week 11 - fetus stuff Flashcards
oogenesis
Egg production in the ovaries
spermatogenesis
Sperm production in the testes
fertilization
a) usual site
Fallopian tubes
b) time when event occurs in relation to ovulation
After ovulation
c) structural component(s) which are involved and are formed
Sperm and egg
d) purpose
To produce humans
fertilization
a) penetration of the corona radiata and zona pellucida
For fertilization to occur, a sperm cell first must penetrate two layers: the corona radiata (the granulosa cells that surround the secondary oocyte), and the zona pellucida (the clear glycoprotein layer between the corona radiata and the oocyte’s plasma membrane)
b) production of the female pronucleus
Once a sperm cell enters a secondary oocyte, the oocyte first must complete meiosis II. It divides into a larger ovum (mature egg) and a smaller second polar body that fragments and disintegrates. The nucleus in the head of the sperm develops into the male pronucleus, and the nucleus of the fertilized ovum develops into the female pronucleus
c) production of the diploid nucleus of the zygote
After the male and female pronuclei form, they fuse, producing a single diploid nu-cleus, a process known as syngamy. Thus, the fusion of the haploid (n) pronuclei restores the diploid number (2n) of 46 chromosomes. The fertilized ovum now is called a zygote
cleavage
a) usual site
Fallopian tubes
b) time when event occurs in relation to ovulation
Will happen after ovulation
c) structural component(s) which are involved and are formed
Cleavage is a period after fertilization, when a 1-cell embryo starts developing into a multicellular organism.
d) purpose
To start the development of the fetus
events of cleavage
The first division of the zygote begins about 24 hours after fertilization and is completed about 6 hours later. Each succeeding division takes slightly less time. By the second day after fertilization, the second cleavage is completed and there are four cells. By the end of the third day, there are 16 cells. The progressively smaller cells produced by cleavage are called blastomeres. Successive cleavages eventually produce a solid sphere of cells called the morula.When the morula enters the uterine cavity on day 4 or 5, a glycogen-rich secretion from the glands of the endometrium of the uterus passes into the uterine cavity and enters the morula through the zona pellucida. This fluid, called uterine milk, along with nutrients stored in the cytoplasm of the blastomeres of the morula, provides nourishment for the developing morula. At the 32-cell stage, the fluid enters the morula, collects between the blastomeres, and reorganizes them around a large fluid-filled cavity called the blastocyst cavity Once the blastocyst cavity is formed, the developing mass is called the blastocyst. Though it now has hundreds of cells, the blastocyst is still about the same size as the original zygote.
implantation
a) usual site
uterus
b) time when event occurs in relation to ovulation
after ovulation during the secretory phase
c) structural component(s) which are involved and are formed
zygote
d) purpose
Fetus will remain there until birth important for the nutriations of the fetus
blastocyte
a) its two major components
embryoblast and trophoblast
b) the structures into which each component identified in (a) will develop
The embryoblast or inner cell mass, is located internally and eventually develops into the embryo.
trophoblast is the outer superficial layer of cells that forms the spherelike wall of the blastocyst. It will ultimately develop into the outer chorionic sac that surrounds the fetus and the fetal portion of the placenta
c) name and function of hormone secreted by outer layer
hcG - maintain the progesterone production of corpus luteum during early pregnancy
d) function of enzymes secreted by outer layer
TIMPs (1–3) - it plays a role in regulating the transcriptional profile of fetal and placental tissues associated with the early stages of pregnancy
proteseron secretion on myometrium and endometrium
Progesterone secretion on the myometrium is what will inhibit contractions of the muscles of the uterine wall, less contraction and more relaxation will help with implantation
reasons to why a time lapse is necessary between ferilixation and implation
The period of rest in the tube appears to be necessary for full development of the fertilized egg and for the uterus to prepare to receive the egg.
the urerine lining following implatation
The decidua basalis is the portion of the endometrium between the embryo and the stratum basale of the uterus; it provides large amounts of glycogen and lipids for the developing embryo and fetus and later becomes the maternal part of the placenta. The decidua capsularis is the portion of the endometrium located between the embryo and the uterine cavity. The decidua parietalis is the remaining modified endometrium that lines the non-involved areas of the rest of the uterus
increased estrogen and progesterone after pregnancy
The increase in estrogen during pregnancy enables the uterus and placenta to: improve vascularization (the formation of blood vessels) transfer nutrients. support the developing baby
emrbyo
a) definition of the term
the early developmental stage while it is in the egg or within the uterus of the mother.
b) time period during pregnancy to which term refers
from the 5th through the 10th week of pregnancy.
c) overall developmental changes which occur
Your baby’s major organs and body parts begin to take shape. The placenta forms during the embryonic stage.
fetus
a) definition of the term
an unborn offspring
b) time period during pregnancy to which term refers
10th week until birth
c) overall developmental changes which occur
All the body parts will take shape, sex organs will develop and it will be a baby by the time it comes out
primary germ layer systems
a) nervous system
ectoderm
b) integumentary system
mesoderm
c) cardiovascular system
mesoderm
d) musculoskeletal system
mesoderm
e) digestive system
mesoderm
f) respiratory system
mesoderm
development in first trimester
a) First month: Three primary germ layers have become differentiated. Body systems begin to form. Heart forms. CNS appears at the start of the third week.
b) Second month: Tissue differentiation into organs and systems continues / emphasis changes to growth and development of each system.
c) Third month: Centers of ossification have appeared in most bones. Heartbeat can be detected.
devlopment in 2nd trimester
e) Fifth month: Fetal heart may be heard. Fetal movement may be felt. Brown fat is deposited and is the site of heat production.
f) Sixth month: Fetal outline may be feltby the examiner. Lungs are not well-developed. Type II alveolar cells begin to produce surfactant. Increased utilization of iron for hematopoieses.
devleopment for 3rd tirmester
g) Seventh month: Testes descend into scrotum.
h) Eighth month: Weight gain is approximately 220 gm./week. Subcutaneous fat is deposited.
i) Ninth month: Weight gain is approximately 220 gm./week. Additional subcutaneous fat deposition has occurred.
j) Mid-tenth month: Weight gain is approximately 220 gm./week.
foramen ovvlae
a) location
a small hole located in the septum, which is the wall between the two upper chambers of the heart (atria)
b) function
makes it possible for the blood to go from the veins to the right side of the fetus’ heart, and then directly to the left side of the heart
ductus arteriosus
a) location
connects the left pulmonary artery near its origin to the descending aorta just distal to the left subclavian artery
b) function
carries blood away from the lungs and sends it directly to the body
ductus venosus
a) location
in the fetal liver connecting the umbilical vein directly to the caudal inferior vena cava or distal left hepatic vein
b) function
allows oxygenated blood in the umbilical vein to bypass the liver and is essential for normal fetal circulation
human chorionic gonadotropin
a) source(s) during embryological period
Will stimulate corpus lutem
b) source(s) during fetal period
plactena
estorgen after pregenecy
a) myometrium
Help with contraction, stimulate actin/myosin proteins
b) endometrium
Will renew the uterus lining every month until ureter is implanted into the wall
c) breast structures
Stimulates growth in milk ducts
d) external genitalia
increasing a normal clear discharge from the vagina and making the vulva and urethra healthy
progestoerone after pregency
a) myometrium
Will inhibit contractions, making it easier for implantation
b) endometrium
inhibits the proliferative activity of the endometrium
c) breast structures
stimulates the formation of the milk glands
d) external genitalia