Chapter 11: Human Reproduction

Question 1

Human reproduction

Answer 1

Joining male (sperm) and female (ova) gametes reproducing fertilised single cell called zygote to new life. This is fertilisation.

Question 2

Gametes

Answer 2

Sex cells (sperm, ova) produced in gonads/primary sex organs (testicles, ovaries).

Question 3

Secondary sex organs

Answer 3

Other organs that support reproduction, fertilisation, developing foetus.

Question 4

Penis

Answer 4

Cylindrical organ to pass urine and sperm. Made of spongy tissue & blood vessels with rich blood supply.

Question 5

Erectile Tissue

Answer 5

Connective tissue with rich blood supply. Has many sponge-like spaces filled with blood when aroused causes erection (penis enlarged).

Question 6

Testicles/testes (male gonads)

Answer 6

Ovals bodies surrounded by scrotum that produce sperm (gametes). Each testes has seminiferous tubules and interstitial cells.

Question 7

Seminiferous tubules

Answer 7

Each testes divided to 200-300 lobules filled with extremely coiled seminiferous tubules. It’s lined with cells producing sperm (gametes). Also joins to form tubule from testes to epididymis.

Question 8

Interstitial cells

Answer 8

Located between seminiferous tubules, secretes testosterone.

Question 9

Scrotum

Answer 9

Skin covered sac divided to 2 sacs. Each 1 contains 1 testis to controls climate for sperm production (2 degrees lower than body temp). Also holds and relaxes testes allowing it to hang low away from body to cool or contract, pulling testes to body for warmth or protection.

Question 10

Epididymis

Answer 10

Long, coiled microscopic tubes allows much space for sperm storage. 1 epididymis lies on each testicle. It collects, stores sperm (to mature, 1 month) from seminiferous tubules.

Question 11

Vas deferens/sperm duct

Answer 11

Firm tubes transporting sperm from each epididymis (from testes) to urethra.

Question 12

Urethra

Answer 12

Channel running from bladder and vas deferens through penis. Transports urine and semen to exterior.

Question 13

Semen

Answer 13

Liquid helps fertilisation by helping sperm to survive (sperm must be liquid to reach egg, otherwise die) especially in urethra and vagina acidic habitat. Made from 3 glands seminal vesicles, prostate, bulbo-urethral glands.

Question 14

Seminal vesicles glands

Answer 14

Pair of pouch-like organs secreting thick fluid rich in sugars to nourish sperm making up most of semen (60%).

Question 15

Prostate gland

Answer 15

Surrounds urethra and secretes thin, milky alkaline fluid becoming part of semen protecting sperm through acidic passage of vagina to egg.

Question 16

Bulbo-urethral gland (Cowper’s gland)

Answer 16

2 small yellow glands under prostate gland secreting clear mucus as lubricant helping sperm to travel through female urethra. Most is secreted with semen, but only small amount.

Question 17

Spermatogenesis

Answer 17

Sperm production (male gametes). Starts from immature cells spermatogonia (spermatogonium plural) to spermatozoa (sperm). Continuous process (after puberty) and takes 72 days.

Question 18

1.

Answer 18

Spermatogenesis occurs in seminiferous tubules of each testis. Lined with immature cells spermatogonia (sperm mother cells) containing diploid (46 chromosomes). Divides by mitosis to make more.

Question 19

2.

Answer 19

At puberty, spermatogonia divide by mitosis providing continuous source of new cells for spermatozoa (sperm) production.

Question 20

3.

Answer 20

Some spermatogonia move to center of seminiferous tubule to grow to primary spermatocyte.

Question 21

4.

Answer 21

Primary spermatocytes are diploid and enter 1st meiosis stage producing 2 secondary spermatocytes that are haploid (23 chromosomes).

Question 22

5.

Answer 22

2nd meiosis division divides each secondary spermatocyte to 2 spermatids producing 4 haploid spermatids.

Question 23

6.

Answer 23

Spermatids mature into spermatozoa (sperm). During this much of cytoplasm of cell is lost and tail’s contractile material forms. Maturing sperm is nourished by special cells from seminiferous tubules.

Question 24

Sperm head

Answer 24

Contains DNA and acrosome (fluid filled vesicle on head). In that fluid is enzymes which breakdown layer of cells surrounding egg for fertilisation.

Question 25

Sperm midpiece

Answer 25

Has mitochondria (provides energy for sperm movement). Around mitochondria is thin layer of cytoplasm (reason why sperm has short survival and why semen is vital).

Question 26

Sperm tail

Answer 26

For propulsion by contractile motion from flagellum like protein.

Question 27

Vagina

Answer 27

Smooth muscle with mucous membrane lining. Receives penis and sperm during intercourse. Hymen is fold of tissue partially covers vagina opening that stretch, tear when intercourse happens for 1st time.

Question 28

Ovaries (female gonads)

Answer 28

Organ within body that produce ova/eggs (female gametes). Located each side of abdominal cavity supported by ligaments. Made of connective tissue (stroma) and surrounded by germ cells. Each germ cell surrounded by follicle.

Question 29

Fimbriae

Answer 29

Funnel opening near ovary to guide ovum (egg) to move to uterine tube. Fringed with finger-like projections just touching surface of ovary.

Question 30

Uterine/fallopian tubes (oviduct):

Answer 30

Funnel opening of each ovary lined with cilia to move ovum from ovary to uterus. Smooth muscles contraction in uterine tube wall also move ovary.

Question 31

Uterus (womb)

Answer 31

Located in pelvic cavity held by ligaments to protect, nourish developing foetus (unborn offspring) in pregnancy. Made of smooth muscle wall and soft mucous lining (endometrium).

Uterus uses muscular contractions to help transport sperm upward to uterine tubes.

Question 32

Cervix

Answer 32

Connects uterus to vagina. Also forms birth canal: cervix, uterus, vagina.

Question 33

Labin majora

Answer 33

2 fleshy skin folds. Covers. protect inner structures of vulva (outer parts). After puberty, surface covered in hair. Inner surface is smooth, moist from oily secretions (lubrication). Made from fat, fibrous tissue and many glands.

Question 34

Labin minora

Answer 34

2 smaller skin folds. Protects inner structures of vulva and produce oily secretions for protection, lubrication. No fat, lack hair and varies shape, size, pigmentations.

Question 35

Clitoris

Answer 35

Like penis, contains erectile tissue, blood supply. Very sensitive and blood fills when aroused for pleasure.

Question 36

Urethra

Answer 36

Embedded within vaginal wall. Female urethra much shorter than male. Begins at bladder and opens to outside.

Question 37

Oogenesis

Answer 37

Ova production (female gametes) in ovaries.

Question 38

1.

Answer 38

Before female baby is born millions of oogonia (immature diploid egg cells) develop in ovaries. These cells divide by mitosis producing cells that develop to ova.

Question 39

2.

Answer 39

At birth, cells are in Prophase I (pauses at puberty) and each ovary has several 100k oogonia which grow becoming diploid primary oocytes (cell which goes into meiosis to form ovum).

Question 40

3.

Answer 40

Each primary oocytes are surrounded by follicular cells (primary follicle).

Question 41

4.

Answer 41

At puberty process of follicle growth begins. As follicle matures primary oocyte in it completes Meiosis I producing 2 haploid cells unequal in size:

• Secondary oocyte larger cell (receives half chromosomes, nearly all cytoplasm).
• 1st polar body smaller cell (receives other half, very little cytoplasm).

Question 42

5.

Answer 42

Meiosis II begins in secondary oocyte but stops at metaphase II.

Question 43

6.

Answer 43

Ovulation female menstrual cycle phase: egg released from ovaries occurs expelling secondary oocyte and polar body from ovary, follicle ruptures.

Question 44

7.

Answer 44

After secondary oocyte enters fallopian tube. If penetrated by sperm, meiosis quickly completes. 1st polar body also undergo 2nd meiosis division producing 2 polar bodies.

Question 45

End product

Answer 45

-1 Ovum/egg (female gametes) and 3 polar bodies produced, all polar bodies disintegrates.

Oogenesis produces 1 ova from each primary oocytes. Spermatogenesis produces 4 sperm from each primary spermatocyte.