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Questions and Answers
What happens when the action potential exceeds -55mV?
What happens when the action potential exceeds -55mV?
- The neuron remains at resting potential.
- Sodium ions exit the neuron.
- The neuron fires. (correct)
- K+ channels close immediately.
Which ion primarily flows into the neuron during the first phase of the action potential?
Which ion primarily flows into the neuron during the first phase of the action potential?
- Ca2+ ions
- Na+ ions (correct)
- Cl- ions
- K+ ions
What is the term for the travel of action potential along the axon?
What is the term for the travel of action potential along the axon?
- Propagation (correct)
- Transmission
- Repolarization
- Refractory period
What occurs during the refractory period of a neuron?
What occurs during the refractory period of a neuron?
Which type of neuron is responsible for transmitting signals from sensory receptors to the central nervous system?
Which type of neuron is responsible for transmitting signals from sensory receptors to the central nervous system?
What happens to K+ ions after the action potential leaves a specific point in the axon?
What happens to K+ ions after the action potential leaves a specific point in the axon?
How do neurons communicate with one another?
How do neurons communicate with one another?
In the context of neuron firing, how can the intensity of a stimulus affect the response?
In the context of neuron firing, how can the intensity of a stimulus affect the response?
What are the two basic cells that make up the nervous system?
What are the two basic cells that make up the nervous system?
What is the approximate weight of the average human brain?
What is the approximate weight of the average human brain?
What is the potential difference of a neuron at rest, also known as resting potential?
What is the potential difference of a neuron at rest, also known as resting potential?
What substance covers the axon and helps in insulating the neuron?
What substance covers the axon and helps in insulating the neuron?
What happens when a neuron is activated and an action potential is generated?
What happens when a neuron is activated and an action potential is generated?
Which ions move more easily in and out of neurons, influencing resting potential?
Which ions move more easily in and out of neurons, influencing resting potential?
How do the central nervous system and peripheral nervous system differ?
How do the central nervous system and peripheral nervous system differ?
What role do sodium pumps and leakage channels play in neurons?
What role do sodium pumps and leakage channels play in neurons?
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Study Notes
The Nervous System
- Nervous system is made up of two main parts:
- Central nervous system (CNS): Brain and spinal cord
- Peripheral nervous system: All other nerves in the body
- Brain is essential for behavior and weighs approximately 1.5kg
- Two basic cell types make up the nervous system, including the brain:
- Glia: Support functions in the nervous system
- Neurones: Receive and transmit information via electrical pulses, enabling thinking, talking, and walking
Neurones
- Dendrites receive signals from other connected neurones
- Axon transmits information from dendrites to other neurones, covered by a fatty substance called Myelin sheath
- Myelin sheath is semi-permeable, allowing some chemicals to enter or exit, but not ions. Ions can travel through ion channels
- Potential difference between inside and outside of the cell changes when a neuron is activated. This difference is measured in millivolts (mV)
- Resting potential of a neuron is -70mV when inactive, meaning the inside is negatively charged due to more sodium ions (Na+) outside the membrane than potassium ions (K+) inside
- Action potential is generated when potential difference changes beyond a limit, causing a spike of positive charge inside the neuron.
- Neuron fires when action potential exceeds -55mV
- Action potential travels along the axon like a wave
Neuron Firing
- Sodium (Na+) ions flood into the cell when action potential reaches a location
- Potassium (K+) ions are pumped out immediately after the action potential leaves
- Not all stimuli lead to an action potential
- Neuron firing is an 'all-or-none' process: either fires or doesn't fire
- Intensity of stimulus is determined by the number of neurons firing
Types of Neurones
- Sensory neurones translate physical stimuli into electrical signals and transmit them to the central nervous system (CNS) via interneurons
- Motor neurones send signals from the CNS to muscles or other body parts, carrying out the brain's desired movements
- Interneurons connect within the CNS and with sensory and motor neurons
Neuron Firing Features
- Intensity of a stimulus influences the number of neurons firing, not the strength of a single neuron's firing.
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