Efferent Division

Question 1

The sympathetic nervous branch of the autonomic nervous system is characterized by what types of fibers?

Answer 1

Short cholinergic pre-ganglionic fibers synapsing with

Long adrenergic post-ganglionic fibers

Question 2

The parasympathetic nervous branch of the autonomic nervous system is characterized by what types of fibers?

Answer 2

Long cholinergic pre-ganglionic fibers synapsing with short cholinergic post-ganglionic fibers

Question 3

In the autonomic nervous system, what type of neurotransmitter is released by the cholinergic fibers?

Answer 3

acetylcholine

Question 4

In the autonomic nervous system, what type of neurotransmitter is released by the adrenergenic fibers?

Answer 4

norepinephrine

Question 5

collateral ganglia vs terminal ganglia

Answer 5

collateral ganglia: A cluster of cell bodies residing outside of the sympathetic chain where some longer pre-ganglionic sympathetic fibers synapse with long post fibers.

terminal ganglia: lie near the effector organ in which the long pre-ganglionic parasympathetic fibers synapse with post fibers.

Question 6

What are the three anatomical pathway for neurons in the SNS? (region where the pre-G synapse with the post-G)

Answer 6

• sympathetic chain adjacent to the spinal cord
• collateral ganglia
• chromaffin cell in the adrenal medulla

Question 7

What is the neuronal pathway of the sympathetic pre-ganglionic neuron in the sympathetic chain?

sympathetic post ganglionic neuron pathway?

Answer 7

The pre ganglionic neuron exits the spinal cord via the ventral root –> to spinal nerve to –> white ramus and synapses with the post neuron in the sympathetic chain.

The post ganglionic neuron leaves the sympathetic chain via the grey ramus back to the spinal nerve and out to the effector organ.

Question 8

What is the origin of parasympathetic fibers?

Answer 8

Brain stem and sacral region (lower end of the spinal cord)

Question 9

The parasympathetic preganglionic neurons include which cranial nerves?

Answer 9

CN 3 - oculomotor
CN 7 - fascial
CN 9 - glossopharyngeal
CN 10 - vagus nerve

Question 10

Which catecholamine hormones do the sympathetic fibers of the adrenal medulla secrete?

Answer 10

20% norepinephrine
80% epinephrine
small amounts of dopamine

Question 11

What are the 3 layers of the adrenal medulla cortex?

Answer 11

From outer to inner layer:
zona gomerulosa
zona fasciculata
zona reticularis

Question 12

What type of receptors do norepinephrine bind to?

Answer 12

In the SNS, norepinephrine are released from the post -G neuron and binds to adrenergic receptors on the effector organ or cell

Question 13

What type of cholinergic receptors do cholinergic neurotransmitters bind to?

Answer 13

In the ANS, all preganglionic neurons are cholinergic and releases ACh which binds to nicotinic cholinergic receptors on the post G neurons

Question 14

Where are muscarinic receptors found?

Answer 14

on the effector cell membrane and bind with acetylcholine released from the post ganglionic cell

Question 15

The function of nicotinic receptor?

Answer 15

binds to acetylcholine released from the post ganglionic fiber and triggers the opening of ion gates in which more Na+ enters the cell as K+ exits. –> depolarization

Question 16

What are muscarinic receptors and its function?

Answer 16

are G-protein coupled receptors located on the effector organs or tissues. They receive PNS post ganglionic neurotransmitters

Question 17

Which region of the brain is the control center for cardiovascular, respiratory and digestive activity (including swallowing and vomiting)

Answer 17

Medulla Oblongata in the lower part of the brain stem

Question 18

Where is the origin of pre ganglionic fibers from the sympathetic nervous system?

Answer 18

sympathetic ganglion chain near spinal cord or collateral ganglia about halfway between spinal cord and effector organ.

Question 19

Where is the origin of post ganglionic fibers from the PNS?

Answer 19

terminal ganglia (in or near effector organs)

Question 20

What type of receptors do the SNS have to receive post ganglionic neurotransmitters?

Answer 20

adrenergic a1,a2, b1,b2

Question 21

where are nicotinic receptors found?

Answer 21

post ganglionic cell bodies in all autonomic ganglia

Question 22

Most arterioles and veins are innervated by

a. sympathetic fibers
b. parasympathetic fibers

Answer 22

parasympathetic input

Question 23

Most sweat glands are innervated by ________ (sympathetic fibers/parasympathetic fibers). The post ganglionic fibers of these nerves secrete ________ (acetylcholine/norepinephrine)

Answer 23

Sympathetic fibers.

These fibers are unusual because they secrete ACh rather than NE

Question 24

What is the neuroeffector junction

Answer 24

refers to the synapse between the post ganglionic neuron and the effector organ

Question 25

What are varicosity

Answer 25

are modified axon endings of sympathetic post gang. neurons located at the neuroeffector junction that releases norepinephrine

Question 26

What is the difference between the events that occur at a neuroeffector junction and a cholinergic neuroeffector junction.

Answer 26

Cholinergic neuroeffector junction is where a PNS neuron synapses with the effector organ.

An adrenergic neuroeffector junction is where SNS neuron synapses with the effector organ

In both cases, the action potential propagated down the post ganglionic axon triggers the voltage gated ca2+ to open. The influx of ca2+ causes the neurotransmitter to be released and diffuses across the synapse. In the PNS, the post neurons are cholinergic which releases ACh that binds to the muscarinic receptors coupled G protein on the effector organ. In addition, ACh binds to an ACh enzyme that degrades ACh into acetate and choline. Choline is reuptake into the axon for reuse.

The SNS contains adrenergic post-G neurons which primarily releases norepinephrine, and epinephrine which binds to nicotinic receptors on the effector organs.

Question 27

What is a neuromuscular junction

Answer 27

A neuromuscular junction refers to the synapse between a motor neuron and a skeletal muscle fibre in the somatic nervous system.

Question 28

White vs grey rami

Answer 28

The grey and white rami communicantes are responsible for conveying autonomic signals, specifically for the sympathetic nervous system. Their difference in coloration is caused by differences in myelination of the nerve fibres contained within,

Question 29

White vs grey rami

Answer 29

The grey and white rami communicantes are responsible for conveying autonomic signals, specifically for the sympathetic nervous system. Their difference in coloration is caused by differences in myelination of the nerve fibres contained within,

The white rami exist only at the levels of the spinal cord and are responsible for carrying preganglionic nerve fibres from the spinal cord to the sympathetic ganglia.

The grey rami exist at every level of the spinal cord and are responsible for carrying postganglionic nerve fibres from the sympathetic ganglia to their effector organs.

Question 30

What is the difference between the autonomic and somatic division in terms of the type of neurotransmitter used at the effector organs

Answer 30

Autonomic nervous system:
Often is acetylcholine in the parasympathetic terminals
Often is norepinephrine in the sympathetic terminals

Somatic nervous system:
Only uses acetylcholine in the terminals

Question 31

Where is the site of origin of the autonomic nervous system vs somatic

Answer 31

ANS: brain and lateral horn of the spinal cord
SNS: ventral horn of the spinal cord for most; those supplying muscles in head originate in brain

Question 32

What type of receptors do motor neurons bind to?

Answer 32

nicotinic receptors on the skeletal muscle cells

Question 33

Motor end plates

Answer 33

specializes muscle membranes

Question 34

terminal bouton

Answer 34

the end of the axon terminal of motor nerves where action potential arrives to

Question 35

What’s an end plate potential

Answer 35

End-plate potential (EPP), chemically induced change in electric potential of the motor end plate of the membrane of the muscle. An EPP leads to depolarization of skeletal muscle fibers resulting in muscle contraction

Question 36

Acetylcholinersterase

Answer 36

an enzyme that degrades acetylcholine into choline for reuptake by the terminal bouton

Question 37

What is latroxin and its effects?

Answer 37

a black widow spider toxin - stimulates the release of acetylcholine, thereby resulting in undesirable muscle contractions, spasms, and rigidity.

Question 38

What are the effects of rattlesnake toxin crotoxin and butulinum toxin?

Answer 38

inhibits the effects of acetylcholine in the neuromuscular junction causing muscle weakness, fatigue….

Question 39

What is organophosphates and how does it act on the neuromuscular junction?

Answer 39

Organophosphate are found in pesticides and nerve gas. It inhibits the enzyme acetycholinersterase to prevent the breakdown of acetylcholine.