The reproductive system

the reproductive system

The only system that is not essential to the life of the individual

Does affect other systems

The male and female reproductive organs:

-produce and store specialized reproductive cells that combine to form new individuals

reproductive organs

-also secrete hormones that play major roles in the maintenance of normal sexual function

reproductive structures

gonads are the organs that produce gametes and hormones

ducts receive and transport gametes

accessory glands secrete fluids into ducts

perineal structures collectively known as external genitalia

the reproductive tract

includes all chambers and passageways that connect ducts to the exterior of the body

male and female reproductive systems

are functionally different

female produces one gamete per month

-retains and nurtures zygote

male produces large quantities of gametes

-produced ½ billion sperm per day

the male reproductive system

testes or male gonads

secrete male sex hormones (androgens)

produce male gametes (spermatozoa or sperm)

the female reproductive system

ovaries or female gonads

-release one immature gamete (oocyte) per month

-produce hormones

uterine tubes

-Carry oocytes to the uterus- if sperm reaches oocyte, fertilization is initiated and oocyte matures into ovum

uterus

-encloses and supports developing embryo

vagina

-connects uterus with exterior

pathway of spermatozoa

testis

epididymis

ductus deferens (vas deferens)

ejaculatory duct

urethra

accessory organs of the male reproductive tract

secrete fluids into the ejaculatory ducts and urethra

seminal glands

prostate gland

bulbourethral glands

male external genitalia

scrotum

-encloses the testes

penis

-erectile organ

-contains the distal portion of the urethra

descent of the testes

testes form inside the body cavity adjacent to the kidneys

→ gubernaculum testis

occurs during the seventh month due to the rapid growth of the fetus

circulating hormones

-Stimulate contraction of the gubernaculum testis

each testis:

-moves through the abdominal musculature

-is accompanied by pockets of the peritoneal cavity

gubernaculum testis

is a bundle of connective tissue fibers

extends from the testis to pockets of peritoneum

locks testes in position (near the anterior abdominal wall) as the fetus grows

the spermatic cord

Accompany the testis during descent

made up of:

-ductus deferens

-testicular blood vessels, nerves, and lymphatic vessels

extend between abdominopelvic cavity and the testes

consists of layers of fascia and muscle

pass through the inguinal canal

descend into the scrotum

inguinal canal

passageways through the abdominal musculature

form during development as the testes descend into the scrotum

male inguinal hernias

They are protrusions of visceral tissues into the inguinal canal

Spermatic cord → causes a weak point in the abdominal wall

temperature regulation in the male reproductive tract

normal sperm development in the testes

-requires temperatures 2^°F lower than body temp

muscles relax or contract

-to move the testes away from or toward the body

-to maintain acceptable testicular temperature

connective tissue capsules in the male reproductive tract

surround tubules

Areolar tissue fills spaces between tubules

Within those spaces are:

-blood vessels

-large interstitial cells

—> produce androgens

—> Testosterone is the most important androgen

spermatogenesis

It is the process of sperm production

begins at the outermost cell layer in the seminiferous tubules

proceeds toward the lumen

cells of spermatogenesis

Spermatogonia (stem cells) divide by mitosis to produce two daughter cells

-one remains as a spermatogonium

-The second one differentiates into the primary spermatocyte

spermatids

spermatozoa

primary spermatocytes

begins meiosis and forms secondary spermatocytes

secondary spermatocytes

differentiate into spermatids (immature gametes)

spermatids

differentiate into spermatozoa

spermatozoa

lose contact with the wall of the seminiferous tubule

enter fluid in the lumen
*sperm cells as we know them

contents of the seminiferous tubules

spermatogonia

spermatocytes at various stages of meiosis

spermatids

spermatozoa

large nurse cells

nurse cells

aka sustentacular cells

They are attached to a tubular capsule

extend to the lumen between other types of cells

spermatogenisis

involves three integrated processes

1. mitosis

2. Meiosis

3. spermiogenesis

spermiogenesis

begins with spermatids

involves major structural changes

spermatids differentiate into mature spermatozoa

maintenance of the blood-testis barrier

isolates the seminiferous tubules

nurse cells are joined by tight junctions that divide the seminiferous tubule into compartments

support of mitosis and meiosis

Nurse cells are stimulated by:

-follicle-stimulating hormone (FSH)

-testosterone

stimulated nurse cells promote:

-division of spermatogonia

-meiotic division of spermatocytes

mature spermatozoon

lacks:

-endoplasmic reticulum

-Golgi apparatus

-lysosomes and peroxisomes

-inclusions and other intracellular structures

loss of these organelles reduces sperm size and mass

sperm must absorb nutrients from surrounding fluid

sperm maturation

Testes produce physically mature spermatozoa that cannot fertilize an oocyte

Other parts of the reproductive system are responsible for:

-function maturation, nourishment, storage, and transport

spermatozoa:

-detach from nurse cells

-are free in the lumen of seminiferous tubules

-are functionally immature

—> are incapable of locomotion or fertilization

—> are moved by cilia lining efferent ductules into the epididymis

the epididymis

is the start of the male reproductive tract

is a coiled tube almost 23 ft long

-bound to the posterior border of the testis

has a head, a body, and a tail

the accessory glands

produce semen, which is a mixture of secretions from many glands

→ each has a distinctive biochemical characteristic

include:

-seminal glands

-prostate glands

-bulbourethral glands (cowper’s glands)

four major functions of male glands

activate spermatozoa

provide nutrients spermatozoa need for motility

propelling spermatozoa and fluids along the reproductive tract

producing buffers

→ counteracts acidity of urethral and vaginal environments

semen

typical ejaculation releases 2-5 mL

Abnormally low volume may indicate problems

→ with prostate gland or seminal glands

sperm count

-is taken of semen collected 36 hours of sexual abstinence

-normal range 20-100 million sperm/mL of ejaculate

ejaculate

Is the volume of fluid produced by ejaculation

contains:

-sperm

-seminal fluid

-enzymes (protease, seminal plasmin, prostatic enzyme, and fibrinolysin)

EXAM QUESTION 29

THE ERECTILE TISSUE THAT SURROUNDS THE URETHRA IS THE

A) membranous urethra

b) penile urethra

c) glans penis

d) corpus spongiosum

e) corpora cavernosa

SKIPPED SOME SLIDES

the uterine cycle

aka the menstrual cycle

a repeating series of changes in the endometrium

lasts from 21 to 35 days

-avg is 28 days

responds to hormones of ovarian cycle

menses and proliferative phase

→ occurs during the ovarian follicular phase

secretory phase

→ occurs during the ovarian luteal phase

menses

is the degeneration of the functional zone

-occurs in patches

is caused by the constriction of spiral arteries

-reduces blood flow, oxygen, and nutrients

weakened arterial walls rupture

→ releases blood into the connective tissue of the functional zone

degenerating tissue breaks away, and enters the uterine lumen

entire functional zone is lost

only the functional zone is affected

proliferative phase

epithelial cells of uterine glands

-multiply and spread across the endometrial surface

-restores the integrity of the uterine epithelium

further growth and vascularization

-completely restores the functional zone

occurs at the same time as:

-enlargement of primary and secondary follicles in the ovary

is stimulated and sustained by:

-Estrogens secreted by developing ovarian follicles

the entire functional zone is highly vascularized

small arteries:

-spiral toward the inner surface

-from the larger arteries in the myometrium

the secretory phase

endometrial glands enlarge, increasing the rate of secretion

arteries of the uterine wall

-elongate and spiral through the functional zone

begins at ovulation and persists as long as the corpus luteum remains intact

peaks at about 12 days after ovulation

generally lasts 14 days

ends as the corpus luteum stops producing stimulatory hormones

menarche

the first uterine cycle

begins at puberty (age 11-12)

menopause

the termination of uterine cycles

age 45-55

amenorrhea

primary amenorrhea

-failure to initiate menses

transient secondary amenorrhea

-interruption of six months or more

-caused by physical or emotional stresses

*LOOK AT SLIDES 154 AND 153