Chapter 16: The Reproductive System Students will be able to understand the male reproductive and...

Chapter 16: The Reproductive System

Students will be able to understand the male reproductive and female

reproductive systems

The Reproductive System

General Information 1. Divided into male and female 2. Both systems contain gonads or primary sex

organs Produce gametes

I. Male Reproductive Anatomy

A. Primary reproductive organs are the testes (male gonads)

Have both exocrine (sperm-production) and endocrine (testosterone-production) function

B. Secondary reproductive organs are those used for storage and movement of sperm

1. Ducts and Tubules 2. Also called accessory reproductive structures

Testes

Mammal Testes


C. Testes 1. Are approximately 4 cm long 2. Are approximately 2.5 cm wide 3. The tunica albuginea, (a fibrous connective

tissue), surrounds the testes 4. The septa are extensions of the tunica

albuginea that divide the testes into lobules a. Lobules contain 1-4 tightly coiled seminiferous

tubules Seminiferous tubules form the sperm

Tunica Albuginea – Cross Section

Seminiferous Tubules

Seminiferous tubules – Cross Section


C. Testes Interstitial cells, lie in the soft connective tissue

surrounding the seminiferous tubules, which produce androgens (i.e. testosterone)

5. The rete testis are tubules the sperm move into after production

6. Sperm move through the rete testis into the first duct or storage unit

a. Lies along the external surface of the testes

Testicular Cross Section with Spermatocytes (spermatogonia)


D. Duct System 1. Consists of the:

a. Epididymis b. Ductus deferens c. Ejaculatory duct d. Urethra

Epididymis


D. Duct system a. epididymis

Lies along the exterior surface of the testes Comma-shaped Highly coiled Can be 6 m long (approx. 20 ft) Lies superior to the testes, runs down the

posterolateral side Temporary storage system Takes 20 days to pass through


D. Duct system b. Ductus Deferens

Also called the vas deferens Runs upward from the epididymis Moves through the inguinal canal into the pelvic cavity Arches over the urinary bladder to the prostrate gland The tube is enclosed by the spermatic cord

Also has blood vessels and nerve bundles Propels live sperm from storage to the ejaculatory

duct Vasectomy occurs along this duct (cut and cauterize)


D. Duct System c. Ejaculatory Duct

Passes through the prostate gland Merges with the urethra Smooth walls create peristaltic waves during

ejaculation Squeezes sperm forward


D. Duct System d. Urethra

Extends from the base of the bladder to the tip of the penis

3 regions Prostatic urethra: surrounded by the prostate

gland Membranous urethra: between the prostrate and

the base of the penis Spongy urethra: length of the penis


E. Accessory glands and semen 1. Seminal Vesicle

a. Located at the base of the bladder b. Produces 60% of the fluid (by volume) of the semen c. The secretion is rich in sugar (fructose), vitamin C,

prostoglandins, etc.. Used to nourish sperm Provide energy conversion capabilities May play a role in ovulation and corpus luteum function

d. Joins the urethra at the connection with the vas deferens (the combination is called the ejaculatory duct)

Seminal Vesicle


E. Accessory Glands and Semen 2. Prostate Gland

a. Single gland b. Encircles the urethra c. Secretes a milky white fluid that activates the

sperm d. Alkaline, which protects the sperm from the

acid environment of the vaginal area e. Prostrate glandular secretions is

(approximately) 40% of the fluid by volume

Prostate Gland


E. Accessory Glands and Semen 3. Bulbourethral glands

a. Once called Cowper’s glands b. Are pea-sized c. Produce a thick clear mucus d. It is the first fluid down the urethra during

stimulation e. Used to lubricate f. There is some debate over “whether there is

sperm leaked into this fluid during stimulation”

Cowper’s Gland (Bulbourethral glands)


E. Accessory Glands and Semen 4. Semen

a. Milky white mixture b. It is sticky c. Has sperm and other glandular secretions

40 to 2.5 million sperm d. The liquid is a transport medium e. Has nutrients and chemicals (used to protect

sperm) f. The pH is between 7.2 – 7.8 g. Contains seminalplasmin, relaxin, and several

enzymes Sp helps to coagulate the semen, after 15 minutes

becomes liquid again


F. External Genitalia 1. 2 parts

a. The scrotum The testes hang outside of the male body Sperm are not produced at normal body temperature

The temperature is about 5 degrees cooler If the outside temperature cools the testes are pulled

toward the body


F. External Genetalia 1. 2 parts (cont)

b. The penis Hangs outside of the body Is designed to deliver sperm to the female body Has a shaft An enlarged tip (glans penis) A loose skin, that folds to cover the tip, foreskin or

prepuce Circumcision is the removal of the foreskin

Internally the spongy urethra is surrounded by 3 areas of erectile tissue that fills with blood during stimulation

I. Male Reproductive AnatomyI. Male Reproductive Anatomy

G. Male reproductive functionsG. Male reproductive functions• 1. Spermatogenesis1. Spermatogenesis

a. The production of sperm via meiosisa. The production of sperm via meiosis b. Creates 4 sperm with each meiotic eventb. Creates 4 sperm with each meiotic event

• Each sperm is haploid (half the chromosomes)Each sperm is haploid (half the chromosomes)• Allows for genetic variationAllows for genetic variation

c. Spermatogonia are stem cells in the c. Spermatogonia are stem cells in the seminiferous tubules which produce more seminiferous tubules which produce more stem cells until puberty and then divide stem cells until puberty and then divide meioticly to form other cellsmeioticly to form other cells


G. Male reproduction functionsG. Male reproduction functions• 1. Spermatogenesis (cont)1. Spermatogenesis (cont)

d. The change over occurs due to the d. The change over occurs due to the hormone, follicle stimulating hormone (FSH)hormone, follicle stimulating hormone (FSH)

• During cell division a stem cell is produced (type During cell division a stem cell is produced (type A), and a primary spermatocyte (type B)A), and a primary spermatocyte (type B)

• Spermatocytes will then undergo meiosis and Spermatocytes will then undergo meiosis and produce spermproduce sperm


H. Testosterone ProductionH. Testosterone Production• 1. Produced by the interstitial cells1. Produced by the interstitial cells• 2. Most important hormone produced by the 2. Most important hormone produced by the

testestestes• 3. Are activated by the hormone luteinizing 3. Are activated by the hormone luteinizing

hormone (LH)hormone (LH) a. Also called interstitial cell – stimulating hormone a. Also called interstitial cell – stimulating hormone

(ICSH)(ICSH) b. Released by the anterior pituitary glandb. Released by the anterior pituitary gland

• 4. Activate other secondary sex characteristics4. Activate other secondary sex characteristics a. Deeper voice, increased hair growth, enlargement a. Deeper voice, increased hair growth, enlargement

of the skeletal muscles, etc.of the skeletal muscles, etc.

II. Female Reproductive system

A. General Information• More complex than the male reproductive

system• Must produce gametes

• Must nurture and protect developing fetus


B. Ovaries• 1. Primary reproductive organ

• 2. Produce both endocrine products (estrogens and progesterone) and exocrine products (eggs/ova)

• 3. The size of almonds

• 4. Has many sac-like structures called ovarian follicles

Ovaries

Ovarian Follicles


B. Ovaries• 5. Ovarian follicles carry an immature egg

called an oocyte• a. Surrounded by follicle cells

• b. Ova mature over time, the follicle enlarges, becomes fluid filled (central region is called the atrum)

• The follicle is now called a Graafian or vesicular follicle, containing a mature ova called a secondary oocyte

• Will be ejected during ovulation

• The follicle is now called a corpus luteum

Oocyte

Oocyte development


B. Ovaries• 6. Ovulation occurs approximately every 28

days

• 7. Supported by suspension ligaments

• 8. Anchored to the uterus by ovarian ligaments

• 9. Held in place by peritoneum called the broad ligament


C. Duct system• 1. Uterine tubes

• 2. Uterus

• 3. Vagina

Uterus

Uterus with Cancerous tumor


C. Duct System• 1. Uterine (Fallopian) Tubes

• a. The initial part of the duct system

• b. Provide a fertilization site

• c. Receives the secondary oocyte

• d. The tubes are approximately 10 cm long

• e. Empty into the super region of the uterus

• f. The distal end contains infundibulum• Funnel shaped, with finger-like projections called

fimbriae (surround the ovary)


C. Duct system• The fimbriae create fluid currents to pull the oocytes

into the fallopian tubes

• g. Oocytes are carried toward the uterus by peristalsis and rhythmic beating of cilia

• h. Oocytes take 3-4 days to reach the uterus

• i. Oocytes are only viable for 24 hrs after ovulation

• j. Fertilization usually occurs in the fallopian tubes


C. Duct system• 2. Uterus

• a. Located in the pelvis

• b. Between the urinary bladder and rectum

• c. It is hollow

• d. Functions to receive, retain and nourish the fertilized egg

• e. Held in place by ligaments (anteriorly-round, posteriorly-uterosacral)


C. Duct system• 2. Uterus

• f. The major portion of the uterus is called the body

• g. The entrance of the uterine tubes are called fundus

• h. The entrance into the vagina is called the cervix

• i. The uterine wall is thick and has 3 layers• Inner (mucosa) layer is the endometrium

• Middle (myometrium) layer is thick with smooth muscle, used during delivery

• Outer (serous) layer is the perimetrium


C. Duct system• 3. Vagina

• a. Thin walled tube

• b. It is 3-4 inches long

• c. Runs from the surface to the cervix

• d. Called the birth canal

• e. Receives the penis

• f. A thin membrane (mucosa) closes the distal end, called the hymen


D. External Genitalia• 1. Also called the vulva

• 2. Includes the following• a. Mons Pubis

• b. Labia Majora

• c. Vestibule

• d. Greater Vestibular Glands

• e. Clitoris

• f. Perineum


D. External Genitalia• a. Mons pubis

• Fatty rounded area

• Overlying the pubic symphysis

• Covered with hair after puberty

• b. Labia majora• Runs posteriorly from the mons pubis

• Encloses two hair free folds• Delicate skin, very sensitive, quickly irritated

• Labia minora


D. External Genitalia• c. Vestibule

• Is the longitudinal cleft enclosed by the LMaj

• Contains the external organs of the urethra

• Contains the external organs of the vagina

• Covered by the labia majora

• d. Greater vestibular glands• Flank the vagina

• Lubricate the distal end of the vagina


D. External Genitalia• e. Clitoris

• Anterior to the vestibule

• It is hooded by a prepuce

• Composed of very sensitive tissue

• Becomes swollen with blood, during stimulation

• f. Perineum• Is the region that includes, the labial folds, the

anus, and the ischial tuberosities

• Diamond shaped

External Female Genitalia


E. Oogenesis• 1. Development starts while the female is still

a fetus

• 2. Oogonia (stem cell) multiply and divide• a. Producing primary oocytes

• b. Surrounded by single layer of follicle cells and are now primary follicles

• c. At birth the oogonia no longer exist

• d. At birth women have approximately 2 million primary oocytes


E. Oogenesis• 3. At puberty the anterior pituitary produces

FSH

• 4. Stimulates follicle growth

• 5. Ovulation will occur each month• a. Ovarian cycle

• b. At puberty approximately 400,000 oocytes remain and a small number of oocytes are activated each month

• c. Only (approx) 500 ova are used in a lifetime


E. Oogenesis• 5. Ovulation will occur each month (cont)

• a. The follicle grows due to FSH and fluid fills the sac

• b. The center is the atrum

• c. The primary oocyte begins meiosis

• Producing one egg/ova (secondary oocyte) and 3 polar bodies

• d. Luteinizing Hormone causes the follicle to rupture the ovary (coronary radiata)

• e. Sometimes causes pain in the abdomen

• Mittelschmerz (middle pain)


E. Oogenesis• 6. If the secondary oocyte is penetrated by a

sperm it is called an ovum (fertilized egg)

II. Female Reproductive system F. Uterine (Menstrual) Cycle

1. Yes, this is the dreaded PMS! 2. Actually it includes the Pre-Menstrual Syndrome 3. The uterus is only capable of implantation for a short

time each month 4. The endometrium responds to hormone changes each

month a. Reacts to the production of estrogen and progesterone,

which are produced by the ovaries

II. Female Reproductive system F. Uterine (menstrual) Cycle

5. There are 3 stages a. Days 1-5 Menstrual phase b. Days 6-14 Proliferative phase c. Days 15-28 Secretory phase


a. Days 1-5 Menstrual phase The endometrial lining is sloughed off Becomes detached from the myometrium Bleeding occurs for 3 to 5 days Lose approximately 50 to 150 ml At the end, estrogen is being produced by the

ovaries


b. Days 6-14 Proliferative phase Stimulated by rising estrogen levels The basal layer of the endometrium regenerates Blood supply and glands are increased Ovulation occurs at some point between day 10

and day 12, at the latest day 14, in response to the rise in LH in blood stream


c. Days 15-28 Secretory Phase Progesterone levels in the blood begin to rise

Causes the blood supply to the endometrium to increase Endometrium glands begin producing nutrients into the

uterus (anticipating fertilization) If fertilization does occur, the ovum will produce a

hormone similar to LH to maintain the endometrium until implantation

LH levels begin to decline


c. Days 15 - 28 Secretory Phase As the hormones decline (LH and FSH), the blood

flow to the endometrium will decrease The endometrium cells die

Cycles back to the menstrual phase

II. Female Reproductive system F. Uterine (menstrual) Cycle (cont)

6. Menstrual Cycle can vary a. Shortest, 21 days b. Longest (typical), 40 days c. Longer than 40 days is an indicator of other

problems

II. Female Reproductive system G. Hormone Production by the Ovaries

1. Estrogens a. Cause the appearance of secondary sex characteristics

Enlargement of the accessory organs, uterine tubes, uterus, vagina, and external genitals

Development of the breasts Appearance of axillary and pubic hair Increased deposits of fat beneath the skin, particulary the hips

and breasts Widening and lightening of the hips Onset of the mensus

II. Female Reproductive system G. Hormone Production by the Ovaries

(cont.) 2. Progesterone

a. Produced by the corpus luteum b. Progesterone is produced as long as LH is

present c. Stops producing progesterone after 10-14 days d. Helps to maintain the pregnancy, and prepare

the breasts for milk production (lactation) Source is now the placenta

II. Female Reproductive system H. Mammary Glands

1. Present in both sexes a. Yes, breast cancer CAN happen in males!

2. Stimulated by sex hormones, especially estrogen

3. Are modified sex glands 4. Contained within the breast

a. Darker pigmented area is called the areola Has large numbers of nerve endings

II. Female Reproductive system H. Mammary Glands (cont)

b. Central protruding area is called the nipple 5. Has 15 to 25 lobes, radiating around the

nipple a. Lobules contain alveolar glands that produce

milk during lactation b. Milk moves into the lactiferous ducts, which

open to the surface of the skin

Chapter 16: The Reproductive System Students will be able to understand the male reproductive and...

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