Reproductive System and Development Exam Notes
Structural Abnormalities and Surgery
- Individuals with structural abnormalities, such as missing portions of their skull due to encephalitis, face a higher risk of injury.
- Surgery involving artificial skull plates (e.g., titanium) is often required to protect the brain.
- Multiple surgeries may be necessary as the child grows to accommodate the increasing brain and skull size.
Exam Review: Reproductive Systems and Development
- The unit is divided into two main sections: reproductive systems and development/labor processes.
- Expect anatomy questions where you identify a structure based on its function and location (e.g., "a band of tissue held tight by a ligament").
- Hormonal questions will be prevalent, so understand testosterone, inhibin, and the menstrual cycle (follicular, ovulation, and luteal phases).
Menstrual Cycle Hormone Graphs
- Assignments involving hormone graphs had issues with the proper division between follicular, ovulatory, and luteal phases.
- Ensure you can clearly distinguish between these phases and the corresponding hormonal changes.
Spermatogenesis and Oogenesis
- Spermatids mature in the epididymis, while spermatozoa are fully mature and located in the vas deferens.
- The primary oocyte is the stage before ovulation, the secondary oocyte is after ovulation but before fertilization, and the ovum is the fully fertilized egg. Do not use "ovum" as a blanket term for all.
Evolutionary Perspective of Reproduction
- Consider the goal of reproduction (pregnancy) to understand the purpose of the menstrual cycle and hormonal fluctuations.
- The hypothalamus detects when pregnancy hasn't occurred and initiates the cycle anew by releasing gonadotropic releasing hormone (GnRH).
- FSH (follicle-stimulating hormone) is released to mature another follicle. LH (luteinizing hormone) needed to rupture one.
Sex Hormones
- Both males and females share GnRH, FSH, and LH. The target tissues and subsequent hormones differ.
- Female sex hormones: GnRH, FSH, LH, estrogen, and progesterone.
- Male sex hormones: GnRH, FSH, LH, testosterone, and inhibin.
- Inhibin regulates sperm production.
Sertoli and Leydig Cells
- Sertoli cells are support cells that provide nutrients and remove waste for sperm cells (which lack cytoplasm).
- Spermatogenic cells produces the inhibit
Ovum Terminology
- Primary oocyte: Before ovulation.
- Secondary oocyte: After ovulation, before fertilization.
- Ovum: Fully fertilized egg.
Birth Control Hormonal Mechanisms
- Birth control often releases high amounts of progesterone, mimicking the luteal phase.
- This suppresses follicle development, preventing ovulation and pregnancy.
Breastfeeding Hormonal Perspective
- Be able to explain breastfeeding from a hormonal perspective, including potential problems when breastfeeding during pregnancy.
Follicle Development and Ovulation
- FSH stimulates follicle growth in the ovary.
- As the follicle grows, it produces estrogen and a small amount of progesterone.
- A surge in estrogen triggers a final surge of FSH, which then triggers a surge in luteinizing hormone (LH).
- LH causes the follicle to rupture, leading to ovulation.
- Ovulation is the release of the secondary oocyte.
Secondary Oocyte Journey
- The secondary oocyte ruptures into the abdominal cavity.
- Fimbriae sweep the oocyte into the oviduct.
- Cilia facilitate movement down the oviduct.
- If cilia aren't functioning, the oocyte can get stuck, leading to ectopic pregnancies (implantation outside the uterus).
- The most common site for ectopic pregnancy is the oviduct.
Fertilization Window
- The secondary oocyte is viable for approximately 24 hours after ovulation.
- Sperm can potentially live in the female reproductive system for up to three days.
Luteal Phase and Implantation Timelines
- After ovulation, the woman enters the luteal phase, a period of uncertainty regarding fertilization.
- Fertilization to implantation takes 10-14 days.
- Cleavage occurs within 30 hours of fertilization (2 to 4 to 8 cells).
- By 72 hours, there are 16 cells, forming a morula.
- Blastulation occurs around days 4-5, forming a blastocyst.
- Implantation begins between days 5-7, with the blastocyst embedding into the endometrium lining.
- Complete implantation takes an additional 3-7 days, totaling 10-14 days.
Corpus Luteum and Hormone Production
- After implantation, trophoblast cells produce hCG (pregnancy hormone).
- hCG signals the hypothalamus to stop the menstrual cycle.
- The corpus luteum, formed from the remnant of the ruptured follicle, produces progesterone and a small amount of estrogen.
- These hormones maintain the endometrial lining by suppressing FSH and LH.
Menstrual Cycle Phases and Hormonal Control
- Follicular phase: Maturing follicle in the ovary, shedding of the old endometrium lining in the uterus.
- Luteal phase: Endometrium lining becomes thicker and richer, preparing for implantation.
- If implantation occurs, hCG is released; if not, the cycle starts again.
Key Concepts for the Exam
- Birth control mechanisms.
- Phases of the menstrual cycle.
- Primary vs. secondary sex characteristics.
- Testosterone and inhibin pathways.
- Spermatogenesis (order of events).
- Role of the spermatogonia and where they are found.
- Oogenesis (differences from spermatogenesis).
- Fertility concepts.
- Erection control (parasympathetic nervous system) and ejaculation control (sympathetic nervous system).
- Corpora cavernosa tissue for erection.
- Semen production and the role of the three glands.
- Prostaglandins (uterine contractions, endometrial shedding, labor).
- Positive feedback loop of labor.
- Alkaline substances in semen (buffer against acidic environments).
- Sperm survival rate through the cervix (1%).
- Female anatomy (Bartholin's gland vs. Skene's gland).
- Uterine layers: endometrium, myometrium, and parametrium.
- Oogenesis start and stop points.
- Superovulation and multiple births.
Twins
- Monozygotic (identical) twins: One secondary oocyte fertilized by one sperm, followed by the zygote undergoing external cleavage rather than internal.
- Complete Physical seperation of cells on division lead to twins.
- Dizygotic (fraternal) twins: Two secondary oocytes fertilized by different sperm. They share the womb at the same time.
Menstrual Cycle and Hormonal Feedback
- Ovulation is a process we want completed and have a positive feedback.
- Make sure you get a really good grasp of that.
- Make sure that you know which phase is positive feedback loop and which ones are negative
Sexually Transmitted Infections (STIs)
- Know which STIs are caused by viruses and which are caused by bacteria.
- Distinguish between curable and manageable STIs.
Pelvic Inflammatory Disorder (PID)
- PID is inflammation or buildup of scar tissue in the oviduct.
- Causes include infections (STIs, UTIs) and injury.
- PID itself is not transmissible, but the underlying infection might be.
Follicular, Ovulatory, and Luteal Phases
- Follicular and luteal phases are negative feedback loops (homeostatic control).
- Ovulation phase is positive feedback loop (rupture of the secondary oocyte).
Prolactin and Oxytocin
- Dopamine suppresses prolactin production.
- Prolactin is trophic (affects the anterior pituitary), while oxytocin is non-trophic (affects the posterior pituitary).
Breastfeeding and Pregnancy Complications
- Two potential complications when breastfeeding during pregnancy: overuse of resources and risk of early contractions due to oxytocin release.
Sperm and Egg Layers
- Acrosome contains enzymes that allow the sperm to penetrate the egg layers.
- Egg layers: corona radiata, zona pellucida, and cell membrane.
- Only the sperm nucleus enters the egg; the rest remains outside.
- After penetration, the cell membrane hardens to prevent other sperm from entering.
Fertility and Sterility
- Sterile: Unable to have children (e.g., no uterus - requires hysterectomy).
- Fertile: May be able to have children with reproductive assistance.
- Hysterectomy does not affect hormonal production by the ovaries.
Reproductive Technologies
- Intrauterine insemination: Occurs within the uterus.
- In vitro fertilization: Occurs in a Petri dish, followed by implantation into the uterus.
Contraception
- Contraceptives often produce high levels of progestin, mimicking the luteal phase.
- This suppresses FSH and LH.
Embryonic Development
- Sequence: zygote, cleavage, blastulation, implantation, gastrulation, morphogenesis, neurulation.
- Know which primary germ layers become which tissues. The mesotherm produces muscle.
- Heart development sequence.
- Teratogen: Anything a female is exposed to during her pregnancy that crosses the placenta and causes some sort of structural abnormality.
Fetal Development
- Day 18 : Heart beats.
- Week 4 : Blood forms.
- Week 5 : Heart pumps the blood.
- Week 8 : Detect heart beat on ultrasound.
Placenta vs. Umbilical Cord
- Placenta: Connection between the endometrium and chorion.
- Umbilical cord: Tether allowing for transfer of material.
- Sampling techniques: CVS, amniocentesis, ultrasound.
Week 3: the heart beats.