Unit 7 - Signallin through the Synapse

Question 1

Synapses

Answer 1

Nerve terminal meets a Neuron, Muscle Cell or Gland.

• Presynaptic cell: send a signal into synaptic cleft
• Postsynaptic cell: receives the signal

Question 2

Three Different Types of Synapses

Answer 2

1. ) Electrical Synapse
   2) Chemical Synapse
2. ) Neuromuscular Synapse

Question 3

Electrical Synapse

Answer 3

Presynaptic and Postsynaptic cell membranes are connected by channels. Channels pass electrical charge.

Question 4

Chemical Synapse

Answer 4

The Neurotransmitters. Transmit signals from a neutron to a target cell across a synapse. Require a few biosynthetic steps. Neurotransmitters are packaged into synaptic vesicles beneath the membrane on the presynaptic side of a synapse, release upon action potential. Bind to receptors in the membrane of the Postsynaptic side of synapse.

Question 5

Neuromuscular Synapse

Answer 5

Termed: the Motor Unit

The presynaptic neutron releases a neurotransmitter that binds to receptors located in a muscle cell.

Question 6

Neurons release…

Answer 6

Acetylcholine (ACh): polyatomic cation of acetic acid and choline, diffuse through synapse.
The only neurotransmitter in the motor division of the somatic nervous system.

Question 7

ACh binds the…

Answer 7

Nicotinic ACh Receptor (nAChR):

• Inotropic receptor located on the plasma membrane of the muscle fibre
• Serve as ligand gated ion channel
• Binding of ACh to the nAChR depolarize the muscle fibre causing a cascade of intracellular reactions that result in muscle contraction.

Question 8

Neurotransmitter Secretion

Answer 8

As an action potential reaches the end of a motor neurone, voltage dependent calcium channels open allowing calcium to enter the neuron

Question 9

Calcium…

Answer 9

binds to sensor proteins on synaptic vesicles triggering vesicle fusion with plasma membrane and subsequent neurotransmitter release from the motor neurone into the synaptic cleft:
- releases by exocytosis into the synaptic cleft, diffuses across cleft

Question 10

ACh one of the most…

Answer 10

Widespread neurotransmitters:
Acts as a neurotransmitter in both the PNS and CNS
Principal neurotransmitter in all autonomic ganglia