p.1
Electrical Signals in Excitable Cells
What are the electrical signals of excitable cells?
They are signals that allow cells to communicate and respond to stimuli.
p.2
Electrochemical Gradients
What do different kinds of gradients depend on for life?
Life depends on different kinds of gradients.
p.2
Action Potential (AP) and Graded Potential (GP)
What are the two important electrical signals in excitable cells?
Action potential (AP) and graded potential (GP).
p.2
Gated vs. Non-Gated Ion Channels
What are the two types of ion channels mentioned?
Gated and non-gated ion channels.
p.2
Action Potential (AP) and Graded Potential (GP)
What is the mechanism of an action potential related to?
The properties of voltage-gated ion channels.
p.2
Neuronal Structure and Function
What is a key characteristic of the structure of a neuron?
It has general components that facilitate signal transmission.
p.2
Electrical Signals in Excitable Cells
What types of bodily signals are discussed?
Types of signals related to excitable cells.
p.2
Resting Membrane Potential (RMP)
What important terminologies describe membrane potential changes?
Terminologies that relate to changes relative to resting membrane potential (RMP).
p.2
Membrane Transport Mechanisms
What are the types of membrane transports mentioned?
Different types of membrane transport mechanisms.
p.27
Resting Membrane Potential (RMP)
What does a change in membrane potential affect?
The resting membrane potential (mV).
p.18
Membrane Transport Mechanisms
What is the function of active transport?
Moves solutes against their gradients (uphill).
p.7
Neuronal Structure and Function
What is the primary role of the nervous system in the human body?
It is the master control system.
p.18
Membrane Transport Mechanisms
What type of transport does the Na+/K+ ATPase pump exemplify?
Primary (1°) active transport.
p.16
Membrane Transport Mechanisms
What is the function of channel proteins in the cell membrane?
They facilitate the transport of ions and molecules across the membrane.
p.21
Electrochemical Gradients
What is the condition of a hypothetical cell permeable to potassium only?
Electrical force exactly opposes chemical force, achieving equilibrium for K+.
p.18
Membrane Transport Mechanisms
What energy source does active transport utilize?
Energy from ATP hydrolysis.
p.40
Neurotransmission and Synaptic Communication
How do neurons communicate with each other?
Through chemical synapses at the axon terminal.
p.39
Action Potential (AP) and Graded Potential (GP)
What is the mechanism by which the nervous system communicates over long distances?
The propagation of action potentials down the axon.
p.9
Action Potential (AP) and Graded Potential (GP)
What does the arrow in the context of excitable cells refer to?
The direction of signal movement.
p.34
Neuronal Structure and Function
What are the different parts of a neuron?
Dendrites, cell body, axon, axon hillock, and synaptic terminals.
p.14
Resting Membrane Potential (RMP)
Why is the resting membrane potential (RMP) always a negative value?
Due to the distribution of ions across the membrane, primarily the higher concentration of potassium ions inside the cell compared to outside.
p.33
Graded Potential (GP) and Action Potential (AP)
What are graded potentials (GP)?
Changes in membrane potential that can be depolarization or hyperpolarization.
p.33
Resting Membrane Potential (RMP)
What should be looked for first when discussing graded potentials?
Resting membrane potential (RMP).
p.7
Neuronal Structure and Function
How do the components of the nervous system connect?
Through a 'wired' network of nerve fibers.
p.13
Resting Membrane Potential (RMP)
What is the typical value of membrane potential (MP)?
Usually a negative value.
p.40
Action Potential (AP) and Graded Potential (GP)
What happens at the axon hillock?
The integration of graded potentials occurs, leading to the generation of action potentials if the threshold is reached.
p.8
Electrical Signals in Excitable Cells
What causes electrical signals in cells?
Changes in the overall balance of negative and positive ions inside and outside a cell.
p.22
Electrochemical Gradients
What causes K+ to move out of the cell in a hypothetically permeable cell membrane?
The K+ chemical gradient (chemical driving force).
p.4
Neurotransmission and Synaptic Communication
Who has access to the slides containing copyright materials?
Only students of MEDF1011, unless otherwise specified.
p.21
Electrochemical Gradients
What establishes the electrochemical gradient?
Both the concentration difference and electrical charge difference between the cytosolic and extracellular surfaces of the membrane.
p.23
Electrochemical Gradients
What happens to the inside of the cell as K+ diffuses out?
The inside of the cell becomes more negative.
p.13
Resting Membrane Potential (RMP)
What is membrane potential (MP)?
An electrical potential difference across the membrane of all living cells, with the inside being negative relative to the outside.
p.23
Electrochemical Gradients
What is the electrical gradient also known as?
Electrical driving force.
p.13
Resting Membrane Potential (RMP)
How is membrane potential (MP) measured?
In millivolts (mV) based on unpaired charges in the cytosol.
p.23
Electrochemical Gradients
What does the electrical gradient do in relation to K+?
It acts to pull K+ back into the cell.
p.17
Membrane Transport Mechanisms
What type of transport does the Na+/K+ ATPase pump use?
Primary active transport using energy from ATP hydrolysis.
p.8
Neurotransmission and Synaptic Communication
What are chemical signals?
Proteins, lipids, or gases secreted by cells that affect neighboring or distant cells.
p.28
Membrane Transport Mechanisms
How do solutes move in facilitated diffusion?
Down their concentration gradients with the help of integral proteins.
p.4
Neurotransmission and Synaptic Communication
Where can the pre-class assignment be found?
On Blackboard (Micro-modules 2 & 3).
p.24
Resting Membrane Potential (RMP)
What happens when the electrical force exactly opposes the chemical force for K+?
Equilibrium of K+ is achieved.
p.40
Action Potential (AP) and Graded Potential (GP)
What is the role of the axon hillock in neuron function?
It converts graded potentials (GPs) produced in dendrites and the cell body into action potentials (APs).
p.7
Neuronal Structure and Function
What are the three key functions of the nervous system?
Stimulus, Effector, Response.
p.39
Action Potential (AP) and Graded Potential (GP)
What happens when an action potential is successfully triggered at the axon hillock?
The action potential travels along the axon membrane without any decrement towards the axon terminal.
p.34
Graded Potential (GP)
What is the effect of distance on the strength of graded potentials?
The strength of graded potentials weakens and may eventually die out.
p.37
All-or-None Principle of Action Potential
What does the all-or-none principle state?
An action potential (AP) either occurs fully or not at all.
p.23
Electrochemical Gradients
What are anions?
Negatively charged ions such as intracellular proteins.
p.27
Action Potential (AP) and Graded Potential (GP)
What initiates an electrical signal in a neuron?
A change in the membrane potential from its reference point.
p.38
Resting Membrane Potential (RMP)
What should be looked for first before an action potential occurs?
Resting membrane potential (RMP).
p.17
Resting Membrane Potential (RMP)
What effect does the Na+/K+ ATPase pump have on the cell's potential?
It builds up a concentration gradient and produces a small negative potential.
p.31
Resting Membrane Potential (RMP)
What is the effect of hyperpolarisation on the membrane potential?
It moves from RMP to a more negative value.
p.15
Resting Membrane Potential (RMP)
What role do K+ leak channels play in resting membrane potential?
They are always open, allowing K+ to leak out based on its electrochemical gradient.
p.22
Electrochemical Gradients
What does A– represent in the context of the cell?
Anions or negatively charged ions such as intracellular proteins.
p.16
Membrane Transport Mechanisms
What role do protein carriers play in the cell membrane?
They assist in the transport of substances by changing shape to move molecules across the membrane.
p.26
Resting Membrane Potential (RMP)
What is the role of the Na+/K+ ATPase pump in forming resting membrane potential?
It builds up a concentration gradient and generates a small negative potential.
p.9
Electrical Signals in Excitable Cells
What types of muscle cells are considered excitable?
Skeletal muscle, smooth muscle, and cardiac muscle.
p.35
Action Potential (AP) and Graded Potential (GP)
Where does the action potential originate?
At the axon hillock, also called the trigger zone.
p.15
Resting Membrane Potential (RMP)
Why is the cytosol negatively charged compared to the extracellular fluid?
Due to higher concentration of K+ inside the cell and K+ leak channels allowing K+ to exit.
p.17
Neuronal Structure and Function
In which types of cells is the Na+/K+ ATPase pump present?
It is present in all cells.
p.21
Electrochemical Gradients
What does the term electrochemical (EC) gradient refer to?
The driving force across a plasma membrane that dictates whether an ion will move into or out of a cell.
p.34
Graded Potential (GP)
What happens to graded potentials as they travel distance?
They undergo decay and weaken in strength (magnitude).
p.26
Resting Membrane Potential (RMP)
Why does the membrane potential become more negative inside the cell?
Due to greater net movement (leakage) of K+ than Na+.
p.36
Action Potential (AP) and Graded Potential (GP)
What is a key characteristic of action potentials in terms of distance?
They communicate over long distances without undergoing decay (non-decremental).
p.35
Action Potential (AP) and Graded Potential (GP)
What is the purpose of graded potentials?
To determine whether an action potential will be produced at the axon hillock.
p.35
Action Potential (AP) and Graded Potential (GP)
What happens if a graded potential exceeds the threshold potential of -55 mV?
An action potential will be inevitably and irreversibly fired.
p.32
Graded Potential (GP)
Where do graded potentials (GP) occur?
Only at dendrites and cell bodies.
p.35
Action Potential (AP) and Graded Potential (GP)
What is the threshold potential?
The minimal level of depolarization necessary for a neuron to fire an action potential.
p.32
Graded Potential (GP)
How do graded potentials communicate?
Over short distances as local signals (undergo decay).
p.31
Resting Membrane Potential (RMP)
What is the relationship between ion movement and membrane potential changes?
Different ions moving across the membrane cause depolarisation and hyperpolarisation.
p.15
Resting Membrane Potential (RMP)
What is the effect of K+ leakage on the interior of the cell?
It becomes electrically negative.
p.33
Graded Potential (GP) and Action Potential (AP)
What happens to graded potentials as they travel distance?
They undergo decay, meaning they are decremental.
p.9
Electrical Signals in Excitable Cells
What are excitable cells?
Cells capable of producing electrical signals, including all neurons and muscle cells.
p.5
Electrochemical Gradients
What is a gradient?
The difference in the quantity or concentration of a physical value between two areas.
p.38
Action Potential (AP) and Graded Potential (GP)
What is the first phase of an action potential?
Initial depolarization approaching the threshold potential.
p.38
Ion Channels and Their Types
What role do Na+ and K+ channels play in an action potential?
They are voltage-gated channels that facilitate the rapid changes in membrane potential.
p.14
Resting Membrane Potential (RMP)
What does RMP indicate about a neuron's state?
It indicates the neuron is at rest, not receiving or transmitting electrical signals.
p.15
Resting Membrane Potential (RMP)
What does a negative resting membrane potential indicate?
The cytosol is negatively charged in relation to the extracellular fluid.
p.27
Action Potential (AP) and Graded Potential (GP)
What are the two types of electrical signals in neurons?
Graded potential (GP) and action potential (AP).
p.12
Electrical Signals in Excitable Cells
What creates ions in an atom or molecule?
An excess of protons (+) or electrons (−).
p.19
Ion Channels and Their Types
What is the function of K+ leak channels?
They are always open, allowing K+ to leak out of the cell.
p.24
Resting Membrane Potential (RMP)
What is the state of K+ when chemical and electrical driving forces are equal in magnitude but opposite in direction?
K+ is said to be at its own equilibrium state.
p.36
Action Potential (AP) and Graded Potential (GP)
Where does the action potential (AP) initiate?
At the trigger zone called the axon hillock.
p.24
Resting Membrane Potential (RMP)
What are anions in the context of the cell's interior?
Negatively charged ions such as intracellular proteins.
p.5
Electrochemical Gradients
What happens to gradients after death?
Death eliminates all gradients.
p.37
Action Potential (AP) and Graded Potential (GP)
What are subthreshold potentials?
Weak depolarizations of graded potentials.
p.39
Action Potential (AP) and Graded Potential (GP)
What does the frequency of action potentials depend on?
The strength of the stimulus.
p.23
Electrochemical Gradients
What is an electrochemical (EC) gradient?
The combined effect of chemical and electrical forces on ion movement across a membrane.
p.11
Neuronal Structure and Function
What role do axons play in neuronal communication?
They carry outgoing information.
p.8
Neurotransmission and Synaptic Communication
Give examples of chemical signals.
Neurotransmitters (NT) and hormones.
p.28
Gated vs. Non-Gated Ion Channels
What is the function of gated channels?
They can open and close, controlling the movement of solute through the cell membrane.
p.30
Action Potential (AP) and Graded Potential (GP)
What are the three types of membrane potential changes?
Depolarization, repolarization, and hyperpolarization.
p.22
Electrochemical Gradients
What is the role of chemical force in the movement of K+ ions?
It drives K+ ions to move out of the cell.
p.19
Ion Channels and Their Types
What are the two main types of ion channels?
Non-gated channels and gated channels.
p.30
Action Potential (AP) and Graded Potential (GP)
What does hyperpolarization indicate?
The potential moving away from the resting membrane potential (RMP) in a more negative direction.
p.3
Gated vs. Non-Gated Ion Channels
What are the three types of gated ion channels?
Voltage-gated, ligand-gated, and mechanically-gated channels.
p.20
Neurotransmission and Synaptic Communication
How is a chemical signal converted in ligand-gated channels?
It is changed into an electrical signal (membrane potential).
p.38
Action Potential (AP) and Graded Potential (GP)
What is an action potential (AP)?
A large and rapid alteration in the membrane potential due to Na+ and K+ voltage-gated channels.
p.5
Electrochemical Gradients
In which direction do substances tend to move in relation to concentration?
From high concentration to low concentration (downhill, down a concentration gradient).
p.36
Action Potential (AP) and Graded Potential (GP)
How does the magnitude of an action potential compare to other signals?
It is larger in magnitude and has a fixed, stereotypical size and shape.
p.13
Resting Membrane Potential (RMP)
Why is the membrane potential (MP) negative?
Because ions arrange themselves along the outer and inner surfaces of the cell membrane, creating an imbalance.
p.5
Electrochemical Gradients
What does life depend on in terms of physical values?
Life depends on gradients.
p.8
Action Potential (AP) and Graded Potential (GP)
What are the two forms of electrical signals?
Graded potential and action potential.
p.32
Graded Potential (GP)
What determines the size of a graded potential?
The strength of the stimulus; it is variable in size.
p.10
Neuronal Structure and Function
What are dendrites?
Highly branched extensions of the neuron cell body that receive and convey electrical signals toward the neuron cell body.
p.20
Gated vs. Non-Gated Ion Channels
What type of signal do mechanically-gated channels respond to?
Mechanical signals, which change to electrical signals.
p.24
Resting Membrane Potential (RMP)
What is the significance of the equilibrium state for K+?
It indicates that the magnitude of the chemical force is the same as the electrical force.
p.17
Resting Membrane Potential (RMP)
What is the concentration of K+ ions inside the cell compared to outside?
K+ is more concentrated inside the cell than outside.
p.26
Resting Membrane Potential (RMP)
What occurs at steady state regarding ion movement in resting membrane potential?
Ion movement through channels and the pump balance each other.
p.17
Membrane Transport Mechanisms
What does the Na+/K+ ATPase pump do?
It actively pumps 3 Na+ ions out of the cell and 2 K+ ions into the cell.
p.10
Neuronal Structure and Function
What is the primary function of a neuron?
To initiate, integrate, and conduct electrical signals.
p.22
Electrochemical Gradients
What is an electrochemical (EC) gradient?
It is the combined effect of the concentration gradient and the electrical gradient for ions across a membrane.
p.10
Neuronal Structure and Function
What is the axon hillock?
The region of the axon that arises from the cell body and is the site where action potential is triggered.
p.32
Graded Potential (GP)
What types of changes can graded potentials cause?
Can be depolarization or hyperpolarization.
p.32
Graded Potential (GP)
Do graded potentials require a threshold potential for generation?
No, they do not require a threshold potential.
p.19
Ion Channels and Their Types
What are examples of non-gated channels?
K+ and Na+ leak channels.
p.20
Gated vs. Non-Gated Ion Channels
What is the function of ligand-gated channels?
They open in response to a specific chemical signal (ligand).
p.29
Membrane Transport Mechanisms
What type of energy does simple diffusion require?
No metabolic energy (ATP).
p.37
Action Potential (AP) and Graded Potential (GP)
What is a sub-threshold stimulus?
A stimulus that will not generate an action potential.
p.40
Graded Potential (GP)
What are graded potentials (GPs)?
Changes in membrane potential that occur in dendrites and the cell body.
p.8
Neurotransmission and Synaptic Communication
What are the two general types of bodily signals?
Electrical signals and chemical signals.
p.34
Graded Potential (GP)
What occurs to the signal as it travels towards the axon hillock?
The signal becomes much smaller.
p.11
Neuronal Structure and Function
What is the function of dendrites in a neuron?
To receive incoming signals.
p.31
Resting Membrane Potential (RMP)
What is the effect of depolarisation on the membrane potential?
It moves from RMP to a less negative value.
p.27
Gated vs. Non-Gated Ion Channels
What do gated channels do in response to a stimulus?
They open and close, leading to a change in the membrane's potential.
p.35
Ion Channels and Their Types
What is significant about the axon hillock?
It has a high density of voltage-gated ion channels.
p.32
Graded Potential (GP)
What are some alternative names for graded potentials?
Synaptic potential, receptor potential, pacemaker potential.
p.3
Membrane Transport Mechanisms
What is the difference between simple diffusion, facilitated diffusion, and primary active transport?
Simple diffusion does not require energy, facilitated diffusion uses transport proteins, and primary active transport requires ATP.
p.29
Membrane Transport Mechanisms
What is an example of counter-transport in active transport (secondary)?
Na+-H+ counter-transport.
p.22
Electrochemical Gradients
What ions are mentioned as being in high concentration in the context of the cell?
High [Na+], High [Cl–], High [K+], High [A–].
p.3
Membrane Transport Mechanisms
What is the function of the Na+/K+ ATPase pump?
To maintain the concentration gradients of Na+ and K+ across the cell membrane.
p.19
Ion Channels and Their Types
What is an example of a voltage-gated channel?
Voltage-gated Na+ and K+ channels.
p.12
Electrical Signals in Excitable Cells
What is the relationship between similar charges?
Similar charges repel one another.
p.3
All-or-None Principle of Action Potential
What is the threshold potential?
The minimum voltage required to trigger an action potential, typically around -55 mV.
p.29
Membrane Transport Mechanisms
Does active transport (secondary) require direct metabolic energy?
No, it uses indirect energy.
p.32
Graded Potential (GP)
What usually causes graded potentials?
Opening of ligand-gated ion channels.
p.10
Neuronal Structure and Function
What is the soma in a neuron?
The part of the cell containing the nucleus and most of the organelles, which integrates signals received by dendrites.
p.12
Electrical Signals in Excitable Cells
What do opposite charges store when separated?
Electrical potential (or voltage).
p.3
Gated vs. Non-Gated Ion Channels
What is the difference between leak and gated ion channels?
Leak channels are always open, while gated channels open in response to specific stimuli.
p.10
Neuronal Structure and Function
What is the role of the axon in a neuron?
To convey electrical signals away from the cell body and to other cells.
p.20
Ion Channels and Their Types
What are leak channels?
Channels that are always open, allowing ions to 'leak' in or out of the cell down their concentration gradient.
p.30
Resting Membrane Potential (RMP)
How are depolarization, repolarization, and hyperpolarization related to resting membrane potential?
They are all relative to the resting membrane potential (RMP).
p.15
Resting Membrane Potential (RMP)
When is the membrane permeability of K+ higher?
When the neuron is at rest.
p.30
Action Potential (AP) and Graded Potential (GP)
What is repolarization?
The potential moving back to its original resting membrane potential (RMP).
p.28
Action Potential (AP) and Graded Potential (GP)
What happens to K+ when its gated ion channel is open?
K+ moves out of the cell.
p.30
Action Potential (AP) and Graded Potential (GP)
What does depolarization refer to?
The potential moving from resting membrane potential (RMP) to less negative values.
p.28
Action Potential (AP) and Graded Potential (GP)
What is required for the generation of action potential (AP) in neurons?
Both gated Na+ and K+ channels.
p.19
Ion Channels and Their Types
What are the types of gated channels?
Voltage-gated, ligand (chemically) gated, and mechanically gated channels.
p.3
Action Potential (AP) and Graded Potential (GP)
What are the phases of an action potential?
Depolarization, repolarization, and hyperpolarization.
p.29
Membrane Transport Mechanisms
What is an example of co-transport in active transport (secondary)?
Na+-glucose co-transport.
p.20
Gated vs. Non-Gated Ion Channels
What triggers voltage-gated channels to open?
A change in membrane potential (voltage).
p.3
All-or-None Principle of Action Potential
What is the all-or-none principle of action potential?
Once the threshold is reached, an action potential is generated fully or not at all.
p.29
Membrane Transport Mechanisms
What are the two types of active transport (secondary)?
Co-transport and counter-transport.
p.10
Neurotransmission and Synaptic Communication
What happens at the axon terminal?
It releases neurotransmitters from the axon.
p.12
Electrical Signals in Excitable Cells
What happens when a cation pairs with an anion?
The net charge is zero (0).
p.20
Gated vs. Non-Gated Ion Channels
What causes mechanically-gated channels to open?
Stretch of the cell membrane.
p.3
Action Potential (AP) and Graded Potential (GP)
How do graded potentials differ from action potentials?
Graded potentials vary in magnitude and can summate, while action potentials are all-or-none and have a fixed amplitude.
p.29
Membrane Transport Mechanisms
What are typical examples of substances that undergo simple diffusion?
Non-polar substances like O2 and CO2.
