Male Reproductive System

Scrotum Purpose: - encase / protect the testes - regulate temperature of testes *sperm production is ideal about 2 degrees cooler than body temp. Body temp rises = scrotum descends Body temp decreases, scrotum pulls testes closer into body

Penis Glans – head of penis Corona – ridge/ where head and shaft meet Corpora Cavernosa – two spongy bodies of erectile tissue on either side of the penis which become engorged with blood from arteries in the penis, thus causing erection. Urethra – exiting path for semen Meatus - external opening of the urethra

STOP Turn to a partner and discuss the following: 1 - Discuss a situation in which triggers the scrotum to ascend and/or descend. Discuss WHY this happens. 2 – Discuss how the corpora cavernosa plays an importance in the reproductive process. **Be prepared to discuss

Testes male gonads (primary sex organs) ~1 and 1/2” long; ~ 1” wide (plum)

Testes Inside Testes… 1. Seminiferous tubules - forms sperm 2. Interstitial cells - In tissue surrounding seminiferous tubules - produce testosterone

Epididymis Duct system - 20’ inches long; - 20 days for sperm to travel through - Temporary storage for immature sperm - Sperm mature as they travel through - When stimulated the walls of epididymis contract and expel sperm into the vas deferens

Vas Deferens a.k.a - ductus deferens -Propels sperm using peristaltic contractions from epididymis to the ejaculatory duct

Urethra -final part of the duct system -base of the bladder -Internal urethral sphincter contracts during ejaculation to prevent urine from entering & sperm from going into bladder

STOP With a different shoulder partner, create an analogy for the functions of the following: Testes Epididymus Vas Deferens Urethra **Be prepared to discuss

Seminal Vesicles (accessory) Location: -base of bladder -merges with vas deferens to form ejaculatory duct so sperm & seminal fluid enter at same time.

Seminal Vesicles (accessory) -Rich in fructose = “sperm food” -Vitamin C -prostaglandins = stimulate female uterine contraction to help sperm up move up into the uterus

Prostate (accessory) Location: Upper part of urethra Purpose: -Secretes alkaline fluid to neutralize semen - acidity left over from urine - help protect sperm in the acidic environment of the vagina -During ejaculation the fluid enters the urethra mixing with the seminal fluid

Bulbourethral Gland (accessory) Location: -inferior to prostate -empty directly into urethra Purpose: -Produce thick mucous that passes first through urethra during ejaculation a.k.a. “pre-ejaculatory fluid” -Cleans urethra and lubricates urethra

STOP With a DIFFERENT partner than the first 2 times, discuss the following: Come up with a general statement that summarizes what the prostate, seminal vesicles, and bulbourethral gland do for the sperm. Decide on 1-2 key terms that you can associate with each of the 3 accessory glands.

Semen -White, sticky fluid -The final mix containing sperm and accessory fluids Testes/Epididymis – produces about 5% Seminal vesicles - produce 60% Prostate - produces 30% Bulbourethral gland – produces 5% Benefit of so much fluid?  dilutes sperm = increases mobility ~ 2- mL /ejaculation ~40-600 million sperm / ejaculation

In summary… The journey of the sperm 1 – Seminiferous tubules (inside testicle) 2 – Epididymis 3 – Vas Deferens 4 – Urethra Structures that add to sperm on it’s journey 1 – Seminal vesicles 2 – Prostate gland 3 – Bulbourethral gland

Let’s recap  Match the following structure to its function ____ Scrotum ____ Testes ____ Epididymus ____ Vas deferens ____ Seminal vesicle ____ Prostate gland ____ Bulbourethral gland Adds nourishment to sperm Sperm matures here for 20 days Sperm are created here Regulate temperature of testes Lowers the acidity of seminal fluid Clears urethra prior to ejaculation Carries sperm to urethra

Skit Time!! #1 – Seminiferous Tubules #2 – Epididymus #3 – Vas Deferens #4 – Prostate Gland #5 – Seminal Vesicles #6 – Bulbourethral Gland #7 – Urethra #8 – Scrotum GOAL: Create a mini-skit that portrays the function of the gland or structure assigned. RULES: No written words No pictures Act/talk out the function

II. Male Physiology Pituitary Gland secretes TWO hormones involved in sperm production LH – Leutenizing hormone FSH – Follicle-stimulating hormone

Luteinizing Hormone (LH) a. released during and after puberty b. stimulates interstitial cells in testes to produce testosterone.

Follicle Stimulating Hormone (FSH) a. released during and after puberty b. stimulates maturation of seminiferous tubules c. stimulates spermatogenesis

Testosterone a. released by: interstitial cells b. produces sperm c. causes secondary sex characteristics i. deepen voice ii. Hair growth iii. Increased muscle mass & bone density What do you think are secondary sex characteristics? Examples?

4. Negative Feedback Control This schematic shows how a man’s hormones and organs work together to regulate sperm production. Positive feedback relationships are indicated with a plus sign; negative feedback relationships with a minus sign. The hypothalamus is part of the brain. It produces gonadotropin releasing hormone (GnRH) in pulses, from once a day to once an hour. GnRH triggers the release of 2 hormones from the pituitary gland: luteinizing hormone (LH) and follicle stimulating hormone (FSH). LH and FSH act on different types of cells within the testes. LH induces the Leydig cells surrounding the seminiferous tubules to secrete testosterone (T). FSH, along with the T from the Leydig cells, induces the Sertoli cells lining the seminiferous tubules to make both inhibin B and immature sperm, or spermatids. Inhibin B acts on the pituitary gland in a negative feedback loop. When enough inhibin is present, the pituitary stops producing FSH. T gives negative feedback to both the pituitary and the hypothalamus, decreasing the production of GnRH and LH directly. The immature sperm travel through the seminiferous tubules to the epididymis. In the epididymis, the spermatids are converted to mature sperm. The process takes about 2.5 months to complete. Only once the sperm are mature do they pass into the vasa deferentia. Male hormonal contraceptives work by attempting to block the production of sperm. Depending on the formulation, the MHC stops the secretion of one or more of the hormones and feedback loops in the diagram.

B. Spermatogenesis 1. Begins during puberty; continues throughout life 2. Millions of sperm made daily 3. Birth to puberty: a. spermatogonia (primitive stem cell) divide (mitosis) to create more stem cells

4. during & after puberty (increase in FSH) a. when spermatogonium divides one stem cell & 2 daughter cells. b. one daughter cell maintains stem cell population c. other daughter cell continues through meiosis

5. Spermiogenesis 1. last stage of spermatogenesis 2. spermatids loose cytoplasm, etc 3. develop tail