Autonomics

Question 1

Autonomic nervous system function

Answer 1

Regulate functions not under voluntary control: respiration, circulation, thermogenesis, heat dissipation, GI function

Question 2

Efferent nerves

Answer 2

Both sympathetic and parasympathetic have two neurons: pre- and post-ganglionic neurons, interacting at autonomic ganglion

Question 3

Structures not innervated by parasympathetics

Answer 3

Peripheral blood vessels, adrenal medulla, skin

Question 4

Pharmacologic targets at cholinergic junction

Answer 4

Uptake- Hemicholinium
Storage- Vesamicol
Release- Botulinum toxin
Termination- AChE inhibitors
Receptors- agonists, antagonists

Question 5

Neurotransmitter of pre-synaptic neuron

Answer 5

Acetylcholine for both sympathetic and parasympathetic

Question 6

Neurotransmitters for post-synaptic neurons

Answer 6

Parasympathetic- ACh

Sympathetic- ACh, norepinephrine, dopamine

Question 7

Production of acetylcholine

Answer 7

Choline uptake by Na+/choline cotransporter, choline and acetyl coenzyme A catalyzed to ACh by choline acetyltransferase, ACh transported into granules for storage

Question 8

Release of acetylcholine

Answer 8

Action potential triggers fusion of membranes, release ACh into synpatic cleft, ACh binds and activates presynaptic or postsynaptic nicotinic or muscarinic receptors, ACh is broken down by ACh esterases in synaptic cleft

Question 9

Muscarinic acetylcholine receptors

Answer 9

G-protein coupled receptors

Question 10

Nicotinic acetylcholine receptors

Answer 10

Ligand-gated ion channels

Question 11

Pharmacologic targets at adrenergic junction

Answer 11

Synthesis- Metyrosine
Storage- Reserpine
Release- Bretylium, guanethidine
Reuptake- Cocaine, TCA, Ang II
Receptors- agonists, antagonists

Question 12

Reserpine

Answer 12

Used clinically to treat hypertension in third world countries

Question 13

Enzymes that degrade catecholamines

Answer 13

COMT- present in kidney, liver, GI tract, other organs

MAO- present in neural tissue

Question 14

Sympathomimetics

Answer 14

Tyramine, amphetamines, ephedrine, are poor agonists of adrenergic receptors

Question 15

Norepinephrine reuptake

Answer 15

Taken up by NET, transported into vesicles by VMAT, displaces NE which is transported to cleft by NET

Question 16

Production of norepinephrine

Answer 16

Tyrosine uptake by Na+/tyrosine cotransporter, tyrosine hydroxylase converts tyrosine into DOPA, DOPA converted to dopamine by dopamine decarboxylase, DA transported to granules and converted to NE by DA-beta-hydroxylase

Question 17

Release of NE

Answer 17

Action potential triggers membrane fusion, release of NE into synaptic cleft, NE binds and activates presynaptic or postsynaptic adrenergic, serotonin, or dopamine receptors, reuptake of NE by presynaptic transporters

Question 18

M2 cholinoceptor

Answer 18

Found in the heart, results in Gi activation (decreases cAMP)

Question 19

M3 cholinoceptor

Answer 19

Found in exocrine glands, vessels, iris circular muscle, results in Gq activation (IP3, DAG)

Question 20

Nn cholinoceptor

Answer 20

Located in autonomic ganglia, adrenal medulla, result in opening of Na, K channels, depolarization

Question 21

Nm cholinoceptor

Answer 21

Found in skeletal muscles, open Na, K channels, depolarization

Question 22

Alpha1 adrenoceptor

Answer 22

Located in smooth muscles, iris radial muscle, result in Gq activation (IP3, DAG)

Question 23

Alpha2 adrenoceptor

Answer 23

Located in presynaptic, smooth muscle, causes Gi activation (decreases cAMP)

Question 24

Beta1 adrenoceptor

Answer 24

Found in heart, juxtaglomerular apparatus of renal tubule, activates Gs (increases cAMP)

Question 25

Beta2 adrenoceptor

Answer 25

Found in smooth muscles, heart, activates Gs (increases cAMP)

Question 26

Heteroreceptors

Answer 26

Receptors that respond to substances released from adjacent neurons or cells, opposite to autoreceptors

Question 27

Adrenergic presynaptic alpha2 receptors

Answer 27

Autoreceptor that negatively regulates the release of NE when NE levels get too high, inhibits inward calcium current that causes vesicular fusion and transmitter release

Question 28

Phenoxybenzamine (POB)

Answer 28

Adrenal gland produces NE and Epi, POB indicated for pheochromocytoma (tumor of adrenal gland), POB inhibits alpha1 and alpha2, negative feedback by alpha2 blocked, POB lowers blood pressure by inhibiting alpha1 but NE and Epi can act on beta2 to increase blood pressure

Question 29

Control of the eye

Answer 29

Eye is under sympathetic and parasympathetic control, iris circular muscle (M3), iris radial muscle (alpha1)

Question 30

Control of ciliary body

Answer 30

Ciliary body under sympathetic and parasympathetic control, ciliary epithelium (beta1), ciliary muscle (M3)

Question 31

Beta1 receptors in eye

Answer 31

Facilitates aqueous humor secretion

Question 32

Alpha1 receptors in the eye

Answer 32

Reduces aqueous humor production

Question 33

M3 receptors in the eye

Answer 33

Mediates ciliary muscle contraction, accommodation of focus for near vision, tenses and opens pores in trabecular meshwork to facilitate aqeuous humor outflow

Question 34

Glaucoma

Answer 34

Damage to optic nerve due to buildup of intraocular pressure inside the eye

Question 35

Aqueous humor exit

Answer 35

Exits through the canal of Schlemm through the trabecular meshwork, if aqueous humor builds up it can cause glaucoma