The rising phase of a typical neuronal action potential is caused primarily by Na⁺ influx through voltage-gated Na⁺ channels. The subsequent K⁺ efflux through voltage-gated K⁺ channels contributes to repolarization.

The order of the reaction of the nervous system:

Afferent (input sensory information) → Interneuron or Integration (processing information) → Efferent (output information to motor nervous) → Response

Acetylcholine is released into the synaptic cleft, where it binds to cholinergic receptors. Acetylcholinesterase hydrolyzes acetylcholine into choline and acetate, terminating its signaling. Choline can then be transported back into the presynaptic neuron for acetylcholine synthesis. At the neuromuscular junction, acetylcholinesterase is concentrated in the synaptic basal lamina.

The sympathetic nervous system increases energy generation in response to stress. Therefore, the stimulation of the adrenal medulla, increase in the production of glucose, and acceleration of heart rate are vital responses to stress. However, an increase in digestion, such as stimulation of the gallbladder, is required in the parasympathetic division during rest.

Sympathetic postganglionic neurons typically release norepinephrine (NE), which binds to adrenergic receptors. Exceptions include sympathetic fibers innervating sweat glands, which release acetylcholine (ACh). Autonomic preganglionic neurons and parasympathetic postganglionic neurons release ACh.

At excitatory nicotinic acetylcholine receptors, acetylcholine opens ligand-gated cation channels, producing a depolarizing postsynaptic potential. If the membrane reaches threshold, voltage-gated Na⁺ channels initiate an action potential, while voltage-gated K⁺ channels contribute primarily to repolarization. Acetylcholine binding does not directly form synaptic vesicles.

A typical myelinated neuron includes dendrites, a cell body, an axon, and a myelin sheath. However, not all neurons are myelinated. An action potential is an electrical signal rather than a structural component.

Local anesthetics block voltage-gated Na⁺ channels in nerve fibers, preventing the initiation and propagation of action potentials and interrupting pain signaling.

In the central nervous system the white matter is usually used for transporting information and the grey matter is for processing information. The white matter is situated inside the cerebrum and the grey matter is outside the cerebrum. In the spinal cord, the position of the white and gray matter are reversed.

All are related to the peripheral nervous system. The peripheral nervous system is divided into the autonomic nervous system (involuntary control) and the somatic nervous system (voluntary control). The autonomic nervous system is then divided into the parasympathetic and sympathetic nervous systems. The vagus nerve is contained in the parasympathetic nervous system to innervate the stomach, liver, large and small intestines, lungs, and heart.

All of A–D are true. Most mature neurons do not undergo mitosis. Axonal regeneration is limited in the central nervous system, although peripheral axons may regenerate under favorable conditions with Schwann cell support.

The rising phase begins when the membrane reaches threshold and voltage-gated Na⁺ channels rapidly open. Voltage-gated K⁺ channels activate more slowly and contribute mainly to repolarization. Therefore, D is incorrect because it implies that the opening of both channel types equally drives the rising phase.

Forebrain parts are cerebrum and diencephalon (thalamus and hypothalamus) and hindbrain parts are pons, medulla oblongata, and cerebellum.

Saltatory conduction occurs in myelinated axons. Current spreads rapidly beneath the insulating myelin sheath, and action potentials are regenerated at the nodes of Ranvier, allowing rapid conduction from node to node.

The cerebellum controls motor coordination and balance, and the hypothalamus controls homeostasis and the basic feelings of desire, such as sexual drive, thirst, and hunger. The pons and medulla oblongata regulate the breathing rates. The cerebrum functions in integrating and analyzing sensory information for motor response.

Under normal physiological conditions, action potentials propagate along axons toward their terminals because recently activated membrane regions are refractory. Chemical synaptic transmission is generally unidirectional, from the presynaptic cell to the postsynaptic cell. Artificial stimulation of an axon may produce bidirectional propagation.