Question

• Know what ligand-gated ion channelsare and their role in direct synaptic transmission
• Neurotransmitters:  know the definition, and the functions of the following –
  • Acetylcholine (also know the toxins that disrupts this)
  • Norepinephrine
  • Dopamine and serotonin
  • endorphins

Answer 1

•Ligand-gated ion channels are commonly known as ionotropic receptors. These are a group of transmembrane ion-channel proteins which open to allow ions such as Na⁺, K⁺, Ca²⁺, and/or Cl⁻ to pass through the membrane in response to the binding of a chemical messenger, such as a neurotransmitter. These ligand gated ion channels bind neurotransmitters and open in response to the ligand binding. These channels control the synaptic transmission between two neurons or between a neuron and a muscle. One subfamily encompasses the Cys-loop channels, so named because of a large extracellular domain containing Cys loops.
• Acetylcholine is an organic chemical that functions in the brain and body of many types of animals as a neurotransmitter and also a chemical message released by nerve cells to send signals to other cells, such as neurons, muscle cells and gland cells. It contracts smooth muscles, dilates blood vessels, increases bodily secretions, and slows heart rate. Intramuscular administration of botulinum toxin acts at the neuromuscular junction to cause muscle paralysis by inhibiting the release of acetylcholine from presynaptic motor neurons.

• Norepinephrine is a naturally occurring chemical in the body that acts as both stress hormone and neurotransmitter. It's released into the blood as a stress hormone when the brain perceives that a stressful event has occurred. The main function of norepinephrine is to mobilize the brain and body for action. It's release is lowest during sleep, rises during wakefulness, and reaches much higher levels during situations of stress or danger, in the so-called fight-or-flight response.

• Dopamine is a type of neurotransmitter which is made by our body and nervous system uses it to send messages between nerve cells. That's why it's sometimes called a chemical messenger. It's main functions includes movement, pleasure, attention, mood, and motivation.

Serotonin is a chemical that is produced by nerve cells . It sends signals between your nerve cells. It is found mostly in the digestive system, although it's also in blood platelets and throughout the central nervous system and it is made from the essential amino acid tryptophan. It helps control your bowel movements. Serotonin in the brain is thought to regulate anxiety, happiness, and mood. Low levels of the chemical have been associated with depression, and increased levels of this chemical brought on by medication are thought to decrease arousal.

• Endorphins are polypeptides made by the pituitary gland and central nervous system. They help one deal with stress and reduce feelings of pain. That's why they are known to be natural pain relievers. They act as analgesics, which means they diminish the perception of pain and they can also act as sedatives. They are manufactured in our brain, spinal cord, and many other parts of our body and are released in response to brain chemicals called neurotransmitters.