Biopsych Lecture 2

Front 1

Behavior

Back 1

an output of the brain resulting from neural processing of external and internal information

Front 2

Neurons

Back 2

electrically active and responsive to chemical signals

Compute, communicate, transmit information

Front 3

Information processing

Back 3

a product of electrical and chemical activity in the brain

Front 4

Parts of the neuron + how they function together

Back 4

Soma (5-50 micrometers)
Axon (axons can be few microns - centimeters in brain to spinal cord)
Axon terminals (synaptic terminals = 1microm.)

Input goes from soma, through axon, to axon terminals

Front 5

3 key concepts about neurons

Back 5

1)Small
2) Terminate in thousands of branches
3) Vary in length

Front 6

Approx how many neurons are there in the brain?

Back 6

More than 100 billion!
(1000 km laid side by side)

Front 7

The adult human brain weighs...

Back 7

3 lbs

Front 8

3 different types of neurons

Back 8

Multipolar, bipolar (usually sensory, processing occurs in middle in soma), unipolar (also often sensory)

Front 9

Nissl stains of nucleus reveal

Back 9

dense packing of neurons (located in nucleus), white matter (contains axons), purple part/gray matter (contains cell bodies), holes in center = ventricles
dense packing in hippocampus

Front 10

What is the function of glial cells? What are 2 main types?

Back 10

To support neurons, gather up/recycle NT . Astrocytes and oligodendrocytes

**Microglia clean up after neuron

Astrocytes support neuron

oligodendrocytes wrap axons with fatty sheath, myelin, to speed up conduction in CNS

Front 11

Node of ranvier

Back 11

gap in the sheath that exposes bare axon

Front 12

Schwann cells

Back 12

also form myelin but only in PNS

Front 13

Multiple sclerosis

Back 13

a demyelinating disease - myelin lost = poor communication in neurons

Front 14

Axons

Back 14

transmit information from input to output w/ action potentials

Front 15

Dendrites/Soma

Back 15

Integrate information - gather information from other neurons, have a branched arborization pattern

Front 16

Axon hillock

Back 16

part connecting soma to axon, integrates electrical activity from the dendrites to trigger action potentials (if threshold met)

Front 17

Axon terminals

Back 17

Contain synapses that release neurotransmitters to transmit info to post-synaptic neuron, can both diverge and converge

Front 18

Key parts of the synapse

Back 18

1) Presynaptic membrane - on axon terminal of pre-synaptic neuron
2) Postsynaptic membrane - on dendrite/cell body of of postsynaptic neuron
3) Synaptic cleft - gap that separates the membranes

Front 19

Electron microscopy can be used to look at...

Back 19

thin tissue samples (sliced like bread from large brain), high synaptic density, neurons

Front 20

Neurons transmit information how?

Back 20

Electrical and chemical activity across neuronal membrane

Front 21

The neuron membrane is..

Back 21

a impermeable lipid bilayer (hydrophobic tails, hydrophillic heads). Protein ion channels allow semipermiability

Front 22

Distribution of ions across membrane is tightly regulated. Ion balance depends on:

Back 22

Chemical concentration gradient
Electrical gradient
State of protein ion channels (open/closed)

Front 23

Describe neurons in resting state

Back 23

1) Extracellular [Na+] high
2) Intracellular [K+] high
3) Na+ permeability low
4) K+ permeability high

**more positive outside, negative inside cell

Front 24

Why doesn't all K+ ions leave to one side?

Back 24

because electrical/concentration gradients stay about balanced

Front 25

What are the two opposing forces that drive ion movement

Back 25

1) Diffusion - causes ions to flow from areas of high -> low concentration along a concentration gradient

2) Electrostatic pressure causes ions to flow towards oppositely charged areas

Eventually a balance between the two is reached

Front 26

Sodium potassium pump function

Back 26

Moves 3Na+ out, 2K+ in So that there are a lot of Na+ outside, a lot of K+ inside

Front 27

Function of K+/Na+ channels in resting state?

Back 27

K+ is open, K+ flows outward because of concentration gradient and inward due to voltage (electrostatic) gradient. K+ reaches equilibrium

Na+ (and large protein anions) does nothing since gates are closed

Result = negative resting potential (more positive outside) of about -60V, as a consequence of K+ movement (which is why it's closer to Ek)

Front 28

The voltage at equilibrium is called...
What is it a function of?
What can it be calculated with?

Back 28

the Equilibrium potential of K+, which is a function of the concentration gradient, and can be calculated w/ Nernst equation

Front 29

Steps of action potential (lecture 3)

Back 29

SETUP (from resting state)
a) Sodium potassium pump moves 3Na+ out, 2K+ in
b) There are lots of K+ inside and Na+ outside. More + charge outside cell. This is due to high permeability to K+ but NOT Na+ in resting state


MAIN STEPS
1) Stimulus causes Na+ gate to open, Na+ floods into cell, potential increases, causing Na+ gate to close
2) K+ gate opens, K+ floods out of cell. Charge becomes too low, K+ gate closes
3) return to resting potential, action potential continues down axon

Front 30

Need to study!

Back 30

1) Action potential voltage curve
2) What anatomy of neuron looks like (label)

Front 31

Definitions from book to know

Back 31

All-or-none property (threshold)
Local potential
Graded response
Afterpotential
Absolute/relative refractory
Conduction velocity + size of axon
Saltatory conduction
Postsynaptic potential

Front 32

Different neuron structures/shapes signify

Back 32

Different purposes. Large arborization = collecting info from a large area.

Locust/invertebrate neuron is large, no myelenation, small number of neurons, same neuron configuration for each locust in same spot.
Used for experiments

Front 33

Brain sizes

Back 33

Elephant/other animals
Do we need to know this???

Front 34

Brownian motion

Back 34

concentration goes from high to low

Front 35

How do you measure intracellular potentials?

Back 35

Insert electrodes (reference = outside, recording = inside) , use amplifier, read recording

Front 36

Current can be injected into neurons but they are...

Back 36

graded potentials (they dissipate) . If you can depolarize to threshold, an AP will occur. You can also hyperpolarize the neuron.

****AP LOOKS REVERSED! Due to...?