Male Reproductive System

what does male reproductive system do?

• responsible for producing sperm cells and hormones

• sperm cell is important to fertilize an egg cell

• hormones are responsible for the development of adult male characteristics

• male reproductive organs + urethra in the same place

• bladder posterior to prostate gland

• rectum is posterior to bladder

external parts & functions of male repro system

penis

• external male organ

• glans: tip

• covered with foreskin that may be removed through circumcision

  • not removed = excess tissue around penis; not harmful but requires cleaning

• acts as conduit for urine to leave body

scrotum

• pair of pouch-like sacs that supports the testes

• controls temperature

  • testes must be slightly cooler than the body to produce sperm cells

• scrotum and testes are external to maintain a certain temperature for sperm

  • testes pulled closer = to warm up

penis anatomy

• shaft = corpus cavernosum, corpus spongiosum

• prepuce = tip (external)

• glans = tip; spongiosum (internal)

• bulb = base; spongiosum

• crus = toward the body

internal parts and functions of male repro system

anterior view

sagittal view

corpus cavernosa

spongey erectile tissue

• smooth muscle

• endothelial cell

• “caverns” that fill with blood to create rigidity (stiffens) during an erection

corpus spongiosum

anterior tube that surrounds the urethra and expands to form the glans

• outer layer is thin and elastic which prevents urethra from being compressed and allows for passage of ejaculate

raphe

groove, ridge, or seam

• divides the scrotum in half

cremaster muscle

• arises from the internal oblique muscle; vertical

• contracts to lift the testes closer to body to conserve heat

• surrounds the testicle and spermatic cords

• job: elevate testicles for temperature regulation

dartos muscle

• contracts and causes wrinkling of the ipsilateral testicle to decrease its surface area and heat loss

• needs elasticity to regulate temp

testicles

glands that produce sperm cells and male sex hormones called testosterone

• testes protrude outside the body because the temperature inside the main body cavity is warmer and not suitable for the development of sperm cells

testes

leydig cells produce testosterone

• seminiferous tubules: tightly coiled, microscopic tubes located within the testes responsible for producing, maintaining, and storing sperm, along with secreting testosterone

• tunica albuginea: dense fibrous connective tissue layers that makes divisions between seminiferous tubules

spermatogenesis

sperm creation

• takes place inside of seminiferous tubules

• spermatogonium: potential sperm that could make mature sperm cells

• meiosis

epididymis

narrow-coiled tube that stores immature sperm cells until they mature and temporarily stored before their release

• sperm develops tails and get stronger

• can store up to 30 days until ejaculated

• sits on top of testes

epididymis structure

• pseudostratified columnar epithelium

• uncoiled = about 6 meters (19.65 ft)

• produces a special fluid to maintain the maturing sperm

urethra

passageway of both urine from urinary bladder and semen from the glands

male urethra

divided into 3 sections

• prostatic: prostate gland region

• membranous: between prostate and root of penis

• spongy/penile: root of penis; has corpus spongiosum

sphincters (internal and external)

• internal sphincter: bladder neck

• pelvic floor: skeletal muscle

• external sphincter: urethra

reasons why a male could have urinary incontinence

urinary incontinence: involuntary loss of bladder control, ranging from occasional leaks to sudden, uncontrollable urges

• sphincters can’t close completely due to weakening of pelvic floor muscle

• prostate enlarges with age —> prostate presses on urethra

seminal vesicles

sac-like pouches attached to the vas/ductus deferens

• produces a sugar-rich fluid that provides energy to sperm cells

  • sperm cell motility: swimming

• sperm cells + sugar-rich fluid = semen

  • remains in females ~5 days

seminal vesicle (cont.)

can temporarily store sperm too

• makes fluid that contains fructose, enzymes, and prostaglandins to keep sperm alive

• contract during ejaculation and release fluid into ejaculatory duct

• fluid makes up about 60% of semen

vas deferens

long, muscular tube that serves as passageway of the sperm cells released from the testes

• connects testes to the seminal vesicle and urethra

• smooth muscle

• transports mature sperm to urethra for ejaculation

vasectomy

vas deferens are cut and sealed

• mature sperm gets reabsorbed by the action of macrophages (WBCs)

• the male needs 20-30 ejaculations until the sperm is cleared from the epididymis

prostate gland

walnut-sized gland located between the bladder and the penis

• secretes fluid that nourishes and protects the sperm

• milky white color and is alkaline to help balance out the acidic environment of female vagina

prostate (cont.)

• like a switch to allow either urine or semen—not both

• vas deferen + seminal vesicle come from prostate gland

benign prostatic hypertrophy (BPH)

noncancerous enlargement of prostate gland

• compresses urethra = difficulty urinating

• etiology: unknown; most likely due to aging and hormone changes

prostate cancer

(prostate lies directly anterior to rectum)

• stage 1: tumor/cancer cannot be felt by doctor during exam

• stage 2: tumor can be felt but it has not spread outside of prostate

• stage 3: tumor has spread outside of prostate into nearby tissues

• stage 4: tumor has spread into nearby organs such as bladder

cowper’s gland

also called the bulbourethral gland, one of the two pea-sized organs found beneath the prostate gland

• responsible for releasing fluid that flushes out foreign matter, lubricates, and neutralizes any acid in the urethra so the sperm will be safe and able to pass through freely

  • ensures sperm doesn’t mix with urine

cowper’s/bulbourethral gland (different views)

sperm cell

• head: where genetic info is

  • acrosome: most external; break through ovum’s outer layer

  • nucleus: genetic info

  • centriole

• neck: connects head to body

• body (mid piece): energy

  • mitochondria: gives energy for sperm to move

  • terminal disc

• tail: propel/give motion

  • plasma membrane

  • axial filament

  • end piece

infertility can be due to genetic makeup of sperm

sperm pathway

1. testes: sperm, testosterone made

2. epididymis: mature sperm stored

3. vas deferens

4. seminal vesicles: gives nutrition (fructose/enzymes/prostaglandin) to semen

5. prostate

6. urethra: corpus spongiosum surrounds urethra (spongy urethra)

7. bulbouretheral gland: clears the urethra