Reproductive Systems

Hormonal regulation of female reproduction involves synchronization between follicle growth, ovulation, and endometrial thickening

In hypothalamus, gonadotropin-releasing hormone (GnRH) is released, leading to the secretion of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) in the anterior pituitary

In ovaries, the release of oestrogen (oestradiol) and progesterone occurs

Menstrual cycle includes three phases: follicular phase (Day 1-13), ovulation (Day 14), and luteal phase (Day 15-28)

Menstrual flow (Day 1-4) marks the loss of functional endometrial layer and starts the proliferative phase

Secretory phase includes vascularization, glandular development, and endometrial thickening

Amenorrhea may be caused by various factors, such as hormonal imbalance, genetic abnormalities, anatomical issues, and underweight or athletic conditions

Menstrual disorders and infertility can also be caused by low sperm concentration and motility

Assisted reproductive techniques are available to help in cases of low sperm concentration and motility, including intrauterine insemination (IUI), in vitro fertilization (IVF), and intracytoplasmic sperm injection (ICSI)

Reproductive structures in females include cyclical gamete production, complex hormonal regulation, and the internal structures for gestation and development

Testes play a key role in male reproduction, as the site for gamete production and the delivery of sperm to the penis

Semen consists of sperm and secretions from various glands, such as the seminal vesicles, prostate gland, and bulbourethral glands

Male and female development is determined by the urogenital ridge, which remains undifferentiated until week 6 and then becomes the mullerian and wolffian ducts, which develop into female and male reproductive structures, respectively.

Spermatogenesis is a continuous process of producing mature sperm in the seminiferous tubules.

Each ejaculate contains around 100 million sperm per milliliter.

Sperm stem cells, called spermatogonia, are located at the periphery and undergo clonal expansion via mitosis before meiotic division.

Meiotic division results in the formation of spermatids, which then differentiate into spermatozoa.

Testosterone, an androgen produced by Leydig cells, plays a direct role in spermatogenesis and secondary sexual characteristics development via androgen receptors.

Gonadotropin-releasing hormone (GnRH) is produced in the pre-optic area and hypothalamus and stimulates the gonadotropes in the anterior pituitary gland to produce FSH and LH.

Viagra, a Phosphodiesterase (PDE) inhibitor, prevents the breakdown of cGMP and prolongs vasodilation, facilitating erection and improving blood flow for sperm transport.

Male gonads require intervention during fetal development for formation and their roles include sperm production and androgen production.

Human pregnancy lasts for approximately 266 days (~ 40 weeks) and is divided into three trimesters.

Fertilization occurs in the distal half of the Fallopian tube, where only a small percentage (~ 0.00001 %) of sperm reach the egg, which has a lifespan of 12-24 hours.

The egg must undergo the cortical reaction to prevent polyspermy and the corpus luteum degradation, securing the fertilized egg until the placenta takes over.

The Blastocyst stage (0-2 weeks) marks the pre-embryonic stage with three stages: cleavage, implantation, and embryogenesis.

The Cardiovascular System undergoes various adaptations in pregnancy, including decreased total peripheral resistance, increased blood volume, and increased cardiac output, as well as less favorable adjustments like increased pressure on pelvic blood vessels, pre-eclampsia, and gestational diabetes.