Lecture 14 Flashcards
Define puberty
Puberty is the period from onset of gonadotropin secretion until first menstrual period or first ejaculation of viable sperm
Define adolescence
Adolescence is the period from onset of gonadotropin secretion until a person attains full adult heigh
What is responsible for the onset of puberty in males and females?
- Hypothalamus continues to develop through childhood, then starts releasing gonadotropin-releasing hormone (GnRH)
- Anterior pituitary releases FSH and LH
- LH causes interstitial cells to produce androgens; mainly testosterone
What age does puberty start and stop?
Boys: 10-12
Girls: 8-10
Describe the roles of both Follicle Stimulating hormone and Luteinizing hormone in
•FSH stimulates nurse cells to secrete androgen-binding protein (ABP)
LH stimulates interstitial cells to produce testosterone
Roles of testosterone in male sexual development and function
Sex drive, Secondary sexual characteristics.
Pubic, armpit, and facial hair. Increases activity of apocrine glands causing acne.
What is the function of androgen binding protein (ABP)? What cells produce this protein? What is the stimulus for the production of ABP?
FSH stimulates nurse cells to secrete androgen-binding protein (ABP)
- Binds testosterone and concentrates it in lumen of seminiferous tubules
- Stimulates spermatogenesis
- No effect of testosterone without FSH and ABP
What hormone is produced when sperm count is high? What is the effect of this hormone and what cells produce it?
- Nurse cells secretes inhibin when sperm count is high
- Inhibits release of FSH
- Still allows for LH, and thus testosterone to be produced
- Inhibin release diminishes when sperm count is low
Climacteric
- Also called andropause
- Declining reproductive function in a male
- Usually begins in the 50s, at the earliest
- Testes atrophy and testosterone levels fall
- Testosterone levels can drop to 20% of levels in a male’s 20s, by age 80
- Sperm count, libido, and ability to maintain erection decreases
- Erection and urination can be hindered by enlarged prostate
Structures of the male duct system.
Epididymides»_space; Ductus deferentes»_space;Ejaculatory ducts»_space;Urethra
Epididymis
Cup-shaped structure that wraps around posterior of testes
•One long, highly coiled tube that is different in structure than seminiferous tubules
•Larger lumen
•Pseudostratified ciliated columnar epithelium
•Sperm mature and are stored here
•Damaged or old sperm are recycled here; can be stored for up to 60 days
•Sperm are not motile in epididymis and don’t become motile until mixed with secretions from accessory glands
Ductus deferentes
A ductus deferens is a 45cm tube that runs through spermatic cord, inguinal canal, and into pelvic cavity
•Lumen of is lined with pseudostratified ciliated columnar epithelium
•Has thick smooth muscle, that allows for strong peristalsis during emission phase of ejaculation
•Target of vasectomy
Ejaculatory duct
Enlarged ampulla meets with duct of seminal vesicle at ejaculatory duct
•1-2cm long tube that opens into prostatic urethra
Urethra
Male urethra is common tube for urine and semen
•18cm long and divided into
prostatic»_space; membranous»_space; spongy (penile) regions
Accessory glands of the male reproduction system
Seminal vesicles
Prostate
Bulbourethral glands
Seminal vesicles
- Paired seminal vesicles (glands) produce about 60% of seminal fluid
* Fluid is alkaline - Fructose to nourish sperm (start to become active)
- Prostaglandins cause smooth muscle to contract –including uterus
- Prosemenogelin, which gets activated and forms sperm clot in vagina
Prostate
- Single prostate secretes into the lumen of urethra through about 20 pores
- Approximately 30% of seminal fluid•Contains citrate -function?
- Also contains enzymes:
* One that converts prosemenogelin to semenogelin
* Prostate-specific antigen liquefies sperm clot about 30 mins later - Antibiotic protein called seminalplasmin that is believed to help prevent UTIs in males
- Also contains calcium which inhibits sperm motility for a period….sperm that take their time have better chance of fertilizing ovum
Bulbourethral glands
- Bulbourethral (Cowper) glands are small paired glands near bulb of penis
- Secrete fluids that have negligible impact on sperm volume (0-5%)
- Fluids lubricate urethra for passage of sperm
- Also lubricates glans of penis for intercourse
- Also buffer sperm against acidity of residual urine
- Remaining 5 -10% of semen is sperm
Two functions of the penis
Removal of urine
introduction of semen into vagina
What are the erectile cylinders of the penile tissue?
- Cylinders have lots of blood sinuses called lacunae that fill during erection
- Two dorsal partitions called the corpora cavernosa collectively or Corpus cavernosum
- Tunica albuginea surrounds corpora cavernosa
- Forms median septum and attaches corpora cavernosa to skin
- One ventral corpus spongiosum surrounds penile urethra that also makes up the glans
Describe the reflexes that result in sexual arousal of a male.
- Parasympathetic neurons from in pelvic nerves release NO onto penile arteries during arousal due to direct stimulation
* Diameter of arteries increases
* Smooth muscle of lacunae relax and erectile tissues engorge with blood
* Erection occurs
•Sympathetic fibers (also in pelvic nerves) can also dilate blood vessels and result in erection due to sexual thoughts and special senses
Four phases of the male sexual response
Excitement»_space; Plateau»_space; Orgasm»_space; Resolution
Excitement
Visual or mental stimulation and mechanical stimulation cause: Increased HR/BP/RR
Efferent parasympathetic impulses from sacral spinal chord cause:
Dilation of arteries»_space; penis engorges»_space; bulbourethral glands secrete fluid.
Plateau
The increased HR/BP/RR is sustained during plateau and prior to emission
