Physio Test 3

Front 1

What happens during cell division?

Back 1

Cell division begins anout 12 hours after conception and within 3 days the new person is a cluster of homogenous cells resemling a cluster of grapes.

Front 2

Whats the difference between an embryo and fets?

Back 2

An embryo is the term for the new person in the first 8 week after conception.
A fetus is the term from 8 weeks till the end of the pregnancy.

Front 3

What big thing happens in week 2 after comception?

Back 3

Cell division continues and forms 3 distinct layers of cells called endoderm,mesoderm, and ectoderm.

Front 4

What is the endoderm?

Back 4

The innermost layer which forms the gut and other internal organs.

Front 5

What is the mesoderm?

Back 5

The middle layer which forms the muscle bone cartilidge, bone vessels, blood and urogenital system.

Front 6

What is the ectoderm?

Back 6

The outer layer which will form the nervous system and skin.

Front 7

How long does cell division last?

Back 7

cell division continues till the person is fully formed

Front 8

How many stages are there in the development of the nervous system?

Back 8

eight

Front 9

what is stage 1?

Back 9

Induction of the neural Plate and Formation of the neural tube

Front 10

What happens to the three layers of the embryo in stage 1?

Back 10

The cells continue to divide and the three layers thicken and take an oval shape.

Front 11

What is the neural plate?

Back 11

The neural plate is a tissue that will form the human nervous system. it becomes recognizable on the dorsal side of the ectoderm

Front 12

How does the neural plate form?

Back 12

the production of the neural plate is induced by chemical signals released from the dorsal surface of the mesoderm layer immediately beneath it.

Front 13

What happens to the neural plate?

Back 13

After 2-3 days its edges or neural folds push up to form th neural groove. The fold continue to push up and after about 23 days post conception they come together to form the neural tube.

Front 14

What major parts are formed from the neural tube?

Back 14

The neural tube becomes the ventricles and the spinal cord. Once formed it sinks down and looses connection with the ectoderm of the surface.

Front 15

What becomes of the neural folds?

Back 15

They become the neural crest and eventually break away and form the neurons and glial cells of the peripheral nervous system

Front 16

what is step 2?

Back 16

Proliferation-The rapid increase in the number of neurons that occurs after formation of the neural tube, as cells of the nervous system tissue.

Front 17

What new developments happen in the fourth week?

Back 17

Distinct areas of the brain beggin to ppear at the anterior end of the neural tube the spinal cord begins to develop of the posterior end of the tube.

Front 18

How many cells are created per minute from this point(proliferation) on?

Back 18

250,000 per minute till birth

Front 19

what is stage 3?

Back 19

Migration- the movement of cells from their site of creation in the neural tube or neural crest to their location inthe mature nervous system.

Front 20

How do the neurons get to their proper location?

Back 20

Neurons get ther in two ways, radial glial cells which act like rungs or railing the neurons pull themselves along. Neurons from the nural crest are guidd by special chemicals that attract or repel them.

Front 21

What is stage 4?

Back 21

Aggregation- The process wherby neurons that have migrated to the same location align themelves properly to form the structures of the nervous system.

Front 22

What is stage 5?

Back 22

Differentiation-the process whereby a neuron takes on the specific characteristics it will hae as a mature neuron(type of dendrite, axon, or neurotransmitter).

Front 23

what is cell-autonomous differentiation?

Back 23

A process where differentiation occirs without outside influence (is generally programmed).

Front 24

what is induced differentiation?

Back 24

A process where neurons rely on the influence of other cells to determine their final form.

Front 25

What is stage 6?

Back 25

The process whereby axons from the appropriate synaptic connections with their target cells (muscles, glands, or other neurons).

Front 26

What is a growth cone and what does it do?

Back 26

It is at the end of the drowing tip of an axon and is a n moebalike structure with microspikes or filopodia which extend like fingers testing the environment.

Front 27

How do neurotrophins relate to growth cones?

Back 27

During the last leg of the growth cones journey it is guided to its terget site by neurotrophins.

Front 28

What is stage 7?

Back 28

Selective cell Death- the process wherby excess axons and those that have arrived at the wrong location are eliminated.

Front 29

How are neurotrophins related to selective cell death?

Back 29

They guide axons to the target site and also decide what axons will survive. If neurons are not stimulated by neurotrophins then they will die this happens to about 50% of the neurons which reach their target.

Front 30

Whats te difference between apoptosis and necrosis?

Back 30

Apoptosis is when neurons are no longer stimulated by neurotophins and commit suicide.
Necrosis is when cell die by injury or exposure to a toxin.

Front 31

What are other functions of neurotrophins?

Back 31

They facilitate memory formation by being secreted and increasing the branching o axons during new experiences.
Also during nervous system injury they decrease pain and increase regrowth of damages axons.

Front 32

What is stage 8?

Back 32

Functional Validation-Theprocess whereby synaptic connection that survive the stage of selective cell death above are strengthened by environmentally induced neural activity. Those synaptic connections that do not recieve environmental stimulation will weaken and die out. This is sometimes known as the "use it or loose it" principle.

Front 33

What are the stages of neural degeneration and neural death?

Back 33

Anterograde degeneration,retrograde degeneration, chromatolysis, transneural degeneration (anterograde and retrograde degenerations)

Front 34

look at drawings/book for nerual death stages definitions

Back 34

did you look?

Front 35

How is the PNS able to recover after damage in certain situations?

Back 35

Schwann cells secrete neurotrophins which stimulate regrowth of the injured axon which is the opposite of what their CNS counterparts do.
The schwann cells also produce sdhesion molecules and guise the regrowth of axons back to their original target sites.

Front 36

Other responses to neural injury.

Back 36

collateral sprouting- neighboring neurons sprout new axonal endings to fill in the receptor sites that had died

Denervation Supersensitivity-heightened sensitivity to a neurotransmitter of the target cell after an incoming axon that has released that neurotransmitter dies. Resulting in an increase in te number of receptor ssites on the postsynaptic cell and an increased effectiveness of the existing sites.