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Questions and Answers
What is the primary function of the dartos and cremaster muscles?
What is the outer layer of the serous membrane that covers the testes?
What is the process by which sperm are produced in the seminiferous tubules?
What is the purpose of the Sertoli cells in the testes?
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What is the approximate number of times smaller a sperm is compared to a female gamete?
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What is the term for the failure of the testes to descend before birth?
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Where do sperm undergo final maturation and are stored until ejaculation?
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What is the function of the seminal vesicles in the male reproductive system?
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What is the role of the prostate gland in the male reproductive system?
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What is the primary function of testosterone in the male reproductive system?
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What is the site of fertilization in the female reproductive system?
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What are the three phases of the ovarian cycle?
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What is the primary function of the corpus luteum during the luteal phase?
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What happens to the primary oocytes during fetal development and after puberty?
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What is the role of cilia in the uterine tubes?
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What is the result of the decline of FSH levels during folliculogenesis?
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What is the narrow, distal end of the uterine tube connected to the uterus?
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Why is it necessary for implantation to occur within 10-12 days of ovulation?
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What is the purpose of the areolar gland in the breast?
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What happens to the endometrial wall when hormonal birth control is used?
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What is the role of the SRY gene in the development of males?
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What is the purpose of the uterine lining during the menstrual cycle?
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What is the result of missing a day of hormonal birth control?
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What is the characteristic of the embryonic cells that can develop into either male or female?
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Study Notes
Gamete and Gonads
- Gamete: specialized sex cell carrying 23 chromosomes
- Male gamete: sperm
- Female gamete: oocyte
- Testes: produce sperm and androgens, located inside the scrotum to maintain 2-3 degrees cooler temperature than body temperature
- Dartos and cremaster muscles: raise and lower the testes
Testes Structure
- Two layers: tunica vaginalis (outer layer of serous membrane) and tunica albuginea (tough connective tissue)
- Tunica albuginea: covers entire testes, separates them into 300-400 lobules
- Seminiferous tubules: where sperm develops inside the lobules, tightly coiled
- Sertoli cells: promote sperm production, eliminate germ cells, and 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 a new cycle starts every 16 days
- Produces 4 haploid daughter cells
Sperm Structure
- Smaller than most cells, 85,000 times less volume than a female gamete
- Structure: head, mid-piece, and tail
Menstrual Cycle
- Uterine lining is shed, rebuilt, and prepares for implantation
- Timing starts with the first day of menses, Day 1 of period
- Menses phase: lining is shed, lasts about 5 days, low levels of progesterone, FSH, and LH
- Proliferate phase: endometrium rebuilds, hormone levels are rising
- Secretory phase: started by progesterone from corpus luteum, prepares for implantation, if hormone levels fall, tissues die, resulting in menses
Breast and Hormonal Birth Control
- Breast: accessory organs that supply milk to the infant
- Mammary glands: produce milk, exit from the nipple
- Areolar gland: surrounds nipple, secretes lubrication fluid to prevent chafing
- Breast support: suspensory ligaments
- Hormonal birth control: manipulates negative feedback system, provides constant hormones, prevents FSH and LH production, endometrial wall does not get as thick, and new birth control pill may result in no menses
Development of Male and Female
- Without chemical prompting, all eggs are female
- In embryos, the same cells can be male or female, known as bipotential
- SRY gene: prompts male development, causes testosterone secretion
- Mullerian duct: in females, forms uterus, uterine tubes, and part of the vagina
- Wolffish duct: in males, forms epididymis, ductus deferens, and seminal vesicles
Puberty
- Stage of sexual maturity, increase in hormone release from hypothalamus, anterior pituitary, and the gonads
- Signs of puberty in males: increased larynx size, deeper voice, increased muscular development, and hair growth
- Signs of puberty in females: fat deposited into breasts and hips, breasts develop, pelvis broadens, and hair growth
Male Reproductive System
- Epididymis: 6 meters long, tightly coiled, continues maturation, and stores sperm in the tail until ejaculation
- Duct system: sperm exit and are pushed to ductus deferens
- Ampulla: where the duct ends, posterior to the bladder
- Seminal vesicles: glands that contribute 60% of semen volume, secrete fructose for ATP
- Prostate gland: muscle and gland tissue, secrets fluid to coagulate semen, doubles in size at puberty, and gradually grows after age 25
- Bulbourethral glands: final addition to semen, thick and salty fluid to lubricate the end of the urethra and vagina, and clean urine residue
Penis
- 3 chambers surrounding the urethra filled with blood during arousal and REM sleep
- NO is released to dilate blood vessels, rapidly increasing blood volume to fill chambers
- Filled chambers put pressure on the venules, preventing drainage
Testosterone
- Secreted by 7th week of development to differentiate male sexual organs, increases again at puberty
- Keeps male reproductive system working properly, produces 6-7 mg/day, and responsible for muscle development, bone growth, secondary sex characteristics, and libido in men and women
Ovaries
- Paired gonads, size of an almond, attached to uterus by ovarian ligament
- Superficial ovarian epithelium covers dense tunica albuginea
- Oocyte develops into 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
- About 28 days, not the same as the menstrual cycle, only during reproductive years
- Has 2 interrelated processes: oogenesis and folliculogenesis
- Phases: follicular, ovulation, and luteal
Oogenesis
- Primary oocytes halt development until puberty and last until menopause
- 1-2 million in an infant, 400,000 at puberty, and 0 at menopause
- Ovulation: releasing an oocyte from the ovary
Folliculogenesis
- Normally leads to ovulation every 28 days, and death to multiple other 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, and now we have a tertiary follicle
- Many follicles reach the tertiary stage at once, but normally only 1 can survive, and the others die
Implantation
- Must happen in 10-12 days, or corpus luteum degrades into corpus albicans and ceases secretion
Uterine Tubes
- Path from ovary to uterus, not connected to ovary
- Cilia propels oocyte to the uterus, beating stronger with greater estrogen concentration
- Muscular contractions help move the oocyte
- Isthmus: narrow end connected to uterus
- Infundibulum: wide distal end with fimbriae
- Ampulla: middle section where fertilization often occurs
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Description
Test your knowledge of gametes, male reproductive organs, and their functions. Learn about the structure and composition of testes, and the muscles that control their movement. perfect for students of biology and anatomy.
