Reflex action is an involuntary and rapid response to a stimulus that bypasses conscious thought. It involves a simple neural pathway called a reflex arc, which includes a sensory neuron, interneuron, and motor neuron. Walking, on the other hand, is a voluntary and coordinated movement involving various muscle groups controlled by the brain's motor cortex and cerebellum. Unlike reflex actions, walking requires conscious intention and coordination between different parts of the brain and muscles.

At the synapse between two neurons, neurotransmitters are released from the presynaptic neuron into the synaptic cleft. These neurotransmitters then bind to receptors on the postsynaptic neuron, causing a change in its membrane potential. This results in the propagation of the electrical signal across the synaptic gap from one neuron to the next.

The cerebellum, located at the back of the brain, plays a crucial role in maintaining posture and equilibrium of the body. It receives sensory input from the vestibular system, which detects changes in head position and movement, and integrates this information to coordinate muscle activity and maintain balance.

The movement of leaves of the sensitive plant (Mimosa pudica) is known as thigmonasty and is triggered by touch or physical disturbance. In contrast, the movement of a shoot towards light, known as phototropism, is a directional response to light stimuli. Thigmonastic movement occurs rapidly and involves changes in turgor pressure within specialized cells, while phototropic movement occurs gradually and involves the differential growth of cells in response to light.