The Peripheral Nervous System

The Nervous System

What are the two divisions of the perripheral nervous system?

The somatic and autonomic nervous systems.

What is the main function of the somatic nervous system?

Controls voluntary responses and transmits sensory and motor information between the external environment and the CNS.

What is the main function of the autonomic nervous system?

Controls involuntary responses, regulating internal organs and vital functions like heart rate, respiration, and digestion.

What are the two branches of the autonomic nervous system (ANS)?

The sympathetic and parasympathetic branches.

What is the function of the sympathetic nervous system?

Prepares the body for emergencies (“fight-or-flight” response).

What is the function of the parasympathetic nervous system?

Conserves energy and manages non-emergency tasks (“rest-and-digest” response).

How many neurons are involved in the autonomic nervous system pathway?

Two neurons: a preganglionic and a postganglionic neuron.

Where does the synapse occur in the autonomic nervous system pathway?

In an intermediate ganglion between the preganglionic and postganglionic neurons.

What neurotransmitter is released by the preganglionic neuron in the sympathetic and parasympathetic systems?

Acetylcholine (ACh) binds to nicotinic receptors.

What neurotransmitter is released by the postganglionic neuron in the sympathetic system?

Noradrenaline (norepinephrine) binds to adrenergic receptors (α and β).

What neurotransmitter is released by the postganglionic neuron in the parasympathetic system?

Acetylcholine (ACh) binds to muscarinic receptors.

What is the role of the adrenal medulla in the sympathetic nervous system?

acts as a sympathetic ganglion, releasing adrenaline and noradrenaline into the bloodstream when stimulated.

How does the adrenal medulla contribute to the fight-or-flight response?

It releases catecholamines (adrenaline and noradrenaline), enhancing sympathetic effects.

Adrenaline is more selective to what receptors?

Beta receptors.

Noradrenalin is more selective to which receptors?

Alpha receptors.