4. Neurotransmitters, Neuronal Communication & Hormones Flashcards
(112 cards)
How large is the gap between two neurons in electrical synapses?
2-4nm
How large is the gap between two neurons in chemical synapses?
20-40nm
Ionotropic receptors control the ion channel…
Directly
When bound with the transmitter the ion channels open and… (ionotropic receptors)
Ions flow across the membrane
What are ionotropic receptors also known as?
Ligand-gated ion channels
What do metabotropic receptors activate?
G-proteins that subsequently control the ion channel
What are the 6 properties of neurotransmitters?
- Synthesized in the presynaptic neurone
- Localised to vesicles in the presynaptic neuron
- Released from the presynaptic neurone under physiological conditions
- Rapidly removed from the synaptic cleft by uptake or degradation
- Presence of receptor on the post synaptic neurone
- Binding to the receptor elicits a biological response
What is the role of Acetylcholine?
A neurotransmitter used by the spinal cord neurons to control muscles and by many neurons in the brain to regulate memory
What is the role of dopamine?
The neurotransmitter that produces feelings of pleasure when released by the brain reward system. Dopamine has multiple functions depending on where in the brain it acts
What is the role of GABA?
The major inhibitory neurotransmitter in the brain
What is the role of glutamate?
The most common excitatory neurotransmitter in the brain
What is the role of glycine?
A neurotransmitter used mainly by neurons in the spinal cord
What is the role of Norepinephrine?
In the PNS, it is part of the fight-or-flight response. In the brain, it acts as a neurotransmitter regulating normal brain processes
What is the role of serotonin?
Involved in many functions including mood, appetite and sensory perception
Continued presence of neurotransmitters in the synaptic cleft would lead to persistent…
EPSPs or IPSPs - even without further APs in the presynaptic neuron
To prevent a continuing firing of EPSPs/IPSPs due to presence of neurotransmitters, they are either…
- Moved back into the pre-synaptic neurone (through reuptake)
- Degraded/neutralised by enzymes
What is the purpose of point-to-point communication?
Restricts synaptic communication
What is the purpose of hormonal communication?
Secretes chemicals into the blood stream to affect the entire body
What is the purpose of interconnected neurons of the ANS?
Simultaneously controls responses in many internal organs
What is the purpose of diffuse modulatory systems?
Specific neurotransmitters regulate arousal, mood, motivation, sexual behaviour, emotion, sleep etc.
Messages that must be widely broadcast through the brain use what kind of system?
Diffuse modulatory
Diffuse modulatory systems each require a specific…
Neurotransmitter
The connections of diffuse modulatory systems are widely dispersed throughout where?
The brain
What are diffuse modulatory systems important for?
Motor control, memory, mood, motivation and metabolic state