Chapter 16: The Autonomic Nervous System

What is the Autonomic Nervous System (ANS)?

Division of the nervous system that regulates smooth muscle, cardiac muscle, and certain glands

What does the ANS regulate?

Smooth muscle, cardiac muscle, and certain glands

Is the ANS voluntary or involuntary?

Involuntary

What structure primarily regulates the ANS?

Hypothalamus

What major role does the ANS play in the body?

Maintaining homeostasis

Does the ANS contain sensory neurons, motor neurons, or both?

Both sensory and motor neurons

What are the primary target organs of the ANS?

Visceral organs and some body wall structures such as sweat glands

What type of neurons make up the input portion of the ANS?

General visceral sensory neurons

What do general visceral sensory neurons do?

Carry impulses from internal organs and joints to the CNS

What blood component do general visceral sensory neurons monitor?

CO₂ levels

What organ condition can general visceral sensory neurons detect?

Stretch of organs and blood vessels

What sensations can general visceral sensory neurons detect from damaged viscera?

Pain and nausea

What urinary function do general visceral sensory neurons monitor?

Fullness of the urinary bladder

What are general visceral motor neurons?

Neurons that carry impulses to cardiac muscle, smooth muscle, and glands

What eye response is controlled by general visceral motor neurons?

Pupil size changes

How do general visceral motor neurons affect blood vessels?

Cause dilation of blood vessels

How do general visceral motor neurons affect the heart?

Adjust the rate and force of heartbeat

How do general visceral motor neurons affect the GI tract?

Regulate movements in the digestive tract

How do general visceral motor neurons affect glands?

Stimulate secretion of most glands

What are the two divisions of the motor portion of the ANS?

Sympathetic division and parasympathetic division

What is dual innervation?

Most organs receiving impulses from both sympathetic and parasympathetic divisions

How do the sympathetic and parasympathetic divisions generally affect organs?

They usually have opposing effects

How many neurons are found in an autonomic motor pathway?

Two neurons

What separates the two neurons in an autonomic motor pathway?

An autonomic ganglion

What is a preganglionic neuron?

The first neuron located in the CNS

What is a postganglionic neuron?

The second neuron that extends to effectors in the body

What are the two major neurotransmitters released by ANS neurons?

Acetylcholine (ACh) and norepinephrine

What is the primary function of the parasympathetic division?

Conserves and restores body energy during rest and recovery

What is another name for the parasympathetic division?

Energy conservation-restoration system

Where do parasympathetic impulses dominate?

Digestive glands and GI tract

Why are parasympathetic impulses important in the digestive system?

Ensure digestion and nutrient absorption

What does SLUD stand for?

Salivation, Lacrimation, Urination, and Defecation

Which ANS division is associated with SLUD responses?

Parasympathetic division

Which SLUD response is not directly associated with digestion?

Lacrimation

What can happen to SLUD responses during extreme stress or fear?

Loss of control over them

Which cranial nerve controls the lens and pupil of the eye?

Oculomotor nerve (III)

Which cranial nerve regulates tear glands, salivary glands, and nasal glands?

Facial nerve (VII)

Which cranial nerve regulates salivation?

Glossopharyngeal nerve (IX)

Which cranial nerve supplies the heart, lungs, diaphragm, and esophagus?

Vagus nerve (X)

What is the primary function of the sympathetic division?

Prepares the body for emergencies and energy expenditure

How does the sympathetic division relate to the parasympathetic division?

Counteracts parasympathetic effects

What are the four E situations regulated by the sympathetic division?

Excitement, Emergency, Exercise, and Embarrassment

What type of response is produced by the sympathetic division?

Fight-or-flight response

How does the sympathetic division affect sweat glands?

Increases secretion

How does the parasympathetic division affect sweat glands?

Decreases secretion

How does the sympathetic division affect blood vessels?

Dilates blood vessels

How does the parasympathetic division affect blood vessels?

Constricts blood vessels

How does the sympathetic division affect respiration?

Increases respiration

How does the parasympathetic division affect respiration?

Decreases respiration

How does the sympathetic division affect the liver?

Increases glycogen release

How does the parasympathetic division affect the liver?

Decreases glycogen release

How does the sympathetic division affect the adrenal glands?

Increases activity

How does the parasympathetic division affect the adrenal glands?

Decreases activity

How does the sympathetic division affect the pupil?

Dilates the pupil

How does the parasympathetic division affect the pupil?

Constricts the pupil

How does the sympathetic division affect salivary gland secretions?

Produces thick secretions

How does the parasympathetic division affect salivary gland secretions?

Produces thin secretions

What is Raynaud disease?

Intermittent contractions of arteries in the fingers and toes

What symptoms occur with Raynaud disease?

Coldness, numbness, and discoloration of the digits

What commonly triggers Raynaud disease?

Emotional distress or cold exposure

Is the exact cause of Raynaud disease known?

No

Who is more commonly affected by Raynaud disease?

Women

What is Horner syndrome?

Disorder caused by lesions on neurons of the brainstem

What are the symptoms of Horner syndrome?

Drooping eyelid, skin flushing, and lack of facial perspiration

What causes Horner syndrome?

Lesions affecting brainstem neurons