Biology: Ch. 3- Embryogenesis and Development

Question 1

What is the difference between determinate and intermediate cleavage?

Answer 1

Determinate cleavage refers to cell division that results in cells having definitive lineages; that is, at least one daughter cell is already programmed to differentiate into a particular cell type
Indeterminate cleavage refers to cell division that results in cells that can differentiate into any cell type (or a whole organism)

Question 2

From zygote to gastrula, what are the various stages of development

Answer 2

Zygote–> 2-, 4-. 8- and 16-cell embryo–>morula–> bastula (blastocyte)–> gastrula

Question 3

During which stage of development does implantation occur?

Answer 3

implantation occurs during the blastula (blastocyte) stage

Question 4

what are the primary germ layers?

Answer 4

1. ectoderm
2. mesoderm
3. endoderm

Question 5

Which organs are formed from each of the primary germ layers?

Answer 5

1. ectoderm- Integument (including the epidermis, hair, nails and epithelia of the nose, mouth, and anal canal), lense of the eye, nervous system (including adrenal medulla), inner ear
2. mesoderm- Muscoskeletal system, circulatory system, excretory system, gonads, muscular and connective tissue layers of the digestive and respiratory systems, adrenal cortex
3. endoderm- Epithelial linings of digestive and respiratory tracts, and parts of the liver, pancreas, thyroid, bladder and distal urinary and reproductive tracts

Question 6

What is induction?

Answer 6

Induction is the process by which nearby cells influence the differentiation of adjacent cells. This ensures proper spatial location and orientation of cells that share function or have complementary functions

Question 7

What tissues do neural crest cells develop into?

Answer 7

Neural crest cells become the peripheral nervous system (including the sensory ganglia, autonomic ganglia, adrenal medulla, and Schwann cells) as well as the specific cel types in other tissues (such as calcitonin-producing cells of the thyroid, melanocytes in the skin and others)

Question 8

What is the difference between determination and differentiation?

Answer 8

Determination is the commitment of a cell to a particular lineage.
Differentiation refers to the actual changes that occur in order for the cell to assume the structure and function of the determined cell type.

Question 9

What are the three types of potency? What lineages can a cell of each type differentiate into?

Answer 9

1. totipotency- Any cell type in the developing embryo (primary germ layers) or in the extraembryonic tissues (amnion, chorion, placenta)
2. pluripotency- Any cell type in the developing embryo (primary germ layers)
3. multipotency- Any cell type within a particular lineage (ex. hematopoietic stem cells)

Question 10

What are the four types of cell-cell communication?

Answer 10

1. Autocrine (signal acts on the same cell that secreted it)
2. Paracrine (the signal acts on local cells)
3. Juxtacrine (a cell triggers adjacent cells through direct receptor stimulation)
4. Endocrine (the signal travels via the bloodstream to act at distant sites)

Question 11

What is the difference between apoptosis and necrosis?

Answer 11

Apoptosis: programmed cell death and results in contained blebs of the dead cell that can be picked up and digested by other cells
Necrosis is cell death due to injury and results in spilling of cytoplasmic contents

Question 12

What is the oxygenation status of blood in the umbilical arteries? in the umbilical vein?

Answer 12

Umbilical arteries- carry deoxygenated blood

Umbilical veins- carry oxygenated blood

Question 13

What are the three fetal shunts?

Answer 13

1. Foramen ovale
2. Ductus arteriosus
3. Ductus venosus

Question 14

Which vessels or heart chambers in the do the three fetal shunts connect?

Answer 14

1. Foramen ovale - connects the right atrium to the left atrium
2. Ductus arteriosus- connects the pulmonary artery to the aorta
3. Ductus venosus- connects te umbilical vein to the inferior vena cava

Question 15

Which organ does each of the three fetal shunts bypass?

Answer 15

1. Foramen ovale- bypasses the lungs
2. Ductus arteriosus- bypasses the lungs
3. Ductus venosus- bypasses the liver

Question 16

What are some of the key developments of the first trimester?

Answer 16

organogenesis occurs (development of heart, eyes, gonads, limbs, liver, brain)

Question 17

What are some of the key developments of the second trimester?

Answer 17

tremendous growth occurs, movement begins, the face becomes distinctly human, and the digits elongate

Question 18

What are some of the key developments of the third trimester?

Answer 18

rapid growth and brain development continue and there is a transfer of antibodies to the fetus

Question 19

What occurs in each of the three phases of birth?

Answer 19

in the first phase of birth, the cervix thins out and amniotic sac ruptures.
In the second phase, uterine contractions, coordinated by prostaglandins and oxytocin, result in the birth of the fetus.
In the third phase, the placenta and the umbilical cord are expelled.