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.