Chapter 3 - Reproductive System Flashcards
foramen ovale
A shunt in the fetus that connects blood flow from the right atrium directly to the left atrium (to bypass blood flow to the lungs)
ductus arteriosus
Shunts leftover blood from the pulmonary artery to the aorta, this allows the deoxygenated blood to travel to the lower half of the fetus’s body to the placenta
Ductus venosus
Shunts highly oxygenated umbilical venous blood from the placenta directly into the inferior vena cava
What is the purpose of shunts in a fetus?
They direct blood away from the liver and lungs, so that these organs can develop
Factors that can induce apoptosis
-DNA damage
-Development
-Viral Infections
-Stress (deprivation of nutrients & oxygen)
-Production of reactive oxygen species (ROS)
Characteristics of apoptotic cells
Condensation of nuclei, cell shrinkage, blebbing of the membrane, fragmentation of cell & nucleus, formation of apoptotic bodies that are eventually digested by macrophages
what is necrosis?
Uncontrolled cell death in response to extreme stress/trauma
What is apoptosis?
Controlled cell death via apoptotic signaling
What is determinate cleavage?
The division of cells which results in the cell committing to a particular lineage/type.
What is indeterminate cleavage?
The mitotic division of cells which doesn’t commit the cell to a specific line. This occurs when the zygote undergoes several mitotic divisions to become a morula.
Pathway from fertilized egg to gastrulation
fertilized egg (zygote) –> 2-cell embryo –> 4-cell embryo –> morula (8 cells) –> blastocyst –> gastrula
What is a morula?
It is the 8-cell stage of development
What is a blastocyst?
A hollow ball of cells with a fluid filled inner cavity. The inner cavity is which the organism develops, while the outer layer of trophoblast cells forms the developing placenta
How are monozygotic (identical) twins formed?
When a single zygote splits into two and then implants in a different region of the uterus.
What is gastrulation? When does it happen?
It is when a blastocyst develops 3 distinct germ cell layers through invagination of itself. This happens week 2 post fertilization.
Which structures of the body arise from the ectoderm?
epidermis, nails, epithelia of nose, mouth, lens of eye, all of nervous system, and inner ear
Which structures of the body arise from the endoderm?
epithelial linings of digestive & respiratory tracts, pancreas, thyroid, bladder, liver, gallblader
Which structures of the body arise from the mesoderm?
Dermis, musculoskeletal system, circulatory system, excretory organs, gonads (genitalia), connective tissue, muscle tissue of digestive & respiratory organs
What is the process of neurulation and when does it occur?
It begins of week 3 and it is when the nervous system starts developing.
Describe the steps of neurulation.
- The notochord forms from the mesoderm.
- The notochord induces the ectoderm to form the neural plate above.
- The neural plate folds inward, surrounding a middle neural groove.
- The grooves invaginate more until they fuse to form the neural tube.
- Neural crest cells from the folds migrate outwards to form the PNS.
What are teratogens?
Substances that interfere with development of the fetus.
At what stage/s of development are the cells considered totipotent?
Fertilization stage up until the morula stage is considered totipotent. Meaning that each cell can “possibly” develop into a new individual.
At what stage/s of development are the cells pluripotent?
At the blastocyst stage and gastrula stage where the stem cells make up the three germ layers. This is because these cells can differentiate into any cell type in any tissue/organ system.
what are inducers?
Specialized cells which release growth factors that signal to other cells to divide and differentiate into a specific cell type (such as a neuron)
During induction, how does the inducer cell communicate with the other cells?
It communicates directly through gap junctions with the other cells or indirectly by releasing signals into the ECM which act on cells in the localr region.
What are the 3 types of cell specialization?
specification, determination, differentiation
What is specification?
When the cell reversibly commits to a specific cell type
What is determination?
The cell commits to a particular function in the future which is irreversible.
What is differentiation?
The cell takes on the determined characteristics of the specific cell type by changing structure and function.
If a cell expresses the enzyme telomerase, what does that do?
It allows the cell to replicate indefinitely without a Hayflick limit.
What are the many functions of estrogen in the body?
-Growth of external genitalia in females
-Growth of uterine smooth muscle
-Slowing of bone breakdown/osteoclast activity
-Reducing LDL protein, increasing HDL
-Contribution to sperm maturation in males
-Secondary characteristics develop in females
During labor, which hormone helps loosen pelvic joints and controls the dilation of the cervix?
Relaxin, hormone secreted by the placenta
During labor which hormone causes uterine contractions?
Oxytocin, secreted by the posterior pituitary gland
What is the function of prolactin?
Milk production
Umbilical arteries carry…
deoxygenated blood and waste AWAY from the fetus
Umbilical veins carry…
oxygenated blood and nutrients TO the fetus
During the 2nd and 3rd trimester of pregnancy, progesterone and estrogen are produced by _________?
The placenta
During the 1st trimester, progesterone and estrogen are produced by?
The corpus luteum which is maintained by the HCG produced by the fetus.
When does an egg cell complete meiosis II?
After the sperm penetrates both layers of the ovuum itself
Why does menopause happen? What happens exactly in the body?
Menopause happens when the ovaries stop releasing an egg (depletion) every month. Ovaries start to atrophy and estrogen + progesterone levels decrease greatly. This causes FSH & LH to surge.
Functions of FSH in males
-Stimulates Sertoli cells triggering sperm production/maturation
-Growth of external genitalia
Function of FSH in females
-Stimulate estrogen production
-Stimulate size growth of eggs in ovaries
Which hormone causes the initial thickening of the endometrial lining in the uterus?
Estrogen
Which hormone oversees the maintenance of the endometrial lining after the initial thickening?
Progesterone
LH function in males
Triggers cells of Leydig to produce testosterone
LH function in females
-Causes an egg to be released at the start of the luteal phase
-After egg release, LH triggers development of the corpus luteum
What is the function of the corpus luteum?
It is a structure that remains and develops after egg release, which secretes progesterone.
Mneumonic to remember name of outer layer of ovum
Corona radiata (corona doesn’t let us go OUTside think OUTer layer)
Inner layer of ovum is called?
Zona pellucida
How many sperm are produced by a single spermatogonium?
8
How many egg cells are produced by a single oogonium?
2
What kind of cells are spermatogonium?
Haploid Stem cells
How many sperm are produced by 1 primary spermatocyte?
4 sperm
How many eggs cells are produced by 1 primary oocyte?
1 egg cell
Sperm traveling through the reproductive system mneumonic
SEVEn UP:
Seminiferous tubules
Epididymis
Vas deferens
nothing
Ejaculatory duct
Urethra
Penis
What are the symptoms of menopause?
Hot flashes, vaginal dryness, atrophy of breast tissue
Where does fertilization occur?
In the fallopian tubes
What causes ovulation to occur?
Surge in the hormone level estrogen which causes a surge in LH, releasing an egg.
What causes menstruation to occur?
Steady decline in progesterone levels due to corpus luteum dying.
What is a zygote?
It is the union/fusion of a sperm and an egg which creates a zygote; first stage of fertilization
What is the inner lining of the uterus called? What is the outer lining of the uterus called?
Endometrium; myometrium
Fertilization of two sperm cells with two eggs results in (fraternal twins/identical twins).
Fraternal twins
How do identical twins come about?
A fertilized egg splits into two, creating identical zygotes with identical genetic material.
