PH1124 - Autonomic Nervous System

Question 1

what is the autonomic nervous system?

Answer 1

• the part of the nervous system responsible for control of the bodily functions not consciously directed, such as breathing, the heartbeat, and digestive processes

Question 2

what is the autonomic nervous system split into? (2)

Answer 2

• sympathetic nervous system

- parasympathetic nervous system

Question 3

How is visceral pain felt?

Answer 3

Sensory neurons to the spinothalamic tract to the thalamus to the cerebral cortex the pain is difficult to localise so is referred to somatic regions of the body.

Question 4

Why is there poor localisation of referred pain?

Answer 4

the afferents from the viscera synapse on the same neurons of dorsal horn as the A beta fibres from skin mechanoreceptors this is then projected via anterolateral column.

Question 5

What is the role of the amygdala?

Answer 5

Main limbic region for emotions so stimulates sympathetic activity especially previously learned fear behaviour.

Question 6

What is the reticular formation?

Answer 6

a nerve network in the brainstem that plays an important role in the influence of the autonomic function.

Question 7

what is the difference between ANS neurons and sensory/motor neurons?

Answer 7

• ANS neurons require two neurons which synapse in the ganglia

Question 8

what is the difference between the ganglionic fibres in the parasympathetic and sympathetic nervous system? (2)

Answer 8

Sympathetic- Short preganglionic fibres and long post ganglionic fibres.
Parasympathetic- long preganglionic fibres and short post ganglionic fibres.

Question 9

what are ganglia?

Answer 9

• clusters of cell bodies in the PNS that contain many synapses

Question 10

Why is the adrenal medulla an exception?

Answer 10

Only one neuron from spinal cord to it. And no innervation from parasympathetic nervous system.

Question 11

Where does the neurons in the adrenal medulla synapse?

Answer 11

Synapses in the gland.

Question 12

which fibres are myelinated, pre or post ganglionic?

Answer 12

• pre

Question 13

what are nicotinic receptors?

Answer 13

• fast action excitatory ion channels that uses acetylcholine

Question 14

what are muscarinic receptors?

Answer 14

• G-protein coupled receptors that use acetylcholine
  M1-M3 in parasympathetic targets and M1/M2 inhibitory.
  M3 excitatory.

Question 15

what type of receptors are noradrenergic/adrenergic receptors?

Answer 15

• G-protein linked receptors

Question 16

what are the post synaptic noradrenergic/adrenergic receptors and are they inhibitory or excitatory? (5)

Answer 16

• α1; excitatory; post-synaptic receptor
• α2; inhibitory; pre-synaptic receptor
• β1; excitatory; post-synaptic receptor
• β2; inhibitory/excitatory; post-synaptic receptor
• β3; excitatory.; post-synaptic receptor

Question 17

What is the main difference between the sympathetic and parasympathetic nervous system ?

Answer 17

The parasympathetic nervous system restores the body to a calm and composed state and prevents it from overworking. The sympathetic nervous system, on the other hand, prepares the body for fight and flight response.

Question 18

what would a nicotinic agonist cause to Ach ganglia?

Answer 18

• short term hypertension, palpitations, secretions and GI stimulation

Question 19

what would an nicotinic antagonist cause to Ach ganglia?

Answer 19

• hypotension, loss of cardiac reflexes, inhibition of secretions, GI paralysis

Question 20

what would a muscarinic agonist cause to parasympathetic effectors? (3)

Answer 20

• M1; secretion of gastric acid
• M2; slowing of the heart
• M3; contraction of smooth muscle

Question 21

what would a muscarinic antagonist cause to parasympathetic effectors? (3)

Answer 21

• M1; reduced secretion of gastric acid
• M2; increased heart rate
• M3; relaxation of smooth muscle

Question 22

what would a noradrenergic agonist cause to sympathetic effectors? (4)

Answer 22

• α1; vasconstriction and contraction of smooth muscle
• α2; vasoconstriction
• β1; cardiac stimulation/gut relaxation
• β2; vasodilation and bronchodilation

Question 23

what would a noradrenergic antagonist cause to sympathetic effectors? (4)

Answer 23

• α1; vasodilation and smooth muscle relaxation
• α2; vasodilation
• β1; gut stimulation
• β2; vasoconstriction and bronchoconstriction

Question 24

What is the neurotransmitter used in the sympathetic nervous system pre and post ganglionic neurons?

Answer 24

Preganglionic- acetylycholine.

Postganglionic- Noradrenaline.

Question 25

What are examples of muscarinic agonists that are used clinically?

Answer 25

Anticholinesterases which are used to reduce salivary secretions pre surgery, to dilate pupils and a laxative.

Question 26

What are the clinical uses of muscarinic antagonists?

Answer 26

To treat motion sickness, asthma and GI or menstrual cramps.

Question 27

how is the enteric nervous system modulated?

Answer 27

• sympathetic and parasympathetic innervation

Question 28

Where are the ganglia located that control peristalsis?

Answer 28

Between longitudinal and circular muscle.

Question 29

Where are the ganglia that cause secretion of blood flow located?

Answer 29

Located in the submucosa.