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BIOL1191 > Chapter 15 - Autonomic Nervous System > Flashcards

Chapter 15 - Autonomic Nervous System Flashcards

1
Q

3 Parts Involved w/ ANS Reflex Arcs

A
  1. Autonomic unipolar sensory neurons associated w/ interoceptors
  2. CNS integrating center
  3. Two autonomic motor neurons (Pre- and post-ganglionic neurons)
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2
Q

Somatic Motor Neurons

A

Single motor neuron type in PNS

  • Cell body in CNS
  • Axon -> skeletal muscle
  • Excitatory
  • Conscious control
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3
Q

Autonomic Motor Neurons

A

2 motor neuron types in PNS: Pre-ganglionic & Post-ganglionic

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4
Q

Pre-ganglionic ANS Motor Neuron

A
  • Cell body in CNS
  • Axon -> PNS ganglion
  • Synapses w/ post-ganglionic neuron in gangion (*Adrenal medulla chromaffin cell is an exception)
  • All pre-ganglionic axon terminals release excitatory ACh
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5
Q

Post-ganglionic ANS Motor Neuron

A
  • Cell body in ganglion
  • Axon -> effector (Smooth/cardiac muscle, gland)
  • Unconscious control
  • Excitatory or inhibitory, depending on neuroendocrine state
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6
Q

Neurotransmitters Released by Post-G ANS Motor Neuron

A
  1. Noradrenaline (Most sympathetic)
  2. ACh (Sympathetic cholinergic & all parasympathetic)
  3. Adrenaline & noradrenaline (chromaffin cells)
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7
Q

Sympathetic Division of ANS

A
  • Thoraco-lumbar flow
  • Pre-g nerve cell bodies in lateral horns of spinal cord T1-L2
  • Pre-g nerve cell axons exit spinal cord via anterior root
  • Axons -> sympathetic paravertebral ganglion chain via white ramus communicans
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8
Q

Pre-g fibers vs. Post-g fibers

A
  • Pre-g fibers = white, because of myelination

- Post-g fibers = gray, due to no myelination

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9
Q

4 Possible Pathways for Pre-g Axon (Within Sympathetic Chain Ganglia)

A
  1. Pre-g axon synapses w/ post-g neuron (Version 1)
  2. Pre-g axon synapses w/ post-g neuron (Version 2)
  3. Pre-g axon passes through sympathetic chain ganglion
  4. Pre-g axon passes through sympathetic chain ganglion w/o synapsing
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10
Q

Pre-g axon synapses w/ post-g neuron (Version 1)

A
  • Pre-g axon synapses w/ post-g neuron
  • Post-g neuron axon leaves ganglion via gray ramus communicans going to spinal nerve
  • Post-g fibers -> skin of neck, trunk & limbs via posterior & anterior rami
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11
Q

Pre-g axon synapses w/ post-g neuron (Version 2)

A
  • Pre-g axon synapses w/ post-g neuron
  • Axon leaves ganglion via sympahetic nerve
  • Post-g fibers -> thoracic cavity & above via sympathetic nerves (*Some go through ANS plexuses)
  • From cervical ganglion, sympathetic cephalic periarterial nerve fibers innervate visceral effectors of the head
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12
Q

Pre-g axon passes through sympathetic chain ganglion

A

Pre-g axon passes through sympathetic chain ganglion & forms a splanchic nerve to abdominopelvic organs

  • Pre-g neuron’s axon synapses w/ post-g neuron in collateral ganglion (AKA “pre-vertebral ganglion”)
  • Post-g fibers from collateral ganglia -> abdominopelvic viscera
  • Effects: vasoconstriction, decreased digestive activity
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13
Q

2 Types of Sympathetic Ganglia

A
  1. Sympathetic Trunk Ganglia (“Paravertebral Ganglia”)

2. Collateral Ganglia (“Pre-Vertebral”)

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14
Q

5 Examples of Collateral Ganglia

A
  1. Celiac Ganglion: -> stomach, liver, gallbladder, pancreas & spleen
  2. Superior Mesenteric Ganglion: -> small intestine & prox. large intestine
  3. Inferior Mesenteric Ganglion: -> urinary bladder, sex organs & dist. large intestine
  4. Aorticorenal Ganglion: -> renal arteries & kidneys
  5. Renal Ganglion: -> cortex of kidneys & ureters
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15
Q

Pre-g axon passes through sympathetic chain ganglion w/o synapsing

A

Pre-g axon passes through sympathetic chain ganglion w/o synapsing to post-g neuron; instead, connects directly to adrenal medulla cells (AKA “Splanchic nerve to adrenal medulla”)

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16
Q

Parasympathetic Division of ANS

A
  • Cranio-sacral flow
  • Pre-g motor neuron cell bodies in brainstem/ gray matter of S2-S4
  • Brainstem’s pre-g axons conveyed via cranial nerves 3, 7, 9, or 10
  • S2-S4 pre-g axons conveyed via anterior roots of pelvic splanchic nerves
  • 2 types of parasympathetic ganglia: Intramural (in wall of innervated organ) or terminal (near innervated organ)
  • Vagal outflow -> heart, lungs, stomach, small & large intestine, gallbladder & pancreas
  • S2-S4 out flow -> large intestine, reproductive organs, urteters & urinary bladder
17
Q

4 Examples of Terminal Ganglia

A
  1. CIliary ganglion of cranial nerve 3
  2. Pterygopalatine ganglion of cranial nerve 7
  3. Submandibular ganglion of cranial nerve 7
  4. Otic ganglion of cranial nerve 9
18
Q

2 Types of Neurotransmitters in the ANS

A
  1. Acetylcholine

2. Noradrenaline

19
Q

Acetylcholine

A
  • Released by cholinergic neurons (both sympathetic & parasympathetic pre-g neurons)
  • Released by ALL parasympathetic post-g neurons
  • Released by SOME sympathetic post-g neurons
  • Released at the NMJ
  • Hydrolysed by acetylcholinesterase
20
Q

Nordarenaline

A
  • Most sympathetic post-g neurons are adrenergic
  • Also, hormonal noradrenaline released by the adrenal medullae
  • Noradrenaline action ended by neuronal re-uptake & glial uptake
  • Re-release/intracellular hydrolysis by monoamine oxidase/catechol-O-methyl-transferase
21
Q

4 Types of Receptors in ANS

A
  1. Nicotinic cholinergic
  2. Muscarinic cholinergic
  3. Alpha-adrenergic
  4. Beta-adrenergic
22
Q

Nicotinic Cholinergic Receptors

A
  • Bind ACh
  • Found on ALL sympathetic & parasympathetic post-g neurons
  • Found on chromaffin cells
  • Found in motor endplates at NMJ
  • Neurotransmitter binding always excitatory
23
Q

Muscarinic Cholinergic Receptors

A
  • Bind ACh
  • Found on ALL parasympathetic effectors
  • Found on a few sympathetic effectors
  • Neurotransmitter binding can be excitatory, if Na+ channels opened (e.g., miosis), or inhibitory, if Cl- or K+ channels opened (e.g., relexation of GE sphincter)
24
Q

Alpha-adrenergic Receptors

A
  • Bind adrenaline & noradrenaline
  • Found in SOME sympathetic effectors
  • Can be excitatory/inhibitory
  • 2 receptor subtypes: Alpha1 & Alpha2
25
Q

Beta-adrenergic Receptors

A
  • Bind adrenaline & noradrenaline
  • Noradrenaline is more potent in Alpha than Beta receptors
  • Adrenaline is equally potent in both Alpha and Beta receptors
  • Found in SOME sympathetic effectors
  • Can be excitatory or inhibitory
  • 3 receptor subtypes: Beta1, Beta2 & Beta3
26
Q

2 Alpha Receptor Subtypes

A
  1. Alpha1: Found in dermal & GI blood vessels, excitatory, cause vasoconstriction
  2. Alpha2: Found in GI smooth muscle, inhibitory, decrease muscle tone & peristalsis
27
Q

3 Beta Receptor Subtypes

A
  1. Beta1: Found in heart & skeletal muscle, excitatory
  2. Beta2: Found in bronchiolar smooth muscle, inhibitory
  3. Beta3: Only found in brown fat/adipose tissue, play a role in thermogenesis
    - Mechanism: mitochondrial metabolism uncoupled from ATP synthesis
28
Q

Visceral Autonomic Reflexes (5 Parts)

A
  1. Interoceptor = dendritic end of sensory neuron/ receptor cell/tissue
  2. Sensory neuron
  3. CNS interneurons = integrating center
  4. 2 motor neurons: pre- & post- ganglionic
  5. Visceral effector
29
Q

Parasympathetic Visceral Reflexes (5 Types)

A
  1. Urination & defecation
  2. Light reflexes: illuminate one eye -> miosis in both eyes
  3. Swallowing, coughing
  4. Cardio-inhibitory reflexes
  5. Digestive motor reflexes
30
Q

Control of ANS by Higher Centers

A
  • Hypothalamus regulates autonomic tone (balance between sympathetic & parasympathetic activity)
  • Hypothalamic inputs: cerebral cortex, limbic system
  • Hypothalamic outputs: hypothalamic nuclei
  • Parasympathetic functions carried out by anterior & medial hypothalamic nuclei
  • Sympathetic functions carried out by posterior & lateral hypothalamic nuclei
  • Control is unconscious
31
Q

6 Generalizations About the ANS

A
  1. Both sympathetic & parasympathetic ANS divisions have excitatory or inhibitory effects
  2. MOST organs receive “dual innervation”
  3. Sympathetic division = more widespread & longer-lasting effects than parasympathetic
  4. Sympathetic division: short pre-g fibers & long post-g fibers; Parasympathetic division: long pre-g fibers & short post-g fibers
  5. Sympathetic Division = “Fight/Flight Activities”
  6. Parasympathetic Division = “Rest/Digest Activities”
32
Q

4 Examples of Sympathetic & Parasympathetic Effects (Excitatory & Inhibitory)

A
  1. Sympathetic Excitatory: Increased HR & force
  2. Sympathetic Inhibitory: Bronchodilation
  3. Parasympathetic Excitatory: Contraction of GI smooth muscle
  4. Parasympathetic Inhibitory: Decreased HR & force
33
Q

Dual Innervation

A
  • When organs are innervated by both sympathetic & parasympathetic fibers
  • Each division creates opposite effects on the innervated organs
34
Q

Difference in Degrees of Divergence

A
  • Sympathetic Division: 1 pre-g axon synapses w/ 20+ post-g neurons
  • Parasympathetic Division: 1 pre-g axon synapses w/ 5 post-g neurons
35
Q

“Fight/Flight” Activities

A
  • AKA “Sympathetic Stimulation/Activation”, caused by noradrenaline release at specific locations + adrenaline & noradrenaline secretion into bloodstream
  • Leads to:
  • Increased alertness, energy & euphoria
  • Inhibition of digestion & urine production
  • Pupillary dilaton
  • Cardio-acceleration
  • Increased breathing rate, bronchodilation & skeletal muscle tone
  • Glycogenolysis
  • Lipolysis
36
Q

“Rest/Digest” Activities

A
  • AKA “Vegetative/Housekeeping” functions
  • Leads to:
  • Pupillary constriction (miosis)
  • Digestion
  • Decreased HR, BP & metabolic rate
  • Urination & defecation
  • Bronchoconstriction
37
Q

8 Examples of Parasympathetic & Sympathetic Nerve Plexuses

A
  1. Cardiac Plexus: Innervates heart
  2. Pulmonary Plexus: Innervates airway
  3. Esophageal Plexus: Innervates esophagus
  4. Celiac Plexus: Innervates GI tract, spleen, kidneys & adrenal medulla
  5. Superior Mesenteric Plexus: Innervates small & large intestine
  6. Inferior Mesenteric Plexus: Innervates genitalia, ureters & kidneys
  7. Hyposgastric Plexus: Innervates pelvic visceral organs
  8. Renal Plexus: Innervates kidneys & ureters
38
Q

6 Organs w/ Only Sympathetic Innervation

A
  1. Sweat Glands
  2. Arrector Pili Muscle
  3. Kidney
  4. Spleen
  5. Blood Vessels
  6. Adrenal Medullae

BIOL1191 (13 decks)

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