Autonomic Nervous System and Behaviour

Question 1

What is the architecture of the peripheral nervous system? - flowchart (7)

Answer 1

1) PNS

2a) Somatic nervous system
2b) autonomic nervous system

3a) sensory division, motor division
3b) parasympathetic, sympathetic and enteric

Question 2

What is the role of the somatic nervous system? (3)

Answer 2

somatic:
- responsible for transmitting sensory info from body -> CNS and then motor commands from CNS -> skeletal muscles

• governs VOLUNTARY movement
• sensory (afferent) neurons carry signals from receptors to CNS so that efferent neurons can carry out movement

Question 3

What is the NMJ? (1)

Answer 3

neuromuscular junction : point at which the motor neurons and skeletal fibres meet and share connections (where neurotrans are released for muscle movement)

Question 4

What is the role of the autonomic nervous system? (2)

Answer 4

• self regulated action of organs
• involuntary actions controlled by the CNS but no conscious/active thought required

Question 5

Give some examples of involuntary actions (6)

Answer 5

heart rate, digestion, respiratory rate, pulmonary response, urination, sexual arousal etc.

Question 6

Explain the differences in the sympathetic and parasympathetic NS (6)

Answer 6

Symp: fight or flight response
-norepinephrine + epinephrine
- increases: HR, Resp, BP, pupil dilation
- decreases: digestion, urine production

Parasymp: rest & digest
-acetylcholine
- increases: digestion
- decreases: HR, Resp, BP, pupil dilation

Question 7

Name the anatomy of the symp NS (3)

Answer 7

ANS:
1st output: spinal cord broken up into medullary, cervical.#, thoracic, lumbar and sacral

symp: use symp chain
1) outputs innervated mainly from thoracic (+ some from lumbar region) -> via pre-ganglionic cells (prevertebral ganglia)
2) ganglionic neurons then output it to liver, GIT, Bladder, genitalia etc

Question 8

Name the anatomy of the parasymp NS

Answer 8

Parasymp: no symp chain = closer to target organs
1)outputs innervated mainly from medullary (+ some sacral)
2) M = eye, lacrimal gland, salivary glands, heart lung, upper GIT
S = bladder, genitals etc (pelvic ganglia)

Question 9

Name the neurotransmitter signal pathway in the autonomic nervous system (3)

Answer 9

Symp: preganglionic-> ganglia w/ nicotinic r-> Ach -> postganglionic -> NA or Ach for smooth muscle, glands (a1/2 r) or for SWEAT GLANDS!!!!

Parasymp: preganglionic -> ganglia w/ nicotinic r -> Ach -. postganglionic -> Ach binds to muscarinic r’s ->smooth muscle, glands

Adrenal medulla: preganglionic ->ganglia w/ nicotinic r -> Ach -> adrenal medulla -> to circ = epinephrine, norephinephrine

Question 10

Why is the ANS pathway to the sweat glands different? (2)

Answer 10

1) Both the pre + post ganglionic cells release Ach

2) then bind to muscarinic r

Question 11

explain the release of adrenaline as an exception (2)

Answer 11

preganglionic cells release Ach directly onto adrenal gland

= releases Adrenaline

travels through bloodstream to targets

Question 12

Define Catecholamines (1)

Answer 12

Monoamine neurotransmitters that are made up of a benzene ring w/ 2 hydroxyl groups + amine side chain

Question 13

Name the main Catecholamines and their lineage (5)

Answer 13

1) L-Tyrosine
— tyrosine hydroxylase—
2) L-dopa
—dopa decarboxylase—
3) Dopamine
— dopamine b-hydroxylase—-
4) Noradrenaline
—Phenylethanolamine N-methyltransferase—
5) Adrenaline

Question 14

Why is L-dopa interesting? (1)

Answer 14

It is administered as a PD’s drug, alongside another drug, to prevent dopamine from getting into the brain (crossing BBB)

Question 15

What is the adrenal gland made up of? (2)

Answer 15

The adrenal gland consists of two functionally different regions:

• Adrenal Cortex: steroid hormones (cortisol,
  aldosterone and androgens)
• Adrenal Medulla: catecholamines (adrenaline and
  noradrenaline)

Question 16

What and where is the adrenal medulla? (3)

Answer 16

• innermost part of adrenal glands
• small triangular shaped glands
• on the top of each kidney

Question 17

What are the main adrenoreceptors and what are their MOA pathways? (3)

Answer 17

a1(A,B,D) (Gq)
a2 (A,B,C) (Gi/o)
b (1,2,3)(Gs)

Question 18

Describe the Gq pathway (5)

Answer 18

Gq =

1) NA/A binds to a1
2) PLC activation
3) PIP2 => IP3 + DAG
4) DAG -> MLCK, IP3 = Ca2+ increase
5)= smooth muscle contraction

Question 19

Describe the Gi/o pathway (5)

Answer 19

Gi/o = inhib ca2+

1) NA/A binds to a2
2a) Inhibits Adenyl cyclase
2b) Inhibits Ca2+
3a) inhibits ATP => cAMP
4a) increases K+ channels = smooth muscle contraction

Question 20

Describe the Gs pathway (4)

Answer 20

Gs = stim ca2+

1) NA/A binds to b
2) stimulates Adenyl cyclase
3) stimulates ATP => cAMP production == X MLCK (= relax not contract), -> PKA + RyR (Ca2+ = heart contract.)
4)heart muscle contraction, smooth muscle relaxation, glycogenolysis

Question 21

Name and explain the postsynaptic agents: AGONISTS for each receptor type (8)

Answer 21

Non-selective b- Agonists:
- Adrenaline: heart attacks, anaphylactic
shock
- Isoprenaline, asthma (no longer)
For:
* Tachycardias
* Arythmias
* Smooth muscle relaxation

b1-Agonists:
- Dobutamime: cardiogenic shock
For:
* Tachycardia
* dsrythmia

b2 -Agonists:
_Salbutamol: asthma
- Terburtaline: asthma
For:
* Smooth muscle relaxation
* Tachycardia
* Tremor
* Peripheral vasodilation

alpha-1-Agonists:
-Phenylephrine: Nasal decongestant
For:
* Decongestion
* Tachycardia

Question 22

Name and explain the postsynaptic agents: ANTAGONISTS for each receptor type (8)

Answer 22

Non-selective b- Antagonists:
- Propanolol: Hypertension, cardiac dysrhythmias, anxiety, angina
For:
* Lower BP
* Reduce HR
* Anti-anxiety
* Bronchoconstriction
* Depression
* Cardiac failure

b1-Antagonists:
- Metoprolol: hypertension, cardiac dysrhythmias, angina
For:
* Lower BP
* Reduce HR
* Anti-anxiety
* Depression
* Cardiac failure

b2 -Antagonists:
-Butoxamine
No clinical
uses

alpha-1-Antagonists:
-Prazosin: hypertension
For:
* Vasodilation
* Postural
hypotension
* Tachycardia
* impotence

Question 23

Describe the MoA for vascular smooth muscle contraction (5+1)

Answer 23

1) activation of the A1 receptor

2) activates the GQ G protein

3) which activates your phospholipases = conversion of PIP -> to DAG and IP3

4) IP 3 then binds to the IP3 receptors located on the intracellular calcium stores = calcium release into the cytosol

5) = activates the myosin light chain kinase =contraction of the muscle.

(therefore an A1 receptor agonist will cause the contraction of vascular smooth muscle leading to vasoconstriction)

Question 24

Describe the MoA for vascular smooth muscle relaxation (4)

Answer 24

1)mediated by the beta 2 adrenergic receptor

2) activates Gs pathway

3) = activation of adenosine = increase in intracellular cyclic AMP

4) in vascular smooth muscle = inhibition of your mice myosin light chain kinase and causes the relaxation of smooth muscle

Question 25

Describe the cardiac muscle mechanism (4)

Answer 25

1) The binding of an agonist to B1 receptor = activation of the G protein

2) = conversion of ATP to cyclic AMP which in these cells activates PKA.

3) PKA = increase in intracellular calcium by releasing + opening these L type calcium channels and that allows the calcium to move into the cell

4) = that leads to the contraction of your cardiac cell.

Question 26

Name the parasympathetic receptors - flowchart(7)

Answer 26

Cholinergic receptors:
1a) Nicotinic (act as off switch to symp)
1b) Muscarinic (metabotropic)

2a)
- Neuronal (Nn)
- Non-neuronal (skeletal muscle) (Nm)

2b)
- M1, M3, M5
- M2, M4

3a) Adrenal, Immune cells, CNS, Ganglia

Question 27

Name the functions of the muscarinic receptors in relation to MoA (5)

Answer 27

image

m1(neural) - ↑ IP 3 , DAG
Depolarisation
Excitation (slow epsp) ↓K+ conductance

m2 (cardiac) - ↓ cAMP
Inhibition, ↓ Ca 2+ conductance
↑ K+ conductance

m3(glandular/smooth muscle) - ↑ IP 3, Stimulation ↑ [Ca 2+ ] i

m4 (CNS) - ↓ cAMP, Inhibition

m5 (CNS)- ↑ IP 3, Excitation

Question 28

What do we know about postsyap targets in muscarinic r’s? (2)

Answer 28

quite heterogenous
= very little selectivity in the

so use one of these 3:
- Acetylcholine
- carbachol
- pilocarpine

Question 29

Muscarinic agonists (3)

Answer 29

Acetylcholine (endo agonist)

Carbachol: Glaucoma, micturition (parasymp mimetic)

Pilocarpine: Glaucoma, Salivary glands (aparsymp mimetic)

Question 30

Muscarinic antagonists (3)

Answer 30

non-selective:
- Atropine (pesticide poisoning, or slow HR in surgery)
- Oxybutanin (overactive bladder)

selective:
- Pirenzepine: M1 antagonist – (Acid secretion - stomach ulcer)

Question 31

explain the physiological antagonism (2)

Answer 31

NA + Ach are not working on the same receptor, but they are antagonising each other in respect to the physiological response of the cell in the Gs pathway in B1r (NA) + M2r (Ach)

Question 32

explain the physiological antagonism of the heart in terms of HR (4 + 1)

Answer 32

1) innervation of the heart by the vagus nerve (which mediates your parasymp + symp)

2)So the sympathetic nerve drives her increased heart rate and increased cardiac strength while the vagus nerve inhibits it.

3) And so the parasympathetic nervous system acts to decrease heart rate by inhibiting the activity of the sinoatrial node = your natural pacemaker of the heart

4)While your parasympathetic fibres release Ach onto the SA node, hyperpolarizing as membrane and slowing the heart rate of of spontaneous depolarization and this results in a decreased heart rate = negative chronotropic.

The vagal tone or the level of parasymp activity is partially influenced during periods of rest and relaxation, and this helps maintain a lower baseline heart.

Question 33

What about cardiac conduction? (3 +1)

Answer 33

1)parasymp also influenced cardiac conduction = parasympathetic fibres innervate the AVN and delaying its conduction of electrical impulses

2) this delay allows for proper coordination between atrial and ventrical contraction, optimising cardiac output.

3)The parasymp + symp work together to maintain cardiac function within this narrow physiological range, and in doing so they ensure the appropriate responses to changing.

But so while the sympathetic nervous system primarily increases heart rate and quality and contractility to prepare the body for increased activity, the parasympathetic nervous system acts to counterbalance these effect and promoting relaxation and the conservation of energy during periods of rest and recovery

Question 34

Summary 1 (5)

Answer 34

• The parasympathetic nervous system regulates the rest and digest response

Functions:
* Constricting pupils (miosis)
* Stimulating digestive activities (e.g., secretion of saliva, gastric acid, and digestive enzymes)
* Promoting peristalsis and smooth muscle contraction in the gastrointestinal tract
* Stimulating urinary bladder contraction (micturition)
* Promoting sexual arousal

• Slows heart rate
• Physiological antagonism of the heart

Question 35

Summarise stress + the HPA + vaso (4)

Answer 35

stress

1) Hypo
—-CRH—
2) AP
—–ACTH—–
3) Adrenal medulla
—–CORT—–

4) = fluid + salt retention (inflammation) due to increased vasopressin

Question 36

Explain the function of glucagon and insulin in response to blood sugar (6)

Answer 36

LOW SUGAR: a1 release glucagon:
- released by pancreas
- promotes glycolysis
- raise blood sugar levels

HIGH SUGAR: b1 release insulin:
- released by pancreas
- promotes glycogenesis
- stimulates glucose uptake from the blood into tissue cells (muscle, kidney, fat)
- lowers blood sugar levels

Question 37

Explain the pancreatic b cell in response to Adrenaline increase (4)

Answer 37

works through a2 receptor MOA

Ach = kickstarts Gs pathway
- increased cAMP levels
= insulin release