Reproduction and Development Chapter 38 The last unit! 

Human Reproductive Systems Male Anatomy

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.

Vas deferens Tubes connecting epididymises to the urethra

Urethra Tube exiting body Transport of urine and semen

Seminal vesicles Secrete a fluid high in fructose Energy for mobile sperm

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

Semen Mixture of sperm and secretions

Penis Specialized adaptation for sperm delivery

Puberty in males

Hypothalamus Controls pituitary secretions FSH  sperm production LH  testosterone production

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

Human Female Anatomy

Ovaries Produce egg cells in follicles Production of hormones Meiosis  1 cell = 1 functional egg 3 polar bodies that form the yolk

Oviducts Fallopian tubes Transport of egg to uterus Fertilization occurs here

Uterus Pear-shaped organ of smooth muscle Embryonic development occurs here

Cervix Narrow lower end of uterus

Vagina Birth canal Muscular passageway exiting body

Puberty in females

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

Menstrual cycle Producing mature eggs and preparing uterus for implantation

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

Development before birth

Fertilization and implantation Egg cell  24 hours Sperm cells  48 hours

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

Implantation Embryo implants in thick uterine lining 7-8 days

Embryonic membranes and the placenta

Amnion Thin inner membrane filled with amniotic fluid Shock absorber Regulates embryonic body temperature

Allantois Outgrowth of digestive tract Umbilical cord forms from blood vessels

Chorion Outer membrane Chorionic villi become part of placenta

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

Fetal development Growth, development, and cellular differentiation

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

Gestation Length of pregnancy About 266 days

Birth, growth, and aging

Birth

Labor Oxytocin secreted from pituitary Cervix dilates, uterus contracts Up to or over 24 hours

Expulsion Uterine contractions force baby through birth canal 20 minutes to 1 hour

Placental stage Expelled 10-15 minutes after birth Uterus contracts  prevents hemorrhaging

Growth hGH

Infancy First 2 years Physical coordination Mental development Tremendous growth Learn to control limbs, walk, first words

Childhood Infancy to adolescence Steady growth Learn to reason and think critically

Adolescence Begins at puberty Reach maximum physical stature and mass

Adulthood No more growth

Aging Decreased metabolism and digestion Skin loses elasticity  wrinkles Less pigment in hair follicles Bones  thinner and more brittle Vision and hearing might diminish

Aging cont. Stature may shorten  disks between vertebrae become compressed Genetic causes Rate varies  interaction of genes and environment