Synapses

Summary

This video explains how neurons transmit nerve impulses and communicate with other cells through synapses. It outlines the types of cells neurons connect with, including sensory receptors, interneurons, and effector cells. The process of synaptic transmission is detailed, covering neurotransmitter release, receptor binding, and the 'all or nothing' response. The video also highlights acetylcholine's role and its breakdown, as well as the harmful effects of neonicotinoid insecticides on insects like honeybees, which block acetylcholine receptors, leading to paralysis and death.

Takeaways

• 🧠 Neurons transmit nerve impulses and communicate with other cells by sending chemicals across synapses.
• 🔗 Synapses are junctions between neurons and other cells, including sensory receptors, other neurons, and effector cells.
• 👂 Sensory receptor cells are involved in sensing stimuli from places like the eyes, ears, nose, and skin.
• 🌀 Interneurons act as intermediaries between sensory neurons and effector cells, transmitting signals to the central nervous system.
• 💪 Effector cells, such as muscle cells, receive signals to initiate a response, like moving away from pain.
• ⚡ Synaptic transmission involves the release of neurotransmitters into the synaptic cleft, which then bind to receptors on the post-synaptic membrane.
• 🔋 Neurotransmitters, like acetylcholine, are broken down and recycled after triggering an action potential.
• 🌐 The 'all or nothing' response ensures that an action potential only occurs if enough neurotransmitters bind to receptors.
• 🧪 Acetylcholine is broken down by acetylcholinesterase, an enzyme present in the synaptic cleft, allowing reuse of its components.
• 🐝 Neonicotinoid insecticides can paralyze insects by permanently binding to acetylcholine receptors, affecting non-target species like honeybees.

Q & A

What is the function of synapses in the nervous system?

Synapses are junctions between neurons and the next cell, allowing for the transmission of nerve impulses from one cell to another across a small gap.

What are the three major types of cells that neurons form synapses with?

The three major types of cells are sensory receptor cells, other neurons (interneurons), and effector cells.

How does a sensory cell involved in pain sensation transmit its message?

A sensory cell picks up pain sensations and sends the message to another neuron, potentially in the spinal cord or brain, which then processes the information.

What is the role of effector cells in a reflex arc?

Effector cells are responsible for the action part of a reflex arc, such as signaling a muscle cell to move the skin away from a source of pain.

What are neurotransmitters and how are they released?

Neurotransmitters are chemicals released into the synapse that facilitate communication between neurons. They are released by exocytosis from vesicles in the pre-synaptic neuron into the synaptic cleft.

What is the synaptic cleft and how wide is it?

The synaptic cleft is the small fluid-filled gap between the pre-synaptic and post-synaptic cells, which is approximately 20 nm wide.

What happens during synaptic transmission when a nerve impulse reaches the end of the pre-synaptic neuron?

Calcium ions enter the cell, causing vesicles with neurotransmitters to fuse with the membrane and release their contents into the synaptic cleft.

How do neurotransmitters affect the post-synaptic neuron?

Neurotransmitters bind to receptors on the post-synaptic membrane, triggering the opening of sodium ion channels and potentially generating an action potential.

What is the 'all or nothing' response in synaptic transmission?

The 'all or nothing' response refers to the fact that if there isn't enough neurotransmitter to bind to receptors and reach the threshold potential, no action potential is generated.

What is Acetylcholine and how does it function in the nervous system?

Acetylcholine is a neurotransmitter composed of an acetyl group and choline. It is released into the synaptic cleft, binds to receptors, and is then broken down by acetylcholinesterase for reuse.

How do neonicotinoids affect insect nervous systems and why are they harmful to beneficial insects?

Neonicotinoids are synthetic compounds that bind permanently to acetylcholine receptors, preventing the action of acetylcholinesterase and leading to paralysis and death in insects. This indiscriminate effect also harms beneficial insects like honeybees.