Reproductive system

• The function of the human reproductive system is to replicate the genes of the different body systems to preserve and pass it on to the offspring.
• The reproductive system requires two different sex cells, gametes, which are produced by the male and female reproductive system.
• Female gametes, or ova, are produced by the ovaries, while male gametes, or sperm, are produced by the testes.
• The sperm fertilizes the egg, forming a zygote, which eventually becomes a fetus then a baby.
• The requirements of the sex cells to form a zygote include gamete motility and enough cytoplasm to divide up into the first cells of a developing embryo, with intracellular nutrients.
• The reproductive system has two different sex cells to meet these requirements.
• The sperm needs to be motile for it to reach the ova because of the acidic environment in the female reproductive system.
• The ova must be able to have enough cytoplasm so when the sperm fertilizes it, it could divide and become a fetus.
• Copulatory organs, such as the vagina and penis, transport or receive the gametes.
• Ovulation normally occurs in only one ovary per cycle, and the ovaries usually alternate from month to month.
• The menstrual cycle runs concurrently with the ovarian cycle and consists of the buildup of endometrium, its breakdown and vaginal discharge, which is 5 days long on average.
• The proliferative phase of the menstrual cycle sees the functional layer of endometrial tissue rebuilt, as it was lost during the last menstruation, and it is 2-3 mm thick by day 14.
• During the secretory phase of the menstrual cycle, the endometrium thickens as a result of fluid accumulation, not mitosis, and is 5-6 mm thick by the end.
• The premenstrual phase, also called the ischemic phase, is the last 2 days of the cycle and is a period of endometrial degeneration.
• The menstrual phase, also called menses, happens when enough menstrual fluid accumulates in the uterus and begins to discharge from the vagina, and the first day of discharge is day 1 of the new cycle.
• Menstrual fluid contains Fibrolysin, which prevents clot.
• Clotted blood may indicate uterine pathology.
• Menstruation sheds the functional layer of endometrium, leaving only the basal layer.
• Primary sex organs, or gonads, produce gametes.
• Secondary sex organs, or accessory organs, help in transporting the sperm or nourishing the fetus/ova.
• External genitalia are bounded by the perineum, while internal genitalia are within the pelvic cavity.
• Mature sperm is stimulated by FSH and LH to produce testosterone, also known as "the male hormone" and "androgen", which is vital for the production of sperm.
• Puberty, from the onset of pituitary gonadotropin secretion (usually around age 10 - 12) until the first ejaculation of viable sperm (typically around age 14), involves the pituitary gland and testosterone.
• The stages of puberty include the growth of the scrotum and testes, the development of apocrine glands, the lengthening of the penis, the growth of seminal vesicles and prostate glands, the appearance of hair in the pubic region, and the development of reproductive capacity.
• The production of testosterone brings about many physical changes in males.
• The feedback mechanism during the production of gonadotropin hormone involves the hypothalamus releasing GnRH, which stimulates the anterior pituitary to release LH and FSH, with FSH targeting Sertoli cells to produce sperm and LH targeting Leydig cells so testosterone will be secreted.
• The female reproductive system includes the ovaries, duct system (uterine tubes, uterus, and vagina), with the ovaries being female gonads that contain egg cells and estrogen (sex hormones), are almond-shaped, 3cm long, 1.5 wide, 1cm thick, and are covered by a white fibrous capsule called Tunica Albuginea.
• The ovarian ligament attaches the medial pole/ovaries to the uterus, the suspensory ligament attaches the lateral pole to the pelvic cavity, the mesovarium anchors the anterior margin of the ovary, and the broad ligament clamps the uterus and encloses the uterine tubes into its superior margin.
• The uterine tubes, also known as oviducts or fallopian tubes, are 10cm long, transport the egg from the ovary to the uterus, have many smooth muscles so they could contract and transport the egg into the uterus, and are enclosed by the mesosalpinx, the superior margin of the broad ligament.
• The uterus is a thick muscular chamber that opens into the roof of the vagina, tilts forward over the urinary bladder, and is where the fertilized egg stays and becomes a zygote.
• The function of the uterus is to harbor the fertilized egg and become a baby.
• Male external genitalia include the penis, scrotum, and testes, while female external genitalia include the mons pubis, labia majora, labia minora, clitoris, vaginal orifice, vestibular bulbs, and vestibular glands.
• Internal genitalia of males include the testes, epididymides, ductus deferentes, seminal vesicles, prostate, bulbourethral glands, while females include the ovaries, uterine tubes, uterus, and vagina.
• The scrotum, a part of the male reproductive system, is an external genitalia that occupies the perineum with the penis, is a pendulous pouch of skin, muscle, and fibrous connective tissue, containing testes.
• The medial septum extends anteriorly along the ventral side of the penis and posteriorly as far as the margin of the anus to maintain the temperature within the testis for sperm production.
• If the temperature within the testis is too warm or too cold, sperm production would not be as good as intended.
• The spermatic cord is a fibrous connective tissue containing the ductus deference, containing lymphatic vessels, testicular nerves and testicular artery, and pampiniform plexus.
• The cremaster is a strips of internal oblique muscle where the spermatic cord is enmeshed.
• The mechanisms for regulating the temperature of the testes include the cremaster and the dartos muscle.
• The dartos muscle contracts when cold, making the scrotum more taut and more wrinkled, helping to hold the testes snuggly in the male’s body and reducing surface area of the scrotum to reduce heat loss.