Ch. 9 Autonomic Nervous System (ANS)

Question 1

Somatic Motor Neurons

Answer 1

Have cell bodies in spinal cord and just one neuron traveling from spinal cord to effector (neuromuscular junction = effector)

Controls skeletal muscle

Question 2

Somatic motor neurons release only ____ which is always ____.

Answer 2

Acetylcholine (ACh); excitatory

Question 3

The ANS has what 2 divisions?

Answer 3

Sympathetic and Parasympathetic divisions

Question 4

The Autonomic motor system has 2 neurons in the PNS. Describe them.

Answer 4

The First has cell bodies in the brain or spinal cord and synapses in an Autonomic Ganglion.

The Second has cell bodies in the ganglion and synapses on the effector.

Question 5

Autonomic neurons release mainly ____ and ____ and may be ____ or ____.

Answer 5

Acetylcholine, Norepinephrine

Excitatory or Inhibitory
–e.g. raise HR, lower HR

Question 6

Autonomic Neurons

Answer 6

Innervate organs not under voluntary control

Effects include:

• cardiac muscle
• smooth muscle of visceral organs and blood vessels
• glands

Part of PNS

Can stimulate or inhibit, depending on organ and receptors

Question 7

Preganglionic Neurons

Answer 7

Originate in midbrain or hindbrain or from thoracic, lumbar, or sacral spinal cord

Autonomic Neurons

Question 8

Postganglionic Neurons

Answer 8

Originate in ganglion

Question 9

Where are Autonomic Ganglia located?

Answer 9

In head, neck, and abdomen as well as in chains on either side of the spinal cord

Question 10

Sympathetic Division: Preganglionic Neurons

Answer 10

Come from thoracic and lumbar regions of spinal cord
–aka Thoracolumbar Division

Synapse in sympathetic ganglia that run parallel to spinal cord

• -aka Paravertebral ganglia
• -these ganglia are connected, forming a sympathetic chain of ganglia

Question 11

Adrenal Glands

Answer 11

Adrenal medulla secretes Epinephrine (adrenaline) and norepinephrine (lesser extent) when stimulated by the Sympathetic Nervous System; the adrenal medulla is innervated directly by preganglionic sympathetic neurons

Question 12

Parasympathetic Division

Answer 12

Preganglionic neurons come from the brain or sacral region of the spinal cord (Craniosacral Division)

Synapse on ganglia located near or in effector organs; called terminal ganglia

Preganglionic neurons do not travel w/ somatic neurons (as sympathetic postganglionic neurons do)

Terminal ganglia supply very short postganglionic neurons to effectors

Question 13

What are the 2 parasympathetic cranial nerves we need to know?

Answer 13

Oculomotor nerve (III) and Vagus nerve (X)

Question 14

Oculomotor Nerve (III)

Answer 14

Motor nerve

Preganglionic fibers exit midbrain and synapse on the ciliary ganglion

Postganglionic fibers innervate the ciliary muscle of the eye
–regulate ciliary muscles of eye (vision)

Question 15

Vagus Nerve (X)

Answer 15

Sensory and motor nerve (mixed nerve)

Preganglionic fibers exit medulla, branch into several plexi and nerves, and travel to ganglia w/in effector organs (heart, lungs, esophagus, stomach, pancreas, liver, intestines)

Vagus controls basal HR (resting)

Question 16

General Functions: Sympathetic

Answer 16

Activates body for “fight or flight” through release of Norepinephrine from Postganglionic neurons and secretion of Epinephrine (adrenaline) from Adrenal Medulla.

Prepares body for intense physical activity in emergencies by increasing HR and blood glucose levels and by diverting blood to skeletal muscles.

Regulates heart, blood vessels, and other organs.

Question 17

General Functions: Parasympathetic

Answer 17

Antagonist to sympathetic divison

Allows body to “rest and digest” through release of ACh (acetylcholine) from Postganglionic neurons

Slows HR and increases digestive activities

Question 18

The Sympathetic system is activated by what 2 receptors?

Answer 18

Alpha and Beta

Question 19

The Parasympathetic system is activated by what receptor?

Answer 19

Muscarinic

Question 20

Synaptic Transmission: Cholinergic

Answer 20

ACh is neurotransmitter used by ALL preganglionic neurons (sympathetic and parasympathetic)

It’s also the neurotransmitter released from MOST parasympathetic postganglionic neurons

SOME sympathetic postganglionic neurons (those that innervate sweat glands and skeletal muscle blood vessels) release ACh.

Question 21

Synaptic Transmission: Adrenergic

Answer 21

Norepinephrine is the neurotransmitter released by MOST sympathetic postganglionic neurons

These synapses are called Adrenergic

*According to lecture, epinephrine can also be released in this transmission

Question 22

Varicosities

Answer 22

Axons of postganglionic neurons have various swellings called Varicosities that release neurotransmitter along the length of the axon

Sympathetic and parasympathetic neurons innervate the same tissues but release different neurotransmitters

*Not a true/classic synapse where it ends at target

Question 23

Adrenergic Stimulation

Answer 23

Can be epinephrine in blood or norepinephrine from sympathetic nerves

Can stimulate or inhibit, depending on receptors

Question 24

Adrenergic Stimulation: Stimulation

Answer 24

Heart, dilatory muscles of iris, smooth muscles of many blood vessels (causes vessel constriction)

*pretty much everything but skeletal muscle

Question 25

Adrenergic Stimulation: Inhibition

Answer 25

Bronchioles in lungs, other blood vessels; inhibits contraction and causes dilation of these structures *inhibits particularly in skeletal muscle

Question 26

Adrenergic Receptors are only found in what system?

Answer 26

Sympathetic

Question 27

How many types of alpha receptors (Adrenergic) are there?

Answer 27

2 types: Alpha 1 Alpha 2

Question 28

How many types of beta receptors (Adrenergic) are there?

Answer 28

2 types: Beta 1 Beta 2

Question 29

Adrenergic Receptors: Alpha

Answer 29

More sensitive to norepinephrine More sensitive to postganglionic neuron

Question 30

Adrenergic Receptors: Beta

Answer 30

More sensitive to blood epinephrine Epinephrine from Adrenal Medulla; sensitive to circulating neurotransmitter

Question 31

Cholinergic Stimulation

Answer 31

ACh released from preganglionic neurons of both sympathetic and parasympathetic division is stimulatory ACh from post ganglionic neurons of the parasympathetic division is usually stimulatory, but some are inhibitory, depending on receptors *In general, sympathetic and parasympathetic effects are opposite

Question 32

What are the 2 types of Cholinergic Receptors?

Answer 32

Nicotinic and Muscarinic

Question 33

Cholinergic Receptors: Nicotinic

Answer 33

Found in autonomic ganglia Stimulated by ACh from preganglionic neurons Serves as ligand-gated ion channels for Na+ and K+

Question 34

Cholinergic Receptors: Muscarinic

Answer 34

Found in visceral organs Stimulated by release of ACh from postganglionic neurons Five types identified; can be stimulatory or inhibitory (opening K+ or Ca2+ channels)

Question 35

Organs w/ Dual Innervation

Answer 35

Most visceral organs are innervated by both sympathetic and parasympathetic neurons; the divisions most often oppose each other - -HR - sym increases, para decreases - -Digestive functions - sym decreases, para increases - -Pupil diameter - sym dilates, para constricts Complementary effects occur when both divisions produce similar effects on the same target --ex: Salivary gland secretion: Parasympathetic division stimulates secretion of watery saliva; sympathetic constricts blood vessels so secretion is thicker

Question 36

Organs w/o Dual Innervation

Answer 36

The following organs are innervated by the sympathetic division only: - Adrenal medulla - Arrector pili muscles in skin - Sweat glands in skin - Most blood vessels Regulated by increase and decrease in sympathetic nerve activity Important for body temperature regulation through blood vessels and sweat glands