Ch 3 Embryogenesis and Development

Question 1

Different types of twins

Answer 1

Dizygotic (fraternal) form from fertilization of 2 different eggs released during 1 ovulation cycle by 2 different sperm. Monozygotic (identical) form when single zygote splits into 2 - genomes identical

Question 2

2 types of cleavage

Answer 2

Indeterminate results in cells then can still develop into complete organisms. Determinate results in a specific, pre fated type of cell

Question 3

Divisions of cleavage

Answer 3

Zygote - embryo - morula - blastula - gastrula

Question 4

Blastocyst cell groups

Answer 4

Trophoblast - chorion & placenta
Inner cell mass - organism

Question 5

Chorion

Answer 5

Extraembryonic membrane that develops into the placenta

Question 6

Umbilical cord connects

Answer 6

Placenta to embryo

Question 7

Umbilical vein and artery

Answer 7

Vein carries O2 blood to embryo
Artery carry deoxygenated blood and waste to placenta for exchange

Question 8

Amnion

Answer 8

Incases amniotic fluid for shock absorption

Question 9

Opening of gastrulation invagination results in

Answer 9

A blastopore, which in deuterostomes develops into anus

Question 10

Gastrulation results in primary germ layers - describe

Answer 10

Ectoderm - integument and nervous system
Mesoderm - musculoskeletal, circulatory, excretory, gonads, connective tissue
Endoderm- digestive and respiratory, lining of internal organs

Question 11

Induction

Answer 11

Ability of one group of cells to influence nearby cells - related to selective transcription. Mediated by inducers (chemicals)

Question 13

Dual embryonic origin of adrenal glands

Answer 13

Adrenal cortex is mesoderm
Adrenal medulla is ectoderm (nervous tissue)

Question 14

Notochord

Answer 14

From mesoderm. Induces neurulation which gives rise to CNS via neural tube

Question 15

Neural crest cells

Answer 15

Gives rise to PNS

Question 16

Cell specialization

Answer 16

1. Specification - designated as specific cell type
2. Commitment of cell to a future function(irreversible)
3. Differentiation - undertake changes that allow the cell to become a specific cell type

Question 17

Stem cells

Answer 17

Cells that have not yet differentiated or give rise to cells that will differentiate

Question 18

Potency in cell differentiation

Answer 18

Totipotent- greatest potency can differentiate into any cell type in fetus or placenta (embryonic mainly)
Pluripotent- any cell type except those found in placental structures
Multipotent - intuitions cell types within a particular group

Question 19

Cell signaling

Answer 19

Autocrine - act in same cell that secreted signal
Paracrine - act in local area (diffusion)
Juxtracrine- direct cell contact
Endocrine - hormone through bloodstream

Question 20

Cell inducers (signaling) are often

Answer 20

Growth factors

Question 21

To assist with O2 transfer, fetal blood cells have

Answer 21

HbF, which has a greater affinity for O2 than adult Hb

Question 22

Umbilical artery vs vein

Answer 22

Umbilical artery carries blood away from fetus to placenta. Umbilical vein is blood toward fetus from placenta

Question 23

Fetus does not depend on lungs and liver, as these functions occur at placenta. Fetus constructs 2 shunts to direct blood away from these organs while they develop

Answer 23

Foramen ovale - one way that connects right atrium to left atrium, bypassing blood to the lungs.
Ductus arteriosus - shunts blood from pulmonary artery to aorta, by passing lung
Ductus venosus - shunts blood from umbilical vein to inferior vena cava, by passing liver

Question 24

First trimester

Answer 24

Major organogenesis, brain mostly developed, bone formation, limbs, after 8 weeks knows as fetus

Question 25

2nd trimester

Answer 25

Big growth, movement, fingers and toes

Question 26

3rd trimester

Answer 26

Growth and brain development, active transport of antibodies

Question 27

Uterine smooth muscle contraction for childbirth is coordinated by

Answer 27

Prostaglandins and oxytocin