CH2 - Cells of nervous system

Question 1

Neurons - other cell structures

Answer 1

Membrane
Cytoskeleton (3 kinds of protein strands, including microtubules)
Cytoplasm (contains mitochondria)
Nucleus (chromosomes consisting of DNA)

Question 2

Dendrite morphology

Answer 2

Stellate (star-shaped) or pyramidal cells

Spiny or aspinous

Question 3

Neurotransmitters

Answer 3

Adrenaline - fight or flight
Noradrenalin - concentration
Dopamine - pleasure
Serotonin - mood
GABA - calming
Acetylcholine - learning
Glutamate - memory
Endorphins - euphoria

Question 4

Glial cells

Answer 4

Astrocytes - most abundant, neurite growth, physical support, chemical content of extracellular space

Ependymal cells - line brain ventricles, produce CSF, cushion & removes waste, protection against viral infection

Microglia - immune, phagocytoses

Oligodendrocyte (CNS)/Schwann cells - myelination

Question 5

Resting membrane potential for diff cells

Answer 5

neuron - -60 to -70 mV
astrocytes - 80-90
skeletal muscle - 95
smooth muscle - 60

Question 6

RMP

Answer 6

outside: NaCl, Ca2+
inside: A-, K

Na K pump - uses 40% metabolc resources, 3 Na out, 2 K in???

Question 7

Electrical potential graph

Answer 7

Threshhold of exctation - depol (influx of Na) - repol (efflux of K) - hyperpol - refractory period (extra K outside diffuses away)

Question 8

Explosive/Hodgkin cycle

Answer 8

Depol - opens na channels - na influx -

Question 9

4 diff types of ion channels

Answer 9

Na in - excitatory postsynaptic potential (EPSP) → depolarization (goal =change Vm)
K out - inhibitory (IPSP(GABA example)) → (re&) hyperpolarization
Cl (only if membrane depolarized) in - neutralizes EPSP→ repolarization
Ca in - (EPSP) → depolarization, Ca also bins w enzymes

H-gate (Na out, closes once peak Vm), M-gate (Na in, closes at rest), n-gate (k out, opens during falling phase)

Question 10

Direction of conduction

Answer 10

Orthodromic - soma –> axon –> axon terminal

Antidromic - experimental

Question 11

typical action potential

Answer 11

10 m/sec conduction velocity * 2 msec = 2 cm long axon

Question 12

AP paths

Answer 12

Inside axon vs across axonal membrane (narrow, many open pores, slower)

Question 13

synaptic cleft

Answer 13

20-50 nm space filled w matrix of fibrous extracellular protein (glue)

Question 14

Synaptic arrangements

Answer 14

Axodendritic (axon to dendrite) (axospinuous (axon to dendritic spine))
Axosomatic (axon to cell body)
Axoaxonic (axon to axon)

Question 15

AP –> NT release

Answer 15

depol of terminal membranes –> Ca2+ channels open –> flood in –> NT released via exocytosis 0.2 msec of Ca influx

Question 16

Types of neurotransmitters

Answer 16

Transmitter-gated (ligand gated, ionotropic) - amines & AA, fast
G-protein coupled (metabotropic) - like most autoreceptors

Question 17

excitatory vs inhibitory NTs general rule

Answer 17

Permeable to Na –> excitatory

Cl –> inhibitory

Question 18

2 types of EPSP summation

Answer 18

Spatial summation = generated spontaneously at diff synapses in same dendrite
Temporal summation = generated at same synapse in rapid succession (1-15 msec)

Question 19

Shunting inhibition

Answer 19

Synapse inhibits current flow from soma to axon hillock

Question 20

Nonsynaptic chemical communication

Answer 20

Neuromodulators - released by neurons that travel farther & dispersed more widely (most are peptides)

Hormones - secreted by endocrine glans or cells - target cells contain receptors for particular hormones