Chapter 15: The Autonomic Nervous System and Visceral Sensory Neurons

Question 1

All autonomic pathways contain 2 neurons in series

Answer 1

1. Preganglionic Neuron

2. Postganglionic Neuron

Question 2

Preganglionic Neuron

Answer 2

is located within the CNS and will synapse with a second neuron
-A single preganglionic neuron generally synapses with several postganglionic neurons

Question 3

Postganglionic Neuron

Answer 3

located within the PNS and will synapse with the effector organ

• Sometimes called the autonomic ganglia
• At the effector organ, postganglionic neuron releases neurotransmitters that diffuses through extracellular fluid to receptors on effector organ

Question 4

Divisions of ANS

Answer 4

Parasympathetic

Sympathetic

Question 5

Parasympathetic

Answer 5

controls routine maintenance or “housekeeping” functions when the body is at rest
-Digestion and waste motility

Question 6

Sympathetic

Answer 6

controls “fight or flight” response

• increase heart rate, vasoconstriction, respiration pupil dilation and cell metabolism
• decreases non-essential functions like digestion and waste motility

Question 7

3 Main anatomical differences in ANS

Answer 7

1. Cell Bodies of preganglionic sympathetic and parasympathetic neurons are located in different regions of the CNS
2. Locations of the ganglia differ
3. Differing relationship between the preganglionic and postganglionic neurons

Question 8

Cell Bodies of preganglionic sympathetic and parasympathetic neurons are located in different regions of the CNS

Answer 8

• Most sympathetic pathways originate in the thoracic and lumbar regions of the spinal cord (thoracolumbar division)
• Most of parasympathetic pathways originate either in the hindbrain or in the sacral region of the spinal cord (craniosacral division)

Question 9

Locations of the Ganglia Differ

Answer 9

• Most sympathetic pathways are found in a chain that runs close to the spinal cord having a short preganglionic neurons and long postganglionic neurons
• Most parasympathetic pathways are located close to the effector organ having long preganglionic and short postganglionic neurons

Question 10

Differing relationship between the preganglionic and postganglionic neurons

Answer 10

• Most sympathetic preganglionic neurons form synapses with 10 or more postganglionic neurons; effects will be widespread
• Most parasympathetic preganglionic neurons from synapses with 3 or fewer post ganglionic neurons; effects will be localized

Question 11

3 important features of the ANS underlie its ability to maintain homeostasis

Answer 11

Dual Innervation
Antagonistic Action
Basal Tone

Question 12

Dual innervation

Answer 12

most organs receive input from both sympathetic and parasympathetic nervous systems to regulate effector organs; checks and balances

Question 13

Antagonistic Action

Answer 13

one is stimulatory and other inhibitory

• Parasympathetic causes bronchioles to constrict by causing smooth muscle to contract
• Sympathetic causes dilation through relaxation of smooth muscle

Question 14

Basal Tone (Basal tonic activity)

Answer 14

under resting conditions autonomic neurons will continually signal