Notice: refer to the schedule for topic changes in the lecture.
For MTh classes, click here and here for the final revised schedule.
For WS classes, click here and here for the final revised schedule.
This topic together with the Female Reproductive System and Reproductive Processes + STDs and birth control methods shall be made available as a handout in the class.
Reproductive System: Male
1. Testes
Primary organ of reproduction; paired oval shaped stucture covered by a dense layer of white, thick, fibrous tissue (tunica albuginea)
Site of spermatogenesis and hormone secretion (testosterone); these are covered externally by a scrotum.
Clinical conditions:
Cryptorchism (maldescended or ectopic testis) or Cryptorchidism
Infertility
Orchitis: testes inflammation
2. Scrotum
A cutaneous outpouching of the abdomen made up of: (1) loose skin/superficial fascia, (2) dartos muscle and (3) cremaster muscle. The testes are separated internally by the median septum which can be seen externally as the perineal raphe. The scrotum primarily functions as a supporting/protective structure enclosing the testes; and acts as a thermoregulator.
3. Spermatic Ducts
- Seminiferous tubules
Germ cells: produce the spermatzoa
Supporting cells (=sertoli cells): mechanical support, protection & nutrition for developing germ cells; release of spermatozoa
Interstitial cells (of Leydig): produce testosterone
- Efferent ductules
Blunt superior end connected to testes
- Epididymis
Mass of coiled tubes (20 ft) lying outside the testes; temporary storage of immature sperm; site of maturation (18 hrs-10days)
- Vas(=ductus) deferens
18 in (length); passageway of mature sperm from the epididymis; storage of mature sperm
- Ejaculatory duct
merged end of vas deferens and seminal vesicles which terminates to the urethra
- Urethra
common passageway of sperm and urine; comprised of three regions: prostatic, membranous, penile (= spongy)
4. Accessory Glands
a. Seminal vesicle gland
Secretes an alkaline, viscid, fructose-rich fluid (H2O, fructose, prostaglandins vitamin C); constitutes 60% semen volume
b. Prostate gland
Secretes a clear viscid fluid (H2O, enzymes, buffering salts, phospholipids); constitutes 13-33% semen volume
Clinical condition: prostatitis
c. Bulbourethral(=Cowper) gl.
Secretes mucus for lubrication of urethra; alkaline fluid against acidity of vagina; constitutes 5% semen volume
5. Penis
Copulatory organ of the male; internally, it is comprised of erectile (=spongy) tissues which are cylindrical masses of cavernous or erectile tissue which fills with blood during stimulation causing erection. There are three erectile tissues: 2 superior corpora cavernosa and 1 inferior corpus spongiosum which encloses the urethra.
Externally, it is composed of three regions: (1) root, which attaches the penis to the abdomen; (2) body, that contains the urethra and erectile tissues and (3) glans penis, the bulbous end of the penis and is usually covered by a foreskin (=prepuce) typically removed by circumcision.
Clinical conditions include impotency (=erectile dysfunction) and circumcision.
6. Semen/seminal fluid (2.5-5ml) composition:
Sperm; 50-120m/ml
Fructose
Fibrinogen
Fibrolysin
Prostaglandins
Spermine
7. Sperm cell (=spermatozoon)
Composed of two regions:
Infertility occurs if sperm falls below 20-25m/ml due to poor motility, poor nutrition, infection
8. Spematogenesis and spermiogenesis
Spermatogenesis is the process by which male spermatogonia develop into mature spermatozoa. Spermatozoa are the mature male gametes in many sexually reproducing organisms. Thus, spermatogenesis is the male version of gametogenesis. In mammals it occurs in the male testes and epididymis in a stepwise fashion, and for humans takes approximately 64 days. Spermatogenesis is highly dependent upon optimal conditions for the process to occur correctly, and is essential for sexual reproduction. It starts at puberty and usually continues uninterrupted until death, although a slight decrease can be discerned in the quantity of produced sperm with increase in age. The continuous production is due to the formation of two types of spermatogonia, spermatogonium A and spermatogonium B. spermatogonium A proceeds to mitosis, thus ensuring continuous production of sperm cells whereas spermatogonium B meiotically divides into 4 spermatids.
Spermiogenesis on the other hand is the differentiation of the spermatids by growing its head and tail typical of a sperm cell.
9. Hormonal Control
Coitus/sexual intercourse/coition: process by which the spermatozoa are deposited in the female reproductive tract.
Stages:
a. excitement
Vasocongestion =Erection in the males
Myotonia, muscle tension
increased heart rate, blood pressure pulmonary ventilation
Secretion of bulbourethral gland in males
(intromission or entry of penis) tactile/ pressure sensations for both male and female
b. plateau increased vasocongestion & myotonia for both male and female
c. orgasm/climax: short/intense reaction, between 3-15 seconds
In males, coincides with ejaculation, comprised of two phases: (1) emission, flow of semen along the spermatic ducts and (2) expulsion, release of semen into the vagina
Intense feeling of release
d. resolution: return to normal: cardiovascular/ respiratory functions
Detumescence or penis becomes flaccid
In males, refractory period: 10mins – several hours, wherein the male is unable to have another erection
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