Human Development Flashcards
1
Q
List the 12 major stages of ontogeny, the approximate length of time involved in each, and the major events that each one includes.
A
- Gametogenesis - formation of sex cells by meiosis (spermatogenesis/oogenesis)
- Ovulation - release of secondary oocyte and accompanying corona radiata cells
- Copulation - sex
- Fertilization - a zygote is formed (2N)
- Cleavage - initial mitotic divisions of the zygote
- Gastrulation - formation of primary germ layers (endo, ecto, meso derm)
- Organogenesis - formation of organs
- Growth - continued formation of organs and their combination to form organ systems
- Birth - fetus expelled from mother’s repro sys
* begins to sustain life partially independant of its maternal parent - Maturation - changes from birth to sexual maturity
- Senescence - physical and functional degredation (you get old)
- Death - pretty obvious
2
Q
List the 12 major stages of ontogeny, the approximate length of time involved in each, and the major events that each one includes.
A
- Gametogenesis - formation of sex cells by meiosis (spermatogenesis/oogenesis)
- Ovulation - release of secondary oocyte and accompanying corona radiata cells
- Copulation - sex
- Fertilization - a zygote is formed (2N)
- Cleavage - initial mitotic divisions of the zygote
- Gastrulation - formation of primary germ layers (endo, ecto, meso derm)
- Organogenesis - formation of organs
- Growth - continued formation of organs and their combination to form organ systems
- Birth - fetus expelled from mother’s repro sys
* begins to sustain life partially independant of its maternal parent - Maturation - changes from birth to sexual maturity
- Senescence - physical and functional degredation (you get old)
- Death - pretty obvious
3
Q
Group the appropriate ontogenic stages into the pre-embryonic, embryonic, and fetal periods.
A
- from ovulation to organogenesis = 2 weeks
- this is PRE-EMBRYONIC PERIOD
- from organogenesis to initial stages of growth = 6 weeks
- this is EMBRYONIC PERIOD (most critical period!!!)
- from eight weeks after fertilization to birth
- this is FETAL PERIOD
4
Q
State several synonyms for sexual intercourse.
A
- copulation
- coitus
- sexual intercourse
5
Q
Explain the logic behind each of the major forms of birth control.
A
- the main goal of birth control is to
- prevent implantation
- prevent ovulation
- kill sperm
- overall to keep a girl from being pregnant!
6
Q
Explain the logic behind each of the major forms of birth control.
A
- the main goal of birth control is to:
- prevent implantation
- prevent ovulation
- kill sperm
- overall to keep a girl from being pregnant!
7
Q
Explain the logic behind each of the major forms of birth control.
A
- the main goal of birth control is to:
- prevent implantation
- kill sperm
- keeping sperm and ova separated
8
Q
Define a woman’s fertile period relative to when ovulation and sexual intercourse occur.
A
- during ejaculation, sperm that enter uterus undergo change called capacitation (necessary to complete ability to fertilize)
- sperm are transported up uterine tube via peristalsis (prostaglandin) and they normally meet ovum (secondary ooctye)
- when sperm contact egg they must break through granulosa cells (corona radiata) and zona pellucida
- this is possible by acrosome (digestive enzyme) - once sperm encounters zona pellucida a chem change occurs which blocks other sperm from entering
- penetration by sperm induces 2nd meiotic division and zygote forms!
* if fertilization doesn’t occur it degenerates 12-24 hours after fertilization!
* fertilization can’t occur if copulation occurs more than 24 hours after ovulation
* sperm can survive 48 hours in female reproductive tract and so fertilization can occur from coitus occuring 1-2 day BEFORE ovulation
9
Q
Differentiate monozygotic and fraternal twins.
A
Monozygotic Twins - fertilization of one ova
- division of conceptus during early cleavage
- if they fail to separate conjoined “siamese” twins may result
Dizygotic Twins - fertilization of two ova
10
Q
Discuss cleavage using the terms morula, blastocyst, embryoblast, trophoblast, and implantation.
A
- third day after fertilization has occurred, the conceptus consists of a solid mass of cells called a MORULA
- it has also completed its slow journey down the uterine tube and has entered the uterus
- fourth day the center of the morula is filled with fluid and the resulting “hollow” ball of cells is called a BLASTOCYST
- inner cells on one side of blastocyst from the INNER CELL MASS (EMBRYOBLAST)
- forms definitive embryo!!!
- outer cells are called TROPHOBLAST
- these interact with the lining cells of the uterus to effect IMPLANTATION (NIDATION)
- some cells of the blastocyst secrete a hormone called chorionic gonadotropin that helps maintain the corpus luteum of the ovary (prevents the sloughing off of the uterine lining)
11
Q
Indicate the basic tissue disposition of each of the three primary germ layers.
A
- after implantation occurs, the embryoblast undergoes significant differentiation resulting in two distinct layers : ectoderm and endoderm
- this is followed by the third layer (mesoderm)
1. Ectoderm - forms the nervous tissue and the epithelium covering the outer body surface
2. Mesoderm - form the c.t. and the muscle tissue as wells as the kidneys and the epithelium of the serous membranes and blood vessels
3. Endoderm - forms the lining epithelium and glands of the visceral body systems
12
Q
Name the four extraembryonic membranes and state the functions of each one.
A
- Amnion - derived from ecto and mesoderm
- forms a fluid- filled, balloon-like sac which envelopes the embryo
- contains cells that slough off the surface of the fetus or amniotic lining and amniotic fluid can be aspirated by needle biopsy (amniocentesis) - cells can be examined for genetic defects
- Chorion - derived from ecto and mesoderm
* forms the fetal contribution to the placenta - Yolk Sac - forms from endoderm and mesoderm
* out- pouching of the primitive gut which produces blood cells for early embryo and some of its cells migrate into developing gonads to become spermatogonia or oogonia - Allantois - forms from endoderm and mesoderm
- helps form blood cells, the umbilical vessels, and participates in the formation of the urinary bladder
- forms tube called URACHUS - joins apex of urinary bladder to umbilical cord
(patent urachus if it persists after birth)
13
Q
Name the four extraembryonic membranes and state the functions of each one.
A
- Amnion - derived from ecto and mesoderm
- forms a fluid- filled, balloon-like sac which envelopes the embryo
- contains cells that slough off the surface of the fetus or amniotic lining and amniotic fluid can be aspirated by needle biopsy (amniocentesis) - cells can be examined for genetic defects
- Chorion - derived from ecto and mesoderm
* forms the fetal contribution to the placenta - Yolk Sac - forms from endoderm and mesoderm
* out- pouching of the primitive gut which produces blood cells for early embryo and some of its cells migrate into developing gonads to become spermatogonia or oogonia - Allantois - forms from mesoderm and endoderm and mesoderm
- helps form blood cells, the umbilical vessels, and participates in the formation of the urinary bladder
- forms tube called URACHUS - joins apex of urinary bladder to umbilical cord
(patent urachus if it persists after birth)
14
Q
Name the three stages of labor and the major event associated with each one.
A
- Dilation stage: cervical canal dilates to 10 cm and the amnion usually ruptures
- Expulsion stage: the fetus is delivered by forceful uterine and abdominal contractions
- Placental stage: the placenta is expelled
15
Q
Name the three stages of labor and the major event associated with each one.
A
- average pregnancy is 266 day +/- 2 weeks
1. Dilation stage: cervical canal dilates to 10 cm and the amnion usually ruptures
2. Expulsion stage: the fetus is delivered by forceful uterine and abdominal contractions
3. Placental stage: the placenta is expelled
