9. Central autonomic nervous system. Monoaminergic and cholinergic neurones and pathways. „Ascending Reticular Activating System” (ARAS) Flashcards
What is homeostasis?
Homeostasis includes all those self-regulatory processes (e.g. autonomic nervous system, endocrine system and immune system) which maintain a fairly stable internal environment for optimal functioning of living cells, tissues and organs.
Beside the (1) sympathetic and the (2) parasympathetic, which nervous system is also distinguished?
The enteric nervous system
What is the ierarchy of autonomic regulations?
- Brain
- Brainstem
- Spinal cord
How does local autonomic response work?
intramulra neuronal networks receive sensory inputs, process information, make decisions and give adequate responses.
How does spinal autonomic reflex work?
Autonomic centres of the spinal cord process viscerosensory input and modulate smooth muscles and glands of internal organs via the sympathetic and parasympathetic efferents.
Interoceptors also provide viscerosensory information for the spinal cord via ____
the pseudounipolar neurons of DRGs.
Interoceptors also provide ____ for the spinal cord via the pseudounipolar neurons of DRGs.
viscerosensory information
How does brainstem autonomic reflex?
Brainstem neuronal networks receive viscerosensory input via the sensory ganglia of cranial nerves and organize viscerosensory responses.
List 4 autonomic cranial nerve ganglia
ciliary ggl., submandibular and pterygopalatine ganglia, otic ggl
Spinal cord, brainstem and the brain are reciprocally interconnected, so viscerosensory inputs may reach the highest levels of the CNS, which then can contribute to the ____
autonomic response.
How does the visceral input reach the CNS? (in case of spinal nerves)
spinal nerves → DRG → spinal dorsal horn → reticular formation, thalamus
How does the visceral input reach the CNS? (in case of CN 9 - 10)
CN 9-10 → inferior ganglia → solitary nucl. → reticular formation, thalamus
Central processes of DRG neurons terminate in (1)____ (which horn?), where from (2)____ tract arises.
- the spinal dorsal horn
- the spinoreticulothalamic
Spinoreticulothalamic tract is a bilateral pathway with contralateral dominance.
-> Terminates in (1)____ and finally reaches (2)____.
- numerous brainstem areas (reticular formation)
- the thalamus
Intermadiate and caudal portion of nucleus of solitary tract (nucleus tractus solitarii, NTS) might also be mentioned as the ____
lateral nucl. of ala cinerea.
Visceral signals arrive into the nucleus of the solitary tract via (1)___ (2)
NTS, among others, projects into (2)____ (3)
- the inferior ganglia of glossopharyngeus and vagus nerves.
- the reticular formation, hypothalamus and thalamus.
What is reticular formation?
Anatomically not well defined diffuse network of almost 100 (!) interconnected brainstem nuclei.
As phylogenetically one of the oldest parts of the brain regulates fundamental functions
What are the 4 fundamental functions of reticular formation?
- Sleep and consciousness
- Somatic motor control
- Autonomic functions
- Pain modulation
As phylogenetically one of the oldest parts of the brain, reticular formation regulates fundamental functions
-> One of these functions is somatic motor control
-> What does this include?
- Muscle tone
- Balance and posture
- Eye movements
- Central pattern generation of swallowing
- Vomitting
- Breathing
- Coughing
- Sneezing
As phylogenetically one of the oldest parts of the brain, reticular formation regulates fundamental functions
-> One of these functions is autonomic functions
-> What does this include?
Cardiovascular control - heart rate and blood pressure
Along the mediolateral axis reticular formation is composed of three columns of nuclei which are __
- midline raphe nuclei
- medial gigantocellular nuclei
- lateral parvocellular nuclei.
Don’t memorize every single nuclei!
Along the rostrocaudal axis of reticular formation, what are the 2 subsystems that can be distinguished?
- Ascending Reticular Activating System
- Reticulospinal system
Appearance features and characteristics of ascending reticular activating system
upward projecting connections contribute to the „Ascending Reticular Activating System”
-> being responsible for arousal, regulation of wakefulness and sleep-wake transition.
Appearance features and characteristics of reticulospinal system
descending fibres form the „Reticulospinal System”
-> containing extrapyramidal motor fibres, autonomic efferents, and pain regulating descending pathways.
Which are the 2 main neurotransmitters used by numerous nuclei of reticular formation?
use monoamines and acetylcholine
Which are the 2 main neurotransmitters used by numerous nuclei of reticular formation?
use monoamines and acetylcholine
Midline raphe nuclei is non-serotoninergic
-> T/F
False
-> It is serotoninergic
What are the 2 typical neurotransmitters of the lateral parvocellular nuclei.?
Adrenaline/noradrenaline
What type of nuclei are mainly – but not exclusively – found in the reticular formation of the brainstem? (based on types of neurotransmitters)
Monoaminergic and cholinergic nuclei
Monoaminergic and cholinergic nuclei are mainly – but not exclusively – found in the reticular formation of the brainstem.
Most of them have a diffuse projection to ___, including the cortex and diffuse descending connections toward the spinal cord.
the higher centres of the CNS
Monoaminergic and cholinergic nuclei are mainly – but not exclusively – found in the reticular formation of the brainstem.
Most of them have a diffuse projection to the higher centres of the CNS, including __ (2)
the cortex and diffuse descending connections toward the spinal cord.
Raphe nuclei project to _____ (6)
the cortex, hippocampus, amygdala, striatum, cerebellum and spinal cord.
What are the functions of Serotoninergic raphe nuclei?
- Modulate slow wave sleep and memory consolidation
- Control mood and emotions (depression, OCD - SSRIs)
- Interact with motor systems
- Increas food intake
- Modulate pain sensation.
Fibres arising from locus ceruleus reach ___
the cortex, thalamus, hypothalamus, cerebellum and the spinal cord
Is locus ceruleus an adrenergic or noradrenergic nucleus?
It is a nonadrenergic nucleus
Give 2 important examples of domainergic nuclei
A9 - substantia nigra
A10 - ventral tegmental area
This is the complete list of the dopaminergic nuclei of the CNS, but only ____ (which area?) is considered as a nucleus of the reticular formation.
the ventral tegmental area
What are the „four major dopaminergic systems”?
- Nigrostriatal dopamine pathway
- Mesolimbic dopamine pathway
- Mesocortical dopamine pathway
- Tuberoinfundibular pathway
the „four major dopaminergic systems”
-> Ventral tegmental area gives rise to 2 pathways which are __
the mesolimbic and mesocortical dopaminergic pathways
The „four major dopaminergic systems”
-> Mesolimbic pathway (reward-reinforcement, desire, pleasure) terminates in _____
the ventral striatum including the nucleus accumbens
The „four major dopaminergic systems”
-> Mesocortical fibres (motivation, emotion, executive functions) reach ____
The prefrontal cortex
Which histaminergic nucleus contains the most relevant group of histaminergic neurons?
tuberomamillary nucleus
Which histaminergic nucleus contains the most relevant group of histaminergic neurons?
tuberomamillary nucleus
Cholinergic nuclei contribute to which subsystem of the reticular formation? How?
Cholinergic nuclei contribute to the asceding reticular activating system by projecting from the RF to the thalamus
What are the cholinergic nuclei?
Cranial and spinal somatomotor nuclei and
preganglionic visceromotor nuclei
Cholinergic nuclei contribute to the asceding reticular activating system by projecting from the RF to the thalamus.
-> Furthermore, all the motoneurons use ____ as neurotransmitter (in the somatomotor and visceromotor cranial nerve nuclei and in the lateral and ventral horns of the spinal cord).
acetyl-choline
Describe Ascending Reticular Activating System
Brainstem reticular formation maintains connections with some forebrain structures, including the thalamus, cortex and hypothalamus.
Ascending Reticular Activating System
-> Besides visceral signals, which signals also reach the reticular formation?
auditory and visual signals
The role of Ascending Reticular Activating System
setting the optimal activity of cortical neuronal networks to process incoming data.
Cholinergic nuclei of the brainstem terminate in ___ and ____
the thalamus and facilitate thalamocortical transmission
What is the role of the monoaminergic projection?
facilitates processing of input from the thalamus.
Which nuclei are considered as monoaminergic projection?
- locus coeruleus – NA
- tuberomamyllary nucleus
- His, ventral tegmental area
- D, raphe nuclei – 5HT
Paraventricular nucleus (PVN) has 3 major sets of neurons
-> The role of **Magnocellular neurosecretory neurons **
They produce vasopressin and oxytocin which are then released from neurohypophysis.
Paraventricular nucleus (PVN) has 3 major sets of neurons
-> The role of Parvocellular neurosecretory neurons
They are related to the CRF-ACTH-cortisol axis (stress response).
Paraventricular nucleus (PVN) has 3 major sets of neurons
-> The role of Centrally projecting neurons
Centrally projecting neurons, among others, to the spinal sympathatic and parasympathetic IML nuclei.
