter the cell. This influx of positive ions can depolarize the membrane, contributing to the formation of a graded potential.
What is the role of dendrites in the generation of graded potentials?
-Dendrites are involved in the generation of graded potentials as they receive synaptic inputs from other neurons. The summation of these inputs in the dendritic region can lead to either depolarization or hyperpolarization of the membrane potential.
What happens during depolarization and hyperpolarization of the membrane potential?
-During depolarization, the inside of the cell becomes less negative or more positive due to the influx of positively charged ions. Hyperpolarization, on the other hand, occurs when the inside of the cell becomes more negative due to the efflux of positively charged ions or the influx of negatively charged ions.
How do the amplitudes of graded potentials vary and what factors influence them?
-The amplitudes of graded potentials vary depending on the strength of the stimulus and the number of ion channels that open. A stronger stimulus or more open channels will result in a larger amplitude, indicating a greater change in membrane potential.
What is the relationship between the duration of ion channel opening and the amplitude of a graded potential?
-The duration that ion channels remain open influences the amplitude of a graded potential. The longer the channels are open, the more ions can enter or exit the cell, leading to a larger change in membrane potential.
Can graded potentials summate, and what are the conditions for this to occur?
-Yes, graded potentials can summate when multiple graded potentials of the same type (either depolarizing or hyperpolarizing) occur close together in time. This summation can result in a larger overall change in membrane potential.
What is the significance of the threshold for an action potential to be generated?
-The threshold is the level of membrane potential depolarization that must be reached for an action potential to be generated. If the graded potential does not reach this threshold, the cell will not produce an action potential.
What are some examples of different types of graded potentials mentioned in the script?
-Examples of different types of graded potentials include postsynaptic potentials, which occur at the synapse in response to neurotransmitter release, and receptor potentials, which occur at sensory receptors in response to stimuli such as touch.
How do the spatial and temporal summation of graded potentials influence the generation of an action potential?
-Spatial summation refers to the summation of graded potentials across different parts of the cell membrane, while temporal summation refers to the summation of potentials over time. Both types of summation can increase the amplitude of the graded potential, potentially reaching the threshold necessary to trigger an action potential.
Outlines
🔬 Graded Potentials and Membrane Polarization
This paragraph discusses the concept of graded potentials, which are small deviations from the resting membrane potential in neurons. It explains how these potentials can either hyperpolarize (become more negative) or depolarize (become less negative) the membrane. The paragraph also describes how graded potentials occur in the dendrites of sensory neurons and can be influenced by mechanical or chemical stimuli. The process of depolarization and hyperpolarization is illustrated with the opening of ion channels allowing the influx of sodium or calcium ions, which carry a positive charge and thus depolarize the membrane, or the efflux of potassium ions, which carry a negative charge and hyperpolarize it. The amplitude of the graded potential is related to the strength of the stimulus and the number of ion channels that open.
🌐 Interaction of Graded Potentials and Types
The second paragraph delves into the interaction of graded potentials, highlighting how they can summate—either by adding together if they are of the same type (both depolarizing or both hyperpolarizing) or by cancelling each other out if they are of opposite types. It also explains how the duration and number of open ion channels affect the amplitude of the graded potential. The paragraph introduces different types of graded potentials based on the stimuli that cause them and where they occur, such as postsynaptic potentials in the dendrites in response to neurotransmitters or receptor potentials at sensory receptors. The discussion also touches on the threshold for action potential generation and how graded potentials that do not reach this threshold will not trigger an action potential, thus stopping the nerve impulse.
Mindmap
Keywords
💡Graded Potential
💡Resting Membrane Potential
💡Depolarization
💡Hyperpolarization
💡Ion Channels
💡Action Potential
💡Neurotransmitters
💡Postsynaptic Potential
💡Receptor Potential
💡Synaptic Transmission
💡Summation
Highlights
Grade potential, or potential difference, is a small deviation from the resting membrane potential.
Grade potential can make the membrane more polarized or less polarized, becoming more negative or less negative.
Grade potential occurs when a stimulus causes the opening of mechanoreceptors or ligand-gated channels, allowing ions to enter and exit the cell.
Mechanoreceptors and ligand-gated channels are found in the dendrites of sensory neurons, motor neurons, and interneurons.
Grade potential happens in the dendritic parts and can be seen in the provided image.
There are two types of grade potential: hyperpolarization and depolarization.
A response to a stimulus that makes the membrane more polarized or more negative is called hyperpolarization.
Depolarization occurs when the response makes the membrane less polarized or more positive.
The resting membrane potential is when the cell is not triggered, and the mechanoreceptors are closed.
Positive ions such as sodium and calcium entering the cell cause depolarization.
The entry of positive ions like sodium and calcium increases the internal charge, leading to depolarization.
Binding with acetylcholine opens channels, allowing sodium and calcium to enter, causing depolarization.
The entry of chloride ions, which have a negative charge, increases the negativity of the cytosol, resulting in hyperpolarization.
The amplitude of the grade potential varies depending on the strength of the stimulus.
A stronger stimulus results in a larger amplitude due to more ion channels opening and a longer duration.
Grade potentials can sum up if they are of the same type, increasing the overall potential.
Opposite grade potentials can cancel each other out if they are combined.
Grade potentials have different names depending on the type of stimulus and where they occur, such as postsynaptic potentials or receptor potentials.
Postsynaptic potentials occur in response to neurotransmitters at the synapse.
Receptor potentials occur at sensory receptors, such as when touching a sharp point.
Transcripts
Hai potensial berjenjang atau grade
potensial adalah deviasi kecil dari Mbak
potensial membran istirahat yang membuat
membran menjadi lebih terpolarisasi di
dalam itu menjadi lebih negatif atau
kurang terpolarisasi di dalamnya kurang
negatif potensial berjenjang terjadi
ketika adanya stimulus yang menyebabkan
terbukanya kanal mekanik maupun karena
ligan sehingga memungkinkan Hyeon masuk
dan mengeksitasi membran plasma karena
on mekanik maupun karena ligan itu
banyak ditemukan di dendrit dari neuron
sensoris sedangkan karena ligan itu
banyak di dendek maupun Salma dari
neuron motoris maupun interneuron tapi
intinya adalah grade potensial itu
terjadinya adalah di bagian dendrit
maupun sama seperti terlihat pada gambar
ini potensial
yang itu ada dua yaitu potensial
berjenjang yang bentuknya
hiperpolarisasi dan potensial berjenjang
yang bentuknya adalah depolarisasi
ketika ada respon atau stimulus namun
membuat membran itu lebih terpolarisasi
atau didalamnya menjadi lebih negatif
maka ini disebut potensial berjenjang
hiperpolarisasi jadi semakin negatif
jika ada respon menyebabkan membran itu
menjadi kurang terpolarisasi atau kurang
negatif naik itu disebut potensial
berjenjang depolarisasi menjadi lebih
positifnya ketika potensial membran itu
istirahat atau sel itu tidak terpicu
maka karena gelombang mekanik akan
tertutup ketikan ada tekanan misalnya
maka akan menyebabkan karena gerbang
mekanik ini terbuka sehingga
memungkinkan ion kalsium maupun natrium
masuk ke
Hai karena masuknya ion yang positif ini
natrium maupun kalsium itu membawa
muatan positif maka akan mendepolarisasi
menipu larisas membran maka dikatakan
potensial berjenjang yang tipe
depolarisasi kemudian misalnya contoh
kedua ketika potensial membran istirahat
maka karena ligan disini akan tertutup
tapi ketika Adanya ikatan dengan
asetilkolin karena Lini akan terbuka
sehingga memungkinkan natrium maupun
kalsium itu masuk ya dan secara
bergantian kalium akan keluar nah
masuknya natrium dan kalsium ini akan
menyebabkan di dalam sel itu akan
menjadi lebih positif sehingga potensial
bercinta yang terbentuk ada potensial
berjenjang depolarisasi ikatan dengan
gliserin itu terbuka maka akan
memungkinkan ion klorida yang muatan
negatif masuk
porno ion klorida masuk muatannya
negatif maka akan meningkatkan
negativitas dari sitosol sehingga
dikatakan potensial berjenjang nya
adalah hiperpolarisasi jika makin
menjauhi minus 76 ikata smaka akan
semakin mendekati sel itu untuk di
Munculkan potensial aksi tapi Makin
menjauh maka akan membuat sel itu untuk
tidak dapat melanjutkan impuls saraf
karena tidak akan memicu potensial aksi
nah sinyal elektrik itu dikatakan
berjenjang karena dia bervariasi dalam
amplitudonya Mengapa bervariasi karena
tergantung pada kekuatan stimulus makin
besar stimulus yang datang kekuatannya
maka akan makin besar amplitudo yang
ditimbulkan Kenapa terjadi begitu karena
menentu
Hai dari semakin banyak atau tidaknya
karena lgerbang ligan maupun mekanik
yang terbuka dan berapa lama sih karena
gerbang itu terbuka Kalau makin lama
atau makin banyak kenal yang terbuka
tentunya akan pakai banyak ion yang
masuk ke dalam sel kalau yang masuk
adalah ion positif maka amplitudo ini
atau geraknya ke atasnya tapi jika yang
masuk adalah ion yang muatannya negatif
contohnya tadi Florida maka geraknya
akan ke bawah terhype terpolarisasi nah
perhatikan di sini ya ini simbol satu
kecil maka yang terbentuk adalah
amplitudo yang kecil ini sedang dan ini
yang kuat rumah si adalah proses ketika
potensial berjenjang itu ditambahkan
jika ada dua potensial berjenjang
depolarisasi yang datang dan kemudian
dijumlahkan maka akan semakin besar
potensial berjenjang depolarisasi nya yg
hai ketika ada dua potensial berjenjang
hiperpolarisasi itu ditambahkan maka
semakin besar pula potensial berjejer
hiperpolarisasi nya kalau ada dua yang
potensial berjenjang yang berlawanan
yang satu depolarisasi dan yang satunya
hiperpolarisasi maka mereka dapat saling
menempel atau menghapus satu sama lain
sehingga potensial berjenjang akan
menghilang ini contohnya ya datang
stimulus satu yang berdekatan dengan
stimulus kedua maka akan di-zoom asikan
atau dijumlahkan sehingga akan muncul
potensial berjenjang depolarisasi yang
lebih besar nah potensial berjenjang itu
punya banyak ada beberapa nama
tergantung pada tipe stimulus yang
menyebabkannya dan tergantung pada di
mana beredar potensial atau potensial
bersin yang itu terjadi ketika potensial
berjenjang itu terjadi dendrit atau koma
dari neuron sesuai
Radar respon dari adanya
neurotransmitter maka itu disebut dengan
potensial postsinaptic potensial
berjenjang yang terjadi pada reseptor
sensoris contohnya tadi ya di ujung jari
menyentuh bolpoin maka itu dinamakan
potensial reseptor
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