1. Unit P: Reproduction
Chapter 27

2. The increased use of fertility drugs
Baby Bonanza
The increased use of fertility drugs
Has caused an increase in the number of multiple births in the United States
Fertility drugs are sometimes too effective

3. Standards
CORE:
I can describe structures and functions of the male and female reproductive systems.
I can outline the pathway of sperm from the male to the fertilization of the egg.
I can compare and contrast male and female gametes.
I can compare and contrast male and female primary and secondary sex characteristics.
ADVANCED
I can outline (with examples) both positive and negative feedback loops.
I can outline the events after implantation to childbirth and outline hormonal control.
I can explain and outline the events of the uterine and ovarian cycle, including the hormonal control.

4. HUMAN REPRODUCTION 27.2 Reproductive anatomy of humans
27.2 Reproductive anatomy of humans
Both sexes in humans
Have a set of gonads where gametes are produced
Have ducts for delivery of the gonads and structures for copulation

5. Female reproductive system
Ovaries
produces eggs & hormones
Uterus
nurtures fetus; lining builds up each month
Fallopian tubes
tubes for eggs to travel from ovaries to uterus
Cervix
opening to uterus, dilates 10cm (4 inches) for birthing baby
Vagina
birth canal for birthing baby

6. Female Reproductive Structures
A woman’s ovaries contain follicles that nurture eggs and produce sex hormones
Oviduct
Ovaries
Follicles
Corpus luteum
Wall of uterus
Uterus
Endometrium
(lining of uterus)
Cervix
(“neck” of uterus)
Vagina
Figure 27.2A

7. Oviducts convey eggs to the uterus where the eggs develop
Oviducts convey eggs to the uterus where the eggs develop
Egg
cell
Ovary
LM 200
Figure 27.2B

8. Other structures of the female reproductive system include
The uterus opens into the vagina which receives the penis during intercourse and forms the birth canal
Other structures of the female reproductive system include
Labia, the clitoris, Bartholin’s glands, and the cervix
Oviduct
Ovary
Uterus
Urinary bladder
(excretory system)
Pubic bone
Urethra (excretory system)
Shaft
Glans
Prepuce
Clitoris
Labia minora
Labia majora
Vaginal opening
Anus
(digestive system)
Bartholin’s gland
Vagina
Cervix
Rectum
Figure 27.2C

9. Male Reproductive Structures
27.3 Reproductive anatomy of the human male
A man’s testes produce sperm
Rectum
(digestive system)
Seminal vesicle
Vas deferens
Ejaculatory
duct
Prostate gland
Bulbourethral gland
Epididymis
Testis
Scrotum
Urinary bladder
(excretory
system)
Pubic bone
Erectile
tissue of
penis
Urethra
Glans of penis
Prepuce
Penis
Figure 27.3A

10. During ejaculation sperm and the nourishing fluid, called semen, are expelled through the penis
Sphincter
contracts
Urinary
bladder
Urethra region here
expands and fills
with semen
Contractions
of vas deferens
of prostate
gland
of seminal
vesicle
of epididymis
First stage
Sphincter remains
contracted
of muscles
around base
of penis
relaxes
Contractions of urethra
Second stage
Semen expelled
Figure 27.3C

11. Several glands contribute to the formation of fluid that nourishes and protects sperm
Urinary bladder
(excretory
system)
Prostate gland
Bulbourethral
gland
Erectile tissue
of penis
Vas deferens
Epididymis
Testis
Seminal
vesicle
(behind
bladder)
Urethra
Scrotum
Glans of
penis
Figure 27.3B

12. The Properties of Sperm Cells Only one sperm fertilizes an egg
The Properties of Sperm Cells
Only one sperm fertilizes an egg
Colorized SEM 500
Figure 27.9A

13. During fertilization a sperm releases enzymes from the acrosome that pierce the egg’s coat … more details on fertilization later!
Plasma membrane
Middle piece
Head
Neck
Mitochondrion (spiral shape)
Nucleus
Acrosome
Tail
Figure 27.9B

14. A negative feedback system of hormones controls sperm production
Stimuli from other areas in the brain
Hypothalamus
Releasing hormone
Anterior pituitary
Negative feedback
FSH LH
Androgen production
Sperm production
Testis
Figure 27.3D

15. Developing sperm cells (haploid; single chromatids)
27.4 The formation of sperm and ova requires meiosis
Spermatogenesis, the formation of sperm cells takes about 65–75 days in the human male
Primary spermatocytes, which are diploid, are made continuously in the testes and undergo meiosis to produce haploid sperm
Primary spermatocyte
Differentiation and onset of Meiosis I
Meiosis I completed
Meiosis II
Differentiation
(in prophase of Meiosis I)
Secondary spermatocyte
(haploid; double chromatids)
Developing sperm cells (haploid; single chromatids)
Sperm cells
(haploid)
Center of seminiferous tubule n 2n
Testis
Scrotum
Penis
Epididymis
Seminiferous tubule
Cross section of seminiferous tubule
Diploid cell

16. Primary oocyte completes meiosis and becomes a haploid ovum
Each month one primary oocyte matures to form a secondary oocyte, which can be fertilized
Primary oocyte completes meiosis and becomes a haploid ovum
Diploid cell
In embryo 2n
Differentiation and onset of Meiosis I
Primary oocyte
(arrested in prophase of Meiosis I)
Present at birth
Completion of Meiosis I and onset of Meiosis II
Secondary oocyte
(arrested at meta- phase of Meiosis II; released from ovary) n
Entry of sperm triggers completion of Meiosis II
Ovum
(haploid)
Second polar body
First polar body
Figure 27.4B

17. 27.5 Hormones synchronize cyclic changes in the ovary and uterus
The ovarian cycle includes changes in the ovary that occur about every 28 days
The menstrual cycle involves changes that occur in the uterus
An Overview of the Ovarian and Menstrual Cycles
Events in the menstrual cycle are synchronized with the ovarian cycle, which occurs about every 28 days
Uterine bleeding, called menstruation
Includes the breakdown of the endometrial lining
Usually persists for 3–5 days
After menstruation
The endometrium, the lining of the uterus, regrows

18. Five hormones synchronize the events in the ovarian cycle
Table 27.5

19. Menstrual cycle Hypothalamus Pituitary Ovaries Body cells GnRHLH
FSH
Hypothalamus
egg development
ovulation = egg release
GnRH
corpus luteum
Pituitary
FSH & LH
estrogen
progesterone
Ovaries
lining of uterus
estrogen
Body cells
2007
days 7 14 21 28

20. The Ovarian Cycle Follicular Phase – Day 1-13
-Starts with anterior pituitary gland releases FSH (follicle stimulating hormone)
-FSH targets the ovaries and causes ONE follicle to ripen

21. AS the follicle begins to mature it releases ESTROGEN
Estrogen causes the uterine lining to rebuild

22. When estrogen levels get high enough they cause a surge in the release of LH or luteinizing hormone
Surge in LH causes the release of egg or OVULATION (Day 14)

23. Ovulation – Day 14 This is when the egg is released from the ovary
The follicle ruptures and the egg exits out, causing a crater on the side of the ovary.

24. Corpus Luteum Luteal Phase Day 15-28
The structure that is left in the ovary is a gland like structure that releases the second female PROGESTERONE
Progesterone causes the uterine lining to thicken even more and become secretory.

25. No fertilization…..
If no fertilization of the egg occurs then the egg will deteriorate.
As well as the corpus luteum also degenerates
This causes - Progesterone & Estrogen levels to drop significantly.

26. Ovarian Cycle

27. Menstrual Cycle Flow Phase Day 1-5
Low levels of both female hormones will cause the uterine lining to be shed (The Flow Phase)
AS well the low levels of hormones will cause the anterior pituitary to release FSH and LH.

28. Proliferative Phase Day 6-14
Estrogen levels increase (from the follicle) and cause the endometrium to rebuild

29. Secretory Phase Day 15 – 28
Progesterone levels cause the endometrium to double in thickness and become secretory

30. The ovarian and menstrual cyclesB
Control by hypothalamus
Hypothalamus
Releasing hormone
Anterior pituitary
Inhibited by combination of
estrogen and progesterone
Stimulated by high levels
of estrogen
FSH LH
Pituitary hormones
in blood
LH peak triggers
ovulation and
corpus luteum
formation
Ovarian cycle
Growing follicle
Pre-ovulatory phase
Mature
follicle
Ovulation
Corpus
luteum
Post-ovulatory phase
Degenerating
Estrogen
Progesterone
and estrogen
Ovarian hormones C D E
Menstrual cycle
Endometrium 5 10 20 25 28
Days
Menstruation 1 4 6 2 3 7 8
The ovarian and menstrual cycles
Figure 27.5

31. If fertilization of an egg occurs
Outer layers of cells of the embryo secrete a hormone – HCG (human chorionic gonadotropin) this causes the corpus luteum (in the ovary) to be maintained.
Corpus luteum continues to produce progesterone (and estrogen) this shuts off the anterior pituitary so no ovulation will occur and also maintains lining of uterus.

32. 27.6 The human sexual response occurs in four phases
27.6 The human sexual response occurs in four phases
The excitement phase
Prepares the sexual organs for coitus
The plateau phase
Is marked by increases in breathing and heart rate
Orgasm follows
Characterized by rhythmic contractions of the reproductive structures
The resolution phase
Completes the cycle and reverses the previous responses

33. CONNECTION 27.7 Sexual activity can transmit disease
CONNECTION
27.7 Sexual activity can transmit disease
Sexual intercourse carries the risk of exposure to sexually transmitted infections (STIs)

34. STIs common in the United States
Table 27.7

35. CONNECTION 27.8 Contraception can prevent unwanted pregnancy
27.8 Contraception can prevent unwanted pregnancy
Contraception is the deliberate prevention of pregnancy
Skin patch
Diaphragm
Spermicide
Condom
Birth control pills
Table 27.8

36. If contraception doesn’t work…..The Process of Fertilization occurs
Sperm surface proteins bind to egg receptor proteins
Sperm and egg plasma membranes fuse, and the two nuclei unite
Changes in the egg membrane prevent entry of additional sperm
The fertilized egg (zygote) develops into an embryo
Nucleus
Acrosome
Sperm
Plasma membrane
Sperm head
Acrosomal enzymes
Jelly coat
Vitelline layer
Receptor protein molecules
Sperm nucleus
Cytoplasm
Egg nucleus
Egg cell
Zygote nucleus
The sperm approaches the egg 1
Proteins on the sperm head bind to egg receptors 3
The plasma membranes of sperm and egg fuse 4
The sperm nucleus enters the egg cytoplasm 5
A fertilization envelope forms 6
The sperm’s acrosomal enzymes digest the egg’s jelly coat 2
The nuclei of
sperm and egg
fuse 7

37. EMBRYONIC DEVELOPMENT
27.9 Fertilization results in a zygote and triggers embryonic development
Embryonic development begins with fertilization: the union of sperm and egg to form a diploid zygote – occurs in oviduct

38. HUMAN DEVELOPMENT
27.16 The embryo and placenta take shape during the first month of pregnancy
Pregnancy, or gestation is the carrying of developing young within the female reproductive tract

39. The Placenta
After 3 months placenta is fully formed and takes over hormone production (estrogen, progesterone) – now the corpus luteum degenerates
The placenta absorbs food and oxygen from the mother’s blood to nourish the embryo (remember fetal circulation??)

40. The most rapid changes occur during the first trimester
27.17 Human development from conception to birth is divided into three trimesters
Each trimester is about three months in length
The First Trimester
The most rapid changes occur during the first trimester

41. By 9 weeks the embryo is called a fetus
By 9 weeks the embryo is called a fetus
Figure 27.17B

42. The Second Trimester
The second trimester involves an increase in size and general refinement of the human features
Figure 27.17C

43. At 20 weeks the fetus is about 19 centimeters long, and weighs half a kilogram
Figure 27.17D

44. The third trimester is a time of rapid growth, which ends in birth
The Third Trimester
The third trimester is a time of rapid growth, which ends in birth
Figure 27.17E

46. 27.18 Childbirth is hormonally induced and occurs in three stages
The birth of a child is brought about by a series of strong, rhythmic contractions of the uterus, called labor
Estrogen makes the uterus more sensitive to oxytocin which acts with prostaglandins to initiate labor
Estrogen
Oxytocin
from ovaries
from fetus and pituitary
Induces oxytocin receptors on uterus
Stimulates uterus to contract
Stimulates placenta to make
Prostaglandins
Stimulate more contractions of uterus
Positive feedback

47. Labor occurs in three stages
Dilation,
Expulsion
Delivery of the placenta
Dilation of the cervix 1
Expulsion: delivery of the infant 2

48. CONNECTION
27.19 Reproductive technology increases our reproductive options
New techniques can provide help to infertile couples
Some of these methods raise important ethical and legal questions
Figure 27.19