1. The Reproductive System

2. The Reproductive System
At first male and female human embryos are nearly identical in appearance

3. The Reproductive System
During the 7th week male pattern development is triggered by the production of testosterone in the gonads of the embryo
Female development is triggered by the production of estrogen in the gonads

4. The Reproductive System
Estrogen and Testosterone are steroid hormones
Both act on cells and tissues to produce physical characteristics of males and females

5. The Reproductive System
Female Characteristics Produced by Sex Hormones:
Breast Development
Widening Hips
Male Characteristics Produced by Sex Hormones:
Facial Hair
Increase muscle development
Deepening of the voice

6. The Reproductive System
Puberty – a period of rapid growth and sexual
maturation during which the
reproduction system becomes fully
functional
Occurs between the ages 9 and 15
One year earlier for females
Begins in the brain
Hypothalamus signals the pituitary to produce two hormones that affect the gonads
Follicle-stimulating hormone (FSH)
Luteinizing Hormone (LH)

7. Male Reproductive System
Release of LH stimulates production of more testosterone Testosterone together with FSH stimulate development of sperm

8. The Male Reproductive System
When puberty is complete, the reproductive system is fully functional meaning that the male can produce and release active sperm
Testes – primary male reproductive organ
Scrotum – external sac that
holds the testes

9. The Male Reproductive System
Sperm Development Seminiferous Tubules – tiny tubes inside testes where sperm develop Epididymis – area where sperm mature and are stored Vas Deferens – some sperm are moved into this tube

10. The Male Reproductive System
Vas Deferens
Extends upward from the scrotum into the abdominal cavity
The Vas Deferens merges with the Urethra
This tube leads to the outside of the body
Glands lining the reproductive tract
Seminal Vesicles
The Prostate Gland
The Bulbourethral Gland
Produce a nutrient rich fluid called Seminal Fluid
Semen – the combination of sperm and seminal
fluid

11. The Male Reproductive System
Sperm Structure
Sperm is a CELL
Nucleus
Mitochondria
Flagellum (tail)

12. Male Reproductive Organs

13. The Female Reproductive System
Ovaries – primary reproductive organ of females
The main function of the female reproductive system is to produce egg cells
Ova (ovum) singular – egg cell

14. Female Reproductive System
Puberty begins when hypothalamus signals the pituitary gland to release FSH and LH FSH stimulates increased production of estrogen

15. The Female Reproductive System
At puberty each ovary contains as many as 400,000 primary follicles
Cluster of cells surrounding a single egg
Follicles help egg mature
Females release only about 400 mature eggs in a lifetime

16. Female Reproductive System

17. The Menstrual Cycle
A regular sequence of events involving the ovaries, the lining of the uterus, and the endocrine system
One ovary usually produces and releases one mature ovum (egg) every 28 days or so……
Regulated by hormones made by the hypothalamus, pituitary, and ovaries
During the Menstrual Cycle
An egg develops within a follicle
Then its released from an ovary
Uterus is prepared to receive a fertilized egg

18. The Menstrual Cycle If the egg is not fertilized it is discharged
Along with the uterus lining
If the egg is fertilized, embryonic development begins and menstrual cycle stops

19. The menstrual Cycle includes:
Follicular Phase – hormones cause follicles to
mature
Usually more than one but can be more
Ovulation – the release of an egg from the ovary
into one of the Fallopian Tubes.
follicle grows more estrogen is released

20. The menstrual Cycle includes:
Luteal Phase – immediately after ovulation
Progesterone (a hormone) is released
Stimulates the growth and development of blood supply

21. The menstrual Cycle includes:
Menstruation – At the start of the new follicular phase,
low estrogen levels cause lining of
uterus to detach
Uterus lining, blood, and unfertilized egg are discharges through the vagina
A new cycle begins on the first day of menstruation

24. Pregnancy Menstrual cycle ceases if pregnant
First two days of the Luteal Phase is the greatest time where fertilizing an egg is greatest.

25. Day 2- Reproductive Cycle
Bellringer: R.A.F.T assignment (yes this will be graded) Imagine you are an egg cell. Describe your story of how you formed into a human fetus (a baby inside a mothers womb) from meeting a sperm cell all the way till birth. Be as specific as you can! (aka, step-by-step story line

26. Pregnancy
If sperm fertilizes an egg; the egg completes meiosis and immediately undergoes mitosis
After several divisions, a ball of cells form and implant itself in the lining of the uterus.
Uterus and embryo release hormones that keep the corpus luteum functioning for several weeks
This helps nourish and protect the developing embryo

27. Fertilization & Development
Gametes – sperm and egg Fertilization – the fusion of a sperm and egg cell

28. Fertilization
Hundreds of millions of sperm are released during ejaculation
If egg is in one of the Fallopian Tubes the chances of fertilization are high

29. Fertilization
Egg is surrounded by a protective layer that has binding sites
Sperm releases enzymes that break down eggs protective layer

30. Fertilization
Once the 2 haploid (haploid =1/2 # chromosomes) sperm and egg come together a nucleus is formed
Zygote – the fertilized egg
AKA - embryo

31. Fertilization
When sperm enters the egg; the egg releases granules to the outside of the cell
This forms a barrier that prevents other sperm from entering the egg.

32. Multiple Embryos
If two eggs are released during the same menstrual cycle and each is fertilized
Result Fraternal Twins
If a single zygote splits apart and produces two genetically identical embryos
Result Identical Twins

33. Implantation Blastocyst – name of embryo after going
through the process of mitosis
A hollow ball of cells are formed

34. Implantation Implantation – 6 – 7 days after fertilization,
Blastocyst attaches to the wall of
the uterus
At this point blastocyst begin to specialize
This process is called Differentiation

36. Gastrulation The formation of three cell layers called: Ectoderm
Mesoderm
Endoderm
Production of key tissue layers and structures of the body

38. Neurulation
The first step in the development of the nervous system
Shortly after gastrulation, a block of mesodermal tissue begins to differentiate into the notochord
Ectoderm near the notochord thickens and forms the neural plate
The raised edges of the neural plate form the neural folds and the neural crest.
The neural folds move together and form the neural tube which form the spinal cord and brain
Neural crest cells migrate and become nerve cells, skin pigment cells, and other structures

39. Neurulation

41. Neurulation
Spina Bifida – Birth disorder in which neural tube does not close completely
Some studies show that the vitamin supplement folic acid can prevent this

42. The Placenta Specialized membranes that protect and nourish the embryo
The embryo is surrounded by the Amnion
A sac filled with Amniotic Fluid
Cushions and protect the embryo

43. The Placenta
Chorion – (another sac) makes direct contact with the tissues of the uterus Chorionic Villi – finger-like projections that form during the 3rd week on the outer surface of the chorion and extend into the uterine lining

44. The Placenta Placenta – a vital organ formed by chorionic villi
and uterine lining
This is the connection between the mother and embryo
This is the embryo’s organ of respiration, nourishment, and excretion
Blood barrier between mother and embryo diffuse across the membrane
Blood does not mix

45. The Placenta Fetus – 8 weeks of development
Most major organs and tissues are formed
Begins to move
8 cm and 28 grams

46. Second Trimester (month 4-6)
Later Development
Second Trimester (month 4-6)
Fetal heart becomes large enough to be heard with a stethoscope
Bone replace cartilage
Hair grows over skin of fetus
Increases in size
Mother’s abdomen grows and
she begins to feel it

47. Third Trimester (month 7-9)
Later Development
Third Trimester (month 7-9)
Organ systems mature
Fetus grows
Doubles in mass
Lungs and other organs
change and prepare for
life outside
Fetus able to regulate
body temperature

48. Later Development
9 months is average length of time for a fetus to develop
Premature Babies – born before 8th month

49. Childbirth Oxytocin – hormone released by posterior pituitary
gland; affects a group of muscles in the
uterine wall
Labor – a series of rhythmic contractions caused by the
muscles in the uterine wall
Contractions become more frequent and more powerful
The opening of the cervix expands
Amniotic sac breaks – fluid rushes out of the vagina
Contractions force the baby out; usually head first

50. Childbirth
Once the baby is born he or she will cough or cry to clear the lungs of fluid
Blood supply to placenta dries up
Umbilical cord is clamped and cut
Small piece stays on the baby
It dries and falls off
Navel – scar left from
umbilical cord
AKA belly button

51. Childbirth More contractions expel the placenta and amniotic sac
Afterbirth
Hormone prolactine (released by pituitary gland) stimulates the production of breast milk

52. FX Animation- from fertilization to birth
As we watch the video, we will stop and I will ask questions about what is happening. Be prepared to use the information from today’s lecture to explain. Take notes if you think it will help (there is an assignment following the video

53. Your Assignment
Revise your R.A.F.T write up using more specific details of an egg’s journey from fertilization to birth. You must include the following terms:
Chorion
Placenta
fetus
2nd trimester
3rd trimester
Oxytocin
Umbilical Chord
Gametes (sperm/egg)
Fallopian Tube
Zygote/embryo
Granules
Mitosis
Blastocyst
Implantation
Gastrulation (ectoderm, mesoderm, endoderm
Neurulation
Mesodermal tissue
Notochord
Spinal chord
Brain
Amnion/amniotic fluid