Nerve Cells

Question 1

What are the five neuralgia cell types and what are their functions?

Answer 1

1. ependymal-produce CSF
2. astrocytes- have a number of processes that come off the cell body, highly specialized and give support, produce substances needed by the nervous tissue sustain them
3. oligodendricytes-interact with multiple axon with cells found in CNS, insulate the axon by producing the myelin sheath
4. Schwann cells-form the myelin sheath around single axon in the PNS
5. Microglia cells- are amebocyte cells that take care of microbes that penetrate and get into the CSF

Question 2

What are the functions of the cerebral spinal fluid?

Answer 2

1. provides cushion
2. Shock absorber
3. Allows the vertebrates to isolate the CNS from the rest of the body, very few places where blood and csf meet blood brain barrier

Question 3

What is the difference between the oligodendricytes and the Schwann cells?

Answer 3

Oligodendricytes form the myelin sheath around multiple axons in the CNS and the Schwann cells form the myelin sheath around a single axon in the PNS

Question 4

What is the cell body in neurons called?

Answer 4

soma

Question 5

You can have many many what but only on what in a typical nerve cell?

Answer 5

many dendrites

only one axon

Question 6

What is the function of dendrites?

Answer 6

Receive the signal and pass it onto the soma

Question 7

What are the gaps in between the section of myelin sheath produced by the Schwan cell on the anon?

Answer 7

Nodes of Ranvier

Question 8

What are the axonal batons?

Answer 8

The tips of the coaxons and they are swollen a little. They contain a lot of activity and store vesicles that contain neurotransmitters.

Question 9

What is the area called on the axonal baton?

Answer 9

Pre synaptic membrane

Question 10

How are neurons connected together?

Answer 10

A actional potential finds it way down the axon sweeps past the axonal baton causing the release of Ca2+

Release of Ca2+ mobilizes vesicles containing the neurotransmitters and they are released into the synapse/nexus/synaptic gap by exocytosis

The neurotransmitter substances migrate across the synapse from the pre synaptic membrane and bind to the post synaptic membrane (dendricytes) and this binding to the receptors open ligand gated channels.

the flow across the ligand gated channels cause the voltage gated channels to open causing an action potential on subsequent neuron

Question 11

You don’t want the continuous flow and release of the neurotransmitter substances so how do you turn them off/get rid of them?

Answer 11

Allow them to diffuse into interstitial fluids. Can also be taken into the next neuron by endocytosis and broken down inside the cell. A final case is the presence of enzymes that once the neurotransmitter is used it is cleaved by the enzyme. Only want the signal to come across one time.

Question 12

Why do we use one neurotransmitter for each signal and move from neuron to neuron?

Answer 12

SO you have signal transduction without decrement (loss of signal strength). Neuron to neuron without losing signal strength.

Question 13

WHat are the four classic neurotransmitter substances?

Answer 13

1. norepinephrine(noradrenaline)
2. epinephrine(adrenaline)
3. acetylcholine
4. gama aminobuteric acid (GABA)

Question 14

What keeps an action potential from only going in one direction within a cell?

Answer 14

The absolute refractory period

Question 15

What keeps the action potential from only going one direction between the neuron?

Answer 15

They are only receptors for the neurotransmitter present on one side of the synapse.

Question 16

What are the three morphological classifications of neurons?

Answer 16

1. multipolar-CNS, multiple dendrites single axon
2. bipolar-2 processes
3. unipolar-single process that splits and goes in two directions

Question 17

What do unipolar neurons make up?

Answer 17

interneuron nets

Question 18

How do you classify neurons based on function?

Answer 18

conduction rates of neurons

Question 19

Invertebrates tend to have faster or slower rates of conduction compared to vertebrates?

Answer 19

slower

Question 20

Three factors that determine the speed at which nerves conduct their impulses?

Answer 20

1. Type of synaptic connection you have
2. Diameter of the neuron
3. Axonal modifications

Question 21

What are specialized gap junctions?

Answer 21

specific spots where there is no synaptic gap/cleft between the pre synaptic membrane and the post synaptic membrane

Question 22

What are the low resistance electrical pathways? And what type of transmission is associated with this structure?

Answer 22

Joining of the cytosol from one cell to the next using specialized gap junctions. Ephaptic transmission is associated with this and it is much faster.

Question 23

Why are low resistance electrical pathway, also called septal synapses, unpolarized?

Answer 23

Current can move back and forth although we do not know why

Question 24

How does diameter affect the speed of conduction?

Answer 24

Increase the diameter allows you to move more quickly down the nerve fiber

Question 25

What is the equation for the rate of conduction in regards to diameter?

Answer 25

u(transmission velocity)=k(animal specific fiber constant) multiplied by the square root of d(diameter)

Question 26

Why do invertebrates use giant neurons as an axonal modification?

Answer 26

to increase speed for escape responses ex: worm cockroach frog on lily pad

Question 27

What axonal modifications do vertebrates use?

Answer 27

myelin sheath to insulate the neurons to increase speed

Question 28

What are Mauthner fibers in fish?

Answer 28

giant neurons in fish fast escape

Question 29

How are the nodes of ranvier an axonal modification to neurons?

Answer 29

they are evenly spaced and appropriately spaced that they are not too many nodes and if there us a disturbance in one node there is a subsequent disturbance in another node

Question 30

What is the saltatory conduction?

Answer 30

Conduction that jumps from node to node in nerves and is fast and only a few ions needed for an action potential which shorten the absolute refractory period allow quick repolarization

Question 31

Do invertebrates have myelinated nerves? If so how do they differ from vertebrate myelinated nerves?

Answer 31

Yes. They differ by:

1. Not as many myelin layers around the axon
2. pockets of fluid in between the wrappings, no fluid in between wrapping of myelin in vertebrates
3. Loosely arranged, sloppier