bio 93 final kms (nervous system)

Neurons

nerve cells that transfer info within body

electrical signals

used for long distance (down axon), convert to chemical

chemical signals

used for short distance (down synapse)

Ganglia

where processing of info takes place, cluster of neurons

axon

where electrical signals travel away from cell body

synapse

junction between axon and another cell

synaptic terminal

swollen ending of a neuron's axon, where neurotransmitters (chemical signals) are released

Glia

cell that insulates/nourishes neuonrs

Astrocytes

support neurons/form blood-brain barrier

Ependymal

proomote circulation of spinal fliud

Microglia

protect nervous system from microorganisms

Oligodendrocytes/Schwann Cells

form myelin sheaths around axons

membrane potential

difference in electrical charge across plasma membrane

messages are transmitted as

changes in membrane potential

resting potential

membrane potentnail of neuron not sending signals

K+ concentration at resting potential

is greater inside the cell

Na+ concentration

is greater outside the cell

NA+-K+ pumps

use ATP to keep K+ concentration greater inside and N+ concentration greater outside

NA+ is pumped

out of cellls, 3 at a time

K+ is pumped

into cell, 2 at a time

leak K+ channel

always open, allow K+ to leak out of cell to set resting potential

Opening of Ion channels

convert chemical potential to electrical potential

voltage Gated Ion Channels

open/close in response to stimuli (change in voltage)

Voltage gated K+ channel

restore membrane potential after depolarizarion, delayed efflux of K+

Voltage gated Na+ channel

depolarize membrane during action potential, rapid influx of Na+, CLOSED at resting potential

Voltage gated Ca+ channel

open when membrane deppolarizes and lets Ca+ in, Important for synaptic release

Depolarization

Graded Na+ channels open, Na+ diffuse into cell, membrane potential becomes less negative

Generation of Action Potential

-55mv electrical charge needed to to trigger action potential, )all or nothing(, no graded response

Refractory Period

After action potential, 2nd action potentnial can start, result of temporary inactivation of Na+ channels

the speed of an action potential is increased

with diameter, by a myelin sheath insulation axons

Node of Ranvier

where action potentials are formed, gaps in myelin sheaths where voltaged gated Na+ channels are

saltatory induction

jumping of action potentials from one node to another in myelinated axons

at electrical synapses

electric current flows from neuron to neuron

at chemical synapses

chemical neurotransmitters carries info across synaptic cleft (most of our synapses)

Arrival of the action potential at the synaptic terminal

depolarizes membrane, opening voltage gated channels that allow Ca2+ to diffuse in

Ca2+ in synpatic terminal

triggers vesicles to fuse with the membrane, releasing neurotransmitters

neurotransmitters diffuse across synaptic cleft

bind to ligand-gated ion channels in post-synaptic membrane, opening channels

postsynaptic potential

change in membrane potential of postsynaptic cell from opening of ligand-gated ion channels by neurotransmitters

temporal summation

2+ Excitatory Postsynaptic Potential (EPSP) produced in rapid succession, triggers action potential

spatial summation

EPSPs produced at the same time by different synapses on the same postsynaptic neuron add together

Temporal and Spatial Summation

result in depolarization of membrane such that threshold potential is reached and action potential is fired

after release, neurotransmitters may

diffuse out of cell, taken by other cells, degraded by enzymes

Acetylcholine

type of neurotransmitter involved in muscle stimulation, memory formation, and learning, has ligand-gated and metabotropic receptors

Biogenic amines

derived from a.a, serotonin, dopamine, epinephrine, norepinephrine affect sleep, mood, attention, learning, and memory

recombinant DNA

nucleotide sequences from two different sources are combined in vitro into same DNA molecule

Plasmids

small circular DNA molecules that separate from bacterial chromosome

Bacterial Plasmids are used for cloning because

readily obtained, easily manipulated, easily introduced in bacteria cell rapidly mulitplied once in the bacteria

cloning vector

the original plasmid in dna cloning, carries foreign DNA into host cell and replicate

restriction enzymes

cut up foreign DNA at specific sequences (restriction sites)

DNA ligase

enzyme that seals bonds between restriction fragments

Cas9

protein that can be used to direct precise cutting of DNA sequences, which are repaired by custom repair RNA template

Dolly the lamb

lamb cloned from adult lamb, suggested reprogramming of original transplanted nucleus was incomplete, demonstrates that cloned animals do not always end up identical to donor

Stem Cell

relatively unspecialized cell that can reproduce
itself indefinitely and differentiate into specialized cells of one or more types