Reproduction

I. Male reproductive system

A. Function: spermatozoa production

B. Primary sex organs: Testes.

1. Structure: enclosed by tough white fibrous capsule

a. seminiferous tubules: lined with specialized stratified epithelium.

b. interstitial cells: produce and secrete male sex hormones in spaces between tubules.

c. spermatogenic cells: give rise to sperm

2. Function: sperm production

a. spermatogenesis: occurs throughout reproductive life cycle of male.

b. sperm cells collect in lumen of seminiferous tubules and pass to epididymis to mature.

c. Mature sperm: .06 mm long.

1. head: flattened, containing nucleus with 23 chromosomes.

2. acrosome: at anterior end, contains enzymes to penetrate egg cell in fertilization

3. body: cylindrical central core, mitochondria in spiral

4. flagellum: elongated tail.

C. Male Accessory Organs

1. Internal

a. Epididymis

1. structure: tightly coiled, threadlike tube. emerges from top of testis, descends along posterior surface to become vas deferens.

2. function: sperm undergo maturation as peristalsis moves sperm through tube.

b. Vas Deferens

1. structure: muscular tube.

2. passes upward along medial side of testis.

c. Seminal Vesicle

1. structure: convoluted saclike structure attached to vas deferens near base of bladder.

2. function: secretes slightly alkaline fluid to regulate pH of tubular contents as sperm conveyed to outside. contains nutrients to nourish sperm

d. Prostate gland

1. structure: below urinary bladder.

2. function: secretes thin, milky fluid with alkaline pH to neutralize sperm cell-containing fluid, enhance motility.

e. Bulbourethral glands

1. structure: composed of tubes, lined with epithelium.

2. location: located below prostate gland, enclosed by muscle fibers of external urethral sphincter.

3. function: epithelium secretes mucuslike fluid released in response to sexual stimulation.

f. Semen

1. fluid conveyed by male urethra to outside containing sperm cells and secretions of seminal vesicles, prostate, and bulbourethral glands.

2. External

a. Scrotum

1. structure: pouch of skin, subcutaneous tissue.

2. function: each contains testis. serous membrane allows for smooth movement of testis.

b. Penis

1. structure: cylindrical organ

a. shaft (body) composed of 3 columns of erectile tissue

1. 2 dorsal corpora cavernosa

2. 1 ventral corpus spongiosum.

b. glans penis: enlargement of corpus spongiosum; covers corpora cavernosa, bears urethral opening.

c. prepuce: loose fold of foreskin behind glans. covers as sheath; may be removed in circumcision.

2. function: conveys urine and semen through urethra.

D. Male Hormones

1. Gonadotropin releasing hormone: secreted by the hypothalamus stimulates the anterior pituitary to secrete gonadotropins

a. luteinizing hormone (LH): promotes development of interstitial cells. to stimulate testes to secrete male sex hormones.

b. follicle-stimulating hormone (FSH): causes supporting cells to be responsive to the effects of testosterone, which stimulate spermatogenic cells to undergo spermatogenesis.

2. Androgens: male sex hormone group.

a. Testosterone: most abundant.

1. stimulates enlargement of testes, accessory organs

2. development of secondary sex characteristics

a. increased body hair growth

b. enlargement of larynx, thickening of vocal cords

c. thickening of skin

d. increased muscular growth, broad shoulders, narrow waist

e. thickening, strengthening of muscles

3. increase in rate of cellular metabolism, RBC production

4. stimulation of sexual activity

3. Regulation: negative feedback.

II. Female reproductive system

A. Functions

1. produces and maintain egg cells

2. transports egg to site of fertilization

3. provides favorable environment for development of offspring

4. moves offspring to outside

5. produces female sex hormones

B. Primary Sex Organs

1. Ovaries

a. function: maturation of oocytes.

C. Accessory organs

1. Internal

a. Uterine tubes openings near ovaries; tube 10 cm long, passes medially to uterus.

1. location: near ovary

2. infundibulum: expansion partially encircling the ovary; has numerous fimbriae (fingerlike extensions).

3. lining: simple columnar cells, some ciliated; secrete mucus, cilia beat toward uterus to help draw egg to uterus

b. Uterus: function: receives embryo if oocyte fertilized; sustains life throughout development.

1. structure: inverted pear shape.

2. location: anterior portion of pelvic cavity, usually bent forward over bladder.

3. body of uterus: upper 2/3, dome-shaped top.

4. cervix: lower 1/3, tubular extension leading toward upper portion of vagina.

5. wall layers

a. endometrium: inner mucosal lining covered with columnar epithelium.

b. myometrium: very thick, muscular layer.

c. perimetrium: outer serosal layer.

c. Vagina: fibromuscular tube; extends from uterus to outside.

1. structure: vaginal orifice partially closed by hymen.

a. mucosal layer: stratified squamous epithelium.

b. muscular layer: smooth muscle fibers.

c. fibrous layer: dense fibrous connective tissue, elastic fibers.

2. function: conveys uterine secretions; transports offspring during birth.

3. location: extends upward, back into pelvic cavity.

2. External

a. Labia Majora

1. structure: adipose tissue, thin layer of smooth muscle, covering of skin.

2. function: enclose and protect external reproductive organs.

b. Labia Minora

1. structure: flattened longitudinal folds within cleft between labia majora.

c. Clitoris

1. structure: small projection at anterior end of vulva.

2. function: composed of two columns of erectile tissue (corpora cavernosa).

d. Vestibule

1. location: space enclosed by labia minora.

D. Female Hormones

1. Gonadotropin releasing hormone from hypothalamus stimulates anterior pituitary gland to release FSH, LH. play primary roles in control of female sex cell maturation.

2. Estrogen: primarily secreted by ovaries.

a. development and maintenance of secondary sex characteristics

1. development of breasts and ductile system of mammary glands

2. increased deposition of adipose in subcutaneous layer

3. increased vascularization of skin.

3. Progesterone: primarily secreted by ovaries.

a. promotes changes in uterus during reproductive cycles.

b. affects mammary glands, regulates secretion of gonadotropins.

E. Mammary glands

1. accessory organs specialized to secrete milk following pregnancy.

2. location: subcutaneous tissue of anterior thorax within elevations (breasts). overlie pectoralis major muscles.

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