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.