Question

(a) Explain the term Synapse.

Hint:

Synapses are crucial for communication within the nervous system. Electrical synapses allow rapid signal transmission, while chemical synapses provide more complex signaling, such as learning and memory.

Answer 1

Step 1: Define Synapse.
A synapse is the junction or gap between two neurons or between a neuron and another cell, such as a muscle or a gland. It is the point at which a nerve impulse is transferred from one neuron to another or to an effector cell. The synapse ensures that electrical signals can be transmitted efficiently across the nervous system, enabling communication between different parts of the body.
Step 2: Types of synapses.
Synapses are classified into two main types: - Electrical synapses: These synapses allow direct flow of ions between cells through gap junctions. This type of synapse allows very rapid signal transmission and is found in certain areas of the brain and the heart. - Chemical synapses: These synapses involve the release of neurotransmitters to transmit the signal across the synaptic cleft (the gap between the cells). The chemical signals then bind to receptors on the postsynaptic cell, initiating a response.
Step 3: Mechanism of transmission at a chemical synapse.
At a chemical synapse, the transmission of nerve impulses occurs as follows: 1. When an action potential (nerve impulse) reaches the axon terminal of the presynaptic neuron, it triggers the release of neurotransmitters stored in vesicles. 2. The neurotransmitters are released into the synaptic cleft (the gap between the two cells) through exocytosis. 3. These neurotransmitters then bind to receptors on the membrane of the postsynaptic neuron (or effector cell, such as a muscle). 4. This binding opens ion channels, leading to a change in the postsynaptic cell's membrane potential and allowing the transmission of the signal to continue. 5. Once the neurotransmitter has completed its action, it is broken down by enzymes or reabsorbed by the presynaptic neuron.