Chapter 16 Pt. 2 (16.3)

Front 1

What is cleavage?

Back 1

Cell division of a zygote, in which the number of cells increases without an change in the size of the zygote.

Front 2

What is a blastocyst?

Back 2

An early stage of embryo development.

Front 3

What is implantation?

Back 3

The attachment of the embryo to the endometrium.

Front 4

What is the chorion?

Back 4

The outer embryonic structure of a developing embryo that will contribute to the placenta.

Front 5

What is the amnion?

Back 5

A fluid-filled extra-embryonic structure.

Front 6

What is human chorionic gonadotropic hormone (HcG)?

Back 6

An embryonic hormone that maintains the corpus luteum.

Front 7

What is the amniotic cavity?

Back 7

The fluid filled cavity surrounding the developing embryo.

Front 8

What is the extra embryonic coelom?

Back 8

The body cavity between the amnion and the chorion.

Front 9

What is the yolk sac?

Back 9

A membranous sac that forms during embryo development of most vertebrates; in humans, it does not contain yolk.

Front 10

What is the placenta?

Back 10

The site for the exchange of nutrients and wastes between mother and fetus.

Front 11

What is chorionic villi?

Back 11

Vascular projections of the chorion.

Front 12

What is the allantois?

Back 12

Extra embryonic structure that contributes to the blood vessels of the placenta.

Front 13

What is the umbilical cord?

Back 13

Structure that connects the fetus to the placenta.

Front 14

What is the first trimester?

Back 14

The period during pregnancy from contraception until the end of the third month.

Front 15

What is gastrulation?

Back 15

Process by which a gastrula is formed.

Front 16

What is a gastrula?

Back 16

Stage of embryonic development in which the embryo is composed of three layers; ectoderm, mesoderm, and endoderm.

Front 17

What is the ectoderm?

Back 17

The outer layer of cells in an embryo.

Front 18

What is the mesoderm?

Back 18

The middle layer of cells in an embryo.

Front 19

What is the endoderm?

Back 19

The inner layer of cells in an embryo.

Front 20

What is the second trimester?

Back 20

The period during pregnancy from the fourth month to the end of the sixth month.

Front 21

What is the third trimester?

Back 21

The period during pregnancy from the seventh month until birth.

Front 22

What are teratogens?

Back 22

Any medication, chemical, infectious disease, or environmental agent that might interfere with the normal development of a fetus or embryo.

Front 23

What is partuition?

Back 23

The act of giving birth; labour.

Front 24

What is relaxin?

Back 24

A hormone produced by the placenta prior to labour; causes the ligaments within the pelvis to loosen.

Front 25

What is oxytocin?

Back 25

A hormone from the pituitary gland; causes strong uterine contractions.

Front 26

What is prolactin?

Back 26

A hormone produced by the pituitary gland and associated with milk production.

Front 27

What is the first step of fertilization to implantation?

Back 27

1. Ovulation

Front 28

What is the second step of fertilization to implantation?

Back 28

2. Fimbraie sweeps egg to fallopian tubes where fertilization occurs to create a zygote. The acrosome allows the sperm to get through the egg's protective barrier. Sperm is ejaculated and travels from the cervix to uterus. The zygote receives 23 chromosomes from the sperm cell and 23 from the oocyte. Several sperm attaches to ovulated oocytes, but only one fuses.

Front 29

What is the third step of fertilization to implantation?

Back 29

The zygote undergoes a number of cellular division on it's way to the uterus. Cleavage occurs, and cells of the zygote gets progressively smaller until the morula is formed (a ball of cells).

Front 30

What is the fourth step of fertilization to implantation?

Back 30

Cells move around to create an outer ring of cells and an inner mass. As the zygote reaches the uterus, it developed into a fluid-filled structure called a blastocyst.

Front 31

What is the fifth step of fertilization to implantation?

Back 31

While in the uterus, the blastocyst attaches to the endometrial wall. This is implantation.

Front 32

Draw a diagram of the blastocyst.

Back 32

Front 33

Draw a diagram of fertilization to implantation.

Back 33

Front 34

What is the first step of development?

Back 34

The outer layer of the blastocyst produces 2 membranes.

Front 35

What two membranes are produced by the blastocyst.

Back 35

1. Amnion - creates a protective sac that encloses the fetus in a fluid (amniotic fluid) filled environment. This cushions the fetus and prevents temperature fluctuations while allowing freedom of movement.

2. Chorion - finger-like projections implant into endometrium and are fetal contributions to the placenta. Projections called chorionic villi creates a large surface area between maternal and fetal blood supplies. Secretes HcG (human chorionic gonadotropic hormone).

Front 36

In order for pregnancy to continue what female process cannot occur? How can this be ensured?

Back 36

Menstruation cannot occur because any shedding of the endometrium would dislodge the embryo from uterus. In order to maintain the endometrium, progesterone and estrogen levels must be maintained. High levels means negative feedback, and LH levels must be maintained to sustain the corpus luteum.

Front 37

How can the woman endometrium be maintained during pregnancy.

Back 37

In the chorion, human chorionic gonadotropic hormone is produced. This maintains the corpus luteum for the first trimester until the placenta is functioning and produces estrogen and progesterone.

Front 38

What is the second step of development?

Back 38

Gastrulation - the process of the inner cell mass in the blastocyst forming the different germ layers. This forms the gastrula.

Front 39

What are the three germ layers?

Back 39

Outer - ectoderm (forms hair, nails, sweat glands, nervous system, eyes, ears, teeth, mouth lining)

Middle - mesoderm (forms muscles, blood vessels + blood, kidneys + reproductive structures, connective tissue, cartilage, bone)

Inner - endoderm (forms liver, pancreas, thyroid, bladder, lining of digestive system, and respiratory tract)

Front 40

What is the third step of development?

Back 40

Placenta forms from cells from the endometrium and the fetus. This is the site of nutrient and waste exchange through diffusion, which allows the passage of drugs, some antibodies, and viruses.

Front 41

What is the fourth step of development.

Back 41

The allantois - an extension of the endoderm - forms. The blood vessels found in the placenta comes from the allantois, and the blood vessels give rise to the umbilical cord (connects embryo to placenta).

Front 42

Draw and label a diagram of a baby in womb.

Back 42

Front 43

Where is and what is the purpose of the amniotic cavity?

Back 43

Between the amnion and embryo, a fluid filled sac that insulates the embryo and fetus from infection, dehydration, impact, and changes in temperature.

Front 44

Where is and what is the purpose of the extra embryonic coelom?

Back 44

The fluid filled space between the amnion and chorion.

Front 45

Where is and what is the purpose of the yolk sac?

Back 45

Site of early red blood cell formation beneath the embryo.

Front 46

What is morphogenesis?

Back 46

The development of an organism or part of it.

Front 47

What occurs in the first trimester?

Back 47

The first trimester occurs in weeks 1-12, germ layers form, heart+brain+limb buds develop, arms+legs move, suckling reflex. By the end of the trimester, external reproductive organs distinguish male from female.

*all organ systems develop, most vulnerable to teratogens

Front 48

What occurs in the second trimester?

Back 48

From weeks 13-24, the fetus moves enough to be noticed and organs continue to develop, and all organs have been formed. The size of fetus increases. Eyelids and eyelashes form, cartilage is replaced with bone cells, and hair covers the body.

*growth and systems continue to mature, fetal movement and reflexes such as suckling occurs.

Front 49

What occurs in the third trimester?

Back 49

Rapid growth of the baby - mostly layers of fat. Organ systems are already established, but continue to develop.

*Rapid growth, systems continue to mature, and many layers of fat develop.

Front 50

What chromosomes make up a female, and what makes up a male?

Back 50

Female = XX

Male = XY

Front 51

How do hormones play a role in sex determination?

Back 51

Male and female development is determinate by hormones circulating in the blood stream. Too much estrogen could mean an organism with male genes appears physically female, while too many male androgens/hormones could make one's sex hormones male even thought the genetic body is female.

Front 52

What is a teratogen?

Back 52

Agents capable of causing developmental abnormalities in utero. Anything the mother inhales or ingests can end up circulating in blood. These compounds can cross the placental barrier and enter fetal blood.

Front 53

What are some examples of teratogens?

Back 53

ex. Cigarrettes - affects size of the baby, alcohol - affects fetuses brain, etc.

Front 54

What are two examples of human reproductive technology?

Back 54

1. In vitro fertilization

2. Fertility drugs

Front 55

How does in vitro fertilization work?

Back 55

Mother is given numerous hormones to produce multiple eggs each month. The eggs are removed just before they leave the follicles in the ovaries - done under anesthetic. The eggs are fertilized with the partners sperm in a petri dish, and the zygotes are allowed to mature until the blastocyst forms. 3-4 eggs are implanted back into the uterus by a catheter, and a pregnancy test is done 2 weeks later to test success.

Front 56

How do fertility drugs work?

Back 56

Fertility drugs stimulate the action of pituitary hormones. Follicle development within the ovary is enhanced and the release of one or more egg cells becomes more probable. Since fertility drugs increase follicle development within the ovary, often causing multiple ovulations, the chances of having fraternal twins increases.

Front 57

How does the fetus prepare for birth?

Back 57

At the end of the third trimester, the fetus turns so that the front of the head faces the back bone. The fetus also drops into the birth canal.

Front 58

What indicates the beginning of birth?

Back 58

Uterine contractions begin, the cervix thins and dilates, the mucous plug that seals the cervix falls out, and the amnion is forced into the birth canal, which bursts. The amniotic fluid lubricates the canal. As the cervix dilates, the uterine contractions being to move the baby through the birth canal. Decreased progesterone also indicates the onset of labour.

Front 59

Draw the birth feedback loop.

Back 59

hypothalamus (releasing factor) ---> posterior pituitary (oxytocin) ---> uterus contracts--->

1. prostaglandins ---> contractions ---> positive feedback to uterus contracts

2. baby's head pushes against cervix to dilate ---> positive feedback to all glands.

Front 60

What is the role of relaxin in partuition?

Back 60

Relaxin is produced by the placenta and causes the pelvis ligaments to loosen and the cervix to soften. This makes a more flexible passageway for the baby during delivery.

Front 61

What is the role of oxytocin in labour?

Back 61

Oxytocin causes strong uterine contractions.

Front 62

What is the role of prostaglandins in labour?

Back 62

Prostaglandins causes strong uterine contractions. These appear in the mother blood prior to labour.

Front 63

What is a way to induce labour?

Back 63

By administering prostaglandins or pitocin- a synthetic form of oxytocin. These stimulate uterine contractions.

Front 64

What are the three stages of labour?

Back 64

Active phase, partition, and afterbirth.

Front 65

What happens in the active phase of birth?

Back 65

The cervix beings to dilate due to muscles contractions caused by oxytocin, since progesterone levels drop and no longer inhibit this hormone. These contractions become more frequent and intense - positive feedback - and the amniotic sac will break due to these contractions. This stage ends when the cervix dilates 10 cm.

Front 66

What happens during partuition?

Back 66

As the contractions continue, the fetus is moved down the birth canal. The hormone relaxin causes loosening of ligaments in the pelvis. Uterine contractions and pushing of the mother push the baby out of the birth canal.

Front 67

What happens during the after birth?

Back 67

Once the baby is born, the umbilical cord is clipped and cut, and a number of contractions expels the placenta and most of the umbilical cord.

Front 68

What hormones stimulate lactation?

Back 68

Prolactin, oxytocin, and estrogen.

Front 69

What is the role of prolactin in lactation?

Back 69

Prolactin levels rise dramatically after birth to stimulate milk production in glands in breasts to begin producing fluid. It also causes production of colostrum (fluid that resembles breast milk but lacks milk fats) that supplies the baby with antibodies.

Front 70

What is the role of estrogen in lactation?

Back 70

Estrogen stimulates release of large amounts of prolactin during pregnancy. Progesterone inhibits.

Front 71

What is the role of oxytocin in lactation?

Back 71

The suckling action of the newborn stimulates nerve endings in the areola of the breast. The sensory nerves sends info to the pituitary gland which increases oxytocin levels. Oxytocin travels through blood to the breasts and uterus causing weak contractions, moving milk to ducts and the uterus to return to pre-pregnancy size.

Front 72

What is the lactation flow chart?

Back 72

hypothalamus (releasing factor) ---> anterior pituitary (prolactin) ---> suckling to baby stimulates posterior pituitary ----> releases oxytocin ---> oxytocin causes muscle contractions that forces milk to milk ducts so the baby can nurse.