The Autonomic System Flashcards
Efferent
Going to organs of the body (exiting the CNS)
Afferent
Going from organs to brain (going at the CNS)
Peripheral Nervous System
- breaks into sensory and motor
- sensory: somatic (touch), special (vision/smell), and visceral sensory (in our organs)
- motor: somatic and visceral motor
PNS - Motor - Visceral aka Autonomic
- sympathetic (fight or flight)
- parasympathetic (rest and digest)
Somatic Motor
- target/effectors: skeletal muscles
- voluntary
- examples: moving your biceps brachii muscle
- # of neurons in pathway: 1
- properties: myelinated
- neurotransmitter: acetylcholine
- ganglia: no
Visceral motor
- target/effectors: smooth and cardiac muscles, glands
- involuntary
- example: changing heart rate, peristalsis
- # of neurons in pathway: 2 preganglionic and postganglionic
- properties: preganglionic (myelinated) and postganglionic (unmyelinated)
- neurotransmitter: preganglionic (acetylcholine) and postganglionic: (Ach or norepinephrine)
- ganglia: yes
Sympathetic
- fight, flight, fright
- activates
- visceral motor axons of the sympathetic act to:
- increase: heart rate (blood flow to muscles), respiration (oxygenate), perspiration (sweat glands activate in order to release watery sweat and engage cooling
- decrease: digestion (want to conserve energy)
- dilate pupils: allow more light to come in and it increases our visual acuity
- causes widespread, long-lasting mobilization of the flight or flight response
Parasympathetic
- visceral motor axons of the parasympathetic division act to:
- increase: blood flow to GI system (digest), activity of salivary glands
- decrease: heart rate, and respiration (calm down)
- pupils constrict
- highly localized and shorter lived
- inhibits
2-neuron pathway: parasympathetic
- Central NS brain stem or sacral spinal cord “craniosacral”
- long preganglionic axon - Peripheral NS: intramural ganglia w/in organ (will synapse at second cell)
- short postganglionic axon - Target: gut tube and digestive glands
Parasympathetic innervation via oculomotor
- preganglionic cell body in brain stem
- long preganglionic axon = oculomotor nerve - Synapse in ciliary ganglion
- short postganglionic axon - Postganglionic nerve innervate sphincter papillae to constrict pupil
Parasympathetic innervation via facial nerve — pterygopalatine ganglion
- Preganglionic cell body in brain stem
- long preganglionic axon = facial nerve - Synapse in pterygopalatine ganglion
- short postganglionic axon - Postganglionic axon project to lacrimal gland, small glands of nasal cavity
- results: lacrimal gland = crying/tears
> Nasal glands = sniffles/mucus
Parasympathetic innervation via facial nerve — submandibular ganglion
- Preganglionic cell body in brain stem
- long preganglionic axon = facial nerve - Synapse in submandibular ganglion
- short postganglionic axon - Postganglionic axons project to submandibular and sublingual glands
- results: salivation/drooling
Parasympathetic innervation via glossopharyngeal nerve
- Preganglionic cell body in brain stem
- long preganglionic axon = glossopharyngeal nerve - Synapse in otic ganglion
- short postganglionic axon - Postganglionic axons project to parotid salivary gland
- result: salivation/drooling
Parasympathetic innervation via vagus nerve
- Preganglionic cell body in brainstem
- long preganglionic axon = vagus nerve (forms plexuses)
- all plexuses will synapse to wall of organs - Synapse in intramural ganglia
- short postganglionic axon - Postganglionic axons project to various target organs of thorax, abdomen, and pelvis (innervates testes and ovaries)
- results: decrease in heart rate, constriction of airways, increased activity of GI organs
Parasympathetic innervation via pelvic splanchnic nerves
- Preganglionic cell body in s2-4 spinal cord segments
- long preganglionic axon = pelvic splanchnic nerves - Synapse in intramural ganglia
- short postganglionic axon - Postganglionic axons project to urinary bladder and reproductive organs
- result: contraction of bladder, erection of clitoris and penis
2-neuron pathway: sympathetic
- Central NS T1-L2 Spinal Cord
- short preganglionic axon - Synapse at PNS
> sympathetic chain ganglion: long string of ganglia
> pre-aortic ganglion: arranged in front of the abdominal aorta
- long postganglionic axon - Target blood vessels (shoot more blood out); sweat glands (cool body down)
Sympathetic chain ganglion pathway
- 1st/central NS neuron: T1-L2 Spinal Cord
- sympathetic chain ganglion
- target: blood vessels of head and neck, heart and lungs, limbs and trunk, sweat glands
Pre-aortic (prevertebral) ganglion pathway
- 1st /central NS neuron: T1-L2 Spinal cord
- pre-aortic (prevertebral) ganglion
- target: blood vessels of GI system, smooth muscle of GI system, adrenal, renal, pelvis and perineum
Synapse at Same Level
- 1st neuron in T1-L2 spinal cord
- Short preganglionic axon travels through white ramus communicans
- 2nd neuron in sympathetic chain ganglion
- Postganglionic axon travels through gray ramus communicans to enter spinal nerve
Ascend or Descend, then synapse
- 1st neuron in T1-L2 spinal cord
- Short preganglionic axon travels through white ramus communicans then ascends (or descends) sympathetic chain
- 2nd neuron in sympathetic chain ganglion
- Postganglionic axon travels through gray ramus communicans to enter spinal nerve
Sympathetic innervation in the head
- 1st neuron in T1-L2 spinal cord
- Preganglionic axon travels through white ramus communicans then ascends sympathetic chain
- 2nd neuron in superior cervical ganglion (every sympathetic axon going to the head is going to synapse there)
- Postganglionic axon travels on carotid arteries to reach head; distributed to target organs via arterial branches
leave chain without synapsing
- 1st neuron in T1-L2 spinal cord
- preganglionic axon travels through white ramus communicans then leaves sympathetic chain through a splanchnic nerve - Neuron in preaortic ganglion (prevertebral)
- Postganglionic axon follows blood vessels
Sympathetic prevertebral ganglia: celiac ganglion
- Preganglionic axons from T5-T9 exit sympathetic chain w/o synapsing
- Greater splanchnic nerve synapses at celiac ganglion
- Long perivascular plexus that targets stomach, spleen, liver, gallbladder, part of small intestine
- result: decreased action of GI organs
Sympathetic prevertebral ganglia: superior mesenteric ganglion
- Preganglionic axons from T10-T11 exit sympathetic chain w/o synapsing
- Lesser and least splanchnic nerves synapse at superior mesenteric ganglia
- Long perivascular plexus targets small intestines, part of large intestine
- results: decreased GI activity
Sympathetic prevertebral ganglia: inferior mesenteric ganglion
- Preganglionic axons from L1-L2 exit sympathetic chain without synapsing
- Lumbar splanchnic nerve synapses at inferior mesenteric ganglia
- Long perivascular plexus targets distal colon, rectum, bladder, reproductive organs
- results: decreased GI activity
Locate cranial nerves on brain