Embryogenesis

Question 1

fertalization

Answer 1

• occurs in ampulla (widening of fallopian tube)
• sperm + 2 oocyte>release acrosomal enzyme>formation of acrosomal apparatus to penetrate cell membrane>cortical rxn (release of Ca ions) to prevent multiple fertalization and increase metabolic rate of zygote> formation of fertalization membrane

Question 2

Dizygotic twin

Answer 2

• fraternal twins
• fertalization of two different eggs released during the same ovulation cycle by two different sperm
• have own placenta, chorion, amnion

Question 3

Monozygotic twin

Answer 3

• identical twins
• classified by the amount of structures they share
• genetically identical
• occurs when a single zygote splits into two

Question 4

Cleavage

Answer 4

• rapid mitotic division that occurs while zygote is moving to the uterus
• 1st cleavage creates an embryo
• two types: indeterminate (can still developed into a complete organism) and determinate (results in cell that are committed to differentiate into a certain cell type)

Question 5

steps after cleavage

Answer 5

1. morula (from more division)
2. blastula - a hollow ball of cells w/ fluid-filled cavity (blastocoel)
3. gastrula

Question 6

Blastula

Answer 6

• filled w/ blastocoel in the cavity
• consists of two cells:
  1. trophoblast - will develop into chorion and placenta
  2. inner cell mass - give rise to the organism

Question 7

Chorion

Answer 7

extraembryonic membrane that develops into placenta

• has chorionic villi that penetrate endometrium
• support gas exchange

Question 8

umbilical cord

Answer 8

consists of:

• arteries x2: co2 rich to placenta
• veinx1: O2 rich from placenta into embryo

Question 9

yolk sac

Answer 9

prior to development of placenta supports embryo

- site of early blood cell development

Question 10

allantois membrane

Answer 10

• early fluid xchange

Question 11

amnion

Answer 11

tough membrane filled with amnionic fluid

• shock absorber
• lessening the impact of maternal motion

Question 12

gastrulation

Answer 12

formation of gastula from blastula (w/ invagination called blastopore)

Question 13

primary germ layer

Answer 13

1. ectoderm (outer)
2. mesoderm
3. endoderm (inner)

Question 14

ectoderm turns into

Answer 14

1. NS
2. adrenal medulla
3. integumentary system (epidermis, hair, nails, epithelia of nose, mouse, lower anal canal)

Question 15

mesoderm turns into

Answer 15

1. muscoloskeletal
circulatory
excretory
gonads
musculat and CT of digestive nad respiratory systems 
adrenal cortex

Question 16

endoderm

Answer 16

epithelial lining of digestive and respiratory tracts
pancreas
thyroid
bladder
distal urinary tracts
liver

Question 17

induction

Answer 17

ability of one group of cells to influence that fate of nearby cells
- usually via chemical substances called inducertys

Question 18

explain dual embryonic origin of adrenal gland

Answer 18

medulla - ectoderm

cortex- mesoderm

Question 19

neurulation

Answer 19

• development of NS
• from ectoderm
• notochord>neural folds surrounded by neural grooves> folds connect into neural tube (CNS) and tip of each fold are neural crest cells (PNS)

Question 20

determination

Answer 20

• commitment of cells to having a particular function in the future
• may occur due to: genetic expression, secretion of specific molecules (morphogens).
• call hasn’t yet produced the products needed to carry out functions of that cell type
• committed to a particular cell lineage

Question 21

Differentiation

Answer 21

• cell assumes structure, function and biochemistry of that cell type
• happens after determination

Question 22

describe potency of stem cells

Answer 22

• determines how many different cell types a stem cell can become
• totipotent>pluripotent>multipotent

Question 23

stem cell

Answer 23

not yet differentiated

can give rise to other cell types

Question 24

totiponent

Answer 24

-can develop into any kind of cell (embryonic+placenta)

Question 25

pluripotent

Answer 25

can develop into any kind of embryonic cell

Question 26

miltipotent

Answer 26

can develop into multiple cells within a particular group

Question 27

type of signals in cell-cell communication

Answer 27

1. autocrine - act on the same cell 2. paracrine - act on the cell in the local area 3. juxtacrine - cell directly stimulating receptor on the neighbour 4. endocrine - via hormones that travel to the distant areas

Question 28

Apoptosis

Answer 28

- programmed cell death - may occur via apoptotic signal or preprogramming - apoptotic blebs - when cell divides into many self-contained pieces and then is digested by other cells w/t leakage of the context - necrosis - cell death as a result of injury w/ potential leakage of cell context

Question 29

senescence

Answer 29

biological aging | - may be due to shortening of telomeres

Question 30

fetal lungs

Answer 30

don't function until birth | gas exchange occur across placenta

Question 31

umbilical artery

Answer 31

carry CO2 rich blood w/ waste products

Question 32

umbilical vein

Answer 32

carry O2 blood w/ nutrients

Question 33

1st trimester

Answer 33

- development of major organs - hardening of cartilage - fairy developed brain - growth ~ 9 cm - called fetus

Question 34

2nd trimester

Answer 34

- growth - movement - looks like human

Question 35

3rd trimester

Answer 35

- rapid growth | - further development