More Brainstem Flashcards
Sympathetic system
Increases heart rate
Parasympathetic system
Vagus nerve - cranial nerve
Decreases heart rate
Sympathetic output
Thoracic and Lumbar regions of spinal cord
Parasympathetic output
Come from brainstem cranial nerves
Output that controls visceral organs is mostly vagus nerve
Preganglionic neurons leave spinal cord how?
Leave through ventral roots
Autonomic outputs from central nervous system to the target organs there are how many neurons in the outputs?
2 neurons
1st neuron
Preganglionic neuron
Preganglionic neurons
Autonomic neurons that leave the CNS and go out to the periphery to make synapses with the 2nd neuron in the pathway which is the post ganglionic neuron and that goes out to the target (e.g heart)
Sympathetic preganglionic neurons release what neurotransmitter?
Acetylcholine
What does acetylcholine activate on postganglionic neurons?
Acetylcholine activates nicotinic acetylcholine receptors on postganglionic neurons
What do post ganglionic neurons release after nicotinic acetylcholine receptors are activated?
Norepinephrine
What does norepinephrine activate?
alpha - a and beta - B adrenergic receptors on the target organs (e.g heart)
Where do axons of parasympathetic preganglionic neurons emerge from?
From the brainstem and the sacral spinal cord
How far to parasympathetic preganglionic neurons extend? What extends the remaining distance?
ALMOST all the way to their peripheral target (e.g heart)
Parasympathetic POSTganglionic neurons extend the remaining short distance
Reticular formation
Central core of gray matter(cell bodies, dendrites and synapses) in the brainstem
It is there all the way through the brainstem
Why is it called the reticular formation?
Because it didnt look organized but now we know it is organized
Integrative functions of brainstem in which the reticular formation is involved
Stereotyped motor responses
Autonomic functions
Ascending arousal (reticular activating system)
Behaviour levels lowest to highest
Lowest - Spinal cord: Protective reflexes, locomotion (walking)
Middle - Brainstem: Stereotyped behaviors (e,g facial expressions and defensive behavior)
Highest - Cerebral Cortex (Complex, Voluntary behavior)
Periaqueductal grey in the brainstem does what
Coordinates behavioral responses
E.g a cat will have its pupils dilate, hair stands on end, arches back and starts hissing
Periaqueductal grey and pain signals coming up from the spinal cord?
Suppresses pain signals coming up from the spinal cord.
Makes humans not feel pain but also makes them really anxious
Reticular formation
Central core of gray matter
What happens to grey matter as we get more rostral in the brainstem?
Grey matter gets more distorted
Ascending Arousal System
Need input from where to remain conscious?
Brainstem
EEG
Electrodes on surface of skull to record electrical activity in the brain
Records average behavior of all neurons in the electrodes area
EEG oscillations in sleep
Characteristic, rhythmic oscillations and amplitude becomes very large
Why is amplitude so large?
Rhythmic bursts
All neurons fire at the same time
Ventral pathway of arousal system
Axons go all the way up to cerebral cortex and all around
Dorsal pathway
Goes from brainstem up to thalamus and neurons in thalamus project all over cerebral cortex
Where do norepinephrine neurons originate
Locus Coeruleus
Where is the Locus coeruleus?
Pons
Neuromodulators activated G coupled protein receptors - metabotropic
Causes long lasting global changes
Norepinephrine neurons fire most when?
Awake
Firing is low in…
Slow wave sleep
There is no firing in…
REM
NE neuron firing correlates with attention level. TRUE or FALSE?
TRUE
When attention needs to be redirected such as when there is a novel event what happens?
Burst of action potentials in NE neurons
3 states of NE neurons correlating to attention:
1) Inattentive, non-alert
2) Focused Attention
3) Scanning
Scanning
NE neurons firing like crazy
Where does dopamine originate?
Substantia nigra
AND
Ventral tegmental area(VTA)
Dopamine function
Learning
Pleasure
Where does acetylcholine originate?
Basal forebrain
Where do acetylcholine neurons project to?
Cerebral cortex, hippocampus and amygdala
Histamine
Wakes you up
Where does serotonin originate?
Brainstem raphe nuclei
