Chapter 9

Question 1

What does the autonomic nervous system do?

Answer 1

regulates organs and organ systems and their smooth muscles and glands

Question 2

What is intrinsic muscle tone?

Answer 2

no nerve stimulation in smooth muscle
- resting

Question 3

What happens when ANS input is cut on smooth muscle?

Answer 3

denervation hypersensitivity
- exaggerated reflexes
- spasms

Question 4

How does ANS affect smooth muscles?

Answer 4

smooth muscles are spontaneously active and contract rhythmically WITHOUT ANS input
- ANS input increases or decreases intrinsic activity

Question 5

What neurotransmitter is at the effector of somatic nervous system? What’s the effector organ? What’s the effect?

Answer 5

acetylcholine
- skeletal muscle
- stimulatory

Question 6

What is the 3-word phrase for sympathetic pathway?

Answer 6

fight or flight

Question 7

What are the 2 pathways for sympathetic pathway?

Answer 7

1) lightly myelinated preganglionic axons -> ACh on ganglion -> unmyelinated postganglionic axon
2) lightly myelinated preganglionic axons -> ACh on adrenal medulla -> Epinephrine/Norepinephrine onto blood vessel

Question 8

What neurotransmitter is at effector of sympathetic pathway? What’s the effect?

Answer 8

norepinephrine
- both stimulatory or inhibitory depending on neurotransmitter and receptors on effector organs

Question 9

What is the 3-word phrase for parasympathetic nervous system?

Answer 9

rest or digest

Question 10

What is the pathway for parasympathetic nervous system?

Answer 10

lightly myelinated preganglionic axon -> ACh onto ganglion -> unmyelinated postganglionic axon

Question 11

What is the neurotransmitter at effector for parasympathetic nervous system? What’s the effect?

Answer 11

ACh
- both stimulatory or inhibitory

Question 12

What are some features of somatic motor systems?

Answer 12

• skeletal muscle
• no ganglia
• one motor neuron
• excitatory
• fast-conducting thick myelinated
• flaccid paralysis and atrophy

Question 13

What are some features of autonomic motor systems?

Answer 13

• smooth and cardiac muscles and glands
• has ganglia
• 2 motor neurons
• BOTH excitatory and inhibitory
• slow-conducting (thin, lightly myelinated TO unmyelinated
• tone and function persist
• denervation hypersensitivity

Question 14

How are the 2 neurons in the ANS connected?

Answer 14

1st neuron = preganglionic neuron (cell body in brain/spinal cord)
2nd neuron = postganglionic neuron synapse

Question 15

Where do postganglionic axons extend from?

Answer 15

autonomic ganglion to target tissue

Question 16

What are the 2 divisions of the ANS?

Answer 16

sympathetic and parasympathetic
- antagonistic effects

Question 17

What is another name for the sympathetic division? Why is it called that?

Answer 17

thoracolumbar division
- preganglionics exit spinal cord from T1 to L2

Question 18

Where do the sympathetic division cells synapse?

Answer 18

on postganglionic in the paravertebral ganglia
- form chain of interconnected ganglia paralleling spinal cord

Question 19

What is mass activation?

Answer 19

all sympathetic division acting as a unit

Question 20

What is divergence?

Answer 20

preganglionics branch to synapse with a number of postganglionic neurons
- small amount to large amount

Question 21

What is convergence?

Answer 21

postganglionics receive synaptic input from a large number of preganglionics

Question 22

What happens when there’s a collateral ganglion?

Answer 22

prevents postganglionics from synapsing in paravertebral ganglion

Question 23

What is the modified collateral ganglion? Why?

Answer 23

adrenal medulla
- secretory cells look like modified postganglionics
- releases 85% epinephrine and 15% norepinephrine into blood in response to preganglionic stimulation

Question 24

When is the adrenal stimulated?

Answer 24

mass activation

Question 25

How is epinephrine made?

Answer 25

by methylating norepinephrine

Question 26

What is the craniosacral division? Why?

Answer 26

parasympathetic division
- long preganglionics originate in midbrain, medulla, pons, and S2-S4

Question 27

Where does parasympathetic division synapse? What is special about the postganglions?

Answer 27

postganglionics in terminal ganglia located next to or within a target organ
- they have short axons that innervate target

Question 28

What nerve has the most parasympathetic fibers?

Answer 28

vagus nerve

Question 29

What does the vagus nerve innervate?

Answer 29

heart
lungs
esophagus
stomach
pancreas
liver
small intestine
upper half of large intestine

Question 30

What does the preganglionic fibers from S2-S4 innervate?

Answer 30

lower half of large intestines
rectum
urinary
reproductive systems

Question 31

Which preganglionics release ACh?

Answer 31

both sympathetic and parasympathetic

Question 32

What do the postganglionics release?

Answer 32

parasympathetic: ACh (cholinergic synapses)
sympathetic: release norepinephrine (adrenergic synapses)
- small amount releases ACh

Question 33

What are varicosities?

Answer 33

unusual synapses from postganglionics

Question 34

What is synapse en passant?

Answer 34

varicosities release neurotransmitters along a length of axon

Question 35

What causes both excitation and inhibition reactions?

Answer 35

adrenergic stimulation
(depends on tissue)

Question 36

What are the different subtypes of a receptor?

Answer 36

alpha- and beta-adrenergic receptors

Question 37

What do the subtypes use as second messengers?

Answer 37

beta: cAMP
alpha: Ca++

Question 38

How are drugs developed?

Answer 38

they affect ANS receptors

Question 39

What are the types of drugs that affect neurotransmitters?

Answer 39

agonists: promote action of neurotransmitter
antagonists: inhibit actions of a neurotransmitter

Question 40

What is the nicotinic receptor stimulated by? What is it blocked by?

Answer 40

stimulated by nicotine
blocked by curare

Question 41

What is the muscarinic receptor stimulated by? What is it blocked by?

Answer 41

stimulated by muscarine (poisonous mushrooms)
blocked by atropine