The Autonomic Nervous System

These flashcards cover essential concepts from the Autonomic Nervous System, including the distinctions between the somatic and autonomic systems, neurotransmitters, ganglia, and responses to both sympathetic and parasympathetic activities.

What is the main function of the somatic nervous system?

To control voluntary movements by innervating skeletal muscles.

What types of neurons does the somatic nervous system include?

Both sensory and motor neurons.

What sensory experiences are associated with the somatic nervous system?

Touch, pain, temperature, proprioception, sight, hearing, taste, smell, and equilibrium.

What are the two divisions of the autonomic nervous system?

Sympathetic and parasympathetic nervous systems.

What is the sympathetic nervous system often referred to?

The fight-or-flight division.

What does the parasympathetic nervous system do?

It slows down most body activities, referred to as the rest-and-digest division.

What is the structure of a somatic motor neuron?

A single, myelinated axon that extends directly from the CNS to the skeletal muscle.

How many motor neurons are typically found in autonomic motor pathways?

Two motor neurons in series.

Where are the cell bodies of preganglionic neurons of the sympathetic nervous system located?

In the lateral horns of spinal cord segments T1 to L2/3.

What are the two major types of sympathetic ganglia?

Sympathetic trunk ganglia and prevertebral ganglia.

What type of division is characterized by the craniosacral output?

Parasympathetic division.

What occurs when there is increased parasympathetic activity?

Decreased metabolic rate, decreased heart rate, increased glandular secretions, increased digestive tract motility, stimulation of urination and defecation.

What responses are associated with increased sympathetic activity?

Heightened alertness, increased metabolic rate, reduced digestive and urinary functions, energy reserves activated, increased respiratory rate, increased heart rate, and activation of sweat glands.

Where do preganglionic neurons of the parasympathetic system originate?

In the brainstem and sacral spinal cord (S2–S4).

What structures are involved in autonomic ganglia?

Sympathetic ganglia and parasympathetic ganglia.

What neurotransmitter do cholinergic neurons release?

Acetylcholine.

What are the two types of cholinergic receptors?

Nicotinic and muscarinic receptors.

What neurotransmitter do adrenergic neurons release?

Norepinephrine (noradrenalin).

What is the primary function of adrenergic α receptors?

Vasoconstriction and closing of sphincters.

What type of adrenergic receptor is found in the heart?

Beta 1 (B₁) adrenergic receptors.

What happens to blood vessels serving the heart and skeletal muscles when adrenergic receptors are activated?

Vasodilation.

What do β3 adrenergic receptors primarily influence?

Heat production from adipose tissue.

How do sympathetic pathways typically reach effectors?

Through a ganglion and usually involve a series of neuronal connections.

What is the anatomical location of sympathetic ganglia?

Close to the spinal cord, either laterally or anteriorly.

What is a distinctive feature of preganglionic axons in the sympathetic division?

They have many branches.

Where are the autonomic plexuses primarily formed?

In the thorax, abdomen, and pelvis along major arteries.

What are examples of autonomic plexuses?

Celiac plexus, superior mesenteric plexus, inferior mesenteric plexus, renal plexus, and hypogastric plexus.

Which cranial nerves contain the cell bodies of parasympathetic preganglionic neurons?

Cranial nerves III, VII, IX, and X.

What is a key difference between the somatic and autonomic nervous systems in terms of control?

Somatic is under voluntary control while autonomic is involuntary.

How are postganglionic neurons characterized in the autonomic system?

Typically unmyelinated.

What body functions do sympathetic responses typically inhibit?

Digestive and urinary functions.

What effect does sympathetic activation have on respiratory rate?

Increases respiratory rate and dilates respiratory passageways.

What responses to increased sympathetic activity enhance physical performance?

Increased heart rate, elevated alertness, and activation of energy reserves.

In relation to autonomic functions, what roles do neurotransmitters play?

They determine the physiological responses of organs based on receptor type.

What is a common characteristic of autonomic motor pathways?

They typically involve a two-neuron chain (preganglionic and postganglionic neurons).

What is the role of the adrenal medullae in the sympathetic division?

To release hormones like epinephrine and norepinephrine into the bloodstream.

In which areas of the body are autonomic receptors located?

Throughout various organs, blood vessels, and glands.