Reproductive System Chapter 27: Anatomy and Physiology of the Male Reproductive System

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22 Questions

What is the primary function of the tunica albuginea in the testes?

To separate the testes into lobules and provide structural support

At what stage of development do the testes typically descend?

Around month 7 in the womb

What is the term for the condition where the testes fail to descend before birth?

Cryptorchidism

What is the function of the Sertoli cells in the testes?

To promote sperm production and eliminate germ cells

What is the duration of one cycle of spermatogenesis?

64 days

What is the term for the male gamete?

Sperm

What is the primary function of the mitochondria in the mid-piece of a sperm cell?

To provide energy for the sperm's movement

What is the primary function of the seminal vesicles in the male reproductive system?

To contribute to the formation of semen

What is the typical volume of a sperm cell compared to a female gamete?

85,000 times smaller

What is the primary function of the epididymis in the male reproductive system?

To continue the maturation of sperm

What is the primary function of the prostate gland in the male reproductive system?

To secrete fluid that coagulates semen

What is the approximate number of sperm cells produced by the male reproductive system each day?

100,000 - 300,000

What is the primary function of the bulbourethral glands in the male reproductive system?

To provide a thick and salty fluid to lubricate the end of the urethra and vagina

What is the role of nitric oxide in the process of arousal and erection in the male reproductive system?

To dilate blood vessels and rapidly increase blood volume

What is the primary function of the ovaries in the female reproductive system?

To produce gametes and support the development of a fetus

What is the process by which the dominant follicle releases an oocyte from the ovary?

Ovulation

What is the role of the corpus luteum in the female reproductive system?

To produce progesterone and prepare the uterus for implantation

What is the primary function of the uterine tubes in the female reproductive system?

To propel the oocyte towards the uterus

What is the role of the cervix in the female reproductive system?

To secrete mucus that assists sperm movement

What is the primary function of the breasts in the female reproductive system?

To produce milk for lactation

What is the role of the SRY gene in the development of the male reproductive system?

To prompt male development and cause testosterone secretion

What is the primary function of the hypothalamus in the regulation of puberty?

To increase the release of hormones from the hypothalamus, anterior pituitary, and gonads

Study Notes

Male Reproductive System

  • Gamete: specialized sex cell carrying 23 chromosomes
  • Sperm: male gamete
  • Oocyte: female gamete
  • Testes:
    • Produce sperm and androgens to support reproduction
    • Located inside the scrotum to maintain a temperature 2-4°C lower than body temperature
    • Surrounded by dartos and cremaster muscles that contract or relax to raise or lower the testes
  • Testes anatomy:
    • Paired, 2-layered male gonads
    • Tunica vaginalis: outer serous membrane
    • Tunica albuginea: tough connective tissue covering the entire testes, separating it into 300-400 lobules
    • Seminiferous tubules: where sperm develops inside the lobules, tightly coiled
  • Sertoli cells: promote sperm production, create the blood-testis barrier due to tight junctions
  • Spermatogonia: stem cells or germ cells of the testes
  • Spermatogenesis: process of producing sperm in the seminiferous tubules, begins at puberty, takes 64 days, and one cycle starts every 16 days, producing 4 haploid daughter cells (spermatids)

Structure of Formed Sperm

  • Smaller than most cells, 85,000 times less volume than female gametes
  • Composed of:
    • Head: haploid nucleus and little cytoplasm, covered in lysosomal enzymes in the acrosome
    • Mid-piece: tightly packed mitochondria
    • Tail: flagellum for movement or motility
  • Produce 100-300 million sperm per day

Sperm Travel

  • Start in seminiferous tubules and move via fluid to epididymis, taking 12 days to move through the epididymis
  • Epididymis: 6 meters long, tightly coiled, continues maturation, and stores sperm in the tail until ejaculation occurs
  • Duct system: sperm exit and are pushed to ductus deferens (thick muscular tube, part of spermatic cord)
  • Ampulla: where the duct ends, posterior to the bladder

Seminal Vesicles and Prostate Gland

  • Seminal vesicles: contribute 60% of semen volume, producing fructose for ATP
  • Prostate gland:
    • As big as a walnut, consisting of muscle and gland tissue
    • Secrete fluid to coagulate semen, which will later de-coagulate in the female
    • Size doubles at puberty and gradually grows after age 25
    • Benign prostatic hyperplasia (BPH): prostate enlargement leading to urinary issues
    • Prostate cancer: second most common cancer in men, detected by Hx, blood test, and rectal exam

Bulbourethral Glands and Penis

  • Bulbourethral glands: add a thick and salty fluid to semen to lubricate the end of the urethra and vagina and clean urine residue
  • Penis:
    • 3 chambers surrounding the urethra fill with blood (vasocongestion) during arousal and REM sleep
    • Nitric oxide (NO) release dilates blood vessels and rapidly increases blood volume to fill chambers

Testosterone

  • Secreted by the testes from the 7th week of development to differentiate male sexual organs
  • Increases at puberty, producing 6-7 mg/day, with low levels leading to infertility
  • Maintains the male reproductive system, promotes muscle development, bone growth, secondary sex characteristics, and libido in men and women
  • Ovaries and adrenal glands secrete a small amount of testosterone
  • Controlled by the hypothalamus and pituitary gland, with GnRH stimulating the release of LH and FSH

Female Reproductive System

  • Produces gametes and hormones, supports and delivers a developing fetus
  • Primarily located inside the pelvic cavity
  • Ovaries: female gonads
  • Oocyte: gamete produced in females
  • Vulva: external reproductive structures
  • Labia minora: protect the reproductive tract and urethra
  • Clitoris: derives from the same cells as the penis, with abundant nerve innervation
  • Hymen: thin membrane that partially covers the vagina
  • Vagina: muscular canal, entrance to the reproductive tract, exit for the fetus, expands for intercourse and childbirth, and has an acidic pH for self-cleaning

Ovaries

  • Paired gonads, almond-sized
  • Attached to the uterus by the ovarian ligament
  • Superficial ovarian epithelium covers dense tunica albuginea
  • Oocytes develop in the outer layer of the cortex
  • Follicle: supporting cells surrounding the oocyte
  • Ovarian medulla: blood vessels, lymph vessels, and nerves of the ovary

Ovarian Cycle

  • 28-day cycle, not the same as the menstrual cycle
  • Only occurs during reproductive years
  • Consists of two interrelated processes: oogenesis and folliculogenesis
  • Follicular phase: follicles mature and prepare to release an oocyte
  • Ovulation: release of a mature oocyte
  • Luteal phase: the dominant follicle becomes the corpus luteum and produces progesterone

Oogenesis

  • Oogonia: ovarian stem cells, divide by mitosis, formed during fetal development
  • Primary oocytes halt development until puberty and last until menopause
  • 1-2 million oogonia in an infant, 400,000 at puberty, and 0 at menopause
  • Ovulation: releasing an oocyte from the ovary
  • Cells divide unequally, with only 1 cell large enough to become a mature ovum, and the other 3 becoming polar bodies

Folliculogenesis

  • Normally leads to ovulation every 28 days, with the death of multiple other follicles
  • Atresia: death of ovarian follicles
  • A few primordial follicles respond to recruitment each day and become primary follicles
  • Primary follicles increase in size and become secondary follicles
  • Oocyte secretes a membrane to increase size, becoming a tertiary follicle

Uterine Tubes (Fallopian)

  • Path from ovary to uterus, not connected to the ovary
  • Isthmus: narrow end connected to the uterus
  • Infundibulum: wide distal end with fimbriae
  • Ampulla: middle section where fertilization often occurs
  • Cilia propel the oocyte to the uterus, with stronger beats in the presence of estrogen

Uterus and Cervix

  • Uterus: muscular organ to nourish the growing embryo
  • Fundus: area superior to the uterine tubes
  • Body of uterus: middle section
  • Cervix: inferior section that projects into the vagina, secreting mucus that assists sperm movement
  • Uterus is held in place by ligaments and consists of 3 layers (perimetrium, myometrium, endometrium)
  • The stratum functionalis is the layer of the endometrium that is shed during menstruation

Menstrual Cycle

  • Uterine lining is shed, rebuilt, and prepares for implantation, with three phases:
    • Menses phase: lining is shed, lasts about 5 days, with low hormone levels
    • Proliferative phase: endometrium rebuilds, with rising hormone levels
    • Secretory phase: started by progesterone from the corpus luteum, preparing the body for implantation

The Breasts

  • Accessory organs that supply milk to the infant, lactation
  • Mammary glands produce milk, which exits through the nipple
  • Areolar glands surround the nipple and secrete lubricating fluid to prevent chaffing
  • Breasts are supported by suspensory ligaments
  • Changing hormone levels lead to swelling and tenderness during pregnancy, and mammary tissue develops and breasts enlarge

Hormonal Birth Control

  • Manipulate the negative feedback system
  • Provide constant hormones to prevent FSH and LH production
  • Endometrial wall will not get as thick
  • New birth control pills may result in no menses
  • Missing the wrong day or two can lead to ovulation

Test your knowledge on the male reproductive system, including the anatomy and physiology of the testes, gametes, and hormones. Learn about the structure and function of the male reproductive organs and how they support reproduction. This quiz covers the basics of chapter 27 in the reproductive system.

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