reproduction and development chapter 38 the last unit!
TRANSCRIPT
Testes
• Produce sperm and hormones
• Seminiferous tubules small, coiled tubes
• Meiosis 1 cell = 4 functional sperm
Epididymis
• Matures and stores sperm
• Located anterior to each testis
• 300 million mature sperm per day
Scrotum
• Outpocketing of body wall
• Contains testes and epididymises
• Temperature 3o C cooler than body temp.
Prostate gland
• Secretes a thinner fluid for mobility
• Closes off urinary bladder during ejaculation
Bulbourethral glands
• Cowper’s gland
• Secrete a clear alkaline fluid
• Protection of sperm against acidic female reproductive tract
Secondary sex characteristics
• Growth and maintenance of gonads
• Production of sperm
• Increased body hair growth
• Increased muscle mass
• Increased growth of long bones
• Deepening of voice
Ovaries
• Produce egg cells in follicles
• Production of hormones
• Meiosis 1 cell = 1 functional egg– 3 polar bodies that form the yolk
Hypothalamus
• Controls pituitary
• FSH development of mature follicle– Secretion of estrogen by ovary
• LH stimulates ovulation
Secondary sex characteristics
• Growth and maintenance of gonads
• Increased body hair growth
• Increased growth of long bones
• Broadening of hips
• Fat deposits: breasts, buttocks, thighs
• Onset of menses
Egg cell production
• Egg cells start development before birth• Arrested in prophase I– Primary oocytes 2 million– 40,000 left at puberty
• FSH stimulates meiosis• Ovulation mature egg ruptures
through ovary– 400 eggs over lifetime
Flow phase
• Days 1-5
• Shedding of endometrial lining
• Uterus contracts to expel
• Blood levels of FSH begin to rise
Follicular phase
• Days 6-14 (variable)• Follicle develops• Estrogen repair of uterine lining• LH blood level spikes just before
ovulation• Ovulation Day 14• Increased body temp., cervix produced
mucous
Luteal phase
• Days 15-28
• LH follicle fills with cells (corpus luteum)
• Corpus luteum secretes progesterone thickens uterine lining
• Progesterone inhibits FSH and LH
• Uterine lining begins to shed
Fertilization
• n + n = 2n (zygote)
• Cap of sperm enzymes to penetrate egg
• Sperm nucleus enters egg
• Egg membrane changes only 1 sperm
• 2 nuclei fuse zygote
Zygote travels to uterus
• 6 days
• Cleavage repeated mitotic divisions
• Blastocyst hollow ball of cells
Amnion
• Thin inner membrane filled with amniotic fluid
• Shock absorber
• Regulates embryonic body temperature
Placenta
• From chorion and uterine wall
• Exchange of nutrients and wastes
• Blood vessels from mother and embryo have no direct contact diffusion
Hormonal maintenance of pregnancy
• hCG (human chorionic gonadotropin) secreted by embryo
• Keeps corpus luteum from degenerating
• Steady supply of progesterone
• After 3 months, uterus takes over
Multiple embryos
• Fraternal twins 2 eggs, 2 sperm
• Identical twins 1 egg, 1 sperm– 1 zygote separates into 2 separate embryos
First trimester
• Organ systems form
• Sensitive to outside influences alcohol, tobacco, other drugs, malnutrition
• 8th week all are formed (fetus)
• Sex can be determined
Second trimester
• Growth
• Could survive outside uterus with assistance
• Cannot maintain constant body temp.
• Immature lungs no regular respiratory rate
Third trimester
• Rapid growth
• Mass of fetus more than triples
• 7th month fetus moves
• 8th month eyes open
• 9th month head in downward position
Labor
• Oxytocin secreted from pituitary
• Cervix dilates, uterus contracts
• Up to or over 24 hours
Infancy
• First 2 years
• Physical coordination
• Mental development
• Tremendous growth
• Learn to control limbs, walk, first words
Aging
• Decreased metabolism and digestion
• Skin loses elasticity wrinkles
• Less pigment in hair follicles
• Bones thinner and more brittle
• Vision and hearing might diminish