UNIT B

Unit B IntroductionReproduction & Development

o 20% of the courseo Duration= 15 lessons, 3 weekso Unit B Exam: Friday, March 28

Only ch. 16•Male Reproduction•Female Reproduction•Fetal Development

NEW HABITS…

• Journaling• Word wall cue cards as a class

ICEBREAKER

guys and girls split into teams Competition: who can get the most correct?

1. Can a women get pregnant without having sex?2. How does the 'pill' work?3. Does PMS exist or is it an excuse for women to be grumpy once a month?4. Is it possible for a male to orgasm and urinate at the same time?5. If a male only has one testicle can he still conceive?

• Why would we study reproduction?• How does this impact our lives?• Why does developing science in this topic matter?

SECTION 16.1-1THE MALE REPRODUCTIVE SYSTEM ANATOMY

CHAPTER 16

MALE REPRODUCTIVE STRUCTURES

SIDE VIEW OF MALE REPRODUCTIVE SYSTEM

Testis

Epididymis

Vas Deferens

Bladder

Seminal Vesicles

Prostate

Cowper’s GlandUrethra

FUNCTIONS OF STRUCTURES

• Testes• the male gonads, or primary reproductive

organs• production of male sex hormones• production of sperm

• Seminiferous tubules• coiled ducts found within testes• where immature sperm cells start to mature

• Epididymis• structure located along the posterior border of the testes• sperm cells finish maturing• contain coiled tubes that store sperm cells once they

have matured

• Vas deferens (pl. vasa deferentia)• tube that conducts sperm toward the urethra• can be cut and tied off at each end as a form of

birth control = vasectomy

• Seminal vesicles• tube like glands• secrete fluids that combine with sperm to make

semen (seminal fluid)• majority of seminal fluid is secreted by seminal

vesicles

• Ejaculatory duct• tube formed where the seminal vesicles come

together• opens into the urethra

MALE REPRODUCTIVE STRUCTURES

• Prostate gland• contributes to semen (seminal fluid)• secretes a fluid that acts a buffer• this fluid protects the sperm cells from the

acidic environment of the vagina

• Cowper’s (bulbourethral) gland• Secretes mucus rich fluid to the semen (seminal

fluid)• This fluid protects the sperm cells from the

acidic environment of the male urethra caused by the passing of urine

MALE REPRODUCTIVE STRUCTURES

• Urethra• exit tube for urine and semen

• Glans penis• bulbous structure at the end of the penis• known as “head” or “knob” of the penis

CIRCUMCISION

• Male circumcision (from Latin circumcidere, meaning "to cut around") is the surgical removal of the foreskin  (prepuce) from the human penis.

In a typical procedure, the foreskin is opened and then separated from the glans after inspection. The circumcision device (if used) is placed, and then the foreskin is removed. Topical or locally injected anaestheisa may be used to reduce pain and stress.

• Ureter • carries urine from kidney to bladder

• Urinary bladder• stores urine until it is ready to be excreted• a sphincter regulates the excretion of urine• urine and semen can never be excreted at the

same time

FORMATION OF THE MALE REPRODUCTIVE SYSTEM

• Human male and female sex organs originate in the same area of the body – the abdominal cavity.

• The reproductive organs are indistinguishable until about the third month of development, when the sex hormones kick in.

• During the last two months of fetal development, the testes descend through a canal into the scrotum (sac that contains the testes).

• Once descended, a thin membrane covers over the canal preventing the testes from re-entering the abdominal cavity.

• This membrane also acts to maintain the temperature of the scrotum.

• The scrotum is a few degrees cooler than the abdominal cavity, because sperm needs to be produced in a cooler environment.

PROBLEMS…

UNDESCENDED TESTICLES

• As a baby boy grows inside his mother's womb, his testicles typically form inside his abdomen and move down (descend) into the scrotum shortly before birth. But in some cases, that move or descent doesn't occur, and the baby is born with a condition known as undescended testicles (or cryptorchidism).

• Cryptorchidism is the most common genital abnormality in boys, affecting approximately 30% of baby boys born prematurely and about 4% born at term.

• In about half of the babies, the undescended testicles move down or descend on their own by the sixth month of life. If spontaneous descent doesn't happen by then, it's important to get treatment because testicles that remain undescended may be damaged, which could affect fertility later or lead to other medical problems.

SEXUAL EXCITEMENT

• During sexual excitement, the erectile tissue within the penis fill with blood.

• Stimulation of the parasympathetic nervous system causes the arteries leading to the penis to dilate, increasing the blood flow.

• As blood moves into the penis it will swell and compress the veins that carry blood away preventing blood from exiting.

SPERMATOGENESIS

• Spermatogenesis - the formation of sperm cells.

• The seminiferous tubules are lines with sperm producing cells called spermatogonia.

• During spermatogenesis, the spermatogonia divide to form spermatocytes.

• The spermatocytes divide to form spermatids, immature sperm cells.

• Pg. 514

• Spermatids contain 23 chromosomes (half of normal human body cell).

• Specialized cells in the seminiferous tubules, called Sertoli cells (nurse cells), nourish the developing spermatids.

• Eventually the spermatids move into the epididymis.

• After 9 – 10 weeks in the epididymis the spermatids mature into sperm cells.

DRAW THIS

SPERM STRUCTURE

• Acrosome – cap on sperm cells that contains enzymes that permit the sperm cell to move through outer layers that surround the egg by breaking them down.

SEMINAL FLUID

• Sperm leave the body as part of a fluid, semen.

• Semen provides a swimming solution for the sperm to move.

• Ejaculation is the process by which sperm leaves the penis.

• Each ejaculation is about 3-4mL of fluid, that contains approximately 500 million sperm cells.

• 3 glands contribute to semen:

1. Seminal vesicles – secrete fluid that contains fructose and prostoglandins.

- fructose acts as a food/energy source for sperm- prostoglandins (hormones) create rhythmic contractions of female muscle, which helps to move the sperm towards the egg.

2. Prostate gland – secretes a buffer type fluid that protects the sperm from the acidic vagina.

3. Cowper’s (bulbourethral) glands – secrete mucus rich fluids that protects the sperm from acidic urine left in the urethra.

• After ejaculation at body temperature sperm cells will live only for 24 to 72 hours.

• When stored at -100 degrees Celsius, sperm cells have been known to remain viable for many years.

• Pg. 514 #1-2, Pg. 515 #3-4 and Pg. 516 #5