Autonomic nervous system

Question 1

What is the sensory input of the ANS?

Answer 1

• mostly interoreceptors
• some somatic senses
• some special senses

• GVA, SVA, Cranial/spinal nerves

Question 2

What is the control of motor output of the ANS?

Answer 2

• involuntary from hypothalamus limbic system, brain stem, spinal cord
• limited from cerebral cortex

Question 3

What is the LMN pathway of the ANS?

Answer 3

2-neuron pathway:
• preganglionic neuron (from CNS)
-> postganglionic neuron (autonomic ganglion)
-> visceral effector

Question 4

What are the neurotransmitters and hormones of the ANS?

Answer 4

• ACh -acetylcholine
• NE- norepinephrine
• epinephrine

Question 5

What are the effectors of the ANS?

Answer 5

• smooth muscle
• cardiac muscle
• glands

Question 6

What are the types of responses from the ANS?

Answer 6

• contraction/relaxation of smooth muscle
• increased/decreased rate and force of contraction of cardiac muscle
• increase/decrease gland secretion

Question 7

Describe the myelination of neurons along the ANS?

Answer 7

• preganglionic neurons are myelinated

* postganglionic neurons are not

Question 8

List the receptors of the ANS?

Answer 8

• Nicotinic
• Muscurinic
• Visceral (baro, stretch, chemo, osmotic & glucose, visceral pain, thermal)

Question 9

Compare nicotinic vs muscurinic receptors

Answer 9

Nicotinic
• ligand-gated ion channels
• faster acting
• sensitive to nicotine

Muscurinic
• G-protein coupled receptor that uses G-protein and secondary messenger system to open ion channel
• sensitive to muscurine (amanita muscaria)

Question 10

Baroreceptor

Answer 10

• in carotid sinus and large arteries -signal change in pressure
• in atria -signal change in blood volume

Question 11

Stretch receptors

Answer 11

• lung inflation / deflation

* signal distension in hollow organs (bladder, gut)

Question 12

Chemoreceptors

Answer 12

• O2 receptors in carotid body and aortic arch

* central chemo signal pH and PCO2

Question 13

Are sensory afferents of the ANS all subconscious?

Answer 13

• mostly yes

* some are conscious: nausea, hunger, pain

Question 14

What is the path of the sensory afferents of the ANS?

Answer 14

• run within spinal nerves/ splanchnic nerves that carry ANS efferents
• in the spinal cord, run with somatosensory ascending tracts and anterolateral tracts

Question 15

Where does afferent sensory ANS information go?

Answer 15

• thalamus
• reticular formation
• hypotalamus
• insular cortex
• solitary nucleus of brainstem
• limbic system
• sensory cortex

Question 16

Describe the CNS integration and motor output?

Answer 16

• hypothalamus -> controls autonomic sympathetic and parasympathetic motor output
• inputs from: brainstem, limbic, cortex
• direct relay to GVE nuclei in brainstem - parasympathetic motor outflow along CN III, VII, IX, X
• direct descending pathways: hypothalamospinal to lateral gray horn (IML nucleus)

Question 17

Describe the sympathetic motor division of the ANS?

Answer 17

Thoracolumbar system
• preganglionic cell bodies in LATERAL GREY HORN of 12 thoracic and upper 2-3 lumbar segments
• 2 groups f ganglia:
-sympathetic trunk ganglia
-prevertebral ganglia

Question 18

What do the prevertebral ganglia do?

Answer 18

innervate organs below diaphragm

Question 19

Describe preganglionic neurons

Answer 19

• myelinated B-fibres
• accompany ventral roots
• form white rami communicantes
• synapse on sympathetic chain as SAME level or BELOW
• may pass through sympathetic chain to prevertebral ganglia via splanchnic autonomic nerves

Question 20

Describe postganglionic neurons

Answer 20

• unmyelinated C fibres
• from grey rami communicantes
• course within all spinal nerves
• sympathetic motor efferents (GVE) from
-T1-3: head and neck
-T3-6: upper limbs
-T7-11: abdominal viscera
-T12-L2: lower limbs, pelvic, perineal organs

Question 21

List the cervical ganglia

Answer 21

• Superior cervical ganglion
• Middle cervical ganglion
• Inferior cervical ganglion

Question 22

Describe the Superior cervical ganglion

Answer 22

Give rise to:
• gray rami communicante -> enter cervical spinal nerves C1-4 (head and neck)
• plexus around internal carotid artery (serve head and neck) -> pupil dilation, lid elevation, secretion viscosity

Question 23

Describe the Middle cervical ganglion

Answer 23

Run to:
• cervical spinal nerves C5 and 6 via gray rami communicantes (upper limb)
• heart

Question 24

Describe the Inferior cervical ganglion

Answer 24

Branches run to:
• spinal nerves C7-T1 via gray rami communicantes (upper limb)
• a plexus around the vertebral artery
• the heart

Question 25

Describe the parasympathetic motor division of the ANS

Answer 25

* GVEs of brainstem nuclei for CNIII, IX and X * Sacral nerve cell bodies found in intermediate gray matter of S2-4 * postganglionics are very short

Question 26

List the parasympathetic ganglion (and include what each does)

Answer 26

* Ciliary -> eye * Pterygopalatine & Submandibular -> sublingual and submandibular glands * Otic -> heart

Question 27

List the adrenergic receptors

Answer 27

* a1 * a2 * B1 * B2 * B3

Question 28

Compare a1 vs a2 adrenergic receptor

Answer 28

``` a1: • excitatory • vasoconstriction • pupil dilation • sweating • closure of sphincters ``` ``` a2: • inhibitory • less insuline secretion • less digestive enzyme secretion • more coagulation ```

Question 29

Compare B1, B2, vs B3 adrenergic receptors

Answer 29

B1: excitatory • + HR, SV • renin, ADH secretion • lipolysis ``` B2: inhibitory • broncho- and vaso-dilation • glycogenolysis • calorigenesis • detrusor, intestinal relaxation ``` B3: thermogenesis in brown fat stores

Question 30

What is the parasympathetic nervous system responsible for?

Answer 30

Rest and digest: • (+) digestive function (CNVII, IX, X): (+) salivary gland secretion, (+) motility, relax sphincters, (+) secretions, contract gallbladder • micturition (S2-4): contract bladder, relax internal sphincter • (-) body functions of physical activity: (-) HR, SV (CNIX, X) • pupil constriction and accommodation for near vision (CNIII)

Question 31

Does the parasympathetic have effect on blood vessels?

Answer 31

NO except for dilatory effects achieved by smooth muscle relaxation of specific blood vessels: • coronaries • face (blushing) • corpora cavernosum of corpus spongiosum of penis, bulb of vestibule and clitoris (arousal)

Question 32

Where do the splanchnic nerves come from (what spinal level)?

Answer 32

* greater T5-9 * lesser 10-11 * least T12

Question 33

List the sympathetic ganglions

Answer 33

* Sueprior, middle, inferior cervical * Celiac * Aortico-renal * Superior mesenteric * Renal ganglion * Inferior mesenteric

Question 34

What does the celiac ganglion innervate?

Answer 34

* liver, gallbladder, bile ducts * stomach, spleen , pancreas * adrenal glands * superior mesenteric ganglion -> small intestine

Question 35

What does the portico-renal ganglion innervate?

Answer 35

* Kidney | * ureter

Question 36

What foes the inferior mesenteric ganglion innervate?

Answer 36

* descending colon * rectum * urinary bladder * external genitals * uretus

Question 37

Compare the sympathetic to parasympathetic system, based on where they come from

Answer 37

Sympathetic • thoracolumbar system • nerves exit from 12 thoracic vert. and L1-3 vert. Parasympathetic • cranio-sacral

Question 38

What are the parasympathetic cranial nerves?

Answer 38

Parasympathetic cranial nerves: vagus, glosso, vagus, facial