week 4 autonomic nervous system

Question 1

what are the differences between the autonomic nervous system and the somatic nervous system

Answer 1

• the autonomic nervous system innervates stuff that you don’t think about e.g. smooth & cardiac muscle, glands, somatic innervates skeletal muscle
• there is a pre-ganglionic fibre and a post ganglionic fibre in the autonomic NS whereas in the somatic there is just one fibre
• in the somatic NS there is the NMJ which uses ionotropic receptors and always excites target, whereas in the autonomic it is a less specialised junction, uses metabotropic receptors and may excite or inhibit target

Question 2

what are the two parts of the autonomic nervous system

Answer 2

Sympathetic
- fight or flight
Parasympathetic
- rest and digest

Question 3

are the ganglion closer to the spinal cord or the target organ in the sympathetic nervous system

Answer 3

• in sympathetic the ganglion are close to the spinal cord

Question 4

are the ganglion closer to the spinal cord or the target organ in parasympathetic nervous system

Answer 4

• closer to target organ
  (think of it because fibres in parasympathetic only come from top and bottom of spine so why would they be close to the spinal cord)

Question 5

what do you call outflow of parasympathetic nervous system

Answer 5

• cranio-sacral

Question 6

what do you call sympathetic outflow

Answer 6

• thoracic-lumbar

- coming from all twelve thoracic regions and the first two lumbar regions

Question 7

what are sympathetic paravetebral ganglia and collateral ganglia

Answer 7

• the paravertebral ganglia sit next to the spinal cord and look like a sort of ladder
• collateral ganglia are pre-vertebral ganglia (form a sympathetic chain)

Question 8

what are the two autonomic nervous system neurotransmitters

Answer 8

• acetylcholine

- noradrenaline

Question 9

what receptors does acetylcholine have in the autonomic nervous system

Answer 9

acts on cholinergic receptors

• nicotinic receptors (PREganglionic)
• muscarinic receptors (POSTganglionic)

Question 10

what receptors does noradrenaline have in the autonomic nervous system

Answer 10

acts on adrenergic receptors

• alpha receptors
• beta receptors

Question 11

what releases acetylcholine in the autonomic nervous system and what receptors does it act on

Answer 11

• both sympathetic and parasympathetic PRE-ganglionic fibres release acetylcholine
• this acts on nicotinic cholinergic receptors

Question 12

what releases noradrenaline in the autonomic nervous system

Answer 12

• sympathetic POST-ganglionic cells of the adrenal medulla release adrenaline and noradrenaline into the blood which acts on alpha of beta receptors

Question 13

so what are the steps in parasympathetic outflow

Answer 13

• pre-ganglionic fibres release acetylcholine which acts on nicotinic cholinergic receptors
• post-ganglionic fibres release acetylcholine which acts on muscarinic cholinergic receptors

Question 14

what are the steps in sympathetic outflow

Answer 14

• PRE-ganglionic fibres release acetylcholine which acts on nicotinic cholinergic receptors
• POST- ganglionic fibres release noradrenaline which acts on alpha or beta adrenergic receptors

Question 15

what is the sympathetic innervation of the eye

Answer 15

• alpha 1 receptors contract radial muscle of the eye = pupil dilates
• beta 2 receptors relax ciliary muscle

Question 16

what is the parasympathetic innervation of the eye

Answer 16

• activates muscarinic receptors which contracts sphincter muscle of iris and pupil gets smaller
• muscarinic receptors contract ciliary muscle

Question 17

what is the sympathetic innervation of the heart

Answer 17

• beta 1 receptors on pacemaker cells increase heart rate

- beta 1 receptors on myocytes increase strength of contraction

Question 18

what is the parasympathetic innervation of the heart

Answer 18

• muscarinic receptors on pacemaker cells decrease heart rate
• little effect on myocytes, so parasympathetic has little effect on strength of contraction

Question 19

what is the sympathetic innervation of the airways

Answer 19

• beta 2 receptors relax smooth muscle in airways and dilates the airways

Question 20

what is the parasympathetic innervation of the airways

Answer 20

• muscarinic receptors make smooth muscle contract and constrict airways

Question 21

what is the sympathetic innervations of the blood vessels

Answer 21

• depends on what receptors the tissues display
• beta 2 receptors in skeletal and cardiac muscle relax the smooth muscle of the vessels and increase blood flow (needed in these areas in fight or flight)
• alpha 1 receptors contracts smooth muscle of vessels elsewhere and restricts blood flow

Question 22

what is the parasympathetic innervation of the blood vessels

Answer 22

• doesn’t innervate blood vessels except in the genitalia or the salivary glands

Question 23

what is the sympathetic innervation of the salivary glands

Answer 23

• beta receptors stimulate thick secretion rich in enzymes

Question 24

what is the parasympathetic innervation of salivary glands

Answer 24

• activate muscarinic receptors and stimulates profuse watery saliva

Question 25

what is the sympathetic innervation of the bladder

Answer 25

• beta 2 receptors relax smooth muscle of bladder wall to decrease pressure (don’t want to pee in fight or flight)
• alpha 1 receptors contract sphincter to stop urination

Question 26

what is the parasympathetic innervation of the bladder

Answer 26

• muscarinic receptors contract smooth muscle of bladder wall
• muscarinic receptors relax sphincter muscle and cause urination (diff. subtypes of muscarinic receptors)

Question 27

what is the sympathetic and parasympathetic innervation of the reproductive tract

Answer 27

• sympathetic = alpha 1 receptors contract smooth muscle of urethra = ejaculation
• parasympathetic = muscarinic receptors relaxes smooth muscle of corpus cavernous = erection