Lecture Notes on Puberty and Male Reproductive System

Vocabulary flashcards related to the lecture notes on puberty and the male reproductive system.

Puberty

The stage of development characterized by the maturation of secondary sexual characteristics and the attainment of sexual maturity. Biologically, this involves hormonal changes driven by the HPG axis, leading to physical changes such as growth spurts, development of breasts in females, and facial hair in males.

Endocrine disrupting factors

External environmental factors, such as certain chemicals, that can interfere with the body's endocrine system, potentially affecting hormonal balance and reproductive function. These factors can mimic or block the actions of hormones, disrupting normal biological processes.

Female menstrual cycle

A recurring cycle of physiological changes in the female reproductive system, driven by hormonal fluctuations. The cycle involves the maturation of an oocyte in the ovary, preparation of the uterine lining (endometrium) for implantation, and menstruation if fertilization does not occur. Key hormones include estrogen, progesterone, follicle-stimulating hormone (FSH), and luteinizing hormone (LH).

Menopause

The cessation of menstruation, typically occurring around the age of 50. Biologically, this is due to the depletion of ovarian follicles, leading to decreased estrogen production. This results in various physiological changes, including hot flashes, mood changes, and bone loss.

Lactational anovulation

The temporary absence of ovulation during lactation (breastfeeding). High levels of prolactin, the hormone responsible for milk production, suppress the release of gonadotropin-releasing hormone (GnRH) from the hypothalamus, thereby inhibiting ovulation.

Precocious puberty

The onset of puberty at an earlier age than expected. This can be caused by various factors, including genetic mutations, hormonal imbalances, or exposure to endocrine disruptors. Biologically, it involves the premature activation of the HPG axis.

DDT

A pesticide that has been detected as an endocrine disruptor. DDT can mimic or interfere with the actions of estrogen, potentially disrupting reproductive and developmental processes.

PCBs

Chemicals found in electrical equipment that can act as endocrine disruptors. PCBs can interfere with thyroid hormone function and affect reproductive health, neurodevelopment, and immune function.

Testes

The male reproductive organs responsible for producing spermatozoa and androgens (e.g., testosterone). The testes contain seminiferous tubules, where spermatogenesis occurs, and Leydig cells, which produce androgens.

Spermatogenesis

The process of sperm production, which occurs within the seminiferous tubules of the testes. This involves a series of mitotic and meiotic divisions, as well as cellular differentiation, to produce mature spermatozoa.

HPG Axis

The Hypothalamic-Pituitary-Gonadal axis, a critical regulatory system that controls reproductive function. The hypothalamus releases GnRH, which stimulates the pituitary gland to release FSH and LH. These hormones act on the gonads (testes or ovaries) to stimulate sex hormone production and gametogenesis.

Seminal vesicle, prostate gland, and bulbourethral gland

Accessory glands that contribute to the production of semen, the fluid that carries sperm. These glands secrete fluids containing nutrients, enzymes, and other substances that support sperm viability and motility.

Suspensory ligament

While the term suggests a muscle tissue holding the penis, it is not a muscle. The suspensory ligaments of the penis are connective tissues that attach the penis to the pubic symphysis, providing support and stability.

Spermiogenesis

The final stage of spermatogenesis, during which spermatids undergo morphological changes to become mature spermatozoa. This includes the formation of the acrosome, condensation of the nucleus, development of the flagellum, and shedding of excess cytoplasm.

Androgens

Sex steroid hormones produced by the testes, primarily testosterone. Androgens play a critical role in the development and maintenance of male secondary sexual characteristics, as well as spermatogenesis and libido.

Seminiferous tubules

Tightly coiled tubes within the testes where sperm are produced. The seminiferous tubules are lined with Sertoli cells and germ cells, which interact to support spermatogenesis.

Sertoli cells

Support cells within the seminiferous tubules that play a crucial role in spermatogenesis. Sertoli cells provide structural support, nutrients, and regulatory signals to developing germ cells.

Leydig cells

Cells located in the interstitial space between the seminiferous tubules that produce androgens, primarily testosterone. Leydig cells are stimulated by LH from the pituitary gland.

Lumen

The fluid-filled space inside the seminiferous tubule. Mature sperm are released into the lumen to make their way through the male reproductive tract.

Germ cell

A cell undergoing mitosis to produce germ cells. These cells eventually undergo meiosis to form sperm.

Cyto differentiation

The process by which a spermatid transforms into a fully differentiated sperm cell, characterized by distinct morphological features such as a head with an acrosome and a flagellum for motility.

Acrosome

An organelle in the sperm head that contains enzymes crucial for fertilization. These enzymes facilitate the sperm's penetration of the outer layers of the egg.

Inhibin

A hormone produced by Sertoli cells in the testes (and granulosa cells in the ovaries) that participates in a negative feedback loop with the hypothalamus and pituitary gland to regulate FSH secretion.

Cremator muscle

A muscle that contracts depending on the temperature of the testes. When contracted brings the testes closer to the body for warmth and when relaxed the testes is further from the body for cooling.

Androgen Regulation

The regulation of androgen production involves a negative feedback loop. High androgen levels inhibit the release of GnRH from the hypothalamus and LH from the pituitary, reducing further androgen synthesis.