Vert. Phys. Exam #1

Front 1

• Dendrites

Back 1

receive synapses from axon terminals. Site that is innervated by other neurons. Presence of ribosomes is only in dendrites, not axons. Contain all organelles located in cell soma unlike axons.

Front 2

• Myelin Sheath

Back 2

membrane wrapping axon. Interrupted by openings known as nodes of Ranvier. They function to increase speed and are generated by glial cells.
• Since lots of protein in synthesized, most neurons contain large quantities of RER. Dense accumulations are called Nissl bodies.

Front 3

• Axon terminals

Back 3

axon usually divides into several fine branches called terminals

Front 4

microtubules

Back 4

25nm; tubulin; form longitudinally oriented filaments in axons and dendrites; aid in axoplasmic transport (supported by blockage of transport caused by drugs that degrade microtubules

Front 5

• Axoplasmic transport

Back 5

axons lack ribosomes so protein supplied form cell body. Demonstrated by ligating axon and observing accumulation of materials on the side of the ligation spot in the soma. Microtubules also aid in the transport.

Front 6

• Glial cells (neuroglia

Back 6

large part of nervous system. Do no generate nerve impulses; maintenance and support of nerve cells.

Front 7

• Afferents

Back 7

convey nerve impulses toward CNS (ex. Sensory axon)

Front 8

• Efferents

Back 8

Convey nerve impulses away from CNS (ex. Motor neuron)

Front 9

• Interneurons

Back 9

neuron that is both innervated by and innervates only other neurons. Motor and sensory neurons are not interneurons. Most neurons are interneurons. People used to think neurons were syncytium. Golgi developed staining technique to disprove.

Front 10

Santiago Ramon y Cajal

Back 10

took up Golgi technique and found elements of nervous system. They are said to be the greatest neuroscientists ever. Together with Golgi they got the Nobel Prize. Ross Harrison invented tissue culture to show axons grew in tissue culture as independent processes

Front 11

Nerve

Back 11

A collection of axons

Front 12

Local potential

Back 12

its amplitude and duration are variable
- graded nature meaning its magnitude and duration depend upon the magnitude of the event producing the potential. The stronger the magnitude the larger the local potential

Front 13

Reflex

Back 13

A sterotyped and simple motor response to a sensory stimulus.

Front 14

Nissl substance

Back 14

Ribosomes in nerve cell bodies

Front 15

Chromatolysis

Back 15

A response of a neuron to section of its axon (axotomy)

Front 16

Kinesin

Back 16

promotes movement of materials along microtubules

Front 17

Ramon y cajal

Back 17

founded modern field of neuroanatomy

Front 18

Hodgkin and huxley

Back 18

explained the action potential in squid axon

Front 19

Neher and Sakmann

Back 19

discovered patch clamp

Front 20

Dorsal root

Back 20

Nerve for afferent axons

Front 21

ventral root

Back 21

nerve for efferent axons

Front 22

gray matter

Back 22

area in CNS lacking myelination

Front 23

ventral horn

Back 23

location of motor neurons in the spinal cord

Front 24

dorsal root ganglion

Back 24

cell bodies of sensory neurons are located here.

Front 25

Ohms Law

Back 25

V=IR

Front 26

Capacitance

Back 26

C=Q/V

Q=charge
V=voltage

Front 27

Bernstein

Back 27

Proposed membrane were impermeadble to all ions except K and resting potential arose due to concentration gradient across the membrane.

Front 28

The Nernst Equation

Back 28

-Statement of equilibrium condition for a single ion species across a membrane.
- E=58/z log [I]o/[I]i
-E refers to equilibrium potential
-this allows one to compute the transmembrane potential a given concentration gradient will produce if the ion is at equilibrium.
-a negative E means the ion wants to leave the cell. (like K+).

Front 29

Driving force

Back 29

The difference b/w the membrane potential (-65) and the E of the particular ion. ex. chloride has small drivng force since it has -67 E.

Front 30

Equation to predict membrane potential (GHK)

Back 30

Vm = 58log P (Na)o + P (K)o + P (Cl)i divided by the opposite of each.

- P = permeability to ion
-Vm = membrane potential

Front 31

Resting potential

Back 31

-K+ is main contributor by diffusing across the membrane separating charge.
-Na and K pump is ultimately needed to maintain it. If blocked, RP will disappear.

Front 32

gNa

Back 32

increase in sodium permability of membrane.
- goes up due to depolarization and then Ina goes upas well therfore allowing more sodium into the cell.
- this is the positive feedback that drives the action potential.

Front 33

Nerve Threshold

Back 33

INa = -INa

depolarization of membrane increases both INa and IK. By positive feedback INa will make the membrane depolarize more. IK causes the membrane to hyperpolarize.
-whichever current predominates determines whether you get an AP
-If INa > IK you get an AP`

Front 34

What happens to K in response to small depolarizations>

Back 34

It moves out!
- IK = gK(Vm-EK).

- as Vm becomes more positive the driving force becomes larger so Ik increases

Front 35

TTX

Back 35

BLocks Na channels so inward current of voltage clamp disappears.

Front 36

TEA

Back 36

loss of delayed outward and only leaves early inward Na ions.

- if Nao = 0 then Na will run down new concentration gradient outward

Front 37

lessons we learned from the patch clamp

Back 37

behavior of individual channels is statistical
-the probability of a channel opening is dependent on the voltage
- channels have very high conductances that open and close unitary very rapidly
-macroscopic events from the voltage clamp technique is simply a summation of all the individual channels