Development Flashcards
Development
The continuous process that an individual changes from one life phase to another
Reproduction
The biological process that a living organism produces an offspring
Human reproduction
- Gamete synthesis
The formation(creation) of reproductive cells called gametes for sexual reproduction
Gametes
- sex cells
- oocytes(eggs,female)
- sperms(male)
- Copulation(sex)
The process of bringing the gametes from the male and female together
- Fertilization(also known as conception)
The combination of gametes to form a zygote
Zygote
A fertilized egg with sperms attached
Meiosis
Meiosis
Has 2 consecutive nuclear divisions
Unique features of meiosis and where they’re found
- Introduces genetic variability, in mutations
- Reduces the chromosomal number by half, in reproductive cells
Unique features of meiosis and where they’re found
- Introduces genetic variability, in mutations
- Reduces the chromosomal number by half, in reproductive cells
Prophase I
Duplicated homolgulus(same) chromosomes pair up to form a tetrad. In a process called synapsis
Synapsis: the arms of non-sister chromatids trade segments of DNA by crossing over at a site called called charisma, allowing the maternal and paternal chromosomes to exchange genetic materials
Metaphase I
- Chromosomes line up by homologous pairs
- the maternal or paternal homogulous pairs are given a side of the metaphase plate
- called indepteknt assortment
At the end of Meisosi 1, egacy daughter cells has
- one memeber of the homologous chromosomes
- half the amount of chromosomes as the parent cell
Meisosis 2
2 daughter cells further seperate to create 4 genetically unique gametes
Location and timing of Fertilixation
Typical location: in the uterine tube
Timing: within a day from when the oocyte releases from the ovary
In humans
Only 1 sperm will get through to penetrating the oocytes called monispermy
Major mechanisms of monospermy
The oocyte membrane block(fast block): binding of the first sperm activates Na+ channels and demolishes egg plasma membrane to prevent more sperms from binding
The cortical reaction(slow block): Ca2+ releases from the smooth ER to fascinate the exocytosis of cortical granules(to sperms can penetrate) to harden the oocyte membrane to make it impenetrable
True or False
The gestation period, (pregnancy), starts with fertilization and ends with birth
False; The gestation period starts from the last menstruation period(a period) and ends with birth
Fertilization would occur when the mother is already 2 weeks pregnant
True or False
The gestation period, (pregnancy), starts with fertilization and ends with birth
False; The gestation period starts from the last menstruation period(a period) and ends with birth
Fertilization would occur when the mother is already 2 weeks pregnant
Prenatal development
Starts when the e zygote starts to divide
The embryonic and Fetal periods
Embryonic period(0 to 8 weeks): begins with the zygote and the conceptua is called an embryo
Fetal period(9 weeks to birth): the concept is is called a fetus
Sig events during the embryonic stage
- cleavage
- blastocyst
- implantation.
How do cells divide during cleavage differ from typical mitotic cell divisions
There isn’t much time for growth between divioons as cells continue to grow without an increase in sizs
Cleavage
- The single cells zygote undergoes rapid cell division without increasing cytoplasm
- each division is half the size of the previous one
- there is a high surface area to volume ratio that helps to enhance the uptake of nutrients, oxygen and waste disposal
Cleavage
- The single cells zygote undergoes rapid cell division without increasing cytoplasm
- each division is half the size of the previous one
- there is a high surface area to volume ratio that helps to enhance the uptake of nutrients, oxygen and waste disposal
After a few days, the conceptua is reported to as an
Early blastocyst
The outer and inner shell of blastocyst
Outer: Triphoblast
Inner cell cluster: Embryoblast or inner cell mass
Implantation
Endometrium:
- once inside the uterus, blastocyst sticks, digests and burrows into the cell wall
Gastrulation
Inside the blastocyst, part of the Embryoblast starts to rearrange its cells
- the start of the forming of embryo
- provides a mechanism to develop a multileveled body plan starting with 3 primary germ layers
The 3 primary germ layers
Ectoderm(ecto: outer)
Mesoderm(meso(soup): middle
Endoderm(endo:within)
Organogenesis
Within each germ layer, cells continue to move and migrate, each forming different set of organs and organ systems
Ectoderm
Undergoes neuralation(the process of creating the nervous system) which leads to
- neural tubes(brain and spinal cord
- epudermis(skin layer)
- hair
- nails
Endoderm
Folds into a tube called the primitive guy( hollow cavity for digestive system)
Which becomes digestive tract, the muscle lining of the respiratory tract and liver and pancreas, lungs
Mesoderm
Forms al ost everything else in the body
- circulatory system
Lungs
Skeletal system
Muscular system
The 4 extra embryonic membranes
Amnion
The fluid filled sac that surrounds and cushions the embryo/fetus and helps maintain a constant temp and forms on the dorsal(back) of the embryo
Yolk sac
A sac developed for the primitive gut as the primary nutrient source for the embryo before the umbilical cord forms
And where the fetal blood forms
Allantois/Umbilical cord
- The structure that contains the veins and arteries and links the embryo to the placenta
- allows for nutrients
- becomes part of the urinary bladder
Allantois/Umbilical cord
- The structure that contains the veins and arteries and links the embryo to the placenta
- allows for nutrients
- becomes part of the urinary bladder
Chorion
- The outermost membrane that encloses the developing embryo and all other membranes
- forms the fetal part of the placenta
- surrounds the membrane and above terms
Placenta
Is a temporary organ that functions as a nutritive, respiratory, excretory and endocrine organ
Functions
Oxygen and nutrients are delivered to the fetus through the umbilical vein, 1 umbilica vein
Carbon dioxide and waste are removed from the fetus through the umbilical arteries, 2 umbilical arteries
Functions
Oxygen and nutrients are delivered to the fetus through the umbilical vein, 1 umbilica vein
Carbon dioxide and waste are removed from the fetus through the umbilical arteries, 2 umbilical arteries
What substances can cross the placenta and reach the fetus
Oxygen
Alcohol
Water
Hiv typically can’t
