6 & 7 - Autonomic System Flashcards
Viscera by visceral sensors
is a kind of sensory input to the ANS. An example is change in blood pressure elicits the ________.
baroreceptor reflex
Other than visceral sensors, the other 2 types of sensor that input to the ANS are _____ and ______.
- Surface of the body by somatic sensors
○ Fall in ambient temperature sensed by peripheral/ cutaneous thermoreceptors triggers the contraction of arrector pilli muscle to raise hair and constriction of cutaneous blood vessels
- External environment by special sensors
Light affects the constriction and dilation of pupil
Considering the generation of ANS, there are 2 control pathways namely:
Somatic control pathways and Autonomic control pathways
What are the 4 differences of somatic and autonomic pathways? Why ANS is relatively slow to to somatic motor control?
- No. of synapses
Somatic: Monosynaptic
Autonomic: Disynaptic - Fiber type
Somatic: Myelinated type A fibers
Autonomic: Autonomic preganglionic neurons are small myelinated type B fibers; postganglionic: unmyelinated C fibers
(overall: fibers of ANS are less myelinated) - Neurotransmitter:
Somatic: Ach
Autonomic: Sympathetic: NE;
Parasympathetic: Acetylcholine - Effect on effectors:
Somatic: always excitatory
Autonomic: depends on the receptors, can be excitatory or inhibitory
Place the discrete effect of the 3 controls in descending order.
Parasympathetic ANS,
Sympathetic ANS,
Somatic motor control
Discrete effect: Somatic motor control > Parasympathetic ANS > Sympathetic ANS
What are the differences between sympathetic and parasympathetic divisions?
- Length of preganglionic neuron
S: Short
PS: Long - Length of postganglionic neuron
S: long
PS: short - Location of ganglia
S: lying close to the spinal cord (distant from effector organs)
PS: at the effector organs - Effect
S: less discrete (allow divergence to other places)
PS: more discrete
Motor nerve endings are specialized into ________, and are matched by post-synaptic specialization into ____________ where receptors for neurotransmitters are concentrated and only expressed in this cell surface area of the effector cell
synaptic knobs;
motor end plates
In _______ innervation, preganglionic neurons group their cell bodies into the _____________. (paired structure forming 2 sympathetic chains)
sympathetic;
sympathetic trunk ganglia
Sympathetic: After entering the sympathetic trunk, the preganglionic neuron may synapse with __________ at the same spinal level
Or send collaterals up/down the trunk to synapse at other spinal levels
-> widespread and less discrete effect
postganglionic neurons
Sympathetic: Preganglionic neurons synpase with postganglionic neurons located in prevertebral/ collateral ganglia (not paired), if they didn’t synapse after passing the sympathetic trunk
As not chained,-> more ___________ effect
(e.g. coeliac, aorticorenal, superior mesenteric, infereior mesenteric)
discrete
Sympathetic: Preganglionic neurons synapse with __________ located in adrenal medulla, which secrete hormones: ________ 80% and _______ 20%
-> widespread and prolonged effect
chromaffin cells;
adrenaline;
noradrenaline
Parasympathetic:
Preganglionic neurons originate from the brainstem in the nuclei of the _________.
cranial nerves (3,7,9,10)
Craniosacral division of ANS
Run for a long distance to meet postganglionic neurons in terminal ganglia
-> More ________ effect
localised
Adrenal medulla, adipose tissue, kidney, most blood vessels, sweat gland, piloerector muscle are only innervated by the _________.
Sympathetic nerves
fight or flight
stressful situations
Lacrimal gland, ciliary muscle are only innervated by the _____________.
Parasympathetic nerves
rest and digest (conserve energy)
NE and EP are synthesized from the amino acid ______as the precursor.
At adrenal medulla, chromaffin cells express additional enzyme (PNMT) to convert _____ to ____ as the major secretory product
tyrosine;
noradrenaline to adrenaline
Liver receives both sympathetic and parasympathetic nerve innervation
_________: stimulation of glucose production
Sympathetic
*Parasympathetic: anatomically but not functionally, if any, stimulation of glycogenesis and inhibition of gluconeogenesis
All autonomic preganglionic neurons release ______ onto _____________receptors.
acetylcholine;
cholinergic nicotinic receptors
Most postganglionic parasympathetic neurons secrete _______ onto ___________receptors.
acetylcholine;
cholinergic nicotinic receptors
Most postganglionic sympathetic neurons secrete ___________ onto _________ receptors (metabotropic receptor) (exceptions: sweat glands)
noradrenaline;
adrenergic
______ receptors are ionotropic receptors > faster action;
_____ receptors are metabotropic receptors >slower action
Nicotinic cholinergic ;
Muscarinic cholinergic
Muscarinic:
Adenylate cyclase >
catalyse ATP > cAMP
> PK > Ca2+ channels open/close
depends on Gi/Gq/Gs protein being stimulated
○ In ANS, neuronal type of nicotinic receptors are involved in generating ______________.
In somatic nervous system, muscle type of nicotinic receptors are involved in generating ___________ in skeletal muscle
EPSP (excitatory postsynaptic potential) ;
end plate potential (EPP)
Muscarinic receptor (Odd) (metabotropic) :
Stimulates muscle ________ (bronchial, intestinal) by binding to _________ that is linked to activation of phospholipase C, generating _____________ , and hence Ca2+ release from intracellular store
contraction;
G protein-coupled receptor (GPCR);
inositol triphosphate (IP3)
Muscarinic receptor (even)(metabotropic) ;
Example: Ach bind to M2 receptor activates ________ to inhibit adenylate cyclase, leading to fall in cAMP, reduced protein kinase A activity and closure L-type Ca2+ channel due to decreased channel protein phosphorylation
The ________ subunit of GK protein activates K+ channel to ________ the cell membrane.
Gi protein;
beta y;
hyperpolarize
Suggest an antagonist for each of the receptors:
A. nicotinic muscle
B. nicotinic neuronal
C. muscarinic
A. Curare
B. Hexamethonium
C. Atropine
Alpha-adrenergic receptors (1,2) and
Beta-adrenergic receptors (1,2,3) are ___________-releasing fibers.
Noradrenaline
When bind to ____ receptors, which G protein is activated respectively?
What are the primary effects respectively?
- a1
- a2
- beta
- Gq protein
- increase phospholipase C (increase Ca2+) - Gi protein
- decrease adenylate cyclase, thus cAMP - Gs protein
- increase adenylate cyclase, thus cAMP
What do NANC fibers release?
VIP and NO (neurotransmitters too!)
In cotransmission of 2 or more NT in ANS:
A. Ach binds to muscarinic cholinergic receptor and produce NO
B. NO diffuse to smooth muscle and increase cAMP levels and cause smooth muscle relaxation.
C. VIP cause smooth muscle to relax by increasing intracellular cAMP or decrease Ca2+
A and C only
B. increase cGMP levels
Pupillary reflex is controlled by the ANS.
Parasympathetic control causes _________ (Miosis) bt activating ________.
Sympathetic control causes ________ (mydriasis) by activating __________.
constriction; pupillary constrictor (circular) muscle ;
dilation; pupil dilator (radial muscle)
______ is used to dilate the pupil for eye examination. (_______receptor blocker)
Atropine;
Muscarinic
Near vision: _______ stimulation. __________contraction increases the curvature of the lens and becomes more convex. (accommodation reflex)
parasympathetic;
Ciliary muscles
Autonomic control of sweat production
- Eccrine sweat glands express ______ receptors and are innervated by sympathetic cholinergic nerves
The less abundant apocrine sweat glands express _______ receptors are controlled by the circulating hormone epinephrine/ direct sympathetic innervation
muscarinic;
adrenergic
*Sympathetic nerves mostly secrete noradrenaline, but in this case, acetylcholine
State the sympathetic cholinergic control on thermoregulation.
Cholinergic nerve: Acetylcholine is secreted to cause vasodilation for heat dissipation + stimulate sweat glands to produce sweat.
OPP:
Adrenergic nerve:
Noradrenaline binds on alpha adrenergic receptors to cause vasoconstriction for heat conservation
State the autonomic control to
(a) increase heart rate
(b) decrease heart rate
(a)
Sympathetic control releasing noradrenaline:
stimulate B1 receptors on SA node, increase Na+ and Ca2+ influx, increase rate of depolarization, increase heart rate
(b)
Parasympathetic control releasing acetylcholine:
stimulate muscarinic receptors on SA node,
increase K+ efflux and decrease Ca2+ influx, hyperpolarizes heart, decrease rate of depolarization, decrease heart rate
Parasympathetic vasodilator fibers
A. are less that sympathetic constrictor fibers
B. occurs in salivary glands and erectile tissues
Both correct
Postganglionic parasympathetic fibers release _________ to indirectly cause vasodilation through endothelial production of ____ / directly through release of_________
acetylcholine;
NO;
NO and VIP
Acetylcholine causes vasodilation by activating the __________ to form ___ at the endothelial cell, ___ then binds to _______ to generate _____ as the second messenger to produce smooth muscle relaxation.
NO synthase; NO;
NO; Guanylate cyclase;
cGMP
Which of the following is true?
A. Both epinephrine and norepinephrine will bind to adrenergic receptors but with different affinity
B. Norepinephrine has a lower affinity to alpha-1 receptor (vasoconstriction)
C. Epinephrine has a lower affinity to beta-2 receptor (vasodilation)
A only
NE should have higher affinity to a1 receptors
E should have higher affinity to b2 receptors
___________ nervous system is the dominant pathway in the constricting the bronchioles and mucus secretion by binding to ________ receptors .
Parasympathetic;
M3
*Stimulation of cholinergic nerves (secrete Ach on M3 receptors) causes bronchoconstriction and mucus secretion
__________ receptors are abundantly expressed on human airway smooth muscle, __________ causes bronchodilation (relieve asthma)
Beta-adrenergic; (B2)
adrenaline
Salivary secretion is increased by __________ stimulation (Ach and VIP) dominant, stimulating ______ receptors. On the other hand, _______ stimulation is for enzyme secretion, and is mediated via ______ receptors.
parasympathetic; Muscarinic (IP3 >Ca2+)
sympathetic;
B1 adrenoceptors
cAMP
_______________ is used to reduce salivary and respiratory tract secretion during surgery
Atropine
act on muscarinic receptors that stimulates salivary secretion
Gastrointestinal function:
Intrinsic nerves from ENS
and Extrinsic nerve from ANS
______ nerves stimulate secretion and motility, relaxes sphincters ;
______ nerves inhibits secretion and motility
Parasympathetic;
Sympathetic
Micturition (urination) reflex is an _________ reflex, but storage and voiding of urine is under voluntary control of higher centers in the brain.
The central and spinal activities are coordinated by the ___________ .
autonomic spinal;
pontine micturition center;
The effects of micturition reflex are mediated by:
A. sacral S2-S4 parasympathetic nerves (pelvic splanchnic nerves)
B. thoracolumbar (T11-L2) sympathetic nerves (hypogastric nerves and sympathetic chain)
C. sacral somatic nerves (pudendal nerves)
A, B and C
During filling of the bladder,
the ______ of the detrusor muscle is controlled by _____ effect on _________receptors.
The _______ of the internal sphincter is controlled by ________ effect on the _________receptors.
Relaxation;
sympathetic; B2
Contraction;
sympathetic; A1
During voiding (emptying) of the bladder, the \_\_\_\_\_\_ of the detrusor muscle is controlled by \_\_\_\_\_ effect on \_\_\_\_\_\_\_\_\_receptors.
The _______ of the internal sphincter is controlled by ________ effect on the _________receptors.
contraction;
parasympathetic;
muscarinic
relaxation;
parasympathetic;
muscarinic
**Rmb that during voiding, everything is parasympathetic control, and muscarinic receptors are stimulated.
___________ are use in the treatment of benign prostatic hyperplasia. Give 3 examples of them.
Relax internal sphincter
= a1 adrenoceptor blockers
- prazosin (short acting)
- Terazosin (long acting)
- Tamsulosin
祖先
What are the side effects of taking a1 adrenoceptor blockers?
A. postural hypotension
B. tachycardia (fast)
C. dizziness
D.sexual dysfunction (difficulty in ejaculation)
All except A
A. should be postiral hypertension
