Chapter 9- The Autonomic Nervous System

Question 1

Describe the divisions of the efferent division of the peripheral nervous system

Answer 1

o Efferent division
 Communication link by which CNS controls activities of muscles, organs and glands
 Two divisions of PNS
 1. Somatic nervous system
 Voluntary
 Innervates skeletal muscle
 2. Autonomic nervous system (ANS)
 Involuntary
 Innervates cardiac muscle, smooth muscle, exocrine/endocrine glands, and adipose tissue/viscera

Question 2

Describe the organization of autonomic motor neurons

Answer 2

o Autonomic nervous system
 1. Sympathetic: fight or flight
 2. Parasympathetic: rest and digest
 Characteristics
 Many organs have dual innervation
 Effect antagonistic in many organs (not always)
 2 neuron chain

Question 3

describe the structure of the sympathetic nervous system, location the ganglia and the preganglionic and postganglionic neurons

Answer 3

 Sympathetic division
 Thoracolumbar division
 Short pre-ganglionic neuronsympathetic chainlong post-ganglionic neuron to effector
 Fight or flight: increase heart rate, BP
 Nervous system neurotransmitters
 Pre-ganglionic neurons release Ach, binds to Ach receptors on post-ganglionic neurons
 Post-ganglionic neurons release NE, binds to NE receptors on effectors
 Sympathetic chain associated with SNS
 Preganglionic axons enter sympathetic chain of ganglia just lateral to spinal cord
 Usually, a synapse with post ganglionic motor neurons in the chain

Question 4

explain the relationship between the sympathetic nervous system and the adrenal medulla

Answer 4

o Adrenal medulla= modified part of sympathetic nervous system
 Stimulation of preganglionic fiber prompts secretion of hormones into blood
 Norepinephrine= 20% of hormone release
 Epinephrine= 80% of hormone

Question 5

describe the structure and innervation pathways of the parasympathetic division of the autonomic system

Answer 5

o Parasympathetic nervous system characteristics
 Craniosacral division
 Long pre-ganglionic neurons, short post-ganglionic neurons
 Rest and digest
o Neurotransmitter
 Pre-ganglionic neurons release Ach, binds to nicotinic receptors on post-ganglionic neurons
 Post-ganglionic releases Ach, binds to muscarinic receptors on effectors

Question 6

identify the neurotransmitter of the sympathetic and parasympathetic divisions and the hormone released by the adrenal medulla

Answer 6

o Neurotransmitters of ANS
 Classified as either cholinergic or adrenergic neurons based upon the neurotransmitter released
 Cholinergic receptors
 Release acetylcholine from pre-ganglionic neurons and from parasympathetic post-ganglionic neurons
 Types
 Nicotinic receptors: found on postganglionic cell bodies of ALL autonomic ganglia
 Muscarinic receptors: found on effector cell membranes
 Adrenergic receptors
 Release norepinephrine (NE) norepinephrine and epinephrine
 From postganglionic sympathetic neurons only
 Alpha receptors
 Beta receptors