Nerve Junctions

• What is the term for the junction between two or more neurons?

  Synapse
• What is the primary neurotransmitter involved in a cholinergic synapse?

  Acetylcholine
• What is the function of mitochondria in a synapse?

  They make ATP to move vesicles across the synaptic cleft
• What is the role of voltage-gated Ca channels in a synapse?

  They allow calcium ions to enter the neuron
• What happens when vesicles bud off the neuron membrane?

  They release neurotransmitters into the synaptic cleft
• What is the function of ion channels in a synapse?

  They open to acetylcholine
• What is the axon terminal's role in relation to the synaptic cleft?

  It moves away from the synaptic cleft
• What are the key components of a synapse?


  • Mitochondria
  • Receptors (post-synaptic)
  • Neurotransmitters (acetylcholine)
  • Voltage-gated Ca channels
  • Vesicles
  • Synaptic cleft
  • Ion channels
  • Axon terminal
• What defines a cholinergic synapse?

  It works with acetylcholine as the neurotransmitter
• How does a synapse facilitate communication between neurons?

  By allowing neurotransmitters to transmit signals across the synaptic cleft
• what is the post synaptic membrane made of


  5 polypeptide molecules, 2 have receptor sites specific to acetylcholine, when it binds the sodium channels open and if acetylcholine is present in synaptic cleft it keeps the channels open
• What is the primary function of a synapse?

  Transmission of an action potential across a chemical synapse
• How does neurotransmitter release occur at a synapse?

  It involves a uni-directional release from pre-synaptic to post-synaptic membranes
• What organelles are abundant in the swelling of synapses?

  Mitochondria
• Why are mitochondria important in synapses?

  They provide energy for actively pumping Ca²+ and establishing a concentration gradient
• What happens to neurotransmitters after they are released?

  They are reabsorbed or degraded
• What are catecholamines often reabsorbed without?

  Degradation
• What role do enzymes play in neurotransmitter function?

  They degrade neurotransmitters to ensure short-lived effects
• Which enzyme degrades acetylcholine?

  Acetylcholine esterase
• What do excitatory post-synaptic potentials (EPSPs) result from?

  Neurotransmitter binding that opens chemically gated ion channels
• How do drugs and poisons interfere with synaptic transmission?

  They can alter neurotransmitter synthesis, reduce degradation, block reuptake, or reduce release
• What effect does sarin have on neurotransmitter activity?

  It inhibits the activity of acetylcholinesterase
• How does cocaine affect noradrenaline levels?

  It blocks the reuptake of noradrenaline
• What happens to calcium ions during synaptic transmission?

  They flow quickly into the synaptic button from tissue fluid
• What do synaptic vesicles contain?

  Molecules of neurotransmitter
• What is the role of the synaptic cleft?

  It acts as a barrier to the direct passage of depolarization
• How do neurotransmitter molecules reach the post-synaptic membrane?

  They diffuse across the synaptic gap
• What types of neurotransmitters are released from adrenergic and cholinergic nerve endings?

  Adrenaline from adrenergic and acetylcholine from cholinergic endings
• What do chemically gated ion channels allow in the post-synaptic membrane?

  Influx of Na+ and efflux of K+
• What results from the opening of chemically gated ion channels on the post-synaptic membrane?

  Depolarization of the post-synaptic membrane
• What do inhibitory post-synaptic potentials (IPSPs) result from?

  Neurotransmitter binding that opens channels permitting hyperpolarization
• How do EPSPs and IPSPs differ in their effects on the post-synaptic membrane?

  EPSPs make depolarization more likely, while IPSPs raise the depolarization threshold