Lecture 21-Reproduction & Development
Covers Chapters 41 & 42
The ability to reproduce starts
at puberty
• As early as 8 and as late as 15:
• Brain maturation causes hypothalamus to re...
Testosterone and estrogen cause development
of sex characteristics
• Testosterone and estrogen stimulate the
development o...
Male Anatomy
• MALE ANATOMY
• Goal is to produce and deliver sperm.
– Penis
– Scrotum
– Testes/Testicles
– Seminiferous Tu...
Male Anatomy
• Penis-tubular shaft of erectile tissue.
When a male is aroused, blood rushes to the
tissue and pressure clo...
The Human Male Reproductive System
Fig. 41-9
pubic bone urinary bladder
ureter
rectum
seminal
vesicle
prostate
gland
bulbo...
Male Anatomy
• Seminiferous Tubules*-coiled tubes
within each testicle. Spermatogenesis
(sperm production) happens here.
–...
Seminiferous Tubules
Male Anatomy
• Epididymus-storage sac for sperm
laying on top of each testicle.
• Vas Deferens-duct for semen.
• Urethra-d...
Semen
• When a man ejaculates, 300 MILLION sperm
leave the body. Sperm is bathed in SEMEN.
These structures all donate flu...
Female Anatomy
• Goal is to produce eggs, receive sperm
and nurture the embryo.
– Vulva
– Clitoris
– Urethra
– Vagina
– Ut...
Female Anatomy
• Vulva - Two layers of folded skin that
protect the female anatomy from injury.
• Clitoris-erectile tissue...
Female Anatomy
• Vagina-muscular organ that serves as the
birth canal and opening for sex and
menstruation.
• Uterus
– abo...
Female Anatomy
• Fallopian Tubes- ducts between each
ovary and the uterus. Pathway that
ONE egg takes each month down FT,
...
The Human Female
Reproductive System
Fig. 41-14
uterine
tube
urinary bladder
pubic bone
urethra
clitoris
labia
ovary
myome...
Spermatogenesis*
• Begins in puberty, stimulated by hormones in
Sertoli Cells
• Spermatogonia are diploid parent cells tha...
Spermatogenesis*
• Spermatogonium differentiates into
primary spermatocyte
• Meiosis I occurs, haploid daughter cells
are ...
Spermatogenesis
Fig. 41-11
spermatogonium
spermspermatids
Differentiation
occurs continuously starting
at puberty
Meiosis ...
Spermatogenesis*
• Once cells finish Meiosis I & II, the
SERTOLI CELLS secrete substances
onto sperm cells to help them ev...
A Human Sperm Cell
Fig. 41-12
tail sheath
flagellum
Tail
Midpiece
Head
mitochondria
nucleus
acrosome
Sperm
Oogenesis*
• Oogenesis starts before a female fetus is
even born.
• By 6 weeks, the fetus has oogonia (cells that
are dest...
Oogenesis and ovulation*
• Each month, about 12 primary oocytes (located in the
ovary, each surrounded by special cells ca...
Hormonal control of ovulation & menstrual cycle
• Hormones produced by the brain drive the
development of follicles (GnRH,...
Fig. 41-17
GnRH
Hypothalamic hormone
level
1 3
7
9
FSH
LH
Pituitary hormone levels
1 4
7
follicle develops
Structures in t...
Human Development
• Fertilization
– Man and Woman have intercourse
– Man ejaculates-300 million sperm released
within his ...
Fertilization*
– Corona Radiata: follicular cells surrounding the egg after it
leaves the ovary
– ZONA PELLUCIDA: species-...
The Secondary Oocyte and Fertilization
Fig. 41-19
DEVELOPMENT
• A series of events that take place after
fertilization leading to the formation of a
new multicellular organ...
Early development
• Egg is usually fertilized in fallopian tube
• By the time it implants into uterine wall,
embryo has di...
(b) An egg within the uterine
tube
(a) The first week of development
day 7
day 4
day 3 day 2
day 1
day 0
embryo
inner cell...
Formation of Blastocyst
Inner Cell Mass becomes organism
• Inner cell mass grows and splits, forming two fluid-
filled sacs separated by a double ...
Gatrulation
Gastrulation
Fetal developments
• Spinal Cord & Brain: 3 weeks
• Heartbeat: 4 weeks
• Tail and gills: 4-5 weeks (like a fish-later
disa...
Control of development
• Zygote contains all genes needed to
make the mature organism.
• What causes different cells to tr...
Transcription Factors and Cell Signaling
control development
• The cytoplasm of the egg (before fertilization) contains
tr...
Control of Development
Human Embryo- 1 month
30 mm amniotic sac
placenta
umbilical
cord
An 8-Week-Old Human Embryo
Fig. 42-10
Childbirth
• 3 Stages of Childbirth
– Dilation: Cervix must dilate from 1cm to 10cm
– Expulsion - Baby comes out
– Deliver...
3 Stages of Childbirth
Lecture 21
Lecture 21
Lecture 21
Próxima SlideShare
Cargando en…5
×

Lecture 21

975 visualizaciones

Publicado el

Publicado en: Salud y medicina, Tecnología
  • Sé el primero en comentar

Lecture 21

  1. 1. Lecture 21-Reproduction & Development Covers Chapters 41 & 42
  2. 2. The ability to reproduce starts at puberty • As early as 8 and as late as 15: • Brain maturation causes hypothalamus to release GnRH (gonadotropin-releasing hormone) • GnRH stimulates pituitary gland to produce – Luteinizing Hormone (LH) – Follicle-Stimulating Hormone (FSH) • LH & FSH stimulate – Production of testosterone in males – Production of estrogen in females
  3. 3. Testosterone and estrogen cause development of sex characteristics • Testosterone and estrogen stimulate the development of secondary sex characteristics: – Male: penis/testes enlarge, pubic/underarm/facial hair, larynx enlarges, muscular development – Female: enlarged breasts, wider hips, pubic/underarm hair, menstruation
  4. 4. Male Anatomy • MALE ANATOMY • Goal is to produce and deliver sperm. – Penis – Scrotum – Testes/Testicles – Seminiferous Tubules (Leydig & Sertoli Cells) – Epididymus – Vas Deferens – Urethra
  5. 5. Male Anatomy • Penis-tubular shaft of erectile tissue. When a male is aroused, blood rushes to the tissue and pressure closes off the veins, preventing blood from leaving the penis, and an erection is the result. • Scrotum-pouch of skin below penis that holds the testes/testicles. • Testes/Testicles-Male gonads: sperm are being produced nearly all the time after puberty.
  6. 6. The Human Male Reproductive System Fig. 41-9 pubic bone urinary bladder ureter rectum seminal vesicle prostate gland bulbourethral gland vas deferens epididymis testis scrotum urethral opening penis urethra
  7. 7. Male Anatomy • Seminiferous Tubules*-coiled tubes within each testicle. Spermatogenesis (sperm production) happens here. – Leydig Cells* & Sertoli Cells*-clusters of cells lying within and between the Seminiferous Tubules. Provide nutrients for developing sperm and hormonally control spermatogenesis. (Testosterone made in Leydig Cells!*)
  8. 8. Seminiferous Tubules
  9. 9. Male Anatomy • Epididymus-storage sac for sperm laying on top of each testicle. • Vas Deferens-duct for semen. • Urethra-duct for urine and semen (sperm) to leave the body.
  10. 10. Semen • When a man ejaculates, 300 MILLION sperm leave the body. Sperm is bathed in SEMEN. These structures all donate fluids to give the sperm nutrition and protection. The purpose of semen is to NOURISH AND PROTECT SPERM. – Seminal Vesicle* – Prostate Gland* – Bulbourethral Gland*
  11. 11. Female Anatomy • Goal is to produce eggs, receive sperm and nurture the embryo. – Vulva – Clitoris – Urethra – Vagina – Uterus – Ovaries – Fallopian Tubes
  12. 12. Female Anatomy • Vulva - Two layers of folded skin that protect the female anatomy from injury. • Clitoris-erectile tissue at the tip of the Vulva (Blood rushes to Vulva and Clitoris when a woman is sexually aroused) • Urethra-opening from bladder to outside the body (this duct is MUCH SHORTER in women: GREATER SUSCEPTIBILITY TO BLADDER INFECTIONS!*)
  13. 13. Female Anatomy • Vagina-muscular organ that serves as the birth canal and opening for sex and menstruation. • Uterus – about the size of a fist! – Walls contract during labor – EMBRYO/FETUS GROWS HERE • Cervix-the lower 1/3 of the uterus • Ovaries-female gonads. Oogenesis (creation of eggs) is happening here! Also, creation of hormones (Estrogen, Progesterone, and a few others) happens here.
  14. 14. Female Anatomy • Fallopian Tubes- ducts between each ovary and the uterus. Pathway that ONE egg takes each month down FT, uterus, cervix, vagina.
  15. 15. The Human Female Reproductive System Fig. 41-14 uterine tube urinary bladder pubic bone urethra clitoris labia ovary myometrium endometrium uterus cervix vagina rectum anus fimbria
  16. 16. Spermatogenesis* • Begins in puberty, stimulated by hormones in Sertoli Cells • Spermatogonia are diploid parent cells that are located in the seminiferous tubules • Spermatogonia undergo mitosis. • One daughter cell remains a spermatogonium, the other will go through meiosis. • (Men will ALWAYS have a source for cells for sperm!)
  17. 17. Spermatogenesis* • Spermatogonium differentiates into primary spermatocyte • Meiosis I occurs, haploid daughter cells are secondary spermatocytes • Meiosis II occurs, and 4 daughter cells are called spermatids • Spermatids differentiate into mature sperm and migrate to the central cavity of the ST
  18. 18. Spermatogenesis Fig. 41-11 spermatogonium spermspermatids Differentiation occurs continuously starting at puberty Meiosis IIMeiosis IMitosis primary spermatocyte secondary spermatocytes
  19. 19. Spermatogenesis* • Once cells finish Meiosis I & II, the SERTOLI CELLS secrete substances onto sperm cells to help them evolve into mature sperm: – Some cytoplasm is removed – ACROSOME develops-tip at sperm head containing digestive enzymes to help the sperm penetrate the egg – TAIL develops to help sperm swim up vaginal canal toward egg
  20. 20. A Human Sperm Cell Fig. 41-12 tail sheath flagellum Tail Midpiece Head mitochondria nucleus acrosome
  21. 21. Sperm
  22. 22. Oogenesis* • Oogenesis starts before a female fetus is even born. • By 6 weeks, the fetus has oogonia (cells that are destined become eggs) • In weeks 9-20, oogonia will enarge and differentiate into primary oocytes. • In weeks 20-birth, all primary oocytes will begin meiosis, stopping at prophase I and there are 1-2 million primary oocytes. • By puberty, some of these cells have degraded and about 400,000 remain.
  23. 23. Oogenesis and ovulation* • Each month, about 12 primary oocytes (located in the ovary, each surrounded by special cells called follicular cells) will restart meiosis, finishing meiosis I. • Result of meiosis I is secondary oocyte and a polar body. • At ovulation, one of the follicles will erupt and release the secondary oocytes into the fallopian tube(s) • Secondary oocyte will only complete meiosis II if fertilized.
  24. 24. Hormonal control of ovulation & menstrual cycle • Hormones produced by the brain drive the development of follicles (GnRH, LH, FSH) • Growing follicles secrete estrogen, which cause more hormones to be released by brain and the lining of uterus to grow • At ovulation, LH surge triggers resumption of meiosis in the growing oocyte and release from follicle • Empty follicle (corpus luteum) secretes estrogen & progesterone, causing uterine lining to thicken • Corpus luteum disintegrates after about 12 days • Drop in estrogen and progesterone causes menstruation
  25. 25. Fig. 41-17 GnRH Hypothalamic hormone level 1 3 7 9 FSH LH Pituitary hormone levels 1 4 7 follicle develops Structures in the ovary ovulation corpus luteum forms and matures corpus luteum degenerates 2 2 5 8 Ovarian hormone levels estrogen progesterone 3 6 6 9 development of the endometrium continued endometrial development menstruation Uterine lining 1 3 (a) Ovarian cycle (b) Uterine cycle
  26. 26. Human Development • Fertilization – Man and Woman have intercourse – Man ejaculates-300 million sperm released within his semen – ONLY ABOUT 200 WILL REACH THE FALLOPIAN TUBES – WOMAN MUST BE OVULATING (or has ovulated less than 48 hours before)
  27. 27. Fertilization* – Corona Radiata: follicular cells surrounding the egg after it leaves the ovary – ZONA PELLUCIDA: species-recognition barrier surrounding the egg. It will only recognize a receptor on the ACROSOME (sperm head), and will only let a human sperm inside. – Enzymatic reaction takes place between ZP and acrosomal enzymes..but there must be enough sperm (enough acrosomal enzyme) to trigger this reaction and let ONE sperm in. – Sperm head drawn into egg cytoplasm – Egg undergoes meiosis II – Sperm and egg unite!
  28. 28. The Secondary Oocyte and Fertilization Fig. 41-19
  29. 29. DEVELOPMENT • A series of events that take place after fertilization leading to the formation of a new multicellular organism: – ZYGOTE-term used when egg and sperm first come together – EMBRYO-term used to describe 1st cell division to 9 weeks. – FETUS-week 9 to birth
  30. 30. Early development • Egg is usually fertilized in fallopian tube • By the time it implants into uterine wall, embryo has divided numerous times and has become a hollow ball of cells: blastocyst • Blastocyst has outer layer of cells (chorion) surrounding an internal cluster of cells (inner cell mass)* • Outer cell layer and uterine lining together become the placenta
  31. 31. (b) An egg within the uterine tube (a) The first week of development day 7 day 4 day 3 day 2 day 1 day 0 embryo inner cell mass of blastocyst blastocyst morula muscle layer endometrium uterine wall 4 cells 2 cells zygote sperm ovulated egg ovary Fertilization occurs within the uterine tube The blastocyst implants in the uterus The Journey of the Egg Fig. 42-6
  32. 32. Formation of Blastocyst
  33. 33. Inner Cell Mass becomes organism • Inner cell mass grows and splits, forming two fluid- filled sacs separated by a double layer of cells: embryonic disk • Two sacs become amniotic cavity and yolk sac (but no yolk in a human embryo) • *Gastrulation at end of second week: two layers of embryonic disk separate, a slit forms, and cells migrate through the slit into the interior of the disk, forming three basic cell layers: – *Endoderm: lining of digestive and respiratory tract, liver, pancreas – *Mesoderm: muscles, skeleton, circulatory system – *Ectoderm: skin, hair, nails, nervous system
  34. 34. Gatrulation
  35. 35. Gastrulation
  36. 36. Fetal developments • Spinal Cord & Brain: 3 weeks • Heartbeat: 4 weeks • Tail and gills: 4-5 weeks (like a fish-later disappear) • Eyes: 7 weeks • Gonads: 8 weeks
  37. 37. Control of development • Zygote contains all genes needed to make the mature organism. • What causes different cells to transcribe different genes, therefore creating the various structures and tissues in the growing embryo?
  38. 38. Transcription Factors and Cell Signaling control development • The cytoplasm of the egg (before fertilization) contains transcription factors that bind to specific areas of DNA and transcribe specific genes. These transcription factors seem to migrate to specific areas of the egg cytoplasm: genes that form brain migrate to one area, genes that form digestive organs migrate to another • Then when egg is fertilized and cell division begins, transcription factors are “sent” to different daughter cells (as cytoplasm is divided between new daughter cells). Each daughter cell will then begin to transcribe specific genes, ultimately making proteins specific to the type of cell or tissue that they are “meant” to become. • Induction: certain cells will begin to release chemical “messages” to nearby cells, which will also activate specific genes in those cells, thus directing which types of proteins will be made.
  39. 39. Control of Development
  40. 40. Human Embryo- 1 month
  41. 41. 30 mm amniotic sac placenta umbilical cord An 8-Week-Old Human Embryo Fig. 42-10
  42. 42. Childbirth • 3 Stages of Childbirth – Dilation: Cervix must dilate from 1cm to 10cm – Expulsion - Baby comes out – Deliver Placenta *Placenta: organ that nourishes (O2 & nutrients in, CO2 and waste out) fetus during pregnancy. After birth, it will separate from the uterine wall, and must be “delivered”
  43. 43. 3 Stages of Childbirth

×