Chapter 3

Question 1

Clevage

Answer 1

Zygote undergoes rapid mitotic cell divisions
Two types:
1. Indeterminate
2. Determinate

Question 2

Indeterminate Clevage

Answer 2

Cell divission where cells can differentiate into any cell type or a whole organism

Question 3

Determinate Clevage

Answer 3

Cell division in cells having definitive lineages
* AT LEAST 1 daughter cell is commited to diffferenting into certain type of cell

Question 4

Stages of Development

Answer 4

Zygote: 2-, 4-, 8-
16-Cell Embryo > morula > blastula/blastocyst (implantation occurs) > gastrula

Question 5

Primary Germ Layers

Answer 5

1. Ectoderm (outermost layer)
2. Mesoderm (middle layer)
3. Endoderm (innermost layer)

Question 6

Ectoderm

Answer 6

Organs:
* Integument (epidermis, hair, nails, epithelia of nose, mouth, anal canal)
* Lens of eye
* Nervous system (adrenal medulla)
* Inner ear

Question 7

Mesoderm

Answer 7

Organs:
* Musculoskeletal system
* Circulatory system
* Excretory system
* Gonads
* Muscular and connective tissue layers of digestive and respiratory systems
* Adrenal Cortex
* Notochord: Rod of mesodermal cells that develop along longitudinal axis under dorsal layer of ectoderm

Question 8

Endoderm

Answer 8

Organs:
* Epithelial linings of digestive and respiratory tracts
* Parts of liver
* Pancreas
* Thyroid
* Bladder
* Distal urinary and reproductive tracts

Question 9

Induction

Answer 9

Nearby cells influence differentiation of adjacent cells
* Ensures proper spatial location and orientation of cells sharing/complementary functions
* Mediated by influencers (chemicals) that diffuse from organizing cells to responsive cells

Question 10

Neural Crest Cells

Answer 10

• Become peripheral nervous system (sensory ganglia, autonomic ganglia, adrenal medulla, Schwann cells)
• Specific cell types in other tissues (calcitonin-producing cells of thyroid, melanocytes in skin)

Question 11

Determination

Answer 11

Commitment of a cell to a particular lineage
* Presence of specific mRNA and protein molecules may result in determination
* May occur from secretion of morphogens (specific molecules from nearby cells)
* Hasn’t produced products needed to carry out functions of cell type
* If fails will lead to absence of structure

Question 12

Differentiation

Answer 12

Actual changes that occur for the cell to assume structure/function/biochemistry of determined cell type
* If fails leads to absence of structure

Question 13

Stem Cells

Answer 13

Cells that haven’t differentiated that lead to other cells that will differentiate
* Thought that can regenerate human tissues (ex: spinal chord and cardiac myocytes)

Question 14

Potency

Answer 14

What determines the tissues a certain stem cell can differentiate into
3 Types:
1. Totipotent
2. Pluripotent
3. Multipotent

Question 15

Totipotent

Answer 15

Any cell type in the developing embryo (primary germ layers) or inextraembryonic tissues (amnion, chorion, placenta)
* Cells with greatest potency
* Embryonic stem cells
* Can differentiate into any cell type in fetus/placental structure

Question 16

Pluripotent

Answer 16

Any cell type in developing embryo (primary germ layers)
* Can differentiate into any cell type but placental structures

Question 17

Multipotent

Answer 17

Any cell type within a particular lineage (ex: hematopoietic stem cells)
* Can differentiate into multiple types of cells within particular group

Question 18

Cell-Cell Communication

Answer 18

1. Autocrine:
   * Signal acts on same cell that secreted it
2. Paracrine:
   * Signal acts on local cells
3. Juxtracrine
   * Cell triggers adjacent cells through direct receptor stimulation
4. Endocrine
   * Signal travels through bloodstream to act at far away sites

Question 19

Apoptosis

Answer 19

Programmed cell death
* Results in contained blebs of dead cell that can be picked up/digested by other cells

Question 20

Necrosis

Answer 20

Cell death due to injury
* Results in spilling of cytoplasmic contents

Question 21

Umbilical Arteries

Answer 21

Carry deoxygenated blood
* More arteries in umbilical chord than veins

Question 22

Umbilical Veins

Answer 22

Carry oxygenated blood

Question 23

Foramen Ovale

Answer 23

Right atrium to left atrium
* Bypasses lungs

Question 24

Ductus Arteriosus

Answer 24

Pulmonary artery to aorta
* Bypasses lungs

Question 25

Ductus Venosus

Answer 25

Umbilical vien to inferior vena cava * Bypasses liver

Question 26

First Trimester

Answer 26

Organogenesis occurs * Development of heart, eyes, gonads, limbs, liver, brain * More severe brain disorders occur here versus second trimester (ex: organ missing)

Question 27

Second Trimester

Answer 27

* Lots of growth * Movement begins * Face becomes human looking * Digits elongate

Question 28

Third Trimester

Answer 28

* Rapid growth * Brain development * Last to develop is lungs * Transfer of antibodies

Question 29

First Phase of Birth

Answer 29

* Cervix thins * Amniotic sac ruptures

Question 30

Second Phase of Birth

Answer 30

Uterine contractions (coordinated by prostaglandins and oxytocin) result in birth

Question 31

Third Phase of Birth

Answer 31

Placenta and umbilical chord expelled

Question 31

Third Phase of Birth

Answer 31

Placenta and umbilical chord expelled

Question 32

Telomerase

Answer 32

Normally, cells divide until telomeres are too short then will stop * Cells continue to divide meaning that telomerase is probably activated and makes cells ablee to continue to divide

Question 33

Incomplete Regeneration

Answer 33

Newly formed tissues aren't indentical in structure/function to tissues injured/lost