CPPS 306 The Central Nervous System

Name the different parts of a neuron and explain their functions

Dendrites = input of information and integration

Soma / perikaryon = cells body, cellular maintenance and information processing

Axon = information transport

Nerve terminals = output of information

What are the two main neuronal cell types in the adults cerebral cortex

Spiny glutamatergic (excitatory) neurons

Non-spiny GABAergic (inhibitory) interneurons

What is the role of spiny glutmatergic neurons in the cortex?

They are excitatory neurons with many dendritic spines that allow for many synapses and provide the main output of the cortex

Can act locally and long distance

What is the role of non-spiny GABAergic interneurons in the cortex

They are inhibitory neurons that act locally (NOT long distance) to regulate and control the activity of nearby excitatory neurons

Fewer synapses, but STRONG inhibitory control

What is the primary role of astrocyte in the CNS?

Astrocytes are glial cells that regualte synaptic activity, neuronal signaling and the local brain environment

What is astocytic domain organization

Refers how astrocytes DONT overlap with one another

They have their own domains in the brain!

How many synapses can a single astorcyte interact with?

Over 100,000 synapses, allowing rapid and widespread modulation of neural activity

What structure make up a tripartite synapse?

• Presynaptic

• Postsynaptic

• Astrocyte

What are microglia’s role in the CNS

Survey and respont to pertubations in their environment

They are the resident immune cell of the CNS

What is the role of oligodendrocytes and schwann cells in the nervous systems

Oligodendrocytes = myelinate many axons (at once) in the CNS

Schwann cells = myelinate axons (one at a time) in the PNS

Name the different types of synapses

Dendrosomatic = dendrite to soma

Dendrodendritic = dendrite to dendrite

Axoaxonic = axon to axon

Axondendritic = axon to dendrite

Axosomatic = axon to soma

Where are the possible sites neurotransmitters released from the presynaptic neuron act on

• Receptors on an adjacent postsynaptic neuron at a s tie close to the release site (1)

• At a extrajuncitonal site (2)

• A far postsynaptic site (3)

• or an distant glial cell (4)

What causes postsynaptic receptor up-regulation

Chronic low neurotransmitter stimulaton, such as a long term antagonist use reduced NT release

• when the postsynaptic cell is not being stimulated enough for a long time, it compensats by

  • Making more receptors

  • become more sensitive to the weak signal

What causes a postsynaptic receptor down regulation?

Chronic high neurotransmitter stimulation, such as long-term agonist use or blocked reuptake

What is one way postsynaptic neurons respond to long-term changes in synaptic activity?

They adjust receptor number to maintain singaling balance

What neurotransmitters does the PNS mainly use

Ach and NE

What are the main neurotransmitters CNS uses?

Uses 12 NT

• Ach

• NE

• 50-HT

• DA

• Glu

• GABA

What is a neurotransmitter

A fast acting chemical released form presynaptic neuron that crosses the synaptic cleft to directly excite or inhibit a postsynaptic cell

• Act on synapse

• Uses ionotropic receptors

• Effects last milliseconds

What is neuromodulator

A slow acting chemical that modulates neuronal activity by acting on receptors away from the release site, influencing how neurons respond to neurotransmitters

• Acts distant from release site

• Uses metabotropic receptors

• Last milliseconds to seconds

• Affects many neurons sites

• Modifies fast neurotransmitter signaling

What are the parts of the brain stem and its primary role

Midbrain, pons, medulla

It controls vital reflexes required for survival (blood pressure, heart rate, breathing)

What are the crucial functions mediated by the brainstem?

Blood pressure & heart rate (baroreceptor reflex)

Breathing (CO₂ sensing)

Vomiting/chemoreceptor trigger zone

Sleep and consiousness

What structures make up the diencephalon and what is its general role?

Thalamus = sensory & motor relay

Hypothalamus = homeostasis & survival behaviours

What is the main function of the thalmus?

It acts as a relay center for sensory and motor information to the cerebral cortex

What does the hypothalamus control

Homeostasis

Autonomic nervous system

Pituitary hormone regulation

Thermoregulation

Survival behaviours

What is the main role of the cerebellum?

It coordinates voluntary movement, balance, and timing

How does the cerebellum influence movmeent?

Recieves input from many sources

Sends output to motor cortex via the thalamus

Important for motor learning and eye movements

What is the primary function of the cerebral cortex?

Controls sensory perception, voluntary motor activity, higher cognition, and consiousness

What higher functions are associated with the cerebral cortex?

Language

Thought and idea generation

Consious awareness

Likely long-term memory storage

What is the limbic system responsible for?

Regualtes emotion, motivation, judgment, behaviour inhibition (thougts and ideas), and memory formation.

What structure make up the limbic system?

Amygdala

Hippocampud

Habenula

Septal area

What is the basal ganglia and what makes it up

A group of deep brain nuceli that regulate voluntary motor control

Caudate + Putament (striatum)

Internal capsule

Thalamus

Does the basal ganglia directly initiate movement and how does it help with smooth movement

No. They modulate and refine voluntary movement to make it smooth and coordianted

Regulate opposing muscle groups, preventing excessive or unwanted contractions

What is the primary brain structue that produces norepinephrine and what is the main role of NE

Locus Coeruleus (in the pons)

Arousal, alertness, attention, and stress responses

Which neurotransmitter mediates central responses to stress?

Norepinephrine

In which two major brain systems does norepinephrine play an important role, and what does it do in each

Reticular activating system (RAS) = basic arousal, alertness, wakefulness

Limbic system = emotional regulatoin (anxiety, dpression, appropriateness)

Where do most dopamine neurons originate in the brain?

Midbrain, specially the substantia nigra, and ventral tegmental area (VTA)

Which dopamine pathway is invovled in parkinsons disease?

The nigrostriatal pathway (substantia nigra → striatum) part of the exrapyramidal motor system

Which dopamine pathway mediates reward and pleasure?

The mesolimbic pathway (VTA → nucleus accumbens / limbic system)

Which dopamine pathway affects cognition and emotion similar to norepinephrine

The mesocrortical patheay

Which brain region mainly produces serotinin

The rostral raphe nuclei

Which brain system is seritonin involved in for psychiatric symptoms

limbic system

• Regulates psychosis, anxiety, and repression

Whats seritonin’s role in the hypothalamus and cerebral cortex

Hypothalamus → Regulates thermoregulation and pituitary secretion

Cerebral cortex → helps shape and organize cortical neural circuits

Where does the ascending and descending seritonin projections originate and project to

Ascending = rostral raphe nuclei → cortex, thalamus, hypothalamus, basalganglia, limbic system

Descending = caudal raphe nuceli → spinal cord

What brain structure mainly makes Ach

Nucleus Basalis

Which brain system uses acetylcholine

Limbic system = Emotions and memory

Extrapyramidal system = parkinsons

Help shape neuronal cicruits

Which brain regions mainly makes histamine

Tubermammillary nucleus

Reticular activating system = arousal

the BBB consists of:

Brail capillary endothelial cells iwth tight junctions

Enzymes of the many endothelial mitochondria

Pericytes and astrocytes end foot processes

Plasma protein binding