Module 27: The Reproductive System

Lesson 2: Testosterone

Hormone Testosterone

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Mỗi bài học (lesson) bao gồm 4 phần chính: Thuật ngữ, Luyện Đọc, Luyện Nghe, và Bàn Luận.
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Dưới đây là danh sách những thuật ngữ Y khoa của module The Reproductive System.
Khái quát được số lượng thuật ngữ sẽ xuất hiện trong bài đọc và nghe sẽ giúp bạn thoải mái tiêu thụ nội dung hơn. Sau khi hoàn thành nội dung đọc và nghe, bạn hãy quay lại đây và luyện tập (practice) để quen dần các thuật ngữ này. Đừng ép bản thân phải nhớ các thuật ngữ này vội vì bạn sẽ gặp và ôn lại danh sách này trong những bài học (lesson) khác của cùng một module.

Medical Terminology: The Reproductive System

alveoli
(of the breast) milk-secreting cells in the mammary gland
ampulla
(of the uterine tube) middle portion of the uterine tube in which fertilization often occurs
antrum
fluid-filled chamber that characterizes a mature tertiary (antral) follicle
areola
highly pigmented, circular area surrounding the raised nipple and containing areolar glands that secrete fluid important for lubrication during suckling
Bartholin’s glands
(also, greater vestibular glands) glands that produce a thick mucus that maintains moisture in the vulva area; also referred to as the greater vestibular glands
blood–testis barrier
tight junctions between Sertoli cells that prevent bloodborne pathogens from gaining access to later stages of spermatogenesis and prevent the potential for an autoimmune reaction to haploid sperm
body of uterus
middle section of the uterus
broad ligament
wide ligament that supports the uterus by attaching laterally to both sides of the uterus and pelvic wall
bulbourethral glands
(also, Cowper’s glands) glands that secrete a lubricating mucus that cleans and lubricates the urethra prior to and during ejaculation
cervix
elongate inferior end of the uterus where it connects to the vagina
clitoris
(also, glans clitoris) nerve-rich area of the vulva that contributes to sexual sensation during intercourse
corpus albicans
nonfunctional structure remaining in the ovarian stroma following structural and functional regression of the corpus luteum
corpus cavernosum
(plural = corpora cavernosa) either of two columns of erectile tissue in the penis that fill with blood during an erection
corpus luteum
transformed follicle after ovulation that secretes progesterone
corpus spongiosum
column of erectile tissue in the penis that fills with blood during an erection and surrounds the penile urethra on the ventral portion of the penis
ductus deferens
(also, vas deferens) duct that transports sperm from the epididymis through the spermatic cord and into the ejaculatory duct; also referred as the vas deferens
ejaculatory duct
duct that connects the ampulla of the ductus deferens with the duct of the seminal vesicle at the prostatic urethra
endometrium
inner lining of the uterus, part of which builds up during the secretory phase of the menstrual cycle and then sheds with menses
epididymis
(plural = epididymides) coiled tubular structure in which sperm start to mature and are stored until ejaculation
fimbriae
fingerlike projections on the distal uterine tubes
follicle
ovarian structure of one oocyte and surrounding granulosa (and later theca) cells
folliculogenesis
development of ovarian follicles from primordial to tertiary under the stimulation of gonadotropins
fundus
(of the uterus) domed portion of the uterus that is superior to the uterine tubes
gamete
haploid reproductive cell that contributes genetic material to form an offspring
glans penis
bulbous end of the penis that contains a large number of nerve endings
gonadotropin-releasing hormone (GnRH)
hormone released by the hypothalamus that regulates the production of follicle-stimulating hormone and luteinizing hormone from the pituitary gland
gonads
reproductive organs (testes and ovaries) that produce gametes and reproductive hormones
granulosa cells
supportive cells in the ovarian follicle that produce estrogen
hymen
membrane that covers part of the opening of the vagina
infundibulum
(of the uterine tube) wide, distal portion of the uterine tube terminating in fimbriae
inguinal canal
opening in abdominal wall that connects the testes to the abdominal cavity
isthmus
narrow, medial portion of the uterine tube that joins the uterus
labia majora
hair-covered folds of skin located behind the mons pubis
labia minora
thin, pigmented, hairless flaps of skin located medial and deep to the labia majora
lactiferous ducts
ducts that connect the mammary glands to the nipple and allow for the transport of milk
lactiferous sinus
area of milk collection between alveoli and lactiferous duct
Leydig cells
cells between the seminiferous tubules of the testes that produce testosterone; a type of interstitial cell
mammary glands
glands inside the breast that secrete milk
menarche
first menstruation in a pubertal female
menses
shedding of the inner portion of the endometrium out though the vagina; also referred to as menstruation
menses phase
phase of the menstrual cycle in which the endometrial lining is shed
menstrual cycle
approximately 28-day cycle of changes in the uterus consisting of a menses phase, a proliferative phase, and a secretory phase
mons pubis
mound of fatty tissue located at the front of the vulva
Müllerian duct
duct system present in the embryo that will eventually form the internal female reproductive structures
myometrium
smooth muscle layer of uterus that allows for uterine contractions during labor and expulsion of menstrual blood
oocyte
cell that results from the division of the oogonium and undergoes meiosis I at the LH surge and meiosis II at fertilization to become a haploid ovum
oogenesis
process by which oogonia divide by mitosis to primary oocytes, which undergo meiosis to produce the secondary oocyte and, upon fertilization, the ovum
oogonia
ovarian stem cells that undergo mitosis during female fetal development to form primary oocytes
ovarian cycle
approximately 28-day cycle of changes in the ovary consisting of a follicular phase and a luteal phase
ovaries
female gonads that produce oocytes and sex steroid hormones (notably estrogen and progesterone)
ovulation
release of a secondary oocyte and associated granulosa cells from an ovary
ovum
haploid female gamete resulting from completion of meiosis II at fertilization
penis
male organ of copulation
perimetrium
outer epithelial layer of uterine wall
polar body
smaller cell produced during the process of meiosis in oogenesis
prepuce
(also, foreskin) flap of skin that forms a collar around, and thus protects and lubricates, the glans penis; also referred as the foreskin
primary follicles
ovarian follicles with a primary oocyte and one layer of cuboidal granulosa cells
primordial follicles
least developed ovarian follicles that consist of a single oocyte and a single layer of flat (squamous) granulosa cells
proliferative phase
phase of the menstrual cycle in which the endometrium proliferates
prostate gland
doughnut-shaped gland at the base of the bladder surrounding the urethra and contributing fluid to semen during ejaculation
puberty
life stage during which a male or female adolescent becomes anatomically and physiologically capable of reproduction
rugae
(of the vagina) folds of skin in the vagina that allow it to stretch during intercourse and childbirth
scrotum
external pouch of skin and muscle that houses the testes
secondary follicles
ovarian follicles with a primary oocyte and multiple layers of granulosa cells
secondary sex characteristics
physical characteristics that are influenced by sex steroid hormones and have supporting roles in reproductive function
secretory phase
phase of the menstrual cycle in which the endometrium secretes a nutrient-rich fluid in preparation for implantation of an embryo
semen
ejaculatory fluid composed of sperm and secretions from the seminal vesicles, prostate, and bulbourethral glands
seminal vesicle
gland that produces seminal fluid, which contributes to semen
seminiferous tubules
tube structures within the testes where spermatogenesis occurs
Sertoli cells
cells that support germ cells through the process of spermatogenesis; a type of sustentacular cell
sperm
(also, spermatozoon) male gamete
spermatic cord
bundle of nerves and blood vessels that supplies the testes; contains ductus deferens
spermatid
immature sperm cells produced by meiosis II of secondary spermatocytes
spermatocyte
cell that results from the division of spermatogonium and undergoes meiosis I and meiosis II to form spermatids
spermatogenesis
formation of new sperm, occurs in the seminiferous tubules of the testes
spermatogonia
(singular = spermatogonium) diploid precursor cells that become sperm
spermiogenesis
transformation of spermatids to spermatozoa during spermatogenesis
suspensory ligaments
bands of connective tissue that suspend the breast onto the chest wall by attachment to the overlying dermis
tertiary follicles
(also, antral follicles) ovarian follicles with a primary or secondary oocyte, multiple layers of granulosa cells, and a fully formed antrum
testes
(singular = testis) male gonads
theca cells
estrogen-producing cells in a maturing ovarian follicle
uterine tubes
(also, fallopian tubes or oviducts) ducts that facilitate transport of an ovulated oocyte to the uterus
uterus
muscular hollow organ in which a fertilized egg develops into a fetus
vagina
tunnel-like organ that provides access to the uterus for the insertion of semen and from the uterus for the birth of a baby
vulva
external female genitalia
Wolffian duct
duct system present in the embryo that will eventually form the internal male reproductive structures
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Dưới đây là các bài văn nằm ở bên trái. Ở bên phải là các bài luyện tập (practice) để đánh giá khả năng đọc hiểu của bạn. Sẽ khó khăn trong thời gian đầu nếu vốn từ vựng của bạn còn hạn chế, đặc biệt là từ vựng Y khoa. Hãy kiên nhẫn và đọc nhiều nhất có kể, lượng kiến thức tích tụ dần sẽ giúp bạn đọc thoải mái hơn.
Testosterone, an androgen, is a steroid hormone produced by Leydig cells. The alternate term for Leydig cells, interstitial cells, reflects their location between the seminiferous tubules in the testes. In male embryos, testosterone is secreted by Leydig cells by the seventh week of development, with peak concentrations reached in the second trimester. This early release of testosterone results in the anatomical differentiation of the male sexual organs. In childhood, testosterone concentrations are low. They increase during puberty, activating characteristic physical changes and initiating spermatogenesis.
The continued presence of testosterone is necessary to keep the male reproductive system working properly, and Leydig cells produce approximately 6 to 7 mg of testosterone per day. Testicular steroidogenesis (the manufacture of androgens, including testosterone) results in testosterone concentrations that are 100 times higher in the testes than in the circulation. Maintaining these normal concentrations of testosterone promotes spermatogenesis, whereas low levels of testosterone can lead to infertility. In addition to intratesticular secretion, testosterone is also released into the systemic circulation and plays an important role in muscle development, bone growth, the development of secondary sex characteristics, and maintaining libido (sex drive) in both males and females. In females, the ovaries secrete small amounts of testosterone, although most is converted to estradiol. A small amount of testosterone is also secreted by the adrenal glands in both sexes.
The regulation of testosterone concentrations throughout the body is critical for male reproductive function. The intricate interplay between the endocrine system and the reproductive system is shown in Figure 1.

The regulation of Leydig cell production of testosterone begins outside of the testes. The hypothalamus and the pituitary gland in the brain integrate external and internal signals to control testosterone synthesis and secretion. The regulation begins in the hypothalamus. Pulsatile release of a hormone called gonadotropin-releasing hormone (GnRH) from the hypothalamus stimulates the endocrine release of hormones from the pituitary gland. Binding of GnRH to its receptors on the anterior pituitary gland stimulates release of the two gonadotropins: luteinizing hormone (LH) and follicle-stimulating hormone (FSH). These two hormones are critical for reproductive function in all humans. In the testes, FSH binds predominantly to the Sertoli cells within the seminiferous tubules to promote spermatogenesis. FSH also stimulates the Sertoli cells to produce hormones called inhibins, which function to inhibit FSH release from the pituitary, thus reducing testosterone secretion. These polypeptide hormones correlate directly with Sertoli cell function and sperm number; inhibin B can be used as a marker of spermatogenic activity. LH binds to receptors on Leydig cells in the testes and upregulates the production of testosterone.

A negative feedback loop predominantly controls the synthesis and secretion of both FSH and LH. Low blood concentrations of testosterone stimulate the hypothalamic release of GnRH. GnRH then stimulates the anterior pituitary to secrete LH into the bloodstream. In the testis, LH binds to LH receptors on Leydig cells and stimulates the release of testosterone. When concentrations of testosterone in the blood reach a critical threshold, testosterone itself will bind to androgen receptors on both the hypothalamus and the anterior pituitary, inhibiting the synthesis and secretion of GnRH and LH, respectively. When the blood concentrations of testosterone once again decline, testosterone no longer interacts with the receptors to the same degree and GnRH and LH are once again secreted, stimulating more testosterone production. This same process occurs with FSH and inhibin to control spermatogenesis.

OpenStax. (2022). Anatomy and Physiology 2e. Rice University. Retrieved June 15, 2023. ISBN-13: 978-1-711494-06-7 (Hardcover) ISBN-13: 978-1-711494-05-0 (Paperback) ISBN-13: 978-1-951693-42-8 (Digital). License: Attribution 4.0 International (CC BY 4.0). Access for free at openstax.org.

The hypothalamus and pituitary gland regulate the production of testosterone and the cells that assist in spermatogenesis. GnRH activates the anterior pituitary to produce LH and FSH, which in turn stimulate Leydig cells and Sertoli cells, respectively. The system is a negative feedback loop because the end products of the pathway, testosterone and inhibin, interact with the activity of GnRH to inhibit their own production.

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Xem video và cảm nhận nội dung bài. Bạn có thể thả trôi, cảm nhận dòng chảy ngôn ngữ và không nhất thiết phải hiểu toàn bộ bài. Bên dưới là script để bạn khái quát nội dụng và tra từ mới.
Script:
  1. Testosterone, a steroid hormone, is produced primarily by Leydig cells in the testes.
  2. Testosterone regulates and maintains the sex organs and sex drive, and induces the physical changes of puberty.
  3. In embryonic development, testosterone facilitates the differentiation of male sexual organs.
  4. Throughout life, normal testosterone levels are essential for maintaining reproductive health, promoting spermatogenesis, and supporting secondary sexual characteristics, muscle development, bone growth, and libido in both sexes.
  5. Testosterone synthesis and secretion are tightly regulated by a complex feedback system involving the hypothalamus, pituitary gland, and testes.
  6. Gonadotropin-releasing hormone (or GnRH) from the hypothalamus stimulates the release of luteinizing hormone (or LH) and follicle-stimulating hormone (or FSH) from the pituitary, which in turn stimulate testosterone production by Leydig cells.
  7. Negative feedback mechanisms ensure the maintenance of appropriate testosterone levels by adjusting GnRH, LH, and FSH secretion in response to changes in testosterone concentrations.
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