Development

Question 1

What is embryonic development?

Answer 1

stage during which all major organs systems are established

Question 2

What is the post-embryonic development stage?

Answer 2

during which growth and refinement of such systems takes place

Question 3

What are the 5 steps of development?

Answer 3

Cell proliferation, cell growth, cell differentiation, pattern formation, morphogenesis

Question 4

What is cell proliferation and how is dynamic equilibrium maintained?

Answer 4

The number of cells increase through cell division. Dynamic equalibrium is maintained though constant, programmed apoptosis and proliferation / differentiation of progenitors

Question 5

What is cell growth?

Answer 5

Proliferating cells undergo cycles of cell division and growth.

Question 6

What is hyperplasticity?

Answer 6

Increase in cell number, too many cell divisions. Increased tissue size b/c too many cells

Question 7

What is hypertrophy?

Answer 7

An increase in cell size leading to a bigger tissue although cell number is the same

Question 8

What is differentiation?

Answer 8

A progenitor cells receives stimuli from the environment and responds by acquiring new morphological/structural and functional characteristics

Question 9

Can a cell go back or dedifferentiate after differentiating?

Answer 9

No, differentiation is unidirectional

Question 10

What is terminal differentiation?

Answer 10

The stage at which a cell can no longer differentiate further.

Question 11

What is pattern formation?

Answer 11

The process whereby cells become organized into tissues, organs and organ systems

Question 12

What is morphogenesis?

Answer 12

The development of morphological characteristics. It entails the last 4 steps/processes.

Question 13

What happens on days 1- 14 of embryonic development?

Answer 13

Initial cell divisions take place

Question 14

What happens on day 14 of embryonic development?

Answer 14

Grastulation: three distinct tissues begin to form and there are no more embryonic stem cells

Question 15

What happens on days 19- 21 of embryonic development?

Answer 15

Neurulation: beginning of the future nervous system.

Question 16

What happens on days 21 - 24 of embryonic development?

Answer 16

Beginning of future head, neck, mouth and nose

Question 17

What happens on weeks 3-8 of embryonic development?

Answer 17

Beginning of organ formation

Question 18

What happens on week 8 of embryonic development?

Answer 18

Fetus is formed

Question 19

When is the ovum released?

Answer 19

Day 14 of the menstrual cycle

Question 20

What is the polidy of the ovum and sperm?

Answer 20

They are both haploid cells that fuse together to make a diploid cell

Question 21

What part of the sperm enters the oocyte?

Answer 21

Just the pronucleus. The pronuclei from the sperm and pronuclei from the egg are initially separated but when they fuse and give the zygote

Question 22

What is the morula?

Answer 22

Loosely packed ball of cells

Question 23

Describe the 16-cell morula stage. What is the first differentiation in mammalian development?

Answer 23

Compaction, the separation of trophoblast from inner cell mass.

Question 24

What are the 2 types of cells in compaction and what do they do?

Answer 24

Inner non-polarized cells and external polarized cells. Ezternal cells from tight junctions to seal the inner cells off and the internal cells from gap junctions to exchange substances.

Question 25

What do the external polarized cells give rise to? Internal non-polarized?

Answer 25

External gives rise to extra-embryonic and placenta and internal gives rise to the embryo.

Question 26

Describe the 32-cell stage, what happens?. What is the first differentiation in mammalian development?

Answer 26

Cavitation happens and a blastocyst is formed.

Question 27

What is the blastocoele?

Answer 27

Fluid filled cavity of the blastocyst

Question 28

When does the blastocyst attach to the uterine wall?

Answer 28

6-7 days after fertilization

Question 29

What is gastrulation?

Answer 29

The process in which a gastrula develops from a blastula by the inward migration of cells.

Question 30

What are the 3 primordial germ layers that make up the gastrula?

Answer 30

Endoderm, mesoderm, ectoderm

Question 31

What marks the beginning of gastrulation? And the ingression of cells give rise to what germ layers?

Answer 31

The primitive streak and the ingression of cells that will give rise to endoderm and mesoderm

Question 32

What is neurulation? What does it also induce?

Answer 32

The folding process in vertebrae embryos which includes the transformation of the neural plate into the neural tube. Also induves the development of mesoderm into distinct sections that will give rise to distinct organs/body parts

Question 33

By the end of what trimester have most organs started their development?

Answer 33

End of first trimester