Human Bio Chapter 19 - The Reproductive System

gametes

male and female reproductive cells (egg and sperm)

gonads

reproductive organs that produce gametes and hormones

transport ducts

receive, transport, and store gametes

accessory glands/organs

secrete fluids

external genitalia

perineal structures (pubic area)

interstitial/leydig cells

produce male sex hormones (androgens - testosterone)

nurse/sertoli cells

provide nourishment for developing sperm

spermatogenesis

mitosis, meiosis, maturation

mitosis

mitotic division of spermatogonia, always undergoing mitosis, push cells towards center of tubule

meiosis

gamete production; spermatocytes, half the amount of chromosomes

maturation

spermatids → spermatozoa → enter lumen of tubule

acrosome

cap containing enzymes for fertilization

nucleus

mass of genetic material

mitochondrion

provides energy for moving tail

flagellum/tail

propels sperm

sperm pathway

sperm detach from Sertoli cells and enter the lumen of the seminiferous tubule, still functionally immature

epididymis

sperm maturation, cleanup damage, abnormal sperm

vas (ductus) deferens

long tube for storage (months?) of sperm

seminal vesicles

60% of semen volume

prostate

several fluids components, including protein with antibiotic properties

bulbourethral (Cowper’s) glands

thick, alkaline mucus to combat vagical acidity

prepuce

foreskin

two types of soft tissue

corpus spongiosum, corpus cavernosum

corpus spongiosum

surrounds urethra

corpus cavernosum

erectile tissue, arteries dilate and fill area with blood

hormonal regulation of male reproduction

GnRH: Gonadotropin releasing hormone

LH: Luteinizing Hormone

FSH: Follicle Stimulating hormone

Ovaries

produce ova (female gametes), each female is born with all the eggs they will ever have for life, secretion of female sex hormones

oogenesis

• mitosis (oogonia (stem cells)) complete mitosis pre-birth

• meiosis 1 - primary oocytes begin process of dividing

• meiosis 2 - secondary oocyte

estrogen (E2)

Causes a spike in LH → ovulation

Female sex characteristics

progesterone (P4)

• maintains pregnancy, quiets uterus

• secretes uterine “milk” from gland to sustain embryo

human chorionic gonadotropin (hCG)

• Maintains CL

• Maternal recognition of pregnancy

perimetrium

outer layer

myometrium

muscular layer responsible for contractions at birth

endometrium

inner layer containing glands

endometriosis

inner uterine layer grows outside the uterus

mammary gland

• lobules of milk glands

• lactiferous ducts

• lactiferous sinuses

reproduction and aging

females:

• menopause: time when ovulation and menstruation cease

• gradual process (ages 45-55)

• decreased E2 and P4, with increasing stimulating hormones

• variety of clinical signs, including hot flashes, anxiety, etc.

males:

• testosterone starts to decline around ages 50-60

• able produce children into elderly ages, much less likely

surgical sterilization

Vasectomy

• ductus deferens cut and tied

• other organs unaffected

Tubal ligation

• fallopian tubes cut and tied