MCAT BIO CH. 13 PART 2

Question 1

What happens after the blastocyst implants in the endometrium?

Answer 1

Trophoblast secretes proteases ha lyse endometrial cells

Question 2

What happens to the blastocyst once it sinks into the endometrium?

Answer 2

Absorbs nutrients through he trophoblast into the inner cell mass

Question 3

Why does the secretory phase of the endometrial cycle is endometrial cells storing glycogen lipids and nutrients?

Answer 3

So that early embryo may derive nourishment directly from the endometrium

Question 4

What happens later in fertilization that allows the blastocyst to have between exchange of nutrients and gases?

Answer 4

Placenta

Question 5

How long does it take for the placenta to develop?

Answer 5

Three months

Question 6

What is the role of the corpus luteum during the first trimester for pregnancy?

Answer 6

Make estrogen and progesterone

Question 7

Why is the corpus luteum no longer needed in the las six months of pregnancy?

Answer 7

The placenta itself secretes sufficient estrogen and progesterone for maintenance of the endometrium

Question 8

The development of the placenta involves the formation of what?

Answer 8

Placental villi

Question 9

What are placental villi?

Answer 9

Chorionic projections extending into the endometrium into which fetal capillaries will grow

Question 10

What are surrounding the placental villi?

Answer 10

Sinuses filed with maternal blood

Question 11

What are the four important structures derived from the inner cell mass?

Answer 11

1. Amnion
2. Yolk sac
3. Allantois
4. Embyo

Question 12

What is the amnion?

Answer 12

It surrounds a fluid-filled cavity which contains the developing embryo

Question 13

What is the yolk sac?

Answer 13

It is the first site of red blood cell synthesis in the embryo

Question 14

What is the allantois?

Answer 14

Forms the blood vessels of the umbilical cod; forms from the embryonic gut

Question 15

What happens after blastulation?

Answer 15

Gastrulation

Question 16

What occurs during gastrulation?

Answer 16

The three primary germ layers become distinct

Question 17

What are the three primary germ layers of gastrulation?

Answer 17

1. Ectoderm
2. Mesoderm
3. Endoderm

Question 18

What is the blastula?

Answer 18

Hollow ball of cells

Question 19

What does the mesoderm derive from?

Answer 19

From the endoderm

Question 20

What is the cavity of the blastula during gastrulation?

Answer 20

Primitive gut; archenteron

Question 21

What is the blastopore?

Answer 21

The opening which will give rise to the anus

Question 22

What is the gastrula?

Answer 22

Whole structure with all three distinct germ layers

Question 23

The gastrula develops from what in humans?

Answer 23

From a double layer of cells called the embryonic disk

Question 24

From which germ layer is the nervous system derived from?

Answer 24

Ectoderm

Question 25

From which germ layer is the pituitary gland and adrenal medulla derived from?

Answer 25

Ectoderm

Question 26

From which germ layer is the cornea and lens derived from?

Answer 26

Ectoderm

Question 27

From which germ layer is the skin and its derivatives derived from?

Answer 27

Ectoderm

Question 28

From which germ layer is nasal, oral and anal epithelium derived from?

Answer 28

Ectoderm

Question 29

From which germ layer is the muscle bone and connective tissue derived from?

Answer 29

Mesoderm

Question 30

From which germ layer is entire cardiovascular system derived from?

Answer 30

Mesoderm

Question 31

From which germ layer is urogenital organs derived from?

Answer 31

Mesoderm

Question 32

From which germ layer is dermis of the skin derived from?

Answer 32

Mesoderm

Question 33

From which germ layer is GI tract derived from?

Answer 33

Endoderm

Question 34

From which germ layer is GI glands derived from?

Answer 34

Endoderm

Question 35

From which germ layer is respiratory epithelium derived from?

Answer 35

Endoderm

Question 36

From which germ layer is epithelial lining of the urogenital organs derived from?

Answer 36

Endoderm

Question 37

From which germ layer is urinary bladder derived from?

Answer 37

Endoderm

Question 38

Blastulation, gastrulation....and then?

Answer 38

Neurulation

Question 39

What is neurulation?

Answer 39

Formation of the nervous system

Question 40

How does neurulation begins?

Answer 40

Portion of the ectoderm differentiates into the neural plate

Question 41

What are at the edges of the neural plate?

Answer 41

Neural crest cells

Question 42

How does the neural plate during neurulation initially folds?

Answer 42

Fold upwards which leaves the bottom of the plate to form a neural tube

Question 43

What does the neural tube develop into?

Answer 43

Central nervous system

Question 44

What happens to the neural crest cells after the neural tube has been developed?

Answer 44

Neural crest cells separate from the neutral tube and the overlying ectoderm migrate to different parts of the embryo

Question 45

What is the formation of the neural tube induced by?

Answer 45

Instructions from the underlying notochord which is mesodermal origin

Question 46

What does the neural tube give rise to?

Answer 46

The vertebral column

Question 47

Neurulation is one component of ....?

Answer 47

Organogenesis

Question 48

During which trimester is the developing human most sensitive to toxins?

Answer 48

The first trimester when the organs are being formed

Question 49

A lack of folic acid in the mother's diet early time period in development can lead to what?

Answer 49

Lead to significant defects int he formation of he neural tube and central nervous system

Question 50

What does totipotent cells mean?

Answer 50

Ability to become any cell type; cells in blastocyst

Question 51

What does pluripotent cells mean?

Answer 51

Cells more specialized but that can still differentiate

Question 52

What does multipoint cells mean?

Answer 52

They can become many but not all cell types

Question 53

What does it mean when a cell has been determined?

Answer 53

The cell fate becomes fixed

Question 54

What precedes, determination or differentiation?

Answer 54

Determination precedes differentiation; cell determined before it differentiates

Question 55

Can determination of a cell be induced?

Answer 55

Yes - by the cell's environment

Question 56

What is dedifferentiation?

Answer 56

Specialized cell un-specializes and may become totipotent

Question 57

What happens during the second trimester?

Answer 57

Organs and organ systems continue to develop structurally and functional

Question 58

What happens during the third trimester?

Answer 58

Rapid fetal growth, significant deposition of adipose tissue

Question 59

What happens to the physiology of the mother during pregnancy?

Answer 59

1. Increase respiratory rate 2. Increased blood volume 3. Increased in glomerular filtration

Question 60

What is the technical term for birth?

Answer 60

Parturition

Question 61

What is parturition dependent on?

Answer 61

Contraction of muscles in the uterine wall

Question 62

What causes the uterine excitability increase during the end of pregnancy?

Answer 62

Change in estrogen ratio, presence of oxytocin secreted by the posterior pituitary, stretching of the uterus

Question 63

What occurs when pregnancy reaches full term?

Answer 63

Rhythmic labor contractions begins

Question 64

What is the first stage of labor?

Answer 64

Dilation of the cervix

Question 65

What is the second stage of labor?

Answer 65

Actual birth involving movement of the baby through the cervix and birth canal

Question 66

What is the third stage of labor?

Answer 66

Expulsion of the placenta after it separates from the wall of the uterus

Question 67

What inhibits the secretion of milk before birth?

Answer 67

Estrogen and progesterone inhibit prolactin and tis the production of milk

Question 68

What hormone is necessary for the release of milk?

Answer 68

Prolactin and oxytocin