Carlson Bio Bases Ch 2

Front 1

supporting cells of the NS

Back 1

-Chemically and physically protect the neuron.
-surround neuron and hold in place, insulate the neuron, act as housekeepers (clean up dead neurons)

Front 2

Two types of supporting cells of the NS

Back 2

Glia (or neuro glia) and Schwann Cells

Front 3

Glia Cells

Back 3

-most important cells of the NS
-Most important supporting cells of the CNS
-Surround neurons and hold them in place
- Insulate neurons
-“housekeepers” – destroy and remove dead neurons
- Control nutrient supply

Front 4

Phagocyctosis

Back 4

cleaning up the debrea

Front 5

types of glia cells

Back 5

Astrocytes
Oligodendrocytes
Microglia
Radial Glia Cell

Front 6

Astrocytes

Back 6

Glia Cell- most common
-Housekeeper
provides support for neurons in CNS; provides nutrients and other substances; regulates chemical composition of extracellular fluid. Their primary job is to clean the debris.

Front 7

Radial Glia Cell

Back 7

Present in neural development
transport neurons to their final destination in neural development

Front 8

Oligodendrocytes

Back 8

forms myelin sheaths around many axons. Their arms are the myelin. Form the myelin sheath around the central nervous system neurons . Insulate the neuron through myelin. 80% lipid and 20% protein
-Only lives in the central nervous system
-In MS these degenerate

Front 9

Microglia

Back 9

act as phagocytes; protect brain from invading microorganisms aide in the immune system
-Inflammatory reaction of the brain

Front 10

Schwann Cells

Back 10

Located in the PNS and wrapped around a myelinated axon, providing one segment of its myelin sheath

Front 11

Schwann Cells vs. Oligodendrocytes

Back 11

o Schwann = PNS; Oligo = CNS
o Schwann = myelinates one axon; Oligo = myelinates many axons
o Schwann = aide in nerve regeneration; Oligo = no role in nerve regeneration

Front 12

Blood-Brain Barrier

Back 12

-A semi-permeable barrier between the blood and the brain produced by the cells in the walls of the brain’s capillaries
-Selectively permeable – only certain substances can cross
-FUNCTION: regulates balance and composition of fluids
-Transmission of messages from place to place in the brain depends on a delicate balance between substances with neurons and in the extracellular fluid that surrounds them

Front 13

Dendrites

Back 13

-Receive incoming messages from other neurons
-The part of the neuron that is altered during learning (which is growth of new dendrites and branching existing dendrites into more efficient means of communication)

Front 14

Soma (Cell body)

Back 14

the metabolic center of the neuron

Front 15

Axon

Back 15

the long, narrow, process that projects from the cell body
-starts at axon hillock and goes out to the terminal button
-covered by myelin sheath
-Information travels down the axon and goes out the terminal buttons and to other dendrites

Front 16

Nodes of Ranvier

Back 16

-the unmyelinated gaps between sections of myelin
-

Front 17

Myelin sheath

Back 17

a fatty insulin that coats the axon. Facilitates the nerve impulse, conduction of the nerve impulse. Helps the nerve impulse (action potential) to conduct more quickly and efficiently.

Front 18

electrolytes

Back 18

substances with opposing electrical charges

Front 19

ions

Back 19

the movement of the ion across the membrane is key to the action potential
-Negative: anion
-Positive: cation

Front 20

membrane potential

Back 20

balance between (1) diffusion and (2) electrostatic pressure

Front 21

Diffusion

Back 21

process whereby molecules distribute themselves evenly throughout the medium in which they are dissolved (wherever they are)
-seeks to equally distribute the molecules high concen--> low concentration
-contribute to keeping the ion at -70

Front 22

Electrostatic Pressure

Back 22

the force exerted by attraction or repulsion of ions (moves ions)
-rule that says opposites will attract (anions and cations)
have to do with ion movement in and out of the cell

Front 23

Axon Hillock

Back 23

the cone-shaped region at the junction between the axon and the cell body
- where the action potential starts

Front 24

Terminal Button

Back 24

-: has synaptic vesicles which contain neuro chemicals called neurotransmitters.
-Secret neuro transmitters into the synapse (the space between neurons) and the next neibor neuron’s dendrite receives the message

Front 25

Synapses

Back 25

gap between terminal button and dendrite
-chemical signals are transmitted

Front 26

Synaptic Vesicles

Back 26

-tiny packets of neurotransmitter molecules they tend cluster in button next to the presynaptic membrane

Front 27

four IONS

Back 27

Sodium: NA+, mostly lives outside cell
Potassium: K+, naturally lives inside the cell
Chloride: CL-, primarily outside cell
Anion: A-, only found inside the cell, can not move, organic ion

Front 28

Axondendrite synapses

Back 28

synapses on dendrites
-receives information on the dendrite and takes the action potential down the axon

Front 29

Axosomatic synapses

Back 29

synapses onto cell bodies
-the soma receives the message,

Front 30

Axoaxonal synapses

Back 30

synapses onto axons
-information is received by the axon on the node of ranvier

Front 31

Cell membrane

Back 31

the semipermeable membrane that encloses the neuron
-Composed of a double layer of lipid layer

Front 32

cytoplasm

Back 32

the clear liquid of the neurons interior
-Gives the cell it’s bulk

Front 33

Contents of the cytoplasm

Back 33

o Mytochondria: little oval beads: provide energy for the cell
--Provides Adenosine triphospate (ATP)-which converts food into energy
o Microtubules: transport substances within the cell
--Axoplasmic transport
o Endoplasmic Reticulum: serves as a storage reservoir in the neuron. Involved in the production of protein.

Front 34

- The Golgi apparatus

Back 34

serves as the wrap and package of the neuron

Front 35

Sodium potassium pump

Back 35

live inside cells, roam around and escort out sodium
-force that continuously pumps Na+ out of axon

Front 36

Sodium-potassium transporters

Back 36

protein found in the membrane of all cells that exchange Na+ for K+
-Exchange = 3 Na+ OUT and 2 K+ IN

Front 37

presynaptic membrane

Back 37

The membrane of the transmitting neuron =

Front 38

postsynaptic membrane

Back 38

Message is received by the

Front 39

synaptic cleft

Back 39

These 2 membranes are separated by a small ga

Front 40

3 Ways Synaptic Vesicles Release NT

Back 40

1) kiss and stay- the vesicle fuses with the postsynaptic membrane and releases some NT, and then the fusion pore closes, sealing the vesicular membrane again. The vesicle remains in place.
2) Kiss and Leave: The vesicle releases NT and reseals but it leaves the docking site and mixes with other vesicles in the terminal button.
3) Merge and Recycle: The vesicle completely fuses with the postsynaptic membrane, losing its identity. Extra membrane from fused vesicles pinches off into the cytoplasm and forms endosomes, from which new vesicles are produced.

Front 41

NT open ion channels by 2 methods

Back 41

1) direct (ionotropic)
2) Indirect (metabotropic)

Front 42

Decremental conduction

Back 42

when a subthreshold depolarization is applied to the axon, the disturbance in the membrane potential is largest near the stimulating electrode and gets progressively smaller as it moves down the axon

Front 43

Saltatory Conduction

Back 43

conduction of AP in a myelinated axon
-dances all the way down the axon
-Axon passively conducts electrical disturbance from node à node

Front 44

2 Advantages of Saltatory Conduction

Back 44

1) ECONOMIC – because Na+ can enter axon ONLY at nodes of Ranvier, less gets in and less needs to be pumped out – expends less E to maintain Na+ balance- protects against static
2) SPEED – transmission between nodes is fast

Front 45

Synaptic transmission

Back 45

primary means of communication b/w neurons – transmission of messages from one neuron to another via a synapse

Front 46

Postsynaptic potentials

Back 46

brief depolarizations or hyperpolarizations that increase or decrease the rate of firing of the postsynaptic axons
--Produced by NT released at the synapse

Front 47

Binding site

Back 47

– location on a receptor protein to which a ligand binds

Front 48

Ligand

Back 48

location on a receptor protein to which a ligand binds
--Shape of NT and shape of binding site are complementary!!

Front 49

Structures Found in the Terminal Button

Back 49

1) Microtubule – transports material between the soma and terminal button
2) Mitochondria – suggests that the terminal button needs E to perform its functions
3) Synaptic vesicle – small, rounded objects in shape of spheres or ovoids – found in terminal button

Front 50

Postsynaptic density

Back 50

postsynaptic membrane under the terminal button – caused by the presence of receptors and protein filaments that hold the receptors in place

Front 51

Small synaptic vesicles

Back 51

-contain NT molecules
-Produced in the Golgi apparatus – located in soma
-Carried by fast axoplasmic transport – to terminal button

Front 52

Large synaptic vesicles

Back 52

--large-dense core vesicles – contain one of the peptides
--Produced in the soma
--Transported via axoplasm to terminal button

Front 53

Proteins

Back 53

--Transport proteins – fill vesicles with NT
--Trafficking proteins – involved in the release of NT and recycling of vesicles

Front 54

Release of Neurotransmitter

Back 54

When AP arrives at the terminal button – several synaptic vesicles (inside presynaptic membrane) fuse with membrane and break open, spilling their contents into the synaptic cleft

Front 55

Activation of Receptors

Back 55

1)Once NT reaches other end of synaptic cleft, they attach to binding sites of postsynaptic receptors
2) When binding occurs, postsynaptic receptors open NT-dependent ion channels and permit the passage of specific ions into or out of the cell
----Presence of NT in synaptic cleft allows particular ions to pass through the membrane, changing local membrane potential

Front 56

Ionotropic Receptors

Back 56

Direct opening
NT binds--> ion channel opens--> ions enter

Front 57

Metabotropic Receptors

Back 57

Most Common mode
Chain of chemical events that open the door
1. NT binds to receptor
2. activates G potein (live in Postsynaptic membrane)
3. activates enzyme which activates second messenger
4. Second messenger is activated then it opens ION channel
5. Once ION channel is open then ION can enter cell

Front 58

Postsynaptic potential is determined by?

Back 58

The ION

Front 59

Excitatory Postsynaptic potential

Back 59

depolarization
NT-dependent Na+ channel – MOST IMPORTANT SOURCE OF EPSPs!!

Front 60

MOST IMPORTANT SOURCE OF EPSPs

Back 60

NT dependent Na+ channel

Front 61

Reuptake

Back 61

collection of NT just liberated by terminal button back into its membrane and is repack/wrapped into a vesicle

Front 62

Enzyme deactivation

Back 62

Enzyme destroys deactivation

Front 63

Acetylcholinesterase (AChE)

Back 63

Enzyme that destroys Ach (acetylcholine)

Front 64

Na+

Back 64

enters ION channel
depolarizes

Front 65

K+

Back 65

leaves ION channel
hyperpolarization

Front 66

Cl-

Back 66

enters ION channel
Hyperpolarization

Front 67

Calicium (Ca2+)

Back 67

Activates enzyme which acts as secondary messenger

Front 68

Two other molecules that chemical communication

Back 68

1. Neuromodulators
2. Hormones

Front 69

Neuromodulators

Back 69

A naturally secreted substance that acts like a NT except that it is not restricted to the synaptic cleft but diffuses through the extracellular fluid

Front 70

Hormones

Back 70

– chemical substances released by endocrine glands that have effects on target cells and other organs