Podcast
Questions and Answers
What is the difference between the central nervous system (CNS) and the peripheral nervous system (PNS)?
What is the difference between the central nervous system (CNS) and the peripheral nervous system (PNS)?
The CNS is made up of the brain and spinal cord, while the PNS is made up of nerves that project from the CNS.
Which of the following is NOT a function of the nervous system?
Which of the following is NOT a function of the nervous system?
What are the three types of neurons?
What are the three types of neurons?
Sensory neurons, interneurons, and motor neurons.
What is the function of a myelin sheath?
What is the function of a myelin sheath?
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The action potential is a gradual event that increases in strength based on the strength of the stimulus.
The action potential is a gradual event that increases in strength based on the strength of the stimulus.
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What is the role of neurotransmitters in nerve signaling?
What is the role of neurotransmitters in nerve signaling?
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What happens when a neurotransmitter binds to a receptor on the receiving neuron?
What happens when a neurotransmitter binds to a receptor on the receiving neuron?
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What does the term integration refer to in the context of the nervous system?
What does the term integration refer to in the context of the nervous system?
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The spinal cord only receives information from the brain and sends commands to the body.
The spinal cord only receives information from the brain and sends commands to the body.
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Briefly describe a reflex arc.
Briefly describe a reflex arc.
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What are the two main divisions of the PNS?
What are the two main divisions of the PNS?
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What is the difference between sensory and motor nerves?
What is the difference between sensory and motor nerves?
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What is the function of the vagus nerve?
What is the function of the vagus nerve?
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The myelin sheath is present on all axons.
The myelin sheath is present on all axons.
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What is the primary function of the sodium-potassium pump
What is the primary function of the sodium-potassium pump
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What happens to the inside of the neuron during depolarization?
What happens to the inside of the neuron during depolarization?
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The threshold is the minimum amount of stimulation required to trigger an action potential.
The threshold is the minimum amount of stimulation required to trigger an action potential.
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What are the different ways in which a neurotransmitter is removed from the synaptic cleft?
What are the different ways in which a neurotransmitter is removed from the synaptic cleft?
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What type of nerve signal causes the receiving neuron to be more likely to fire an action potential?
What type of nerve signal causes the receiving neuron to be more likely to fire an action potential?
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Study Notes
Nervous System Overview
- The nervous system is responsible for receiving and processing sensory information from both internal and external environments.
- The nervous system is divided into the Central Nervous System (CNS) and the Peripheral Nervous System (PNS).
- CNS consists of the brain and spinal cord.
- PNS consists of nerves.
Nervous System Components
- Neurons: Cells that transmit nerve impulses between parts of the nervous system.
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Neuroglia (Glial cells): Support and nourish neurons.
- Microglia: Remove bacteria and debris.
- Astrocytes: Provide metabolic and structural support to neurons.
- Oligodendrocytes: Form myelin sheath in the CNS.
- Schwann cells: Form myelin sheath in the PNS.
Neuron Anatomy
- Cell body: Contains the nucleus and other organelles.
- Dendrites: Short extensions receiving signals from sensory receptors or other neurons.
- Axon: Conducts nerve impulses. Individual axons are nerve fibers, which form a nerve. Some axons are covered by a protective myelin sheath. The myelin sheath is interrupted by nodes of Ranvier.
Neuron Types
- Sensory neurons: Transmit nerve signals from sensory receptors to the CNS.
- Interneurons: Found entirely within the CNS, receiving input from sensory neurons and other interneurons.
- Motor neurons: Transmit nerve impulses away from the CNS to effectors (muscles, glands, or organs).
Action Potential
- The process of signal conduction is called an action potential, occurring in neuron axons.
- A stimulus triggers an action potential when the threshold voltage is reached (around -55mV).
- Action potentials are all-or-nothing events.
- Stimulus strength does not change the action potential strength, but can cause more action potentials to occur in a given period.
Action Potential Propagation
- Unmyelinated axons: Action potentials along the entire axon.
- Myelinated axons: Action potentials jump from node to node (saltatory conduction), which is faster.
- Myelin sheath: Insulates the axon, and when damaged/absent, nerve conduction can be impaired.
The Synapse
- Synapse: A small gap between sending and receiving neurons.
- Neurotransmitters: Chemical messengers that carry signals across the synapse.
- Neurotransmitters released into the synaptic cleft, bind with specific receptors on the receiving neuron.
Signal Transmission
- Calcium ions trigger neurotransmitter release.
- Neurotransmitters bind to receptors resulting in excitation or inhibition of receiving neurons.
- Neurotransmitters are removed from the cleft to prevent continual stimulation or inhibition.
Drug Therapy
- Neurological drugs promote, prevent, or replace the action of neurotransmitters at synapses.
Integration
- Integration: Summation of excitatory and inhibitory signals.
- Inhibitory impulses drive the neuron away from action potentials.
- Inhibitory signals can prevent action potentials if they outweigh excitatory ones.
Spinal Cord Function
- The spinal cord acts as a communication pathway between the brain and the peripheral nervous system.
- Sensory receptors sends signals in ascending tracts to the brain.
- Interneurons relay signals to motor neurons.
- Stimulus response involves motor axons causing muscles to contract.
Peripheral Nervous System
- The PNS consists of nerves outside the CNS.
- Cranial nerves arise from the brain, and spinal nerves arise from the spinal cord.
- Cranial nerves primarily control functions of the head, neck, and facial regions. Vagus nerve controls internal organs.
- Some nerves are sensory, some motor, others mixed.
Case Study (Sarah)
- Sarah exhibited symptoms indicative of Multiple Sclerosis (MS).
- MS damages the myelin sheath, affecting nerve signal conduction.
- Diagnostic tools like MRI and Somatosensory Evoked Potential (SSEP) can identify neurological issues.
Questions to Consider (from the slides)
- How does myelin sheath deterioration affect nerve cell function?
- How do MRI and SSEP tests reveal neurological problems?
- Why do many MS patients eventually require wheelchairs?
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