Reproductive System

Honors Anatomy & Physiology

Male Anatomy

Structures & Their functions

External Genetialia: Penis – copulatory organ

Shaft, glans (enlarged tip), prepuce (foreskin) Erectile (spongy) tissue – connective tissue, smooth muscle, and vascular

spaces Erection – sexual arousal triggers parasympathetic release of NO causing

arterioles to dilate, engorgement restricts drainage Testes (gonads)-1.5” x 1” sperm & testosterone production Scrotum – maintain testes temp 3oC lower than body temp

(retractable) Duct System (sympathetic control over ejaculation)

Epididymis –20 ft long, 20 days for sperm to become motile, may be stored for months (ejaculated by smooth muscle or phagocytized)

Ductus deferens – 18” long, thick smooth muscle Ejaculatory duct – through the prostate and empties into

urethra Urethra – both urine & sperm (has priority!)

3 regions: prostatic urethra, membranous, spongy

Semen Semen – milky white, sticky secretion of

sperm & secretions 2-5mL per ejaculation 20-150milliom sperm per mL Catabolism of fructose provides ATP for

flagella Prostaglandins stimulate uterine peristalsis Accessory Glands

Seminal vesicles – 60% of semen: yellow, viscous alkaline fluid w/fructose, ascorbic acid, prostaglandins enhancing sperm motility

Prostate Gland – 30% of semen: milky acidic fluid w/enzymes to activate sperm

Bulbourthral glands – pea sized glands secrete a thick clear mucus to neutralize acidic urine in urethra “pre-ejaculate”

Structure of the testis Surrounded by 2

membranes: Tunica vaginalis Tunica albuginea

Divided into 250-300 lobules

Ea/w 1-4 seminiferous tubules (sperm production)

Surrounded by myoid cells – contract to squeeze sperm out of testis into rete testis

Spermatogenesis Begins @ age 14 Makes ~400million

sperm/day Spermatogonia –

divide by mitosis @puberty some

become primary spermatocytes generating secondary spermatocytes

Producing non motile spermatotids

Female Anatomy

Female External Genitalia Vagina – 3-4” birth canal &

copulation organ 3 layers: outer fibroelastic,

smooth muscle, ridged mucosa

Acidic pH – antimicrobial but hostile to sperm

Hymen – vascular membrane in virgins

Mons pubis – fatty ridge Labia: majora & minora –

enclose the vestibule or entrance Vestibular glands – secrete

mucus Clitoris – innervated erectile

tissue hooded by prepuce

Ovaries

Produce Ova (eggs) & Sex hormones Ovarian ligament anchor to uterus & suspensory

ligament to pelvic wall Ovarian follicles ea/contains oocyte surrounded by

follicle cells Primordial follicle – 1 layer cells surround oocyte Primary follicle – 2 + layers of cells Secondary follicle – fluid filled cavity appears Graafian follicle – follicle bulges from ovary surface,

mature oocyte Ovulation – oocyte ejected from ovary Corpus luteum – follicle degenerates into scars/pits

Oogenesis Fetal period – oogonia divide by

mitosis (7 million) Primary oocytes

in primary follicles begin meiosis I, and stall in prophase I (2 milion)

Puberty 250,000 oocytes remain 1 selected every 28 days to

complete meiosis I, first polar body undergoes apoptosis, secondary oocyte is suspended in metaphase II when ovulated

<500 released over 40 years After fertilized, it completes

meiosis II, creating a second polar body that deteriorates and 1 large ovum

Ovarian Cycle @puberty pituitary releases FSH & LH

stimulating ovaries Follicular Phase (days 1-14)

Menstration (days 1-5 ) endometrium sheds Low estrogen & progesterone

Proliferative Phase (day 6-14) FSH & LH follicle growth estrogen (- feedback on release FSH & LH, +

feedback on estrogen) Endometrial lining thickens Cervical mucus thins

Ovulation (day 14) estrogen causes surge of LH & FSH, then

drops Ovary expels 2o oocyte w/corona radiata Mittlschmerz – abdominal pain due to

ovarian wall stretching Luteal /Secretory Phase (days 14-28)

estrogen progesterone (thickens endometrium) Corpus luteum degenerates

21-40 days, avg 28 days)

Female Duct System Uterine (fallopian) tubes

Receive ovulated oocyte About 4” long Fimbraie – ciliated finger like projections on distal

end create current to capture oocytes Infundibulum – funnel shaped structure Smooth muscle (peristalysis) & mucosa ciliated lining

Uterous (womb)- nourish fertilized ovum Inverted pear in size and shape 3 regions: fundus, body, & cervix 3 layers of wall:

Perimetrium – outermost layer Myometrium – smooth muscle Endometrium – 2 layers of mucosal lining (inner layer

sheds)

Menopause 20’s reproductive peak 30’s ovarian function

(quality of oocytes) declines, still ~100,000 oocytes left

By 50, only ~3 oocytes left Estrogen production

declines Menstrual periods erratic &

shorter, until ovulation & menstruation ceases

Menopause reached after 1 year w/o menstruation

Mammary Glands Produce milk by modified

sweat glands Areola – ring of

pigmented skin surrounding nipple

Ea gland/ 15-25 lobes consisting of lobules containing alveoli that produce milk

Milk passes into lactiferous ducts which open at nipple