Autonomic nervous system Flashcards
What is the sensory input of the ANS?
- mostly interoreceptors
- some somatic senses
- some special senses
• GVA, SVA, Cranial/spinal nerves
What is the control of motor output of the ANS?
- involuntary from hypothalamus limbic system, brain stem, spinal cord
- limited from cerebral cortex
What is the LMN pathway of the ANS?
2-neuron pathway:
• preganglionic neuron (from CNS)
-> postganglionic neuron (autonomic ganglion)
-> visceral effector
What are the neurotransmitters and hormones of the ANS?
- ACh -acetylcholine
- NE- norepinephrine
- epinephrine
What are the effectors of the ANS?
- smooth muscle
- cardiac muscle
- glands
What are the types of responses from the ANS?
- contraction/relaxation of smooth muscle
- increased/decreased rate and force of contraction of cardiac muscle
- increase/decrease gland secretion
Describe the myelination of neurons along the ANS?
- preganglionic neurons are myelinated
* postganglionic neurons are not
List the receptors of the ANS?
- Nicotinic
- Muscurinic
- Visceral (baro, stretch, chemo, osmotic & glucose, visceral pain, thermal)
Compare nicotinic vs muscurinic receptors
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)
Baroreceptor
- in carotid sinus and large arteries -signal change in pressure
- in atria -signal change in blood volume
Stretch receptors
- lung inflation / deflation
* signal distension in hollow organs (bladder, gut)
Chemoreceptors
- O2 receptors in carotid body and aortic arch
* central chemo signal pH and PCO2
Are sensory afferents of the ANS all subconscious?
- mostly yes
* some are conscious: nausea, hunger, pain
What is the path of the sensory afferents of the ANS?
- run within spinal nerves/ splanchnic nerves that carry ANS efferents
- in the spinal cord, run with somatosensory ascending tracts and anterolateral tracts
Where does afferent sensory ANS information go?
- thalamus
- reticular formation
- hypotalamus
- insular cortex
- solitary nucleus of brainstem
- limbic system
- sensory cortex
Describe the CNS integration and motor output?
- 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)
Describe the sympathetic motor division of the ANS?
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
What do the prevertebral ganglia do?
innervate organs below diaphragm
Describe preganglionic neurons
- 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
Describe postganglionic neurons
• 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
List the cervical ganglia
- Superior cervical ganglion
- Middle cervical ganglion
- Inferior cervical ganglion
Describe the Superior cervical ganglion
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
Describe the Middle cervical ganglion
Run to:
• cervical spinal nerves C5 and 6 via gray rami communicantes (upper limb)
• heart
Describe the Inferior cervical ganglion
Branches run to:
• spinal nerves C7-T1 via gray rami communicantes (upper limb)
• a plexus around the vertebral artery
• the heart
Describe the parasympathetic motor division of the ANS
- 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
List the parasympathetic ganglion (and include what each does)
- Ciliary -> eye
- Pterygopalatine & Submandibular -> sublingual and submandibular glands
- Otic -> heart
List the adrenergic receptors
- a1
- a2
- B1
- B2
- B3
Compare a1 vs a2 adrenergic receptor
a1: • excitatory • vasoconstriction • pupil dilation • sweating • closure of sphincters
a2: • inhibitory • less insuline secretion • less digestive enzyme secretion • more coagulation
Compare B1, B2, vs B3 adrenergic receptors
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
What is the parasympathetic nervous system responsible for?
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)
Does the parasympathetic have effect on blood vessels?
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)
Where do the splanchnic nerves come from (what spinal level)?
- greater T5-9
- lesser 10-11
- least T12
List the sympathetic ganglions
- Sueprior, middle, inferior cervical
- Celiac
- Aortico-renal
- Superior mesenteric
- Renal ganglion
- Inferior mesenteric
What does the celiac ganglion innervate?
- liver, gallbladder, bile ducts
- stomach, spleen , pancreas
- adrenal glands
- superior mesenteric ganglion -> small intestine
What does the portico-renal ganglion innervate?
- Kidney
* ureter
What foes the inferior mesenteric ganglion innervate?
- descending colon
- rectum
- urinary bladder
- external genitals
- uretus
Compare the sympathetic to parasympathetic system, based on where they come from
Sympathetic
• thoracolumbar system
• nerves exit from 12 thoracic vert. and L1-3 vert.
Parasympathetic
• cranio-sacral
What are the parasympathetic cranial nerves?
Parasympathetic cranial nerves: vagus, glosso, vagus, facial
