Neurophysiology 3: Autonomic Nervous System, Control of Movements, Cerebral Metabolism Flashcards
What are the 2 types of neurons?
preganglionic and postganglionic
Where do preganglionic neurons originate from?
CNS
Where do postganglionic neurons originate from?
ganglia
What kind of nervous system is self-governing? It does not require a will a controls processes like digestion and body temperature homeostasis.
autonomic nervous system
What chain of neurons are very close to the spinal cord?
sympathetic chain of ganglia
What level in does the spine does the sympathetic preganglionic neurons originate from?
T1-L2
The sympathetic ganglia innervates one target organ only. True or False?
False. One sympathetic ganglia can innervate several target organs.
What ganglion innervates majority of the abdominal and visceral organs?
Celiac Ganglion
What ganglion innervates the heart?
Stellate Ganglion
Where does the parasympathetic preganglionic neurons originate from?
- Nuclei of Cranial Nerves: 3, 7, 9, 10
- S2-S4
*at brain stem
Where are parasympathetic ganglia found?
at close apposition w/ target organ
How many target organs can a parasympathetic ganglia innervate?
One
What are the 3 configurations (directions) of a preganglionic sympathetic neuron?
- direct synapse
- pass upwards/downwards the chain
- can totally skip ganglions to innervate another
Where are the preganglionic neurons located in the spinal cord?
intermediolateral cell column (grey matter of spinal cord)
Does the parasympathetic nervous system have a long or short preganglionic fiber?
long. Because it needs to get to the target organ.
What are the two main neurotransmitters used by the Peripheral ANS?
acetylcholine & norepinephrine
Does the sympathetic nervous system have a long or short preganglionic fiber?
short. ganglion is nearer to CNS, and so fibers are shorter
What neurotransmitter does the preganglionic neurons in the sympathetic and parasympathetic use?
acetylcholine
All preganglionic neurons are cholinergic. True or False?
True. This includes the sympathetic and parasympathetic nervous system
What does cholinergic mean?
uses acetylcholine
All postganglionic neurons in the sympathetic nervous system use acetylcholine. True or False?
False. Most sympathetic postganglionic neurons are adrenergic.
All postganglionic neurons in the parasympathetic nervous system use acetylcholine for transmission. True or False?
True. Parasympathetic postganglionic neurons are cholinergic.
What are the exceptions in the sympathetic nervous system that does not use adrenaline as a transmitter?
sweat glands, smooth muscles, and some blood vessels
When a vesicle engulfs acetylcholine, is it already a complete compound?
Yes.
What are the ingredients for acetylcholine?
Acetyl-CoA (acetate component) + Choline
Describe the synthesis of norepinephrine.
- Start = Tyrosine –> Dopa (via hydroxylation)
- Dopa –> Dopamine (via decarboxylation)
*dopamine is engulfed by vesicle from here. - Dopamine –> Norepinephrine (via hydroxylation)
- Norepinephrine –> Epinephrine (methylation)
*some are converted to epinephrine
Norepinephrine has at least how many receptor subtypes? name them.
Five (5) Subtypes:
1. Alpha 1
2. Alpha 2
3. Beta 1
4. Beta 2
5. Beta 3
Acetylcholine has at least how many receptor subtypes?
Two (2) Main Subtypes:
1. Nicotinic
2. Muscarinic (M1, M2, M3)
Cell receptors exert their action via ion channels. True or False?
False. Some can do this via G protein. Receptors attached to a G protein enact target organ effect.
i.e. When specific Gi (inhibitory) protein is activated, target organ will also become inhibited.
What part of the body is rich in Alpha 1 receptors?
arteries
What does a Gq protein do?
stimulatory/activation
Alpha 1 + Gq protein at the arteries. What will happen?
it will constrict the arteries
What organ is rich in Beta 1?
heart
What receptor is rich in the heart?
Beta 1
B1 + Gs = ?
increased heart rate
B2 is rich in which organ?
lungs
What G proteins are the lungs attached to?
GS and GI
What characteristics are present in the medication of patients with asthma?
Beta 2 agonist (activates B2)
B3 receptors are mostly found where?
fats
Odd numbered Muscarinic receptors are attached to what kind of G proteins?
GQ (stimulatory)
Even numbered Muscarinic receptors (M2) are attached to what kind of G protein?
Gi (inhibitory)
Muscarinic receptors receive what neurotransmitters?
acetylcholine
Norepinephrine attaches to what kind of receptors?
A1, A2, B1, B2, B3
What receptors are rich in the heart?
B1 & M2
When you want to keep your pee in, what neurotransmitter is used?
adrenergic (sympathetic)
When you pee, what state are you in?
parasympathetic (cholinergic)
The sinoatrial node of the heart is rich in what type of autonomic receptor?
B1
Reflexes occur in 2 arcs? What are they?
sensory arc & effector (efferent) arc
What autonomic reflex regulates blood pressure?
Baroreceptor Reflex
What is the sensory part of the baroreceptor reflex?
carotid sinus and nodose ganglion.
Nodose ganglion receives information from carotid sinus.
Describe the mechanism/pathway that occurs when someone gets high blood pressure.
- carotid sinus (detect)
- nodose ganglia (neuron)
- activate NTS (receive info)
- CVLM (inhibitory. When activated, it will inhibit RVLM)
- RVLM (stimulatory) –> because it is inhibited, it won’t be able to send stimulatory signals to preganglionic sympathetic neurons. And so, the heart and blood vessels will relax. Causing lower blood pressure.
What happens during low blood pressure?
- carotid sinus (detect)
- nodose ganglion (transmit info)
- NTS cannot activate.
- CVLM cannot activate (i.e. cannot inhibit RVLM)
- RVLM remains active
- Preganglionic sympathetic neurons are activated. In turn, heart rate increases blood vessels constrict
What possible intervention can you do when someone experiences a very high heart rate?
carotid massage. You manually introduce pressure on the carotid sinus, this makes your body think that you have high blood pressure and thus mellow down sympathetic ganglion to decrease heart rate and pressure.
The Micturition Reflex is also known as what?
Urination Reflex
When you let your bladder relax (expand) and external sphincter to constrict, what are you essentially doing?
letting pee stay inside. u don’t urinate.
In relation to urinating, the parasympathetic innervation allows for what?
to urinate
In relation to urinating, the sympathetic innervation allows for what?
to hold urine
What allows us to hold our pee voluntarily?
Pudendal Nerve (somatic).
It innervates external voluntary sphincter. (at a certain point in time)
When bladder is holding on to a lot of urine, what happens?
- Pelvic Nerve senses bladder
- activate parasympathetic arm (you will URINATE)
The central autonomic network interacts with the endocrine and behavioral responses via what?
hypothalamus
What network of the brain region coordinates with the sympathetic and parasympathetic responses?
Central Autonomic Network
What is the role of the central autonomic network and hypothalamus in integrating autonomic, endocrine, and behavioral responses?
- blood pressure
- energy metabolism
- reproductive behavior
- body temperature
- defensive behavior
- sleep wake cycle
What hypothalamic nuclei is responsible for the sleep wake cycle?
suprachiasmatic nucleus and lateral hypothalamic area
“SLeep”
What hypothalamic nuclei is responsible for the defensive behavior?
- Paraventricular
- Ant. Hypothalamic
- Lateral Hypothalamic
- dorsal pre-Mamillary
“PALM”
What hypothalamic nuclei is responsible for body temperature?
preoptic region
What hypothalamic nuclei is responsible for reproductive behaviors?
- Ventromedial
- Ventral pre-mamillary
- Medial Preoptic
“VeVe-Me”
What hypothalamic nuclei is responsible for energy metabolism?
- paraventricular
- arcuate nuclei
“PAn”
What hypothalamic nuclei is responsible for blood pressure?
paraventricular
What do you call the ‘folds’ in the brain?
Gyrus
What do you call the “lubog” part of the brain?
Sulcus
What do you call the “deep lubog” part of the brain?
Fissure
What is the functional units of the prefrontal cortex?
superior, middle, and inferior frontal gyrus
What is the functional unit of Broca’s area?
Pars orbitalis & Pars triangularis
What is the functional units of the motor cortex?
pre-central gyrus
Which part of the brain is the primary motor area?
Pre-central Gyrus
Which lobe is mostly for sensory?
Parietal Lobe
According to the Brodmann Area, what is the primary motor area?
Brodmann Area 4
The primary motor area is Brodmann Area 4. Thus, our will to move originates from here. True or False?
False. The primary motor complex only “executes” those commands/will.
Where does the “will to move” originate from? i.e. the initiators
- Somatosensory Association Area
- Visual Association Area
- Prefrontal Cortex
- Auditory Association Area
Why is the Central Sulcus of Rolando important?
It separates the frontal lobe (primary motor cortex) and the parietal lobe (primary somatosensory cortex).
The lateral sulcus separates the frontal and parietal lobe from the temporal lobe. It is notable for its proximity to which regions of the brain?
Broca’s area and Wernicke’s area (speech and language)
What are the 2 areas in the cerebral cortex that are responsible for controlling movement?
- Premotor Area (BA 6)
- Primary Motor Area (BA 4)
Describe the neural pathway involved in planning and initiating voluntary movement?
Association Area (initiators)→ Basal Nuclei → Thalamus (VA & VL nucleus; motor) → Premotor Area → Primary Motor Area
A stroke occurs at the medial part of the brain. Which part of the body is affected?
contralateral Legs/Feet
*Medial Region of Motor Cortex: region closer to center (longitudinal fissure) controls lower extremities
What are the 2 direct pathways (pyramidal) that control movement?
- corticospinal
- corticobulbar (brainstem)
What is the corticobulbar pathway responsible for?
Facial expressions, mastication
The corticospinal pathway can further be classified into 2. What are they and how do they differentiate?
- Lateral: decussates
- Anterior: doesn’t decussate
Which corticospinal pathway decussates at the level of the medulla?
lateral
The primary motor cortex is situated at which Brodmann Area?
4
What are the 4 brainstem motor centers that contribute to the control of movements?
- superior colliculus
- Red Nucleus
- Reticular formation
- Vestibular nuclei
What are the indirect motor pathways?
- tectospinal tract
- rubrospinal tract
- Reticular Formation
a. lateral reticulospinal
b. medial reticulospinal - vestibulospinal tract
What is the brainstem center of the tectospinal tract?
superior colliculus
What is the brainstem center of the rubrospinal tract?
red nucleus
What is the brainstem center of the lateral and medial reticulospinal tract?
reticular formation
(1) “Huy! May ipis sa likod mo,” kuya said. The flutter of its wings eerily grazed my ears. I immediately snapped my head to the side to see where it was. (2) It flew towards and me, but years of taekwondo made me nimble and was able to regain my balance after a swift dodge.
What indirect motor paths were used?
(1) tectospinal + reticulospinal
(2) vestibulospinal + reticulospinal
What is the brainstem center of the vestibulospinal tract?
vestibular nuclei
All indirect motor pathways are involuntary. True or False?
True
There are 2 types of reticulospinal tract. What are they and how are they different?
- Lateral Reticulospinal: inhibit muscle of trunk and proximal
- Medial Reticulospinal: excites muscle of trunk and proximal
What happens during decortication?
Lesion is above Red Nuclei.
a. Upper Extremity is flexed
b. Lower Extremity is extended
What happens during decerebration?
Lesion is below Red Nuclei.
a. Upper Extremity is extended
b. Lower Extremity is flexed
What is the function of the basal ganglia?
1) Initiation of movements
2) Suppression of unwanted movements
3) Regulation of muscle tone (via the
reticulospinal tract)
4) Regulation of non-motor processes
(cognitive, linguistic, limbic functions,
memory, planning)
What are the 3 pathways of the basal ganglia?
Hint: “circuit”
- Direct Circuit
- Indirect Circuit
- Substansia Nigra
What is the main function of the Direct Circuit pathway of the Basal Ganglia?
Promote movement
What neurotransmitters does the Direct Circuit pathway of the Basal Ganglia use?
- Glutamate = excitatory
- GABA = inhibitory
Describe the pathway of the direct circuit pathway of the basal ganglia.
“Coke, Pepsi, In can, Tall CappuCcino”
1. Cortex
2. Putamen
3. GPi
4. Thalamus
5. Cortex
6. Corticospinal Tract
Describe the pathway of the indirect circuit pathway of the basal ganglia.
“Coke, Pepsi, maX, Sprite, in can, tall
cappuccino”
- Cortex
- Putamen
- GPe
- STN
- GPi
- Thalamus
- Cortex
- Corticospinal Tract
What is the main function of the indirect circuit pathway of the basal ganglia?
inhibition/modulation of movement
What is the main function of the substantia nigra?
- produces dopamine
- It is the “battery of the circuit”.
- promotes the direct pathway
- inhibit indirect pathway
What neurotransmitter does the substantia nigra use?
dopamine ONLY, for both direct and indirect. Only the receptors are different
Identify the receptors substantia nigra uses.
- Dopamine 1 receptor: stimulatory
- Dopamine 2 receptor: inhibitory
Give an example of a disease that is caused by the degeneration in the substantia nigra. Explain its mechanism
Parkinson’s Disease. (hypokinetic):
- direct pathway is underactive (stimulate movement)
- indirect pathway (movement suppresser) is overactive
Both pathways don’t receive enough dopamine. Hence, movement is slow
Describe the mechanism of Chorea
- hyperkinetic
- degeneration at the indirect pathway
- indirect pathway is underactive (reduced inhibition)
- direct pathway is overly stimulated
Hence, there is too much movement
What is STN for?
send excitatory signal to GPi to increase its inhibitory effect
Describe what happens in Ballismus (disorder)
STN is damaged. GPi is not stimulated thus it cannot inhibit thalamus. Thalamus sends too much excitatory signal to motor cortex causing big and violent involuntary movements
What part of the brain acts like a consultant?
cerebellum
What are the pathways of the cerebellum that it uses to modulate movement?
- cortico-ponto-cerebellar tract (CPCT)
- spinocerebellar tract
- Dentato-rubro-thalamic tract (DRTT)
- compare command signal w/ sensory info*
What is CPCT for?
Monitoring intentions for movement
What is the spinocerebellar tract for?
monitor actual movements
What is DRTT for?
send out corrective feedback
Which indirect / extrapyramidal pathway allows an individual to look briskly and
reflexively towards visual and auditory stimuli?
Tectospinal
Which tract allows the cerebellum to monitor intentions for movements and to receive
input from the cerebrum?
Cortico-ponto-cerebellar
Where do sensory signals enter the cord through?
dorsal roots
where are the 2 destinations sensory signals can go to?
- gray matter
- higher level of the nervous system
what tract is responsible for the voluntary control of the muscle
corticospinal tract
What are the 2 types of anterior motor neurons?
- gamma motor neuron: innervate intrafusal fiber (muscle fiber)
- alpha motor neuron: innervate extrafusal fiber (main meat of muscle)
What is the dorsal root for?
sensory
What are the inhibitory cells that transmit
inhibitory signals to the surrounding motor neurons (lateral inhibition)?
renshaw cells
What muscle sensory receptor is responsible for sensing the length of the muscle and is distributed throughout the belly of the muscle?
Muscle SpindLes
What muscle sensory receptor detect tendon tension or rate of change of tension? (located in muscle tendons)
Golgi Tendon Organ
What are the 2 types of spindle nerve endings?
- Primary Afferent
- Secondary Afferent
What are the 2 types of intrafusal muscle fiber?
- nuclear bag muscle fiber
- nuclear chain fiber
What is the muscle stretch reflex for?
It contracts the muscle when the body detects over-stretching. This is done to prevent injury.
Describe the mechanism of the muscle stretch reflex.
- muscle spindle detects over-stretching
- afferent impulse travels via type la nerve fibers
- enter dorsal root
- dorsal fiber goes to ant. horn & synapse with ant. motor neuron –> facilitate contraction
Note: this reflex is monosynaptic. Only one synapse between sensory (type la afferent) & motor neuron. Allows for quick reflex
How much resting cardiac output does the brain receive?
15%
How much blood flows through the brain per minute?
~750 to 900 ml/min.
What metabolic factors dictate blood flow to the cerebrum?
- CO2 concentration
- O2 concentration
- Hydrogen Ion
- Increased glutamate
What happens when hydrogen ion (acidity) is increased?
increase blood flow
When Mean Arterial Pressure is within 60-180 mmHg, what mechanism can blood vessels do?
narrow or widen. (increase glutamate = vasodilation)
Autoregulation is effective within what range? (Mean Arterial Pressure)
60-180 mmHg
What are the functions of the Cerebrospinal fluid?
- mechanical protection
- chemical protection
- circulation
What produces the cerebrospinal fluid?
Choroid plexus
The average total volume of circulating cerebrospinal fluid in an adult is (in mL):
80-150
Which structure is responsible for cerebrospinal fluid production?
Choroid plexus
What are the special features of brain metabolism?
- Higher metabolic rate compared
to the rest of the cells in the
body - Lack of significant anaerobic
metabolism - Reliance on glucose
