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HAN 202 > Chapter 28 Human Development > Flashcards

Chapter 28 Human Development Flashcards

1
Q

pregnancy

A

-events that occur from fertilization until the infant is born

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2
Q

conceptus

A

-the developing offspring

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3
Q

gestation period

A
  • time from the last menstrual period until birth

- about 280 days

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4
Q

embryo

A

-conceptus from fertilization through week 8

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5
Q

fetus

A

-conceptus from week 9 through birth

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6
Q

from egg to zygote

A
  • the oocyte is viable from 12 to 24 hours (one day)
  • sperm is viable 24-48 hours after ejaculation (two days)
  • for fertilization to occur, coitus must occur no more than two days before ovulation OR 24 hours after ovulation
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7
Q

fertilization

A

-when the sperms chromosomes combine with those of a secondary oocyte (immature egg) to form a fertilized egg (zygote)

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8
Q

sperm transport

A
  • propelled by whiplike tail movement of their flagella
  • forceful uterine contractions which disperse them throughout uterine cavity
  • ejaculation sperm (40-500 million)
  • leak out of the vagina immediately after deposition
  • are destroyed by the acidic vaginal environment
  • fail to make it through the cervical mucus
  • are dispersed in the uterine cavity or destroyed by phagocytes
  • few (100 to a few thousands) reach the uterine tubes
  • total trip=5 inches
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9
Q

accomplishing fertilization

A
  • sperm need to pass 2 layers (corona radiata and zone pellucida) to reach oocyte
  • sperm must be capacitated before they can penetrate the oocyte
  • secretion of the female tract weaken acrosome membrane
  • capacitation- sperm membranes become fragile so hydrolytic enzymes can be released and break through the first layer of the oocyte
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10
Q

acrosomal reaction

A
  • sperm binds to zona pellucida, releases enzymes that digest holes in this layer
  • Ca+ levels within the sperm rise to trigger the reaction
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11
Q

sperm penetration

A
  • an acrosomal process forms and binds to receptors on oocytes plasma membrane
  • sperm and oocyte membranes fuse
  • nucleus is pulled into oocyte cytoplasm
  • only one sperm is allowed to penetrate the oocyte (monospermy)
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12
Q

once sperm enters oocyte…

A
  • waves of Ca+ are released into oocytes cytoplasm this activates:
    1. oocyte to prepare for 2nd meiotic division
    1. cortical reaction- zonal inhibiting proteins (ZIPS) are released, this blocks other sperm from entering
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13
Q

sperm inside the oocyte

A
  • after the sperm penetrate the secondary oocyte it completes meiosis 2 forming the ovum and second polar body
  • sperm and ovum nuclei swell, forming pronuclei
  • pronuclei approach each other and mitotic spindle forms between
  • chromosomes of the pronuclei intermix
  • fertilization is complete
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14
Q

cleavage

A
  • rapid mitotic division of zygote without increase in size
  • this increases surface area, increases # of cells
  • easier for uptake in nutrients, O2, and removal of wastes
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15
Q

evolution of the zygote

A
  • zygote
  • blastomeres (36 hours) - 2-8 cells
  • morula (72 hours)- 16 or more cells
  • blastocyst (4-5 days)- fluid filled hollow sphere -> this reaches the uterus to implant
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16
Q

identical twins

A

-one egg and one sperm

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17
Q

fraternal twins

A

-two eggs and two sperms

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18
Q

cojoined twins

A

split occurs late

-two identical twins are not fully separated

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19
Q

blastocyst- two types

A
  • trophoblast cells- single layer of flat cells that are immunosuppressive and participate in placenta formation
  • inner cell mass- becomes the embryonic disc
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20
Q

implantation

A
  • blastocyst floats for 2-3 days- nourished by uterine secretions
  • implantation begins 6-7 days after ovulation
  • trophoblast adheres to the endometrium
  • secrete enzymes which irritate the endometrium
  • if implantation fails the blastocyst is aborted
  • a minimum of 2/3 of zygotes fail to implant
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21
Q

which of the following stages is the true moment of fertilization

A
  • when the sperm penetrates the oocyte membrane
  • once the male pronucleus is present inside the oocyte
  • once the chromosomes of the male and female pronuclei are united*
  • when the zygote implants in the wall of the uterus
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22
Q

what happens if 2 sperm penetrate the egg

A
  • the zygote would be non functional**

- you would have twins

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23
Q

capacitation refers to changes occurring in _____

A
  • sperm before fertilization*
  • sperm during fertilization
  • oocytes before fertilization
  • oocytes after fertilization
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24
Q

human chorionic gonadotropin (hCG)

A
  • secreted by trophoblast cells, later the chorion
  • prompts corpus luteum to continue secretion of progesterone and estrogen
  • hCG levels rise until the end of the second month, then decline as the placenta begins to secrete progesterone and estrogen
  • hCG levels are used in pregnancy tests
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25
Q

placentation

A
  • formation of the placenta from embryonic and maternal tissues
  • placenta:
    1. embryonic tissues- the chorion (develop from the inner cell mass) (baby)
    1. maternal tissue -> decidua basalis (comes from mom)
  • mother and baby’s blood supply lie close but do NOT intermix
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26
Q

chorionic villi

A

-grow into blood-filled lacunae (maternal)

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27
Q

placenta

A

-nutritive, respiratory, excretory, and endocrine organ for the fetus

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28
Q

after successful implantation has occurred, the corpus luteum is maintained by the hormone ____ secreted by the trophoblast cells

A
  • FSH (follicle stimulating hormone)
  • hCG (human chorionic gonadotropin)**
  • decidua basalis
  • relaxin
29
Q

which of the following develops into the embryo

A
  • placenta
  • macula densa
  • inner cell mass*
  • zona pellucida
  • trophoblast
30
Q

embryonic development: gastrula to fetus

A
  • Gastrulation:
  • during implantation, the blastocyst starts to convert to a gastrula
  • inner cell mass develops into the embryonic disc (subdivides into epiblast and hypoblast)
  • the 3 primary germ layers and the extraembryonic membranes develop (week 3)
31
Q

extraembryonic membranes

A
    1. amnion- form amnionic sac
    1. yolk sac- forms part of digestive tube
    1. allantois- umbilical cord
    1. chorion- helps form the placenta
  • all formed within first 2-3 weeks of development
32
Q

gastrulation

A

-embryonic disc (2 layer) becomes a 3 layered embryo (endoderm, mesoderm, and ectoderm)
-appearance of primitive streak (dorsal groove)
-notochord: mesodermal cells and form axial support
-

33
Q

ectoderm

A
  • nervous system and skin, hair, nails epidermis

- endoderm and ectoderm are considered epithelia

34
Q

endoderm

A
  • epithelial linings of the digestive, respiratory, and urogenital systems
  • endoderm and ectoderm are considered epithelia
35
Q

mesoderm

A
  • forms all other tissues

- ie: muscles

36
Q

organogenesis

A
  • formation of body organs and systems
  • at 8th week:
  • all organ systems are recognizable
  • end of the embryonic period
37
Q

specialization of ectoderm: neurulation

A
  • Neurulation:
  • first major event of organogenesis
  • gives rise to brain and spinal cord
  • neural plate folds inward as a neural groove and fuse into neural tube
  • neural crest cells- cranial, spinal, and sympathetic ganglia, and adrenal medulla
38
Q

neural tube defects

A
  • Treatment- folic acid

- spina bifida

39
Q

Which of the following structures form the placenta

A
  • chorionic villi and lacunae
  • decidua capsularis and decidua basalis
  • trophoblast and decidua capsularis
  • chorion and decidua basalis*- chorion (fetus), decidua basalis (mom)
40
Q

embryonic ectoderm gives rise to the ______ in the adult organism

A
  • skin
  • nervous tissue
  • epithelial lining of the gut
  • both a and b*
  • all of the above
41
Q

which of the following is the first major event in organogenesis

A
  • neurulation*
  • cardiovascular formation
  • urinary system development
42
Q

development of fetal circulation

A
  • first blood cells arise in the yolk sac
  • by the end of the 3rd week embryo has a system of paired vessels and can hear babys heart beat
  • unique vascular modifications
  • **umbilical arteries (deoxygenated blood) and umbilical vein (oxygenated blood)
43
Q

week 9 fetus

A

-time of rapid growth of body structures established in the embryo

44
Q

effects of pregnancy: anatomical changes

A
  • relaxin- (placenta) causes pelvic ligaments and the pubic symphysis to relax to ease birth passage
  • increase in lordosis
  • reproductive organs become engorged with blood- pigmentation may increase
45
Q

expansion of uterus

A
  • occupies most of the abdominal cavity
  • before conception- size of fist and resides in pelvis
  • 4 months- fundus is halfway between pubic symphysis and umbilicus
  • 7 months- fundus is well above the umbilicus
  • 9 months- fundus reaches the xiphoid process
46
Q

physiological changes in pregnancy: GI tract

A

-morning sickness due to elevated levels of estrogen and progesterone

47
Q

physiological changes in pregnancy: urinary system

A
  • increased urine production due to increased metabolism and fetal wastes
  • stress incontinence
48
Q

physiological changes in pregnancy: respiratory system

A
  • tidal volume increases
  • dyspnea
  • may occur later in pregnancy
49
Q

physiological changes in pregnancy: CV system

A
  • blood volume increases 25-40%
  • blood pressure and pulse rise
  • venous return from lower limbs may be impaired
50
Q

teratogens

A
  • harmful substances that can cross placental barriers and enter the fetal blood which may cause congenital abnormalities or even death
  • alcohol- mental retardation
  • nicotine- hinders O2 delivery
  • medications- sedatives, antihypert
  • thalidomide- sedative of 1960s to prevent morning sickness
51
Q

parturition

A
  • parturition giving birth to the baby
  • labor events that expel the infant from the uterus
  • stages of labor:
    1. dilation-
    1. expulsion
    1. placental
52
Q

initiation of labor

A
  • during the last few weeks of pregnancy
  • fetal secretion of cortisol stimulates the placenta to secrete more estrogen
  • causes production of oxytocin receptors
  • antagonizes calming effects of progesterone, leading to Braxton hicks contractions (weak irregular contractions) in uterus- false labor
53
Q

-initiation of labor: surfactant protein A

A
  • from fetal lungs

- causes softening of the cervix

54
Q

initiation of labor: fetal oxytocin

A

-causes the placenta to produce prostaglandins

55
Q

initiation of labor: maternal emotional and physical stress

A
  • activates the hypothalamus, causing oxytocin release, causing powerful uterine contractions
  • positive feedback mechanism occurs
  • oxytocin stimulates placenta to make prostaglandins which stimulates more vigorous contractions of uterus
56
Q

stages of labor

A
    1. dilation- longest stage can last 6-12 hours or more
    1. expulsion- lasts about 30 mins
    1. placental- afterbirth- occurs about 30 mins later
56
Q

stages of labor

A
    1. dilation- longest stage can last 6-12 hours or more
    1. expulsion- lasts about 30 mins
    1. placental- afterbirth- occurs about 30 mins later
56
Q

stages of labor

A
    1. dilation- longest stage can last 6-12 hours or more
    1. expulsion- lasts about 30 mins
    1. placental- afterbirth- occurs about 30 mins later
57
Q

dilation stage

A
  • initial weak contractions
  • 15-30 minutes apart
  • 10-30 seconds long
  • becomes more vigorous and rapid
  • cervix dilates fully to 10 cm
  • amnion ruptures, releasing amniotic fluid - water breaking
  • engagement occurs- head enters the true pelvic
  • babys head is sideways to pass through true pelvis
  • in late dilation babys head rotates posteriorly once past the true pelvis
58
Q

expulsion stage

A
  • strong contractions every 2-3 minutes about 1 minute long
  • urge to push increases (in absence of local anesthesia)
  • crowning occurs when the largest dimension of the head distends vulva
  • lasts about 30-50 min
  • delivery of infant
59
Q

placental stage

A
  • strong contractions continue, causing detachment of the placenta
  • delivery of the afterbirth (placenta and membranes) occurs about 30 mins after birth
  • all placenta fragments must be removed to prevent postpartum bleeding
60
Q

placenta previa

A
  • placenta formation adjacent to uterus

- presents a problem when uterus and cervix stretch may cause separation of placenta

61
Q

neonatal period

A
  • four weeks period immediately after birth

- physical status is assessed 1-5 minutes after birth -> apgar score

62
Q

apgar score

A
  • heart rate
  • respiration
  • color
  • muscle tone
  • reflexes
  • 0-2 points each
  • 8-10 score is healthy
63
Q

first breath

A
  • increase CO2 -> central acidosis -> stimulates respiratory control centers to trigger the first inspiration
  • surfactant in alveolar fluid helps reduce surface tension
  • respiratory rate- about 45 per minute for first two weeks, then declines
  • premies usually put on respirators, lungs still immature
64
Q

lactation

A
  • production of milk by the mammary glands
  • anterior pituitary releases prolactin
  • oxytocin causes the letdown reflex- actual ejection of milk from mammary glands
  • colostrum- yellowish secretion rich in vitamin A, protein, minerals, and IgA antibodies -> released in the first 2-3 days
65
Q

what is the definition of cleavage

A
  • a period of fairly rapid mitotic divisions of the zygote without intervening growth*
  • the attachment and burrowing of the blastocyst into the uterus
  • formation of the placenta
  • the transformation of the two-layered embryonic disc into a three layered embryo
66
Q

which does not occur during gastrulation

A
  • formation of the 3 germ layers
  • appearance of the primitive streak
  • the blastocyst converts to a gastrula
  • zygote formation*
  • all of the above

HAN 202 (16 decks)

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