Ch. 23 Prengancy, Growth, and Development

Growth

increase in size; involves increase in cell numbers

Development

includes growth and aging; continuous process by which an individual changes during life

Prenatal period

What is the period of life from fertilization to birth?

Postnatal period

What is the period of life from birth to death?

Fertilization (contraception)

the union of a secondary oocyte and a sperm cell; takes place in the infundibulum of a uterine (fallopian) tube

6 days

How long can sperm survive in the female tract?

Corona radiata, acrosomal enzymes

Sperm first invade the _____, layer of follicular cells that surround the oocyte, dissolving it with ______

Zona pellucida

In the second step, sperm dissolve the ______, glycoprotein layer that closely surrounds secondary oocytes

Zona pellucida hardens

What happens to the zona pellucida when a sperm enters the oocyte?

Secondary oocyte completes meiosis

What happens when the sperm nucleus enters the oocyte?

Pronuclei

What do you call the nuclei of the sperm and oocyte as they approach each other in fertilization?

Zygote

cell produced by the fusion of the nuclei of a mature oocyte and a sperm cell as a result of fertilization

Pregnancy

event where there is the presence of a developing offspring in the uterus; consists of three trimesters (pre-embryonic, embryonic, and fetal) that each last 3 months

Pre-embryonic stage

stage of pregnancy from fertilization through the second week of pregnancy; includes cleavage, blastocyst formation, implantation, and development of extraembryonic membranes

Cleavage

rapid cell division and distribution of the zygote’s cytoplasm into progressively smaller cells (blastomeres)

Morula

solid mass of about 16 cells that move into uterus

Blastocyst

hollow ball of cells that attaches to endometrium of uterus

Inner cell mass of blastocyst

portion of the blastocyst that gives rise to the embryo proper

Trophoblast

cells forming wall of blastocyst that develop into structures that assist embryo, and produces hCG (human chorionic gonadotropin) which maintains corpus luteum during early pregnancy

Dizygotic (Fraternal) twins

twins that are produced when two ovarian follicles are released simultaneously; no more alike than regular siblings

Monozygotic twins

twins that are produced from a single fertilized oocyte if two inner cell masses form within a blastocyst; are genetically identical

Implantation

attachment of blastocyst to the uterine lining aided by the secretion of proteolytic enzymes that digest part of the endometrium

Ectopic pregnancy

occurs if a blastocyst implants in tissues outside the uterus

Tubal pregnancy

occurs if a blastocyst is implanted in the uterine tube

Human chorionic gonadotropin (hCG)

hormone that maintains the corpus luteum during the early stages of pregnancy and prevents blastocyst rejection by immune system and stimulates hormones of the placenta

Placenta

vascular structure that attaches the fetus to the uterine wall and performs nutrient, gas, and waste exchange between the embryo and the mother

Chorion

outermost extraembryonic membrane formed by trophoblast and second layer of cells that line trophoblasts

Chorionic villi

projections that extend from the outer surface of the chorion and helps attach an embryo to the uterine wall; contain embryonic capillary networks for nutrient exchange

Lacunae

Irregular spaces in endometrium around chorionic villi, formed by action of proteolytic enzymes; fill with maternal blood

Embryonic blood vessels

transport blood to and from embryo, via connecting stalk attaching embryo to developing placenta

Amnion

second extraembryonic membrane that develops around the embryo in the second week of pregnancy

Amniotic fluid

fluid that fills space between embryonic disc and amnion; protects and cushions embryo and keeps a constant temperature for the embryo

Umbilical cord

cordlike structure that connects the fetus to the placenta; suspends the embryo in the amniotic cavity and contains 2 umbilical arteries and one umbilical vein to transport blood between embryo and placenta

Amniochorionic membrane

membrane formed from the fusion of the amnion and chorion

Yolk sack

extraembryonic membrane that forms during the second week of pregnancy that is attached to the underside of embryonic discs and forms blood cells during early cell development

Embryonic disc

flattened area in the developing embryo from which the germ layers arise

Allantois

extraembryonic membrane that forms during the third week of pregnancy between the yolk sac and connecting stalk; forms blood cells and umbilical blood vessels

Placental membrane

membrane that separates embryonic blood from maternal blood and exchanges nutrients and respiratory gases between embryo and mother

Placental progesterone

hormone used by the adrenal glands to synthesize estrogens

Embryonic stage

stage of pregnancy from 3rd week to 8th week that includes gastrulation and organogenesis; this is the most critical stage where embryo implants and all body parts form

Gastrulation

movement of cells within the embryonic disc to form multiple layers; outer ectoderm and inner endoderm form by week 2, mesoderm forms between them in this process

Primary germ layers

consists of the ectoderm, mesoderm, and endoderm; layers of cells in the embryo that divide and differentiate into organs

Organogenesis

formation of organs from the three primary germ layers

Gastrula

embryonic stage after the blastula where cells differentiate into the primary germ layers

Epithelia

What type of cells make up the ectoderm and endoderm?

Connective tissue cells

What type of cells makes up the mesoderm?

Ectodermal cells

cells that form nervous system, special sensory organs, epidermis, hair, nails, skin glands, linings of mouth and anal canal

Mesodermal cells

cells that form muscle tissue, bone tissue, blood, blood vessels, lymphatic vessels, internal reproductive organs, kidneys, and epithelial linings of body cavities

Endodermal cells

cells that form the pancreas, gallbladder, and linings of the digestive tract, respiratory tract, urinary bladder, and urethra

Teratogens

factors that cause malformations by affecting embryo during periods of rapid growth, development, or specialization

Fetal stage

stage of pregnancy that begins at the end of eight weeks of prenatal development and continues until birth; consists of rapid growth

Beginning of fetal stage

during this time in the fetal stage the head is relatively large and lower limbs are short

3rd month in fetal stage

point in fetal stage where body lengthens quickly, and growth of head slows

12th week in fetal stage

point in fetal stage where external reproductive organs can be distinguished as male or female

4th month in fetal stage

point in fetal stage where the lower limbs lengthen and the skeleton continues ossification

5th month in fetal stage

point in fetal stage where growth slows, hair grows, and muscles contract

6th month in fetal stage

point in fetal stage where fetus gains weight and skin is wrinkled

7th month in fetal stage

point in fetal stage where eyes open, fat is deposited, and skin gets smoother

Final trimester in fetal stage

point in fetal stage where organs specialize and grow and brain cells form networks

Digestive and respiratory systems

What body systems are the last to mature in the fetal stage?

First week of embryonic stage

Cells undergo mitosis, blastocyst forms; inner cell mass appears; blastocyst implants in uterine wall

Second through eighth week of embryonic stage

stage of prenatal development where inner cell mass becomes embryonic disc; primary germ layers form, embryo proper becomes cylindrical; main internal organs and external body structures appear; placenta and umbilical cord form, embryo proper is suspended in amniotic fluid

Ninth through twelfth week of fetal stage

stage of prenatal development where ossification centers appear in bones; sex organs differentiate; nerves and muscles coordinate so that the fetus can move its limbs

Thirteenth through sixteenth week

stage of prenatal development where Body grows rapidly; ossification continues

Seventeenth through twentieth week

stage of prenatal development where muscle movements are stronger, and woman may be aware of slight flutterings; skin is covered with fine downy hair (lanugo) and coated with sebum mixed with dead epidermal cells (vernix caseosa)

Twenty-first through thirty-eighth week

stage of prenatal development where Body gains weight, subcutaneous fat deposited; eyebrows and lashes appear; eyelids reopen; testes descend

Fetus

prenatal human after eight weeks of development

Maternal blood

during fetal development, _______ supplies O2 and nutrients and removes wastes

Fetal hemoglobin

carries 20 to 30% more oxygen than adult hemoglobin

Umbilical vein

transports oxygen rich blood from placenta to fetus

Ductus venosus

blood vessels that breaks off from umbilical vein, bypasses liver, and joins inferior vena cava; oxygen-rich blood from placenta mixes with oxygen-poor blood from lower portion of fetus here ; mixture passes through inferior vena cava to right atrium.

Foramen ovalae

opening between the right and left atria in fetal heart; most of blood entering right atrium is shunted into left atrium, since fetal lungs are not functional

Ductus arteriosus

Connecting vessel that shunts most of blood from pulmonary trunk directly into aorta; conducts some blood from the pulmonary trunk to the aorta, bypassing the lungs

Umbilical arteries

Carry the blood containing carbon dioxide and wastes from the internal iliac arteries to the placenta

Reoxygenated

Blood that enters the umbilical arteries is ______ in the placenta

Secretion of human chorionic gonadotropin (hCG)

this maintains the corpus luteum which secretes secretes estrogens and progesterone, and inhibits FSH and LH to stop reproductive cycles

Placental estrogens and progesterone

hormones that inhibit FSH, LH, and uterine contractions; also enlarge the reproductive organs and maintain the uterine wall

Placental lactogen

hormone secreted by the placenta that stimulates breast development and preps the mammary glands to secrete milk

Relaxin

polypeptide hormone from the corpus luteum that inhibit the smooth muscle in the myometrium to suppress uterine contractions and relax the pelvic ligaments until birth

Aldosterone

hormone that promotes renal reabsorption of sodium and water retention

Parathyroid hormone (PTH)

hormone that maintains calcium concentrations in the maternal blood

Growth of the uterus

this process displaces abdominal organs; requires eating of smaller meal and causes heartburn and increased urination

Food intake must be increased

to obtain adequate nutrition, vitamins, minerals, and proteins for mother and fetus

Parturition

What is the name for the process of birth?

Progesterone levels decrease

What happens to progesterone levels during birth?

Becomes thin

What happens to the cervix during the birth process?

Positive feedback birth system

stretching of uterus and vagina causes an increase in oxytocin secretion and uterine contraction

Head down, facing cervix

What is the typical position of the fetus during birth?

Abdominal wall muscles

muscles that aid in uterine contractions

Afterbirth

the process of expelling the placenta from the uterus; involves bleeding due to damaged vascular tissues and is stimulated by oxytocin

Involution

process involving the shrinking of the uterus and the the sloughing off of endometrium as discharge

Ductile systems

Estrogens cause the __________ to growth and branch and deposit fat around them

Alveolar glands

Progesterone stimulates the development of the ______ at the ends of the ducts

Colostrum

the first milk produced by the mother that is a thin, watery fluid that is rich in antibodies and proteins and low in carbohydrates and fats compared to mature milk

Suckling

action that causes milk to be ejected by a reflex involving secretion of oxytocin; also causes continued secretion of prolactin

Do not ovulate

Breastfeeding mothers typically _______ for several months due to inhibition of FSH and LH secretion by prolactin

Periods of the postnatal period

neonatal period, infancy, childhood, adolescence, adulthood, and senescence

True

True or false, Dying is part of the life cycle

Neonatal period

period from birth to the end of the 4th week of life where newborn begins to carry on respiration, obtain nutrients, digest nutrients, excrete wastes, regulate body temperature, and make cardiovascular adjustments

Infancy

period from end of fourth week postbirth to one year where growth rate is high; teeth begin to erupt; muscular and nervous systems mature so that coordinated activities are possible; communication begins