Pharmacology of the autonimic NS

Question 1

what NS provides voluntary responses?

Answer 1

Somatic

Question 2

what does the autonomic NS do?

Answer 2

provides involuntary responses

Question 3

what are the divisions of the autonomic NS

Answer 3

parasympathetic - rest and digest

sympathetic - fight or flight

Question 4

what are slow responses to change mediated by?

Answer 4

complex processes - hormones, neurotransmitters, GF, cytokines and other substances causing changes in gene expression leading to a long term adaptation

Question 5

what is the autonomic system defined as?

Answer 5

the neuronal groups and fibre connections that control the activity of the heart, visceral organs, blood vessels and glands

Question 6

how does the autonomic NS maintain homeostasis?

Answer 6

by directly or indirectly (by controlling blood supply) facilitating the response of virtually every organ system to varying external and internal demands

Question 7

what does the parasympathetic branch do

Answer 7

important for digestion, excretion, visual accommodation

Question 8

what does the sympathetic branch do

Answer 8

important for controlling the cardiovascular system and reflex responses to stressful situations
-more widespread innervation and effects than parasymp

Question 9

what are the properties of the parasympathetic pathway

Answer 9

• same structure and chemicals wherever in the body
• acetylcholine NT in the ganglia activating the post ganglionic nerve which also releases Ach NT.
  receptors for each are different.
  in the ganglion there are nicotinic receptors and in the effector organs at the NMJ are muscarinic cholinergic receptors

Question 10

what are the properties of the sympathetic pathway

Answer 10

have different structures

• releases Ach and had nicotinic cholinergic receptors
• however the neuroeffector junction is different, releases noradrenaline and has alpha or beta adrenergic receptors

Question 11

what is the general system of the sympathetic and parasympathetic NS

Answer 11

• both have 2 nerve fibres in series
• different location of ganglia for symp and parasymp
• there are not discrete nerve endings but periodic effect as it runs along the effector called varicosities which is where the NT is present

Question 12

what does the somatic motor neurone do

Answer 12

• for completeness not part of ANS
• release Ach onto muscle fibres which have nicotinic receptors but the nicotinic receptor structure is different to in the autonomic system so drugs can directly effect them

Question 13

what are cholinergic receptors and what forms do they come in?

Answer 13

-important for ANS function and respond to Ach
two forms
-muscarinic
-nicotinic

Question 14

properties of muscarinic receptors

Answer 14

• present in effector muscle or gland and respond to Ach
• G protein coupled
• 5 subtypes M1-M5
• M2 receptors in the heart when activated reduce cAMP
• M3 receptors are in smooth muscle and glands. When activated causes increase in IP3/DAG increasing Ca conc for contraction

Question 15

properties of nicotinic receptors

Answer 15

• present on the effector muscle or gland respond to Ach
• channel and receptor combined, when Ach binds causes depolarisation to activate the cells
• present on the muscle in somatic NS are N1 and in ganglionic receptors are N2

Question 16

what happens in both nicotinic and muscarinic receptors

Answer 16

aCH BINDS CAUSIG CHANNELS TO OPEN ACTIVATING THE CELLS

Question 17

what are adrenergic receptors?

Answer 17

important to ANS function and respond to both noradrenaline and adrenaline and come in two forms
- alpha and beta

Question 18

what are the properties of alpha adrenergic receptors

Answer 18

have two subtypes a1 and a2, each has three subtypes which ca be differentially targeted by drugs

Question 19

what happens when a1 adrenergic receptors are activated?

Answer 19

activated Gq to stimulate IP3/CA2 and DAG second messenger pathways major effect is to raise cellular Ca2+

Question 20

what happens when a2 adrenergic receptors are activated?

Answer 20

activated Gi to inhibit adenylate cyclase and decr cellular cAMP, mainly located pre-synaptically, acts to decr release of noradrenaline

Question 21

what are the properties of beta adrenergic receptors?

Answer 21

3 subtypes and they all activate Gs to increase cAMP

Question 22

what are the three beta adrenergic subtypes and what are there specifications

Answer 22

B1 - cardiac subtype
B2 - main vascular and airways subtype
B3 - mainly found in adipose also important in bladder

Question 23

non adrenergic, non cholinergic neurotransmission- what are other neurotransmitters released along with

Answer 23

Ach or Noradrenaline

- called co transmission

Question 24

NANC - what may stronger levels of stimulation cause

Answer 24

different patterns of neurotransmitter release, therefore allowing differential control of target cell function

Question 25

NANC - where can NANC transmission occur

Answer 25

in both ganglionic and post ganglionic synapses and is particularly important in CNS neurones and in the enteric NS

Question 26

example of NANC neurotransmission - neuropeptide y and ATP

Answer 26

- release of neuropeptide Y and ATP along with NA which promotes vasoconstriction

Question 27

example of NANC neurotransmission - nitric oxide and vasoactive intestinal polypeptide with Ach

Answer 27

this causes vasodilation | - released by some post ganglionic sympathetic

Question 28

what are some sympathetic effects

Answer 28

-inc HR and force of contraction -vasoconstriction in splanchnic circulation ( abdominal organs) incr blood pressure - vasodilation of the arteries in the heart and skeletal muscles and increased renin release from the kidney, increase blood inc blood pressure - bronchodilation - inc blood glc and free fatty acids - pupil dilation - piloerection decreased GI motility - slowing digestion - loss of erection in males - sweating - ejaculation - bladder relaxation

Question 29

in fight or flight how does SNS respond

Answer 29

all activated at once | - at non stressful times can be organ specific

Question 30

parasympathetic effects

Answer 30

- dec HR - Inc GI tract and other secretions - inc GI contractions which mix and propel GI contents - bronchoconstriction - visual accommodation - pupil constriction - defecation - erection

Question 31

what organs do Symp and Parasymp NS have antagonistic effects?

Answer 31

heart pupils GI tract Urinea muscle

Question 32

what organs do Symp and Parasymp NS not have antagonistic effects?

Answer 32

arteries exocrine glands metabolism renin

Question 33

under resting conditions what NS is the heart dominated by?

Answer 33

parasymp

Question 34

what is the baroreceptor reflex

Answer 34

an autonomic reflex that controls blood pressure

Question 35

what is the process of the baroreceptor reflex

Answer 35

- BP distends arterial wall - afferent nerve endings stimulated by inc stretch - signal to NTS (nucelus tractus solitarus in brain stem) - inc parasympathetic drive to heart which decr HR and cardiac output - symp drive to heart veins and arteries decr - decr heart rate and force of contraction - arterial constriction and total peripheral resistance decr - venous construiction dec which decr cardiac output BP falls to set point

Question 36

what happens if bp falls

Answer 36

opposite to long process

Question 37

what is the enteric nervous system

Answer 37

- the brain of the gut | - complex network of sensory, motor and interneurons forming 2 layers within the wall of the GI tract

Question 38

enteric nervous system- what NANC does it use

Answer 38

Ach, vasoactive intestinal polypeptide and nitric oxide

Question 39

enteric nervous system- what does it coordinate and control

Answer 39

peristalsis, fluid transport, glandular secretion, blood flow within GI tract

Question 40

what is peristalsis

Answer 40

series of wave like muscle contractions that move food to different processing stations in the digestive tract