Autonomic Nervous System

Question 1

What is the autonomic nervous system is involved with the involuntary control of?

Answer 1

Regulation of the functioning of internal organs

Maintenance of the internal environment

Question 2

What does the autonomic nervous system directly innervate?

Answer 2

Cardiac muscle

Glands

Smooth muscle

Question 3

What can the autonomic nervous system be divided into?

Answer 3

Sympathetic, parasympathetic and enteric nervous system

Question 4

How do the sympathetic and parasympathetic nervous system vary in their interaction with metabolic resources?

Answer 4

Sympathetic maximises use of metabolic resources

Parasympathetic conserves metabolic resources

Question 5

How do axons of the ANS reach effector organs, what kind of pathway is this called, and what organ is the only exception to this?

Answer 5

Via pre/postganglionic axons with a ganglion in the centre

Disynaptic pathway

Only exception is supply to the adrenal medulla

Question 6

What is the myelin content of preganglionic and postganglionic?

Answer 6

Preganglionic = Myelinated

Postganglionic = Unmyelinated

Question 7

What neurotransmitter do ganglion cells use, and what receptors do they bind to on postganglionic axons?

Answer 7

ACh

Bind to ionotropic nicotinic receptors

Question 8

What neurotransmitter do postganglionic sympathetic axons use, what type of receptors do the bind to on effector organs, and what is the only exception?

Answer 8

Noradrenaline

Bind to metabotropic adrenergic receptors

Only exception is sweat glands, which use ACh

Question 9

What are the different types of adrenergic receptors and where are they found?

Answer 9

alpha-1 (smooth muscle of blood vessels)

Beta-1 (heart)

Beta-2 (bronchial smooth muscle)

Question 10

What neurotransmitter do postganglionic parasympathetic axons use, what type of receptors do the bind to on effector organs?

Answer 10

ACh

Bind to muscarinic metabotropic receptors

Question 11

What is the sympathetic trunk

Answer 11

Interconnected paravertebral ganglia that extends from the cervical region down to the sacral region

Question 12

Through what do preganglionic fibres enter the sympathetic trunk, and at what levels can this occur?

Answer 12

White rami communicans

T1-L2

Question 13

Through what do postganglionic fibres exit the sympathetic trunk

Answer 13

Gray rami communicans

Question 14

When preganglionic fibres enter the sympathetic trunk one of two things can happen, what are they?

Answer 14

1) Can synapse in the ganglion

2) Can pass through the ganglion and and into splanchnic nerves, where they can then synapse onto prevertebral ganglia

Question 15

Are there more pre or postganglionic fibres, to what ratio is this, and what is the purpose of this?

Answer 15

More postganglionic fibres (1:10 ratio)

Allows for mass responses

Question 16

How do postganglionic fibres from the prevertebral ganglia supply viscera?

Answer 16

They form a plexus around the visceral organ

Question 17

What are the three ganglia in the cervical sympathetic trunk?

Answer 17

Superior, middle and inferior

Question 18

What causes Horner’s syndrome, and what does it affect?

Answer 18

Disruption of sympathetic supply to the head between preganglionic fibres and the hypothalamus (e.g. due to a lesion)

Affects eyelids, pupils and skin of the face

Question 19

What are the different thoracic splanchnic nerves that go to the prevertebral ganglia, and what do they innervate?

Answer 19

Greater, Lesser and Least splanchnic nerves

Innervate the abdomen

Question 20

What are the preganglionic fibres of the parasympathetic NS within and what do they supply?

Answer 20

Brainstem (supply head, heart, lungs and abdomen)

Grey matter spinal cord that form S2-S4 spinal nerves (pelvic organs)

Question 21

What type of nerves does the brainstem use in the parasympathetic nervous system?

Answer 21

Cranial nerves

Question 22

What type of nerves does the spinal cord use in the parasympathetic NS?

Answer 22

Pelvic splanchnic nerves

Question 23

What cranial nerves are involved in the parasympathetic NS, and what are their cranial nerve nuclei called?

Answer 23

Occulomotor nerve = Westphal-Edinger nucleus

Facial nerve = Superior salivatory nucleus

Glossopharyngeal nerve = Inferior salivatory nerve

Vagus nerve = Nucleus ambiguous

Question 24

What do sacral parasympathetic fibres from the spinal cord form?

Answer 24

Sacral plexus

Question 25

What are the functions of the sacral plexus?

Answer 25

Contraction of bladder wall and inhibition of sphincter

Inhibition of rectal sphincter

Vasodilation of erectile tissue

Question 26

What are the 2 plexi of the enteric NS, where are they located and what is their function?

Answer 26

Auerbach’s plexus which regulates muscle contraction and is found in between the muscle layers

Meissner’s plexus regulates glandular secretions and is found on the inside wall