NSC EXAM 1

neuron doctrine

brain composed of independent cells; signals transmit on synapses (gaps)

\#unipolar

single extension with receptive pole and output zone

\#bipolar

one axon, one dendrite; USUALLY SENSORY

\#multipolar

one axon, many dendrites; MOST COMMON

\#input zone (at dendrites)

collect and integrate info from environment or cells

\#integration zone (soma to axon)

decide to make the neural signal

\#conduction zone (along axon)

info transmits long distances

\#output zone (at terminal buttons)

transfer info to other cells

\#what are the two types of brain cells?

neurons and glial cells

\#sensory neurons

respond to environment; light, odor, touch

\#motoneurons

contact muscles or glands

\#interneurons

receive input from and send input to other neurons (most neurons in CNS)

\#what are the four types of glial cells?

astrocytes, oligodendrocytes, ependymal cells, microglia

\#astrocytes

most numerous glial cell, fill space between neurons for support; regulate ECM composition; stabilizes, brain moves together

\#oligodendrocytes

wrap several axons, inside brain and spinal cord; at nodes of Ranvier

\#microglia

phagocytes that clean up dying neuron debris; not from the brain, are "immigrants" and clean up; PAC MAN!

\#ependymal cell

secrete and absorb cerebral spinal fluid; lines ventricles

\#synapse

where two neurons communicate in one direction

\#presynaptic neuron

on the terminal buttons of neuron transmitting info

\#postsynaptic neuron

on dendrites of neuron receiving info

\#neural plasticity

dendritic spines have; immune system cells also able to do this

\#dendritic spines form from

DNA and microtubules

\#synapse

\#peripheral nervous system

include cranial and spinal nerves

\#preganglionic neurons

from CNS to autonomic ganglia

\#postganglionic neurons

from autonomic ganglia to targets in body

\#innervate sympathetic chain

preganglionic cells in spinal cord

\#ipsilateral

same side

\#anterior

head end

\#proximal near center

dorsal toward back

\#contralateral

opposite side

\#distal

toward periphery

\#ventral

toward belly

\#posterior

tail end

\#afferent flow

sensory; carries impulse into region

\#efferent flow

motor, carries impulse away from region

\#white matter

made of axon bundles; white because myelin sheaths cover axons

\#gray matter

made of cell body clusters

\#four cortical lobes

frontal, parietal, occipital, temporal

\#midsagittal view

right and left hemisphere

\#basal ganglia

movement control; coordination, posture

\#limbic system

emotional memory, regulation; emotions that guide that movement; thalamus \= CENTER of brain

\#cerebral cortex

surrounds limbic system, which surrounds basal ganglia, which surrounds thalamus

\#diencephalon

first brain in evolution; powers REFLEXIVE control of behavior; thalamus, hypothalamus, mammillary bodies

\#reticular formation

sleep and arousal; temperature and motor control

\#pons

has motor and sensory nuclei to face

\#medulla

transition of brain to spinal cord; heart rate and breathing

\#cerebellum

motor coordination and learning; underneath occiptal lobe

\#meninges

brain wrappings; CONNECTIVE TISSUE that covers the brain

\#dura mater

topmost layer of brain; tough hard protective

\#subdural space

right under dura mater

\#in between dura mater and pia mater is

CSF (made by ependymal cells); fluid flows inside to outside

\#arachnoid membrane

bottom of subdural space;

\#subarachnoid space

under arachnoid membrane and above pia mater; BLOOD VESSELS run here, full of CSF

\#pia mater

pia \= soft, soft mother, keeps brain moist right above the artery and brain surface

\#cerebral ventricles

make CSF (cerebrospinal fluid) to surround and cushion brain

\#cerebral cortex layers

neocortex; 6 layers, white matter at top - myelin

\#pachygyria

only 3 cortical layers; have profound mental retardation

\#Computerized axial tomography (CT)

DENSITY; X-ray absorption shows tissue density; denser \= whiter; ONLY STRUCTURE

\#what is between the bone and brain, denser than brain, not as dense as bone?

blood

\#Magnetic Resonance Imaging (MRI)

1) strong magnets cause protons in brain tissue to line up parallel
2) pulse of radio waves knocks protons over
3) protons reconfigure, emit radio waves that differ by tissue density

ONLY STRUCTURE
*white areas \= abnormal

\#Positron Emission Tomography (PET)

brain activity; use radioactive chemicals in bloodstream and maps destinations by emissions (shows activity) ; which regions contribute to specific functions; functional CT

\#Functional MRI (fMRI)

METABOLIC ACTIVITY; detect brain metabolism changes, like oxygen use; can show how networks of structures collab; FUNCTIONAL activity of brain (super useful)

\#nucleus

DNA in chromosomes, mRNA transcribe from DNA, gene expression

\#rough ER

membranes with ribosomes, site of protein synthesis

\#smooth ER

regulate cytoplasm

Golgi - stacks of flat membrane compartment packaging products for shipment

\#neuron membrane

lipid bilayer surrounds cell and separates cytoplasm from ECM; charge separator

\#instrinsic proteins

receptors, ion channels; gives properties for signaling

\#microtubules

spirals of tubulin; tracks for movement within neuron; railroad tracks (STATIONARY)

\#neurofilaments

static support structures

\#microfilaments

associated w/cell membrane; double helix actin

\#anterograde transport (what protein?)

kinesin is the enabling protein that allows material to move from soma to terminals along microtubules; MOST MOLECULES are using kinesin

\#retrograde transport (what protein?)

dynein enables material from terminals to soma along microtubules

\#vesicles have

neurotransmitters

\#neuron cytoskeleton

\#larger axon characteristics

more complexity, more distance, faster signal

\#sequence of signals

synapse to synaptic cleft to neuronal membrane to ion channel

\#electrostatic pressure

causes ions to flow to oppositely charged areas (electrical gradient)

\#resting potential

selectively permeable to K+; at rest K+ ions move into negative inside and build up, will diffuse out along concentration gradient (-60 mV)

\#sodium potassium pump

pumps Na+ out and K+ in to maintain resting potential; uses 40% of your brain's energy; if fails, brain dies

\#graded potentials in dendrites

doors open to Na+, rush inside, door closes

\#depolarizing response

positive into the negative cell

\#hyperpolarizing response

adding negative into the negative cell

\#when membrane reaches threshold

triggers action potential; inside cell becomes briefly positive

\#all or none action potential

action potentials increase in frequency with increased stimulus strength

\#hillock (soma to axon)

action potential starts here

\#action potentials increase in what, when stimulus is strengthened?

frequency

\#graded potentials start at the

synaptic site of the dendrite

\#during the absolute refractory period of the Na+ channel

the inactivation gate closes and blocks Na+ from passing

\#action potentials travel in one direction because of

refractory state after depolarization

\#channelopathy

genetic abnormality of ion channels; epilepsy, migraine, weakness

\#when the neurotransmitter binds to the postsynaptic receptor it will cause an

EPSP (more Na+ enters) or IPSP (more Cl- enters)

\#if all IPSPs and EPSPs balance, the determination of action potential will depend on

how close the Na+ ion channel or Cl- ion channel is to the axon hillock; the closer will dictate the event that occurs

\#at the axon hillock there needs to be

enough charge at that location exactly to fire

\#transmitters can bind to presynaptic autoreceptors which

decrease the release of the transmitter; after binding will degrade or reuptaken

\#electrical synapses

ion flow directly into adjacent neurons; no time delay,; faster, synchronized, saves energy (in epilepsy there is a chemical change to this kind of structure); ions pass freely between (problem: every room has the door open; no selectivity)

\#ligands fit receptors to

activate or block them; lock and key

\#endogenous ligands

neurotransmitters and hormones (ex. ACh)

\#exogenous ligands

drugs and toxins from outside body

\#up-regulation

increase in number of receptors (ex: NICOTINE receptors when start smoking; sensitization)