Autonomic Nervous System and Behaviour Flashcards
What is the architecture of the peripheral nervous system? - flowchart (7)
1) PNS
2a) Somatic nervous system
2b) autonomic nervous system
3a) sensory division, motor division
3b) parasympathetic, sympathetic and enteric
What is the role of the somatic nervous system? (3)
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
What is the NMJ? (1)
neuromuscular junction : point at which the motor neurons and skeletal fibres meet and share connections (where neurotrans are released for muscle movement)
What is the role of the autonomic nervous system? (2)
- self regulated action of organs
- involuntary actions controlled by the CNS but no conscious/active thought required
Give some examples of involuntary actions (6)
heart rate, digestion, respiratory rate, pulmonary response, urination, sexual arousal etc.
Explain the differences in the sympathetic and parasympathetic NS (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
Name the anatomy of the symp NS (3)
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
Name the anatomy of the parasymp NS
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)
Name the neurotransmitter signal pathway in the autonomic nervous system (3)
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
Why is the ANS pathway to the sweat glands different? (2)
1) Both the pre + post ganglionic cells release Ach
2) then bind to muscarinic r
explain the release of adrenaline as an exception (2)
preganglionic cells release Ach directly onto adrenal gland
= releases Adrenaline
travels through bloodstream to targets
Define Catecholamines (1)
Monoamine neurotransmitters that are made up of a benzene ring w/ 2 hydroxyl groups + amine side chain
Name the main Catecholamines and their lineage (5)
1) L-Tyrosine
— tyrosine hydroxylase—
2) L-dopa
—dopa decarboxylase—
3) Dopamine
— dopamine b-hydroxylase—-
4) Noradrenaline
—Phenylethanolamine N-methyltransferase—
5) Adrenaline
Why is L-dopa interesting? (1)
It is administered as a PD’s drug, alongside another drug, to prevent dopamine from getting into the brain (crossing BBB)
What is the adrenal gland made up of? (2)
The adrenal gland consists of two functionally different regions:
- Adrenal Cortex: steroid hormones (cortisol,
aldosterone and androgens) - Adrenal Medulla: catecholamines (adrenaline and
noradrenaline)
What and where is the adrenal medulla? (3)
- innermost part of adrenal glands
- small triangular shaped glands
- on the top of each kidney
What are the main adrenoreceptors and what are their MOA pathways? (3)
a1(A,B,D) (Gq)
a2 (A,B,C) (Gi/o)
b (1,2,3)(Gs)
Describe the Gq pathway (5)
Gq =
1) NA/A binds to a1
2) PLC activation
3) PIP2 => IP3 + DAG
4) DAG -> MLCK, IP3 = Ca2+ increase
5)= smooth muscle contraction
Describe the Gi/o pathway (5)
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
Describe the Gs pathway (4)
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
Name and explain the postsynaptic agents: AGONISTS for each receptor type (8)
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
Name and explain the postsynaptic agents: ANTAGONISTS for each receptor type (8)
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
Describe the MoA for vascular smooth muscle contraction (5+1)
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)
Describe the MoA for vascular smooth muscle relaxation (4)
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
Describe the cardiac muscle mechanism (4)
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.
Name the parasympathetic receptors - flowchart(7)
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
Name the functions of the muscarinic receptors in relation to MoA (5)
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
What do we know about postsyap targets in muscarinic r’s? (2)
quite heterogenous
= very little selectivity in the
so use one of these 3:
- Acetylcholine
- carbachol
- pilocarpine
Muscarinic agonists (3)
Acetylcholine (endo agonist)
Carbachol: Glaucoma, micturition (parasymp mimetic)
Pilocarpine: Glaucoma, Salivary glands (aparsymp mimetic)
Muscarinic antagonists (3)
non-selective:
- Atropine (pesticide poisoning, or slow HR in surgery)
- Oxybutanin (overactive bladder)
selective:
- Pirenzepine: M1 antagonist – (Acid secretion - stomach ulcer)
explain the physiological antagonism (2)
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)
explain the physiological antagonism of the heart in terms of HR (4 + 1)
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.
What about cardiac conduction? (3 +1)
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
Summary 1 (5)
- 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
Summarise stress + the HPA + vaso (4)
stress
1) Hypo
—-CRH—
2) AP
—–ACTH—–
3) Adrenal medulla
—–CORT—–
4) = fluid + salt retention (inflammation) due to increased vasopressin
Explain the function of glucagon and insulin in response to blood sugar (6)
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
Explain the pancreatic b cell in response to Adrenaline increase (4)
works through a2 receptor MOA
Ach = kickstarts Gs pathway
- increased cAMP levels
= insulin release
