Autonomic Nervous System Physiology

Question 1

role of autonomic nervous system

Answer 1

involuntary branch of efferent division of PNS
ANS controls internal environment
heart rate, circulation, digestion, respiration

Question 2

internal organs controlled by ANS

Answer 2

Heart
Lungs
Stomach & GIT, spleen, pancreas
Bladder & rectum
Kidney & liver
Eye (pupil)

Question 3

Medulla and Pons in brain stem control

Answer 3

Centres controlling cardiovascular, respiratory & digestive fcts.

Question 4

Hypothalamus controls

Answer 4

Heart rate, B.P. respiration (via medulla)

Question 5

spinal cord controls

Answer 5

Integrates autonomic reflexes not subject to higher control

e.g. urination, defecation

Question 6

Regions regulating the ANS output

Answer 6

Medulla and pons
Hypothalamus
Spinal cord

Question 7

parasympathetic

Answer 7

rest and digest - promotes normal maintenance of body

secretion and mobility of the body of different parts of the digestive tract

Question 8

sympathetic

Answer 8

fight or flight - emergency
increase cardiac outputpulmonary ventilation, routes blood to muscles, raises blood glucose and slows down digestion, kidney filtration and other functions not needed during emergencies

Question 9

each ANS pathway from ___ to ___ is ___

Answer 9

Each ANS pathway from CNS to organ/effector is two-neuron chain

Question 10

Origin of parasympathetic ANS nerve fibre

Answer 10

cranial (X – vagus nerve) and sacral (lower spinal cord)

Question 11

structure of parasympathetic pathway

Answer 11

long and myelinated preganglionic nerves

short and unmyelinated postganglionic

Question 12

Origin of preganglionic sympathetic SNS nerve fibre

Answer 12

Preganglionic - thoracic and lumbar regions of spinal cords (T1-L3)

Question 13

structure of ANS sympathetic pathways

Answer 13

short and myelinated preganglionic nerves

long and unmyelinated postganglionic nerves

Question 14

where does the sympathetic ganglia lie

Answer 14

in a chain along either side of the spinal cord - sympathetic trunk

Question 15

name 2 main neurotransmitters used in ANS

Answer 15

Acetylcholine (ACh)

Noradrenaline (NA)

Question 16

where is ACh released

Answer 16

preganglionic ANS nerves

Postganglionic parasympathetic nerves

Question 17

what nerves stimulate the release of Noradrenaline

Answer 17

Postganglionic sympathetic nerves

Question 18

2 portions of adrenal gland

Answer 18

inner - adrenal medulla

outer - adrenal cortex

Question 19

how is adrenal medulla innervated

Answer 19

Medulla modified sympathetic ganglion w/out postganglionic fibres

Question 20

what do the preganglionic fibres of adrenal medulla stimulate

Answer 20

Preganglionic fibre directly stimulates hormone release from chromaffin cells

Question 21

what neurotransmitter does adrenal medulla stimulate the release of

Answer 21

20% noradrenaline

80% adrenaline

Question 22

three layers of the adrenal cortex (outer - inner)

Answer 22

zona glomerulosa
zona fasciculata
zona reticularis

Question 23

exceptions to rules of ANS

Answer 23

Blood vessels
Arterioles & veins (not arteries or capillaries) innervated by sympathetic NS only
Liver (glycogen stores)
Gluconeogenesis (glucose released) by sympathetic NS
Sweat glands
Mainly sympathetic innervation and terminal fibre release ACh(!) not NA(!)

Question 24

Limitation of neurotransmitters of the ANS

Answer 24

stimulate activity in some tissues but decrease activity in others
NA increases heart rate but decrease contraction of digestive tract

Question 25

if the tissue/organ targets posses one or more receptor

Answer 25

binding of NT induce tissue specific response

Question 26

2 types of receptors

Answer 26

ionotrophic receptor - dont open ion channels but change conformation to allow ions - for fast responses metabotrophic receptor - something must be bound has a cascade and activate other ion channels - for slow responses

Question 27

where are Acetycholine receptors and Noradrenaline receptors in sympathetic nervous system

Answer 27

AChR at ganglion | NA-R -target tissue

Question 28

2 types of receptors that bind to acetylcholine

Answer 28

nicotonic | muscarinic

Question 29

nicotonic cholinergic receptors are found in ...

Answer 29

Found on all postganglionic ANS cell bodies

Question 30

nicotonic cholinergic receptors are activated by ..

Answer 30

R activated by ACh released from preganglionic parasymp. or symp. nerves R also activated by tobacco derivative nicotine

Question 31

are nicotonic cholingergic receptors ionotropic or metabotropic

Answer 31

ionotropic - fast responses | depolarisation - fast - new impulse is transmitted

Question 32

target tissues of muscarinic cholinergic receptors

Answer 32

Found on effector cell membranes - smooth muscle, glands, cardiac muscle

Question 33

nicotonic cholinergic receptors are activated by ...

Answer 33

Binds ACh released from postganglionic parasympathetic nerves also activated by mushroom poison muscarine

Question 34

are muscarinic cholingergic receptors ionotropic or metabotropic

Answer 34

metabotrophic receptor | 5 types

Question 35

location and function of inhibitory muscarinic receptors

Answer 35

M2 Located on cardiac tissue Receptor couples to increase K+ conductance, inhibit calcium channels e.g. decrease heart contraction

Question 36

location and function of excitatory muscarinic receptors

Answer 36

M3 Located in digestive system G protein couples to Ca2+ second-messenger system e.g. Increase glandular secretions, increase GIT motility

Question 37

2 Classes of Adrenergic receptors that bind NA and AD

Answer 37

alpha - a1 and a2 | Beta - B1, B2, B3

Question 38

A1 location

Answer 38

excitatory response | Located on most sympathetic target cells

Question 39

a1 function

Answer 39

G protein couples to Ca2+ second-messenger system | e.g. Increase contraction of arterioles → raised blood pressure

Question 40

a2 location

Answer 40

: inhibitory response | Located in digestive system

Question 41

a2 function

Answer 41

G protein couples to inhibit cyclic AMP system | e.g. decreased smooth muscle contraction → reduced GIT motility

Question 42

b1 location

Answer 42

Located in heart

Question 43

b1 function

Answer 43

excitatory Couples via G protein to cyclic AMP/PKA e.g. contraction of cardiac muscle → increased rate & force

Question 44

b2 location

Answer 44

Skeletal muscle (AD in blood), smooth muscle of some vessels & organs

Question 45

b2 function

Answer 45

inhibitory Couples via G protein to cyclic AMP/PKA e.g. relaxation of smooth muscle → bronchiolar dilation

Question 46

how is excess acetylcholine removed

Answer 46

destroyed by acetylcholinesterase

Question 47

how is excess noradrenaline removed

Answer 47

Re-uptake by pre- and post-synaptic cell then metabolized/re-cycled

Question 48

potential targets for Pharmacological intervention

Answer 48

``` NERVE TERMINAL Neurotransmitter release POST SYNAPTIC MEMBRANE Neurotransmitter-receptor interaction NEUROTRANSMITTER EFFECT TERMINATION Neurotransmitter degradation ```

Question 49

how do drugs interfere with ANS

Answer 49

mimic agonist or inhibit antagonist ANS response and receptors

Question 50

function of atropine

Answer 50

Blocks muscarinic R Blocks parasympathetic actions at effector tissues Reduces salivary and bronchial secretion (e.g. during surgery

Question 51

example of muscarine antagonist

Answer 51

atropine

Question 52

adrenergic agonist

Answer 52

salbutamol | atenolol

Question 53

function of salbutamol

Answer 53

Activates b2 adrenergic receptors Dilates bronchioles – treatment of asthma / COPD Lask of effect at b1 means no effect on heart

Question 54

function of atenolol

Answer 54

Blocks b1 adrenergic receptors | CVS: Lowers blood pressure - treatment of hypertension

Question 55

example of autonomic function

Answer 55

Dysautonomia

Question 56

causes of Dysautonomia

Answer 56

Trauma, Inflammation Drugs Neurodegenerative disease

Question 57

dysautonomia

Answer 57

deficiency of sympathetic activity to lesion /compression (trauma, tumor)