Transcript AUTONOMIC REFLEX - Semmelweis University
AUTONOMIC REFLEX ARC
,
SPINAL PATHWAYS
Dr Gallatz Katalin
Divisions of the autonomic nervous system (ANS) sympathetic parasympathetic Autonomic nervous system regulates activity smooth and cardiac muscle and certain glands and adrenal medulla Autonomic reflex arc is responsible for important fuctions such as gut peristalsis, sweating, defecation, micturation (emptying the bladder), ejaculation etc.
Sympathetic nervous system Central neurons can be found in the lateral horn (intermediolateral cell column)
PREGANGLIONIC NEURONS
Cross-sectional anatomy of the spinal cord
Autonomic or Visceral Reflexes Components of that reflex arc :
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afferent part : -sensory receptor -sensory neuron (spinal ganglion)
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integrating center
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efferent part - preganglionic neuron and fiber
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postganglionic neuron pre or paravertebral ganglion and fiber
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visceral effector
-to the skin sudomotor, vasomotor, pilomotor 3. r. communicans albus 5. r. communicans griseus
szimpatikus
– paravertebralis ggl.
IML Th-L
From Dr. Kozsurek
IML Th-L
3. r. communicans albus 5. r. communicans griseus
sympathetic
– prevertebral ggl.
From Dr. Kozsurek
Preganglionic neuron
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cell body in the intermediolateral cell column of spinal cord, - axon is myelinated type B fiber – preganglionic fiber – that passes to the autonomic ganglion Postganglionic neuron (vegetativ ganglion)
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cell body lies outside the CNS in an autonomic ganglion
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axon is unmyelinated type C fiber – postganglionic fiber that terminates in a visceral effector
The preganglionic axon 1. may synapse on the postganglionic cells in the paravertebral ganglion at segmental level 2. may enter the synaptic chain and travel rostrally and caudally to a paravertebral ganglion 3. some preganglionic axon pass through the sympathetic trunk and form the splanchnic nerves, these fibers travel to a prevertebral gaglion 4. some preganglionic axons in the splanchnic nerve innervate chromaffin cells of the adrenal medulla directly
Locations of autonomic ganglia
• Sympathetic ganglia paravertebral ganglia laterally to the vertebral column
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prevertebral ganglia near to the branches of the abdominal aorta celiac ganglion superior mesenteric inferior mesenteric aorticorenal ganglion • Parasympathetic ganglia
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intramural ganglia, in wall of organ ( n. X.) or ganglia of cranial nerves III., V.,VII., IX.
-to the skin sudomotor, vasomotor, pilomotor 3. r. communicans albus 5. r. communicans griseus
szimpatikus
– paravertebralis ggl.
IML Th-L
From Dr. Kozsurek
Neurotransmitters in the sympathetic neurons
Neurotransmitters in the parasympathetic neurons
Spinal pathways
Descending (Motor) Tracts
• Two groups of tracts:
– direct (pyramidal) tracts – indirect (extrapyramidal) tracts
• Two neurons in pathway
– upper motor neurons – lower motor neurons
Descending (Motor) Tracts
• upper motor neurons originate in gray matter of cerebral cortex or other gray matter • lower motor neurons exit via ventral root impulses to effectors and carry
Descending Motor Tracts Extrapyramidal Tracts
• • • •
Tectospinal tract
(tectum of midbrain) – reflex turning of head in response to sights and sounds
Reticulospinal tract
(reticular formation) – controls limb movements important to maintain posture and balance
Vestibulospinal tract
(vestibular nuclei) – postural muscle activity in response to vestibular signals
Rubrospinal tracts
– originate in ‘red nucleus’ of midbrain; control flexor muscles • •
(Olivospinal tract –human?) MLF medial longitudinal fascicle
– Coordinates the eye and head movements in response vestibular signals
Descending Motor Tracts
Corticospinal Tract
• Precise, coordinated limb movements • Two neuron pathway – upper motor neuron in cerebral cortex – lower motor neuron in spinal cord • Decussation in medulla and in the spinal cord
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Ascending pathways Dorsal colunm ascending tracts • Deep touch, visceral pain, vibration, and proprioception • •
Gracile fascicle
(Goll)
and cuneate fascicle
(Burdach) • carry signals from arm and leg •
Decussation
and 2nd order neuron
in medulla
• 3rd order neuron in thalamus carries signal to cerebral cortex
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EPICRITIC ÉS PROPRIOCEPTIV Gracile fascicle (Goll) Cuneate fascicle (Burdach) Dorsal (Flechsig) and ventral spinocerbellar (Gowers)tract From Dr. Kozsurek
Spinocerebellar Pathways
• Proprioceptive signals from limbs and trunk travel up to the cerebellum Dorsal spinocerebellar tract (Flechsig) - uncrossed Ventral spinocerbellar (Gowers) tract - crossed
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Spinothalamic Pathway
• Pain, pressure, temperature, light touch, •
Decussation
of the second order neuron occurs in
spinal cord
• Third order neurons arise in thalamus and continue to cerebral cortex
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Ascending tracts - SENSORY PATHWAYS Spinothalamic tract – PROTOPATHIC sensibility From Dr. Kozsurek
Spinoreticular Tract
• Pain signals from tissue injury •
Decussate in spinal cord and ascend with spinothalamic fibers
• End in reticular formation (medulla and pons) • 3 rd and 4 th order neurons continue to thalamus and cerebral cortex
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CU – cuneate fascicle (Burdach), GR – gracile fascicle (Goll
) CU GR
Spinothalamic tract Flechsig: tractus spinocerebellaris dorsalis Gowers: tractus spinocerebellaris ventralis Dr. Kozsurek Márk anyagából