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:
- afferent part:
-sensory receptor
-sensory neuron
(spinal ganglion)
- integrating center
- efferent part
- preganglionic neuron and fiber
- postganglionic neuron
pre or paravertebral ganglion and fiber
- visceral effector
Th-L
IML
-to the skin
sudomotor, vasomotor,
pilomotor
3. r. communicans albus
5. r. communicans griseus
szimpatikus – paravertebralis ggl.
From Dr. Kozsurek
Th-L
IML
3. r. communicans albus
5. r. communicans griseus
sympathetic – prevertebral ggl.
From Dr. Kozsurek
Preganglionic neuron
- 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)
- cell body lies outside the CNS in an autonomic ganglion
- 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
- prevertebral ganglia near to the branches of the
abdominal aorta
celiac ganglion
superior mesenteric
inferior mesenteric
aorticorenal ganglion
• Parasympathetic ganglia
- intramural ganglia, in wall of organ ( n. X.) or ganglia of
cranial nerves III., V.,VII., IX.
Th-L
IML
-to the skin
sudomotor, vasomotor,
pilomotor
3. r. communicans albus
5. r. communicans griseus
szimpatikus – paravertebralis ggl.
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 and carry
impulses to effectors
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
13-19
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
13-20
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
13-22
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
13-23
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)
• 3rd and 4th order neurons continue to thalamus and
cerebral cortex
13-25
CU – cuneate fascicle (Burdach), GR – gracile fascicle (Goll)
CU
GR
Gowers
Spinothalamic tract
Flechsig: tractus spinocerebellaris dorsalis
Gowers: tractus spinocerebellaris ventralis
Dr. Kozsurek Márk anyagából
Thank you for your attention!