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Biology 12 Human Reproduction – Chapter 27 Name _______________________

Human Biology - Reproductive System (Estimated Time: 9-11 hours)Vocabulary

acrosome, anterior pituitary, cervix, clitoris, corpus luteum, Cowper’s glands, ductus (vas) deferens, endometrium, epididymis, estrogen, follicles, follicle-stimulating hormone (FSH), follicular phase, gonadotropin-releasing hormone (GnRH), head, homeostatic regulation, human chorionic gonadotropin (HCG), hypothalamus, implantation, interstitial cells, luteal phase, luteinizing hormone (LH), menstruation, midpiece, ovarian cycle, ovaries, oviducts (fallopian tubes), ovulation, oxytocin, penis, positive feedback mechanism, progesterone, proliferative phase, prostate gland, scrotum, secretory phase, seminal fluid, seminal vesicles, seminiferous tubules, sperm, tail (flagellum), testes, testosterone, urethra, urethral opening, uterine cycle, uterus, vagina

It is expected that students will:

C14 Analyse the functional inter-relationships of the structures of the male reproductive system

C14.1 identify and give functions for each of the following:– testes (seminiferous tubules and interstitial cells)– scrotum– epididymis– ductus (vas) deferens– prostate gland– Cowper’s glands– seminal vesicles– penis– urethra

C14.2 describe the path of sperm from the seminiferous tubules to the urethral openingC14.3 list the components seminal fluid (as contributed by the Cowper’s glands, prostate

gland, and seminal vesicles), and describe the functions of each componentC14.4 identify the tail (flagellum), midpiece, head, and acrosome of a mature sperm and

state their functionsC14.5 describe the functions of testosteroneC14.6 describe the homeostatic regulation of testosterone levels by the hypothalamus,

anterior pituitary, and testes

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C15 Analyse the functional inter-relationships of the structures of the female reproductive system

C15.1 identify and give functions for each of the following:– ovaries (follicles and corpus luteum)– oviducts (fallopian tubes)– uterus– endometrium– cervix– vagina– clitoris

C15.2 describe the functions of estrogenC15.3 describe the sequence of events in the ovarian cycle, with reference to the

follicular phase, ovulation, and the luteal phaseC15.4 describe the sequence of events in the uterine cycle, with reference to

menstruation, the proliferative phase, and the secretory phaseC15.5 describe the control of the ovarian and uterine cycles by hormones including

gonadotropin-releasing hormone (GnRH), follicle-stimulating hormone (FSH), luteinizing hormone (LH), estrogen, and progesterone

C15.6 describe the hormonal changes that occur as a result of implantation, including– production of human chorionic gonadotropin (HCG) to maintain the

corpus luteum– increased production of progesterone by the corpus luteum

C15.7 describe a positive feedback mechanism involving oxytocin

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Video - Reproduction : Shares in the Future. Do worksheet.

Human Reproduction – The Male

C14.1 identify and give functions for each of the following:– testes (seminiferous tubules and interstitial cells)– scrotum– epididymis– ductus (vas) deferens– prostate gland– Cowper’s glands– seminal vesicles– penis– urethra

a) Label the above structures on the following diagram:

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b) For each of the parts identified on the previous diagram, describe its function(s):

♂testes _______________________________________________________________________Made up of seminiferous cells (sertoli and spermatogonia) and interstitial cells (Leydig, which

produce testosterone )– male gonad – occur in pairs. Produce sperm, and testosterone hormone –

found in the scrotal sac – move in and out of the body within the scrotum depending on the

external temperature.

♂scrotum _____Pouch of skin outside the abdomen which houses the testes and keeps them

viable and at the correct temperature. ___________________________________________

♂seminiferous tubules ___________________________________________________________Sperm are formed by meiosis and begin to mature in these tubules. ______________________________________________________________________________

♂epididymis _________

________Stores sperm, they mature (gain mitochondria) until ejaculated.

♂ductus (vas) deferens ________Path from seminiferous tubules to urethra. ___________________________________________________

♂prostate gland

Produces fluids to be added to the semen

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♂Cowper's glands _______________________________________________________________

______________________________________________________________________________

♂seminal vesicles _______________________________________________________________

______________________________________________________________________________

♂penis _______________________________________________________________________

______________________________________________________________________________

♂urethra ______________________________________________________________________

______________________________________________________________________________

______________________________________________________________________________

This photograph shows a close up of the testis. Label the seminiferous tubules, sperm, and interstitial cells.

What is produced by the seminiferous tubules? ____spermatazoa (sperm)______

What is produced by the interstitial cells? _testosterone = androgen (male hormone) _____

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What is the process illustrated by this diagram?

________spermatogenesis____

Label the diagram using Fig 27.5Ahttp://www.siumed.edu/~dking2/erg/RE025b.htm cross section of portion of testes

http://www.siumed.edu/~dking2/erg/RE028b.htm cross section though a seminiferous tubule.

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http://www.siumed.edu/~dking2/erg/RE028b.htm

http://www.siumed.edu/~dking2/erg/RE025b.htm

http://www.siumed.edu/~dking2/erg/testis.htm#germ sperm cell formation C14.2 describe the path of sperm from the seminiferous tubules to the urethral opening

____seminiferous tubules____ → _____epididymus (mature)____ → ______vas deferens

(ductus deferens)____ → _____ejaculatory duct____ → _______urethra________

On the diagram below, trace the path of sperm in the male before ejaculation.

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http://www.siumed.edu/~dking2/erg/testis.htm#germ

C14.3 list the components of the seminal fluid (as contributed by the Cowper’s glands, prostate gland, and seminal vesicles), and describe the functions of each component

Two seminal vesicles contribute 60% of the volume of semen – thick yellowish, alkaline, contains mucus and fructose, ascorbic acid and prostaglandins. (In this situation prostaglandins induce smooth muscle of female uterine

wall to contract.) Prostrate secretes directly into urethra thin milky fluid containing citrate

(sperm nutrient) Bulbourethral Glands secrete clear mucous that neutralises any urine in

the urethra before ejaculation and also carry some sperm released before ejaculation.

C14.4 identify the tail (flagellum), midpiece, head, and acrosome of a mature sperm and state their functions

Label the following diagram of a mature sperm:

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State the function of each of the labelled parts from the diagram on the previous page.

a) tail

________________________________________________________________________

b) middle piece

________________________________________________________________________

c) head

________________________________________________________________________

d) acrosome

_contains a vesicle filled with hydrolytic enzyme to breakdown the membrane surrounding the ovum so that fertilization can occur.

Activity: Reproductive System of the Human Male (27.4)

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C14.5 describe the functions of testosterone

Primary sex characteristics:

______________________________________________________________________________

______________________________________________________________________________

______________________________________________________________________________

______________________________________________________________________________

Secondary sex characteristics:

______________________________________________________________________________

______________________________________________________________________________

______________________________________________________________________________

______________________________________________________________________________

______________________________________________________________________________

The male and female reproductive systems are controlled by the hypothalamus region of the brain working together with the anterior pituitary gland, as illustrated in the following diagram. Highlight the pituitary hormones that control reproduction:

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C14.6 describe the homeostatic regulation of testosterone levels by the

hypothalamus, anterior pituitary, and testes

Hypothalamus of brain releases GnRH, Gonadotropic Releasing Hormone.

GnRH stimulates anterior pituitary to release FSH and LH FSH stimulates sperm production in seminiferous tubules of testes;

LH stimulates testosterone in the interstitial cells (Leydig) of the testes

Testosterone inhibits the hypothalamus and anterior pituitary so levels of GnRH, FSH and LH stabilize. This is negative feedback.

Testosterone production drops because of lower levels of LH(an example of negative feedback)

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Human Reproduction – The Female

C15.1 identify and give functions for each of the following:– ovaries (follicles and corpus luteum)– oviducts (fallopian tubes)– uterus– endometrium– cervix– vagina– clitoris (on diagram on next page only)

a) Label these diagrams with the parts listed above:

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b) For each of the parts identified on the previous diagrams, describe its function(s):

♀ovaries (follicles and corpus luteum)

-Female gonad, producing egg cells and reproductive hormones (estrogen, progesterone)

♀oviducts (Fallopian tubes)

-Tube carrying egg to the uterus from the ovaries. Site of fertilization

♀uterus

-Organ where egg implants and embryo/fetus develops.

♀endometrium

-Uterus lining, well supplied by blood vessels. Shed if fertilization does not occur; becomes

maternal side of placenta if fertilization occurs.

♀cervix

-Opening of the uterus into the vagina.

♀vagina

-Birth canal; tube between the cervix and the outside opening.

♀clitoris

-Organ that engorges with blood to become erect during sexual arousal.

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C15.2 describe the functions of estrogen

Primary sex characteristics:

______________________________________________________________________________

______________________________________________________________________________

______________________________________________________________________________

______________________________________________________________________________

Secondary sex characteristics:

______________________________________________________________________________

______________________________________________________________________________

______________________________________________________________________________

______________________________________________________________________________

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C15.3 describe the sequence of events in the ovarian cycle, with reference to the follicular phase, ovulation, and the luteal phase

Label this diagram with the above terms:

______________________________________________________________________________

______________________________________________________________________________

______________________________________________________________________________

______________________________________________________________________________

______________________________________________________________________________

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Here is a photograph of an ovary showing several follicles. Label a follicle and a developing ovum.

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C15.4 describe the sequence of events in the uterine cycle, with reference to menstruation, the proliferative phase, and the secretory phase

______________________________________________________________________________

______________________________________________________________________________

______________________________________________________________________________

______________________________________________________________________________

______________________________________________________________________________

______________________________________________________________________________

______________________________________________________________________________

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C15.5 describe the control of the ovarian and uterine cycles by hormones including gonadotropin-releasing hormone (GnRH), follicle-stimulating hormone (FSH), luteinizing hormone (LH), estrogen, and progesterone

Note: this is figure 27.6 in text. See explanations in text. (Concept 27.6 on pp 542 and 543)

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Write notes here for control of ovarian and uterine cycles:

1. Hypothalamus secretes GnRH which stimulates the anterior pituitary to secrete FSH and LH

2. FSH stimulates follicle in ovary to grow during follicular phase; estrogen secreted from follicle

3. Estrogen stimulates proliferative phase of the uterine cycle

4. Burst of LH stimulates ovulation around day 14

5. LH stimulate development of corpus luteum during luteal phase; progesterone is secreted from corpus luteum

6. Progesterone stimulates the secretory phase of the uterine cycle

7. High levels of estrogen and progesterone exert negative feedback effect on the hypothalamus and anterior pituitary, turning off FSH and LH

8. Corpus luteum degenerates, so levels of estrogen and progesterone fall

9. Endometrium is lost because of low levels of estrogen and progesterone.

10.Low levels of estrogen and progesterone mean the hypothalamus and anterior pituitary are no longer inhibited, so levels of FSH and LH start to rise again for the next cycle

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This table summarizes the hormones that control female reproduction:

Ovulation http://www.nucleusanimationlibrary.com/animation-preview?ccat=all&clang=English&animationid=67312

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http://www.nucleusanimationlibrary.com/animation-preview?ccat=all&clang=English&animationid=67312


C15.6 describe the hormonal changes that occur as a result of implantation, including– production of human chorionic gonadotropin (HCG) to maintain the

corpus luteum– increased production of progesterone by the corpus luteum

http://www.nucleusanimationlibrary.com/animation-preview?ccat=all&clang=English&animationid=75011 Fertilization

In text, Concept 27.15 pp 554-555

1. Implantation refers to the attachment of the embryo to the lining of the uterus (the

endometrium).2. The embryo must signal the mother’s body that it is there, otherwise menstruation will

occur, and the baby will be spontaneously aborted. Remember that menstruation results when the levels of estrogen and progesterone (produced by the corpus luteum) drop at the end of the menstrual cycle (when the corpus luteum degenerates).

3. The embryo produces a hormone called Human Chorionic Gonadotropin (HCG) which enters the mother’s blood and cause the corpus luteum to be maintained, instead of degenerating.

4. Because the corpus luteum is maintained, the ovary keeps producing estrogen and progesterone.

5. The estrogen and progesterone maintain the lining of the uterus, so the baby can be nourished.

6. After about 3 months, the placenta itself is making enough estrogen and progesterone that the embryo no longer needs to make HCG.

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Fertilization or conception occurs in the oviduct. Twenty-four hours later, cleavage begins. Three to four days after fertilization, the embryo reaches the uterus as a ball of

16 cells. By one week after fertilization, the blastocyst forms as a sphere of cells

containing a cavity. After a few more days, the blastocyst implants in the endometrium. The embryo secretes hormones to control the mother’s reproductive system.

o The embryonic hormone human chorionic gonadotropin (HCG) acts like pituitary LH to maintain secretion of progesterone and estrogens by the corpus luteum for the first few months of pregnancy.

o Some HCG is excreted in the urine, where it is detected by pregnancy tests.

https://www.youtube.com/watch?v=h82ltr84_Yg&feature=youtu.be&src_vid=KXRbV33J5qk&feature=iv&a nnotation_id=annotation_2692649789 Baby development during pregnancy.

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https://www.youtube.com/watch?v=h82ltr84_Yg&feature=youtu.be&src_vid=KXRbV33J5qk&feature=iv&annotation_id=annotation_2692649789

https://www.youtube.com/watch?v=h82ltr84_Yg&feature=youtu.be&src_vid=KXRbV33J5qk&feature=iv&annotation_id=annotation_2692649789

For the first 2–4 weeks of development, the embryo obtains nutrients directly from the endometrium.

The outer layer of the blastocyst, the trophoblast, invades the endometrium and later forms the placenta.

The placenta allows diffusion of material between maternal and embryonic circulations, supplying nutrients, providing immune protection, exchanging respiratory gases, and disposing of metabolic wastes for the embryo.o Blood from the embryo travels to the placenta through arteries of the

umbilical cord and returns via the umbilical vein. Splitting of the embryo during the first month of development can result in

identical, or monozygotic (one-egg), twins. Fraternal, or dizygotic, twins arise when two follicles mature in a single cycle,

leading to separate fertilization and implantation of two genetically distinct embryos.

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Organogenesis, the development of the body organs, occurs during the first trimester.

o By the end of week eight, all the major structures of the adult are present in rudimentary form, and the embryo is called a fetus.

o The heart begins beating by the fourth week; a heartbeat can be detected at 8 to 10 weeks.

o During organogenesis, the embryo is most sensitive to environmental insults such as radiation or drugs that can lead to birth defects.

By the end of the first trimester, the fetus is well differentiated but only 5 cm long.

The mother is also undergoing major changes.o High levels of progesterone initiate changes in the maternal reproductive

system, including increased mucus in the cervix to form a protective plug against infection, growth of the maternal part of the placenta, enlargement of the uterus, and cessation of ovarian and menstrual cycling.

o The breasts enlarge rapidly and may be tender.o About three-fourths of all pregnant women experience nausea during the

first trimester. During the second trimester, the fetus grows rapidly to 30 cm and is very

active.o The mother may feel movements during the early part of the second

trimester, although fetal activity is not visible through the abdominal wall until one to two months later.

o Hormonal levels stabilize as HCG levels decline; the corpus luteum deteriorates; and the placenta takes over the secretion of progesterone, which maintains the pregnancy.

During the third trimester, the fetus grows rapidly to about 3–4 kg in weight and 50 cm in length.o Fetal activity may decrease as the fetus fills the space available to it.o Maternal abdominal organs become compressed and displaced, leading to

frequent urination, digestive blockages, and back strain. A complex interplay of local regulators (prostaglandins) and hormones

(estradiol and oxytocin) induces and regulates labor. Birth, or parturition, is brought about by strong, rhythmic uterine contractions. The process of labor has three stages.

o The first stage is the opening up and thinning of the cervix, ending in complete dilation.

o The second stage is the expulsion of the baby as a result of strong uterine contractions.

o The third stage is delivery of the placenta. Lactation is unique to mammals.

o In response to suckling by the newborn, as well as changes in estradiol levels after birth, the hypothalamus signals the anterior pituitary to secrete prolactin, which stimulates the mammary glands to produce milk.

o Suckling also stimulates the secretion of a posterior pituitary hormone, oxytocin, which triggers release of milk from the mammary glands.

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Reproductive immunologists are working to understand why mammalian mothers do not reject the embryo as a foreign body, despite its paternal antigens.o The symptoms of rheumatoid arthritis, an autoimmune disease of the joints,

become less severe during pregnancy, suggesting that regulation of the immune system may be altered by pregnancy.

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describe a positive feedback mechanism involving oxytocin

In text, Concept 27.17 on p 558

1.

Baby in uterus stimulates stretch receptors2. Stretch receptors send nerve impulse to hypothalamus3. Hypothalamus sends oxytocin to posterior pituitary along axons of neurosecretory cells4. Posterior pituitary sends oxytocin in blood. Oxytocin causes uterus to contract pushing baby

harder against the stretch receptors.5. More impulses sent to hypothalamus; more oxytocin; more contractions...etc6. This is an example of positive feedback because the original stimulus makes the response even

stronger. Positive feedback does NOT lead to homeostasis. The only way out of this one is for the baby to be born!

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https://www.youtube.com/watch?v=ZDP_ewMDxCo Labour and birth Labour involves the following stages:

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https://www.youtube.com/watch?v=ZDP_ewMDxCo

Here are some birth control methods for both male and female. Each method acts at a specific point in the

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reproductive process:

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