L4 The Autonomic Nervous System

Question 1

Which part of the nervous system gives rise to the somatic and autonomic systems?

Answer 1

Peripheral Nervous System

Question 2

Which part of the PNS is responsible for voluntary control?

Answer 2

Somatic nervous system

Question 3

Which neurotransmitter(s) does the somatic nervous system use?

Answer 3

Only acetylcholine

Question 4

Which neurotransmitter(s) does the autonomic nervous system use?

Answer 4

Acetylcholine and noradrenaline

Question 5

If there is only one neuron connecting to the effector, is it somatic or autonomic?

Answer 5

Somatic. Autonomic uses 2 neurons to connect to the effector

Question 6

Which tissues can be affected by the autonomic system?

Answer 6

Smooth or cardiac muscle, glands, adipose tissue and others. The somatic system only connects to skeletal muscle.

Question 7

Which part of the PNS only has excitatory effects?

Answer 7

Somatic. The autonomic can be inhibitory and excitatory, but somatic is only ever excitatory.

Question 8

In the autonomic system, where will you find myelinated axons?

Answer 8

Pre-ganglionic axons are myelinated; post-ganglionic axons are non-myelinated.

Question 9

If the cell body lies inside the CNS, is that cell part of the somatic or autonomic nervous system?

Answer 9

Somatic. In the ANS, cell bodies lie outside the CNS in ganglia.

Question 10

Parasympathetic fibres emerge from the brain and spinal cord at the __1__ level. This is known as the __2__ region.

Answer 10

1. sacral

2. craniosacral

Question 11

Which cranial nerves contain outflow of the parasympathetic NS?

Answer 11

Occulomotor, facial, glossopharyngeal, and vagus

Question 12

Sympathetic fibres originate from the __1__ and __2__ regions of the spinal cord (from __3__ to __4__). This region is known as the __5__ region.

Answer 12

1. thoracic
2. lumbar
3. T1
4. L2
5. thoracolumbar

Question 13

Which system innervates more organs, the sympathetic or the parasympathetic?

Answer 13

Sympathetic

Question 14

The sympathetic nervous system has [short/long] pre-ganglionic fibres and [short/long] post-ganglionic fibres.

Answer 14

Short pre-ganglionic fibres

Long post-ganglionic fibres

Long post-ganglionic fibres can branch and influence many organs at the same time.

Question 15

The parasympathetic nervous system has [short/long] pre-ganglionic fibres and [short/long] post-ganglionic fibres.

Answer 15

Long pre-ganglionic fibres

Short post-ganglionic fibres

Because parasympathetic slows things down/stops them completely you only want the fibres affecting one organ at a time. The ganglia lie in or near the organ being affected.

Question 16

What are the key functions of the parasympathetic nervous system?

Answer 16

SLUDD

Salivation
Lacrimation
Urination
Digestion
Defecation

Question 17

Are the effects of the parasympathetic and sympathetic nervous systems always antagonistic?

Answer 17

No. Sometimes they can be similar

E.g. Salivation - both stimulate saliva secretion but parasymp creates watery enzyme-rich saliva. Symp causes secretion of small amounts of viscous saliva.

Question 18

Type I receptors elicit an excitatory response to ACh. What is a Type I receptor?

Answer 18

Nicotinic ion-gated channel

Question 19

Type II receptors (__1__ receptors) are __2__ channels.

Answer 19

1. muscarinic

2. gated

Question 20

Sympathetic pre-ganglionic axons always use __?__ as the neurotransmitter.

Answer 20

acetylcholine

Question 21

Are ACh and NA excitatory or inhibitory?

Answer 21

They can be excitatory or inhibitory depending on what the bind to.

Question 22

Nicotinic receptors elicit an [excitatory/inhibitory] response from ACh.

Answer 22

excitatory

Question 23

Parasympathetic fibres always use acetylcholine for both pre- and post-ganglionic neurotransmission. True or false?

Answer 23

True. The preganglionic synapse has a nicotinic (Type I) cholinergic receptor, while the postganglionic synapse has a muscarinic (Type II) cholinergic receptor.

Question 24

Positively charged ion channels elicit an __1__ response (e.g. Na+), while negatively charged ion channels elicit an __2__ response (e.g. Cl-)

Answer 24

1. excitatory

2. inhibitory

Question 25

Which is faster, G-protein coupled receptors or ion channels?

Answer 25

Ion channels

Question 26

Did you know?

Answer 26

Nicotinic ACh receptors fall in three main types: muscle (NMJ), ganglionic and CNS

Question 27

How many subunits form a nicotinic ligand-gated ion channel receptor?

Answer 27

5

The composition can vary. They may be all the same subtype (homomeric), or there may be several different types (heteromeric).

Question 28

Muscarinic receptors are typically [1. G-protein coupled/ ion channel] receptors and there are __2__ subtypes known as __3__.

Answer 28

1. G-protein coupled receptors
2. 5
3. M1-M5

Question 29

There are __1__ types of muscarinic receptor found in the CNS. These are __2__.

Answer 29

1. three

2. M1, M4 and M5

Question 30

In the heart you can find one type of muscarinic ACh receptor: M_?_. What effect does activation of this receptor have?

Answer 30

M2

Activation of M2 receptors lowers conduction velocity at sinoatrial and atrioventricular node, thus lowering heart rate.

Question 31

In glands and smooth muscle you will find one type of muscarinic ACh receptor: M_?_.

Answer 31

M3

Question 32

What are the subtypes of adrenoceptor?

Answer 32

There are 5 subtypes: alpha 1, alpha 2, beta 1, beta 2, beta 3.