DL MAY
BLOG 1
2 Mar 2021, 19:51
1. Which types of ion channels are found on the nerve cell membranes?
Voltage-gated and Ligand-gated channels
2. Name 3 differences between voltage-gated and ligand- gated ion channels.
| Voltage-gated | Ligand-gated |
| React to changes in membrane potential | React to the binding of a neurotransmitter to an ion channel |
| metabotropic | ionotropic |
| all or nothing action potential | graded potential |
3. Compare ionotropic and metabotropic receptors.
| Ionotropic | Metabotropic |
| opening of ion channels | metabolic changes |
| receptor has multiple subunits | 7 transmembrane G protein-coupled receptors |
| ionotropic receptors effects only the immediate region | effects are more widespread throughout the cell |
| second messenger absent | formation of second messenger |
4. Classify the CNS receptor into ionotropic and metabotropic and know the transductions mechanism of each.
Ionotropic: GABAA Nicotinic EAA 5-HT3
Metabotropic: divided into two groups nl. Adenylyl Cyclase and Phospholipase C
Adenylyl Cyclase: Contains R+ (b1+2D1) and R- (D2, a2, 5-HT1A, M2) bound receptors. When R+ get stimulated it results in the conversion of ATP to c-AMP. When R- get stimulated it results suppression of c-AMP.
Phospholipase C: All receptors are positively bound (a1, 5-HT2, M1, H1). When stimulated it result into the conversion of PIP2 to DAG and IP3.
5. Explain the difference between EPSP and IPSP and give examples of each
IPSP: When an inhibitory pathway in the CNS is stimulated by γ-aminobutyric acid (GABA) binding to a GABA receptor and stimulating the receptor, the post synaptic potential is hyperpolarised due to the selective opening of chlorine channels so that an inhibitory post synaptic potential can be developed which will eventually "suppress" the CNS. e.g., EAA.
EPSP: When an excitatory path is stimulated, because eg. glutamate binds to the NMDA receptor and it stimulates depolarization which will result in an excitatory membrane potential.
6. What is the role of of calcium in the development of synaptic potential?
Calcium is responsible for the release of neurotransmitters by means of depolarization of the cell membrane when action potential arrives at the axon terminal.