Nervous System II

neurotransmitter removal

reuptake (brought back into terminal) and enzymatic breakdown

reuptake inhibitors

prevents reuptake, which increases amount of neurotransmitter

receptors

proteins that recognize chemical signals; neurotransmitters produce change

-based on receptor, neurotransmitters can be excitatory or inhibitory

ionotropic (ligand-gated) receptor

ion flow; charges membrane potential; FAST

metabotropic (G-protein coupled) receptor

second messenger system; intracellular signaling; changes cell activity (ex. gene txn); SLOW

acetylcholine (ACh) production

choline + acetyl CoA → acetylcholine

acetylcholine primary biosynthetic enzyme

choline acetyltransferase

acetylcholine receptors

-nicotine (ionotropic, fast)

-muscarinic (metabotropic, slower)

enzyme that breaks down acetylcholine

acetylcholinesterase (AChE)

-ACh → choline + acetate; choline pulled back into presynaptic terminal and recycled

major functions of acetylcholine

neuromuscular transmission, autonomic signaling, attention/memory in CNS

-ex. decreased levels in dementia

monoanime neurotransmitters

dopamine, norepinephrine, epinephrine, serotonin, histamine

-all stored in vesicles and released by exocytosis

dopamine (DA) production

tyrosine → L-DOPA → dopamine

dopamine primary biosynthetic enzyme

tyrosine hydroxylase

dopamine receptors

-D1-like receptors (metabotropic, modulates positively (increases activity); D1, D5

-D2-like receptors (metabotropic, modulates negatively (decreases activity); D2, D3, D4

dopamine signal termination

-MAO and COMT metabolize

-dopamine transporter (DAT) returns DA into cell

cocaine inhibits

dopamine transporter

major functions of dopamine

movement, reward, cognition

norepinephrine (NE) production

tyrosine → L-DOPA → dopamine → norepinephrine

norepinephrine primary biosynthetic enzyme

dopamine ß-hydroxylase

norepinephrine receptors

-alpha receptors (metabotropic; α1, α2)

-beta receptors (metabotropic; ß1, ß2, ß3)

noreprinephrine signal termination

-MAO and COMT metabolize

-norepinephrine transporter (NET) returns NE to cell

major functions of norepinephrine

arousal, cardiovascular regulation, stress response

epinephrine (E) production

tyrosine → L-DOPA → dopamine → norepinephrine → epinephrine

epinephrine receptors

same as norepinephrine

-alpha receptors (metabotropic; α1, α2)

-beta receptors (metabotropic; ß1, ß2, ß3)

epinephrine signal termination

same as norepinephrine

-MAO and COMT metabolize

-norepinephrine transporter (NET) returns to cell

major functions of epinephrine

fight or flight, elevated heart rate and blood pressure, bronchodilation, elevated blood glucose

serotonin (5-HT) production

tryptophan → 5-hydroxytryptophan → serotonin

serotonin primary biosynthetic enzyme

tryptophan hydroxylase

serotonin receptors

-5-HT₃ receptors (ionotropic; Na⁺, Ca⁺ goes through)

-other receptors (metabotropic; 5-HT_{1-7 (no 3)})

serotonin signal termination

-MAO metabolizes

-serotonin transporter (SERT) returns 5-HT to cell

major functions of serotonin

mood, sleep, appetite

GABA (γ-aminobutyric acid)

major inhibitory neurotransmitter in CNS; decreases neuronal activity

GABA production

glutamate → GABA; cleared from synaptic cleft by transporters

GABA primary biosynthetic enzyme

glutamate decarboxylase

GABA receptors

hyperpolarization

-ionotropic GABA_A (fast inhibitory)

-metabotropic GABA_B (slower modulatory)

GABA signal termination

-GABA-T and SSADH metabolize

-GABA transporter (GAT) reuptakes GABA

major functions of GABA

reduces neuronal excitability, anxiety reduction, sleep regulation, motor control

glutamate

major excitatory neurotransmitter in CNS

glutamate production

glutamine → glutamate

glutamate primary biosynthetic enzyme

glutaminase

glutamate receptors

-ionotropic (fast excitatory; AMPA, NMDA, Kainate)

-metabotropic (modulatory; mGluRs)

glutamate reuptake

EAAT transporters reuptake glutamate, converted to glutamine in glia

major functions of glutamate

excitatory neurotransmission, learning, synaptic plasticity, sensory transmission

parts of brain

cerebrum

higher cognitive, sensory, motor neurons

-has left & right hemispheres

-has gray and white matter

gray matter

outer, cerebral cortex; made of dendrites, neuronal cell bodies

white matter

underlying; connects regions; made of axons

corpus callosum

connects hemispheres

diencephalon

deep central region including thalamus and hypothalamus

brainstem

connects brain with spinal cord and supports vital functions

cerebellum

coordination and balance

gyrus/gyri

ridge (bump) in brain

sulcus/sulci

groove in brain

fissure

deeper groove in brain

anterior

front

posterior

back

superior

top/above

inferior

bottom/below

lateral

away from midline

medial

toward midline

saggital plane

divides left & right hemispheres

coronal

divides anterior & posterior

axial

divides superior & inferior

brain lobes

frontal lobe

decision making, speech, voluntary movement

parietal lobe

sensation, sensory, spatial awareness

temporal lobe

memory, hearing, language

occipital

vision

cortical functional areas

basal ganglia

regulation of movement

striatum

-major input region of ganglia

-caudate + putamen

hippocampus

learning, memory formation

thalamus

major relay/integration center, sensory info sent out

hypothalamus

homeostasis, autonomic & endocrine regulation, temperature, hunger, thirst

protection of CNS

DAP (dura, arachnoid mater, pia mater); subarachnoid space

dura

tough layer inside skull

arachnoid mater

middle layer

pia mater

thin inner layer

subarachnoid space

contains cerebrospinal fluid; between brain and pia mater

cerebrospinal fluid

absorbs shock, maintains chemical environment, waste removal

choroid plexus

produces cerebrospinal fluid

ventricles

lateral ventricles → third ventricle → cerebral aqueduct → fourth ventricle → subarachnoid space