neurotransmission, neurochemistry, and neuroanatomy (copy)

Afferent

receiving information, towards cell body

Efferent

sending information, away from cell body

Active zone

where neurotransmitter vesicles bind to then release their content into the cleft

PSD

postsynaptic density, high density of receptors

what happens to postsynaptic potential when a anion enters?

it becomes inhibitory postsynaptic potential

-An anion has negative charge

cholinergic type

refers to anything involving or activated by acetylcholine (ACh), a crucial neurotransmitter for muscle control, learning, memory, and autonomic functions

ACh

what is Acetacholine (ACh) inactivated by?

- Inactivated by enzymatic degradation: once the neurotransmitter is broken down by enzymes, it’s permanently deactivated and its pieces can’t be recycled to make the same neurotransmitter again.

-the enzyme acetylcholinesterase(AChE), which rapidly breaks it down in the synaptic cleft into choline and acetic acid(acetate), preventing continuous nerve stimulation

what happens to postsynaptic potential when a cat ion enters?

it becomes an excitatory postsynaptic potential

what do acetocholyine receptor do when associated with ligand gated ion channels?

responsible for neurotransmission, binds to the gate for it to open and allow ions to travel through membrane

Catecholinergic types

NE - norepinephrine

Epi - epinephrine

DA - dopaminergic

where is NE - norepinephrine mainly found?

- Cell bodies located on locus coeruleus

whats another name for Epi - epinephrine?

- Adrenaline

what is the first system of DA - dopaminergic?

- Its called the mesolimbic DA system:

starts in the cell bodies in VTA (ventral tegmental area), and it controls motivation, which affects behavior

Serotonergic type

serotonin (5-HT):helps regulate mood, sleep, appetite, and overall emotional balance.>works through g coupled proteins

what is serotonin (5-HT) inactivated by?

- Inactivated by reuptake

Amino acidergic types

glutamate and GABA

Glutamate

- excitatory NT

- EPSP - excitatory post synaptic potential; stimulates an AP, depolarizes neuron

- Bind to ligand gated ion channels - directly change the electrical state of a neuron by allowing positive ions to enter

-after signaling then broken down by biotransformation(metabolic)

- "True" neurotransmission

GABA

- inhibitory NT

- ISPS - inhibitory post synaptic potential which hyperpolarizes neuron

- prevents threshold from being reached which makes an occurance of an action poetenial less likely

- Bind to ligand gated ion channels(cholrine channels)- directly change the electrical state of a neuron(more negative)

-After signaling it is broken down by buotransformation

- "True" neurotransmission

Ligand-gated ion channels

- NT binding receptor opens an ion channels

- Inotropic = ions move directly across the membrane

- Fast neurotransmission:Rapid onset, but a short duration of effects

-point-to-point communication between one neuron and one other neuron.

EPSP

cell becomes depolarized (postive ions move in or negative ions move out), an AP is more likely to occur, Na+ moves in cell

IPSP

cell becomes hyperpolarized (negative ions move in or positive ions move out), Cl- moves in or K+ moves out

G-Protein-coupled receptors

- Metabotropic effect-means that the neurotransmitter changes neuron activity indirectly

i. When a neurotransmitter (NT) attaches to the receptor on the neuron, it turns on a G-protein inside the cell. The NT itself does not enter the cell.

ii. Intracellular (second) message is created-The activated G-protein triggers the production of a second messenger inside the neuron. This messenger carries the signal from the receptor to other parts of the cell.

iii. Second messenger alters neuronal function (modulation)

The second messenger changes how the neuron behaves. Instead of directly causing the neuron to fire, it modulatesactivity—making the neuron more or less likely to respond.

iv.Slow

- But, the duration of the effect is longer: mood, motivation, tiredness, usually from one neuron to multiple other neurons (so it can affect a whole structure)

Firing rate

# of APs over time

Summation

Summation is the combining of graded potentials (depolarizations) produced by presynaptic action potentials so that the postsynaptic neuron reaches threshold and fires.

Spatial summation

occurs when action potentials from different presynaptic neurons arrive at the same postsynaptic neuron at the same time. Their graded potentials add together, helping the postsynaptic neuron reach threshold.

Temporal summation

occurs when two or more action potentials from the same presynaptic neuron arrive at the postsynaptic neuron very close together in time.

- The first action potential causes a brief depolarization, and before the membrane potential returns to resting level, the next action potential arrives.

- These graded potentials add together, helping the postsynaptic neuron reach threshold.

rostral

anterior

-toward the front of the brain (the forehead area).

caudal

posterior

- (toward the back of the brain).

dorsal

superior

up / superior in the brain

example

-The parietal lobe is dorsal to the temporal lobe.

-The somatosensory cortex is dorsal to deeper brain structures.

ventral

inferior

toward the bottom or underside of the brain.

Ipsilateral

Structures localized to the same side

Contralateral

Structures localized to different sides

Nucleus

in CNS, large area of cell bodies(grey matter) with clear boundaries

Locus

in CNS, small are of cell bodies with clear boundaries

Substantia

in CNS, large area of cell bodies with no clear boundaries

Ganglia

in PNS, collection of cell bodies in a defined area

Cortex

- Primarily cell bodies

- surface/outercovering of the brain

- Cell bodies are not myelinated, so the cortex is grey matter

- About 10% of the brain

Fiber

- White matter

- One singular, myelinated axon

Tract

- white matter

- Collection of fibers that start at one structure and terminate at one common structure

Bundle

- White matter

- A collection of fibers that pass through the same region, but do not start and end at the same spots

Commissure

- White matter

- A type of bundle that is contralateral; goes from one brain hemisphere to the other

Nerve

- White matter

- Axon bundles in the PNS

- Nerves = PNS only (neurons = CNS)

CNS

i. Brain

ii.Spinal cord

PNS

Everything outside spinal cord

Grey matter

lacks myelin, made up of cell bodies, makes up cortex (outside of brain)

Whiter matter

contains myelin, made up of axons, inside of brain

Gyri

parts of the brain folds that rises

Sulci

part of the brain fold that go in, the grooves

Fissure

a deep sulcus

Lateral sulcus

divides frontal and temporal lobes, dorsal from ventral

Central sulcus

divides frontal from parietal lobes, rostral(anterior) and cuadal(posterior)

Parietoccipital sulcus

separates parietal from occipital lobe

Superior longitudinal sulcus

separates the two brain hemispheres

Frontal lobe

high cognition

Parietal lobes

somatic (senses)

occipital lobe

sight

Temporal lobes

hearing, many other diverse functions

Cortex Layer 1

molecular layer, no cell bodies, only synapses + dendrites of other neurons to receive and send info

Cortex Layer 2 + 3

function together, pyramidal cells, its axons go to other cortical areas, receive and send information from toher parts of the cortex

Cortex Layer 4

stellate (star shaped) cells, sends information between the cortext and thalamus

Cortex Layer 5 + 6

function together, pyramidal cells, axons go to other parts of the brain (noncortical), receive and send information from other parts of the brain

Cortex circuitry is ...

columnar, meaning that the info that leaves the cortex integrates all the information from that column (vertical) of neurons (as opposed to horizontal rows)

Dicencephalon components

thalamus, hypothalamus, epithalamus

Thalamus

- A relay

- All ascending and descending information goes here first, undergoes some low level processing, and then is sent to the proper part of the cortex or another structure

-The thalamus receives sensory and motor information, processes and organizes it, and then sends it to the appropriate areas of the cerebral cortex. It also helps regulate alertness, sleep, and attention.

Hypothalamus

- Indirectly controls the endocrine system because it controls the pituitary gland

- Controls visceral states: the states of organs

- Ex: hunger, blood pressure, thermoregulation; all unconscious/Automatic

- Primtive emotion: largely suppressed in humans, predatory and territorial aggression in animals, usually only occur in humans with use of drugs (ex: some people are aggressive when drunk)

Epithalamus

-Secretory, epithelial cells

- Pineal gland: an endocrine gland, secretes melatonin which regulates circadian rhythm

- contains the Choroid plexus: creates cerebrospinal fluid (CSF)

cerebellum

- Integrates sensory and motor information, makes motor maps

- Exacts control over movements

- No direct access to motor neurons: has to send info to cortex which sends to lower motor neurons

-maintains balance

brainstem components

midbrain, pons, medulla

midbrain

- Procesing of visual and auditory information

- Contains the DMS

DMS

The dorsal midbrain system (DMS) is involved in visual and auditory reflexes, especially reflexive movements of the eyes and head in response to sensory stimuli.

Pons

Relay, creates a connection between the cerebellum and cerebrum

Medulla

- Visceral motor muscle functioning

- Muscles are controlled at an unconscious level: breathing, blood pressure, cardiovascular function

- Primitive brain reflex: sneezing, vomitting, yawning, hiccups

modulation

Adjusting how strongly or how likely neurons respond to signals, rather than directly causing them to fire or stop firing.

translation

changes electrical state of neuron

enzygamatic degradation

byproducts that can't become NTs again

biotransformation

inactive byproducts -> reactivated once returned to cell

reuptake

NTs pumped back into presnynaptic neuron -> repackaged -> reused (not modified)

diffusion (as form of neurotransmitter inactivation)

Diffusion deactivates neurotransmitters when they spread away from the synaptic cleft until their concentration is too low to bind receptors. This commonly occurs with G-protein–coupled receptors because they act through complex, widespread circuits, allowing neurotransmitters to affect and move across a larger area.

precentral gyrus

primary motor cortex

-controls voluntary movement of skeletal muscle

postcentral gyrus

primary sensory cortex

what is NE norepinephrine main function?

- Function in arousal and sleep, maintain routine bodily functions

how is NE norepinephrine inactive?

- Inactivated by reuptake

What receptors do NE-norepinephrine bind to?

Receptors = g protein-coupled receptors (modulation)

why is epi- epinephrine considered a hormone?

its released from the medulla into the bloodtream, acting a a hormone that affects many organs.

where is epi- epinephrine found and whats its function?

In CNS for modulation function. Adrenomedulla releases epinephrine during sympathetic NVS into blood stream

how is epi-epinephrine inactivated?

inactivated by reuptake

which type of receptors are epi-epinephrine associated with?

Receptors = g protein coupled receptors (modulation)

what is the 2nd system of DA- dopaminergic?

its called the basal ganglia dopamine system: controls movement

what is the primary function of DA-dopaminergic?

controls movement and associated with motivational behavior

what happens if theirs a lack of DA-dopaminergic?

parkisons disease

how is DA-dopaminergic inactivated?

by reuptake

what receptors is DA-dopaminergic associated with?

G protein coupled receptors

what type of receptors are serotonin (5-HT) associated with?

- G - protein-coupled receptors (modulation)

what is the primary function of serotonin (5-HT)?

- Modulate mood and affect

what are SSRI’s and what do they do?

- they are selective serotonin reuptake inhibitors and they block reuptake to treat depression

where is serotonin (5-HT) found?

- Location = raphe nuclei located in the midline of the brainstem

whats a another name for G protein coupled receptors?

neuromodulartransmission (slow onset and long duration)

diffuse neuromodullary system?

function is neuro-modulation