Chapter 12 - Producing offspring Flashcards
Acrosomal reaction
Release of an enzyme from the acrosome when the spermatozoa fuses with the ovum to break down the matrix of the zona pellucida so the sperm has access to the plasma membrane of the ova
Afterbirth
Refers to the placenta and the remains of the umbilical cord, amnion and chorion. Expelled after the birth of a baby
Amnion
Membrane that forms a cavity around the embryo, secretes amniotic fluid into the cavity to protect the embryo: shock absorber and maintains constant temp
Amniotic fluid
fluid contained within the amnion, protects the embryo against injury
birth canal
passage formed by the uterus, dilated cervix and the vagina through which the fetus travels at birth
blastocyst
hollow ball of cells formed during early embryonic development. referred as a blastocyst when inner cell mass and outer cell mass are formed
chorion
one of the embryonic membranes that forms part of the placenta, protective outer layer, involved in exchange of nutrients and waste products between mother and developing fetus.
chorionic villi
finger like projections that develop from the outer layer of cells of the early embryo, grow into the maternal tissue to form part of the placenta. they are surrounded by a pool of the mothers blood
corona radiata
outermost layer of cells that surrounds the ovum, follicle cells held together by materials containing acid. protects the ova, in fertilisation one sperm penetrates the corona radiata
ductus arteriosus
fetal blood vessel that enables blood in the pulmonary artery to bypass the lungs and flow directly into the aorta
ductus venosus
fetal blood vessel that enables blood to bypass the liver
ectoderm
outer tissue layer of the embryo, forms outer layers of the body: hair, nails, epidermis of the skin
embryo
early stage of development of an organism, from fertilisation to the end of the eight week of pregnancy
endoderm
innermost germ layer, gives rise to epithelium of alimentary canal, vagina and urinary bladder
foramen ovale
opening between the atria of the fetal heart, allows blood to flow directly from the right atrium into the left atrium
gestation
period of development of an organism in the uterus. time between conception and birth
implantation
process where an embryo sinks into the lining of the uterus
inner cell mass
group of cells in the blastocyst that develop into the embryo
insemination
deposition of sperm within the vagina
labour
sequence of events that precede birth and result in the expulsion of the fetus through the vagina
medoderm
middle germ layer, gives rise to skeleton, muscles, connective tissues
multipotent stem cells
stem cells that are able to give rise to a limited number of other cell types. blood stem cells give rise to red blood cells, white blood cells and platelets
parturition
process of birth
placenta
organ that supplies nutrients to and removes waste from the fetus, produces a number of hormones like estrogen and progesterone which support the uterine lining and the placenta. structure allows for close proximity for diffusion without direct mixing.
primary germ layer
embryonic tissue from which all tissues and organs of the body will develop
proliferation
process which cells replicate themselves. no differentiation
pronucleus
refers to the nucleus of the ovum and sperm that fuse at fertilisation
semen
liquid that nourishes and aids in the transport of sperm, made of sperm and fluid from the seminal vesicles, bulbo urethral gland and prostate gland
first stage labour
cervix dilates and labour pains
second stage labour
fetus is delivered
third stage labour
afterbirth is expelled
thalidomide
drug that was meant to help with morning sickness but caused babies to be born with limb malformation
totipotent stem cell
stem cell able to create any of the types of cells necessary for embryonic development
umbilical arteries
two arteries within the umbilical cord - away from fetus
umbilical cord
cord that attaches the fetus to the placenta
umbilical vein
single vein within the umbilical cord that carries blood from the placenta to the fetus
zona pellucida
thick glycoprotein membrane that surrounds the plasma membrane of the ovum
zygote
fertilised ovum
loser sperm assist winning sperm in fertilising the ovum
enzymes released from other sperm help to break down the materials that holds the cells in the corona radiata together, to allow the winning sperm to penetrate the ova
females reproductive system assists the sperm in reaching the ovum
in ovulation the cervical mucus becomes thinner and more hospitable, which allows the sperm to travel through the cervix.
sperm mortality
death of sperm before it is able to fertilise the ova. high amounts die from the harsh conditions of the female reproductive tract.
fertilisation membrane
forms when the plasma membrane of the oocyte and spermatozoa fuse, nucleus of the sperm enters the ovum. prevents the entrance of any more sperm.
sperm enters the ova
- tail of sperm is absorbed
- sperm head moves in the form of the male pronucleus
- entrance of sperm stimulates ova to complete the second meiotic division
- nucleus of ovum develops into female pronucleus
female pronucleus
when the ova undergoes the second meiotic division, the nucleus of the ova develops into a female pronucleus
fertilisation is complete when
female and male pronucleus fuse to form a single nucleus with a diploid number of chromosomes
zygote moves from oviduct to uterus
from the cilia movement in the fallopian tubes and muscle contractions in the wall of the fallopian tube
cleavage
cell division without any cytoplasmic growth. Zygote to a blastocyst, rapid divisions to create more but smaller cells
differentiation
unspecialised cells become specialised to perform specific functions in the body. caused by signals that cause genes to be switched on for differentiation to occur - chemical signals from other cells, physical contact with neighbouring cells
proliferation
process of rapid cell division to produce more cells - identical size and content to parent cell. cells do not undergo differentiation
potency
ability of a cell to become different types of cells: totipotent, pluripotent, multipotentc
stem cell
type of cell that has ability to develop into many different cell types in the body - not specialised into a specific cell time. Capable to divide and differentiate
for a zygote to form, the sperm must penetrate the
corona radiata
flexibility of cells
ability to become different types of cells - referred as potency
totipotent
most flexible, ball of cells before formation of inner cell mass - able to become embryo, placenta and umbilical chord through differentiation
pluripotent
give rise to tissues in an embryo. inner cell mass.
multipotent
give rise to cells with specific function eg blood stem cells give rise to platelets, WBC, RBC
chorionic villi
grow into the endometrium through proliferation to form the placenta through differentiation
implantation
blastocyst attaches itself to the lining of the uterus so blastocyst is able to absorb nutrients for development from glands and blood vessels of the uterine lining in order to support its growth
ectoderm
outermost germ layer - outer layers of the body: hair, nails, epidermis of skin
primary germ layer
embryonic tissue from which all tissues and organs in the body will develop
mesoderm
middle germ layer: skeleton, muscles, connective tissue
endoderm
epithelium of alimentary canal, vagina and bladder
structure of umbilical cord
two umbilical arteries (carry blood to chorionic villi), single umbilical vein (blood from placenta through unbilical cord to to the uterus
placenta develops
from fetal and maternal tissue in first 3 months of gestation. once blastocyst is implanted in endometrium, finger like projections (chorionic villi) develop from the chorion, growing into the endometrium. Surrounded in maternal blood
gestation
280 day period of fetal development. when embryo/fetus is carried in the uterus.
parturition
process of birth, follows the events of labour
labour
sequence of events before birth that result in the expulsion of the fetus through the vagina
first stage of labour
final three months of gestation, uterus does weak irregular contractions which become stronger and more frequent. end is when the cervix is completely dilated
labour pains
name for contractions when they are strong and occur every 30 minutes
second stage of labour
delivery of fetus. amnion breaks and amniotic fluid leaves the vagina. time from full dilation to birth. mother uses abdominal muscles along with contractions to push the fetus through the vagina. Babies dead pushes against the cervix which stimulates the release of oxytocin that enhances ocntractions
third stage of labour
Afterbirth is expelled - amnion, chorion and placenta.
what closes at birth
ductus venosus and ductus arteriosus and foramen ovale
liver bypassed in fetus
ductus venosus - blood from umbilical vein bypasses the liver and goes straight to inferior vena cava
lungs bypassed in fetus
ductus arteriosus means blood goes straight into the aorta from the pulmonary arter OR blood in the right atrium flows straight into the left atrium through the foramen ovale, where it will leave the body through the aorta.
MEANS OXYGENATED BLOOD CAN FLOW TO DEVELOPING FETAL TISSUE QUICKLY.
why are lumps bypassed
collapsed and non functioning means has considerable resistance to blood flow. means oxygen delivery to vital organs in the fetus is optimised
when infant starts breathing
larger amounts blood flow from heart to lungs as lungs no longer have resistance to blood flow - blood flow ductus arteriosus decreases, all thats left is fibrous tissue. more blood is returning from lungs so pressure in left atrium increases, causes foramen ovale to close against the wall of the atrium. will become permanently closed.
when umbilical cord is cut
increases CO2 in babies blood which stimulates lungs to function. blood no longer flows through umbilical vessels or ductus venosus so ductus venonsis constricts until it is cut off. Bypass aorund liver is lost so all blood passes through the liver.
hole in the heart
when foramen ovale fails to close - insufficient oxygen in the babies blood as deoxygenated blood is being pumped through the aorta.
