Exam 1

4 neuron functional zones

input zone - dendrites

integration zone - axon hillock

conduction zone - axon

output zone - axon terminals

What kind of neurons make up most of the CNS?

interneurons

astrocytoma

tumor in brain or spinal cord - cancerous - astrocytes rapidly multiplying

Alexander disease

genetic mutation causes astrocytes unable to get rid of GFAP (something they produce) --\> they fill up and die

Multiple sclerosis

oligodendrocyte injury from autoimmune attack

Sympathetic nervous system

fight or flight

parasympathetic nervous system

rest and digest

white matter

axon bundles - no neurons/cell bodies

gray matter

clusters of neuron cell bodies

corpus callosum

white matter

basal ganglia

Center of the brain - a bunch of neurons for movement

Parkinson's disease

basal ganglia dies

limbic system

emotional memory, regulation

cortex area

consciousness, decision-making

Midbrain function

Reticular formation - sleep, arousal, body temperature

If you go into a coma, what has failed?

The midbrain

pons function

connection of nerves to the eyes and face.

medulla function

heart rate, breathing

cerebellum function

motor coordination, learning

what part of your brain can you live without?

cerebellum

meningococcal meningitis

bacteria enters subarachnoid fluid

tumor of the dura name

meningioma tumor

subdural hematoma

blood under dura mater

what do cerebral ventricles do?

make CSF

how much CSF is produced per day?

16oz

hydrocephalus

CSF circulation failure - entire 16oz doesn't leave brain each day

how is hydrocephalus treated?

CSF drainage tube

CT scan

X-ray

Shows tissue density

MRI

magnetic fields and radio waves cause protons in brain tissue to line up

PET scan

Show brain activity

Radioactive chemicals to map destination

best neural imaging for brain tumors

PET scan

Functional MRI

Show brain activity

Detects changes in metabolic activity (ex. oxygen use)

Show how networks in brain collaborate

Diffusion tensor imaging

shows brain connections (images axons of neurons)

soma

cell body

intrinsic proteins

proteins on surface of cell membrane (receptors, channels, etc)

Kinesin transport type/direction

anterograde transport (soma --\> terminals)

Dynesin transport type/direction

retrograde transport (terminals --\> soma)

Lissencephaly

"Smooth brain" - microtubules fail

MELAS syndrome

Mitochondria fails --\> brain can't get oxygen --\> seizure

concentration gradient

Diffusion - ions flow from areas of high concentration to low concentration

Electrical gradient

Electrostatic pressure causes ions to flow towards oppositely charged areas

ion channels

proteins on membrane that allow ions to pass in/out

Gated channels open in response to? (3 things)

Voltage

Chemicals (drugs)

Mechanical action (vibration)

What ion are neurons selectively permeable to?

K+

sodium-potassium pump

3 Na+ out, 2 K+ in

What does tetrodotoxin do?

Blocks voltage-gated Na+ channels

Where are graded potentials located?

Dendrites

Where are action potentials located?

Axon

Threshold for neuron to fire

-40mV

Where is "trigger" for action potential located?

Axon hillock

Action potential when do Na+ channels open and close?

-40mV open, +40mV close

Absolute refractory phase

+40mV - no more action potentials can be produced

Relative refractory phase

While K+ channels are open and K+ is leaving - only strong stimulation can produce action potential

What is myelin's purpose?

Help action potentials regenerate FAST

What helps action potentials travel only in one direction?

Refractory period

Myelinated vs unmyelinated axons speed and energy use

Myelinated - 10x faster, and saves 40% more energy

How do action potentials cross synapse?

Chemical signals

excitatory postsynaptic potential (EPSP)

Depolarization - Na+ ions enter \= more positive

inhibitory postsynaptic potential (IPSP)

Hyperpolarization - Cl- ions enter \= more negative

How are ESPS and ISPS integrated?

dendrites vote, axon hillock decides

What gates on ESPS or IPSP?

chemically gated - transmitter binding causes them to open

what happens to neurotransmitters after binding?

degradation or reuptake

What is the primary neurotransmitter in muscles?

Acetylcholine

How does RAID work?

blocks acetylcholinesterase --\> more acetylcholine --\> more muscle action --\> twitch to death

where do electrical synapses exist?

heart and some places of brain

what causes epilepsy?

injury or genetic defects on electrical synapses --\> excessive firing

Ligands

Chemicals that bind to receptors to activate/block them

endogenous ligands

neurotransmitters, hormones

exogenous ligands

drugs, toxins from outside the body

Up-regulation

increase of number of receptors - sensitization

Down-regulation

Decrease in number of receptors (as a defense) - tolerance

Example of up-regulation

Nicotine addiction

example of down-regulation

benzodiazepines

Tonic-clonic seizure

Stiffness and then jerking

Loss of consciousness and violent muscle contractions

absence seizure

Happen hundreds of times a day - pausing/freezing for a couple seconds

focal seizure - impaired awareness

Barely conscious, drooling

In L/R temporal brain

myoclonic seizure

Rhythmic/repetitive muscle jerk seizure

98% chance of mental retardation

focal seizure - aware

Awake and aware, twitching

In motor cortex

glycine

Inhibitory neurotransmitter --\> causes inhibition (relaxation)

Opisthotonos

generalized rigidity - glycine is blocked by tetanospasmin

Ionotropic receptor

simple, direct - open when bound by transmitter (ligand-gated ion channel)

metabotropic receptor

complicated, indirect - transmitter binds, receptor activates G-protein, binds to other proteins or ionotropic receptor

75% of drugs act on what type of receptor?

metabotropic receptors

agonist

initiate normal effects of receptor

antagonist

prevents receptor from being activated by other ligands

competitive antagonist

doesn't let other ligands bind

noncompetitive antagonist

sneaky --\> binds somewhere else, makes other ligands NOT WANT TO bind

4 common amino acids

Glutamate

Aspartate

Glycine

GABA

2 types of monoamines

catecholamines and indolamines

catecholamines

dopamine, norepinephrine, epinephrine

indolamine

serotonin

soluble gases

nitric oxide, carbon monoxide

what does glutamate operate?

Sodium and Calcium ionic entry (ionotropic receptors) and mGluRs

excitotoxicity

neural injury causes excess release of glutamate --\> causes neurons to kill themselves

what goes GABA do?

Inhibitory --\> activates ionotropic receptors like Cl- channels

most common inhibitory neurotransmitter in brain

GABA

agonists of GABA

Valium, barbiturates

most common neurotransmitter in spinal cord

Glycine

What does glycine do?

Acts like GABA - inhibitory, binds to ionotropic receptors

catecholamine synthesis

dopamine --\> norepinephrine --\> epinephrine