Autonomic and Somatic Nervous System: Key Concepts for ANS Review

Flashcards covering somatic vs autonomic nervous system, sympathetic and parasympathetic divisions, neurotransmitters and receptors, anatomical pathways, reflex arcs, and basic pharmacology concepts from the lecture notes.

What is the somatic nervous system responsible for in terms of input and response, and give an example explained in the notes.

Somatic nervous system processes sensory input that leads to a voluntary motor response, such as smelling grilled cheese and then moving your muscles to approach it.

What is the autonomic nervous system (ANS) and what are its two main divisions?

The ANS regulates subconscious bodily functions and is divided into the sympathetic (fight or flight) and parasympathetic (rest and digest/rest and restore) divisions.

Differentiate the sympathetic and parasympathetic divisions in terms of their primary roles.

Sympathetic = fight or flight responses (prepare for rapid action); Parasympathetic = rest and digest/rest and restore (promotes maintenance and conservation of energy).

From which regions of the CNS do the sympathetic and parasympathetic divisions originate (thoracolumbar vs craniosacral)?

Sympathetic originates from the thoracic and lumbar spinal cord (thoracolumbar); Parasympathetic originates from cranial nerve nuclei and sacral spinal cord (craniosacral).

Where are sympathetic ganglia located and what is the typical length of their preganglionic vs postganglionic neurons?

Sympathetic ganglia form a chain (sympathetic trunk) beside the spinal cord; preganglionic neurons are short and postganglionic neurons are long.

Where are parasympathetic ganglia located relative to target organs and what is the length of their preganglionic vs postganglionic neurons?

Parasympathetic ganglia are near or on the target organs; preganglionic neurons are long and postganglionic neurons are short.

What neurotransmitters and receptors are associated with the sympathetic nervous system, including the role of the adrenal gland?

Postganglionic neurotransmitter: norepinephrine (noradrenaline); adrenergic receptors: alpha and beta subtypes (alpha1, alpha2, beta1, beta2); the adrenal gland releases epinephrine (adrenaline) and norepinephrine into the bloodstream to amplify the response.

What neurotransmitter and receptor are associated with the parasympathetic nervous system?

Neurotransmitter: acetylcholine; receptors: cholinergic (nicotinic and muscarinic).

In the sympathetic response, what is the role of the adrenal gland in addition to neuronal transmission?

The adrenal gland releases epinephrine (adrenaline) and norepinephrine into the bloodstream, producing widespread effects beyond direct neural synapses.

Which receptors correspond to the sympathetic adrenergic system and what are their general organ-specific effects?

Adrenergic receptors include alpha1, alpha2, beta1, and beta2: alpha1 (vascular effects, mainly vasoconstriction), alpha2 (modulatory/sedative effects in some contexts), beta1 (heart rate and contractility increase), beta2 (bronchodilation in the lungs).

Which receptors correspond to the parasympathetic cholinergic system and where are they typically located?

Cholinergic receptors include nicotinic (on postganglionic neurons and at the neuromuscular junction) and muscarinic (on target organs).

What is the general pattern of preganglionic and postganglionic lengths in the sympathetic vs parasympathetic systems?

Sympathetic: short preganglionic, long postganglionic; Parasympathetic: long preganglionic, short postganglionic.

Explain the basic anatomy of a sympathetic reflex pathway starting from the spinal cord to the organ.

Preganglionic neuron from thoracic-lumbar spine synapses in the sympathetic chain ganglion (short); postganglionic neuron (long) travels to the organ, with effects on heart, lungs, etc.

Explain the basic anatomy of a parasympathetic reflex pathway starting from the brainstem or sacral region to the organ.

Preganglionic neuron from cranial nerve nuclei or sacral region travels long distance to an organ near or on the organ; postganglionic neuron is short near the organ.

What is a reflex arc and which components are typically involved?

A reflex arc is a rapid, automatic pathway that may involve sensory input, dorsal horn with interneurons in the spinal cord, and ventral motor neurons to the muscle; brain input may be included or bypassed depending on the reflex.

What is ipsilateral versus contralateral in the context of reflex arcs?

Ipsilateral: the reflex occurs on the same side of the body as the stimulus; contralateral: the reflex involves the opposite side.

What is the neuromuscular junction (NMJ) and its significance in motor control?

The NMJ is the synapse between a motor neuron and a muscle where acetylcholine is released to trigger muscle contraction, with a small gap between cells.

How can drugs mimic or block autonomic receptor effects, and what is an example discussed in the notes?

Drugs can target receptors to mimic (agonists) or block (antagonists) autonomic effects; example: beta blockers block beta adrenergic receptors to slow heart rate and reduce contractility.

Why is the term ‘rest and digest’ used for the parasympathetic system, and what general effects does it produce on organs like the heart and GI tract?

Rest and digest describes parasympathetic activity that conserves energy, slows heart rate, increases GI motility and secretions, and supports digestion.